Corneal Wavefront Aberration: Asymmetries in the topography and refractive index of the corneal surface that affect visual acuity.Corneal Topography: The measurement of curvature and shape of the anterior surface of the cornea using techniques such as keratometry, keratoscopy, photokeratoscopy, profile photography, computer-assisted image processing and videokeratography. This measurement is often applied in the fitting of contact lenses and in diagnosing corneal diseases or corneal changes including keratoconus, which occur after keratotomy and keratoplasty.Aberrometry: The use of an aberrometer to measure eye tissue imperfections or abnormalities based on the way light passes through the eye which affects the ability of the eye to focus properly.Refraction, Ocular: Refraction of LIGHT effected by the media of the EYE.Refractive Errors: Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.Accommodation, Ocular: The dioptric adjustment of the EYE (to attain maximal sharpness of retinal imagery for an object of regard) referring to the ability, to the mechanism, or to the process. Ocular accommodation is the effecting of refractive changes by changes in the shape of the CRYSTALLINE LENS. Loosely, it refers to ocular adjustments for VISION, OCULAR at various distances. (Cline et al., Dictionary of Visual Science, 4th ed)Pupil: The aperture in the iris through which light passes.Astigmatism: Unequal curvature of the refractive surfaces of the eye. Thus a point source of light cannot be brought to a point focus on the retina but is spread over a more or less diffuse area. This results from the radius of curvature in one plane being longer or shorter than the radius at right angles to it. (Dorland, 27th ed)Lenses: Pieces of glass or other transparent materials used for magnification or increased visual acuity.Myopia: A refractive error in which rays of light entering the EYE parallel to the optic axis are brought to a focus in front of the RETINA when accommodation (ACCOMMODATION, OCULAR) is relaxed. This results from an overly curved CORNEA or from the eyeball being too long from front to back. It is also called nearsightedness.Keratomileusis, Laser In Situ: A surgical procedure to correct MYOPIA by CORNEAL STROMA subtraction. It involves the use of a microkeratome to make a lamellar dissection of the CORNEA creating a flap with intact CORNEAL EPITHELIUM. After the flap is lifted, the underlying midstroma is reshaped with an EXCIMER LASER and the flap is returned to its original position.Retinoscopes: Instruments for RETINOSCOPY that determines the refractive state of the EYE, such as the degree of NEARSIGHTEDNESS; FARSIGHTEDNESS; or ASTIGMATISM. In principle, a retinoscope provides a light source to illuminate the RETINA, and then locates the aerial image of the retina in space to obtain an index of the refractive quality of the patient's lens system.Cornea: The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed)Diagnostic Techniques, Ophthalmological: Methods and procedures for the diagnosis of diseases of the eye or of vision disorders.Lasers, Excimer: Gas lasers with excited dimers (i.e., excimers) as the active medium. The most commonly used are rare gas monohalides (e.g., argon fluoride, xenon chloride). Their principal emission wavelengths are in the ultraviolet range and depend on the monohalide used (e.g., 193 nm for ArF, 308 nm for Xe Cl). These lasers are operated in pulsed and Q-switched modes and used in photoablative decomposition involving actual removal of tissue. (UMDNS, 2005)Chromosome Aberrations: Abnormal number or structure of chromosomes. Chromosome aberrations may result in CHROMOSOME DISORDERS.Visual Acuity: Clarity or sharpness of OCULAR VISION or the ability of the eye to see fine details. Visual acuity depends on the functions of RETINA, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast.Optics and Photonics: A specialized field of physics and engineering involved in studying the behavior and properties of light and the technology of analyzing, generating, transmitting, and manipulating ELECTROMAGNETIC RADIATION in the visible, infrared, and ultraviolet range.Equipment Design: Methods of creating machines and devices.Lasers: An optical source that emits photons in a coherent beam. Light Amplification by Stimulated Emission of Radiation (LASER) is brought about using devices that transform light of varying frequencies into a single intense, nearly nondivergent beam of monochromatic radiation. Lasers operate in the infrared, visible, ultraviolet, or X-ray regions of the spectrum.Hyperopia: A refractive error in which rays of light entering the eye parallel to the optic axis are brought to a focus behind the retina, as a result of the eyeball being too short from front to back. It is also called farsightedness because the near point is more distant than it is in emmetropia with an equal amplitude of accommodation. (Dorland, 27th ed)Eye: The organ of sight constituting a pair of globular organs made up of a three-layered roughly spherical structure specialized for receiving and responding to light.Optometry: The professional practice of primary eye and vision care that includes the measurement of visual refractive power and the correction of visual defects with lenses or glasses.Presbyopia: The normal decreasing elasticity of the crystalline lens that leads to loss of accommodation.Cathode Ray Tube: A vacuum tube equipped with an electron emitting CATHODE and a fluorescent screen which emits visible light when excited by the cathode ray. Cathode ray tubes are used as imaging devises for TELEVISIONS; COMPUTER TERMINALS; TEXT TELECOMMUNICATION DEVICES; oscilloscopes; and other DATA DISPLAY devices.Privacy: The state of being free from intrusion or disturbance in one's private life or affairs. (Random House Unabridged Dictionary, 2d ed, 1993)Confidentiality: The privacy of information and its protection against unauthorized disclosure.Computer Security: Protective measures against unauthorized access to or interference with computer operating systems, telecommunications, or data structures, especially the modification, deletion, destruction, or release of data in computers. It includes methods of forestalling interference by computer viruses or so-called computer hackers aiming to compromise stored data.Informed Consent: Voluntary authorization, by a patient or research subject, with full comprehension of the risks involved, for diagnostic or investigative procedures, and for medical and surgical treatment.Genetic Privacy: The protection of genetic information about an individual, family, or population group, from unauthorized disclosure.Internet: A loose confederation of computer communication networks around the world. The networks that make up the Internet are connected through several backbone networks. The Internet grew out of the US Government ARPAnet project and was designed to facilitate information exchange.Corneal Surgery, Laser: Surgical techniques on the CORNEA employing LASERS, especially for reshaping the CORNEA to correct REFRACTIVE ERRORS.Epithelium, Corneal: Stratified squamous epithelium that covers the outer surface of the CORNEA. It is smooth and contains many free nerve endings.Cataract: Partial or complete opacity on or in the lens or capsule of one or both eyes, impairing vision or causing blindness. The many kinds of cataract are classified by their morphology (size, shape, location) or etiology (cause and time of occurrence). (Dorland, 27th ed)Patents as Topic: Exclusive legal rights or privileges applied to inventions, plants, etc.Postural Balance: A POSTURE in which an ideal body mass distribution is achieved. Postural balance provides the body carriage stability and conditions for normal functions in stationary position or in movement, such as sitting, standing, or walking.Posture: The position or attitude of the body.Refractive Surgical Procedures: Surgical procedures employed to correct REFRACTIVE ERRORS such as MYOPIA; HYPEROPIA; or ASTIGMATISM. These may involve altering the curvature of the CORNEA; removal or replacement of the CRYSTALLINE LENS; or modification of the SCLERA to change the axial length of the eye.Ophthalmologic Surgical Procedures: Surgery performed on the eye or any of its parts.Cataract Extraction: The removal of a cataractous CRYSTALLINE LENS from the eye.Photorefractive Keratectomy: A type of refractive surgery of the CORNEA to correct MYOPIA and ASTIGMATISM. An EXCIMER LASER is used directly on the surface of the EYE to remove some of the CORNEAL EPITHELIUM thus reshaping the anterior curvature of the cornea.Carboxypeptidases A: Carboxypeptidases that are primarily found the DIGESTIVE SYSTEM that catalyze the release of C-terminal amino acids. Carboxypeptidases A have little or no activity for hydrolysis of C-terminal ASPARTIC ACID; GLUTAMIC ACID; ARGININE; LYSINE; or PROLINE. This enzyme requires ZINC as a cofactor and was formerly listed as EC 3.4.2.1 and EC 3.4.12.2.Arecaceae: The palm family of order Arecales, subclass Arecidae, class Liliopsida.Combretum: A plant genus of the family COMBRETACEAE. Triterpenes and combretastatin have been identified in members of this genus.Eichhornia: A plant genus of the family PONTEDERIACEAE that is used as a biological filter for treating wastewater.Paullinia: A plant genus of the family SAPINDACEAE. The seed of P. cupana is the source of guarana powder which contains 4% CAFFEINE.Maytenus: A plant genus of the family CELASTRACEAE.MART-1 Antigen: A melanosome-specific protein that plays a role in the expression, stability, trafficking, and processing of GP100 MELANOMA ANTIGEN, which is critical to the formation of Stage II MELANOSOMES. The protein is used as an antigen marker for MELANOMA cells.Burning Mouth Syndrome: A group of painful oral symptoms associated with a burning or similar sensation. There is usually a significant organic component with a degree of functional overlay; it is not limited to the psychophysiologic group of disorders.Ophthalmic Solutions: Sterile solutions that are intended for instillation into the eye. It does not include solutions for cleaning eyeglasses or CONTACT LENS SOLUTIONS.Dry Eye Syndromes: Corneal and conjunctival dryness due to deficient tear production, predominantly in menopausal and post-menopausal women. Filamentary keratitis or erosion of the conjunctival and corneal epithelium may be caused by these disorders. Sensation of the presence of a foreign body in the eye and burning of the eyes may occur.Lens Implantation, Intraocular: Insertion of an artificial lens to replace the natural CRYSTALLINE LENS after CATARACT EXTRACTION or to supplement the natural lens which is left in place.Phacoemulsification: A procedure for removal of the crystalline lens in cataract surgery in which an anterior capsulectomy is performed by means of a needle inserted through a small incision at the temporal limbus, allowing the lens contents to fall through the dilated pupil into the anterior chamber where they are broken up by the use of ultrasound and aspirated out of the eye through the incision. (Cline, et al., Dictionary of Visual Science, 4th ed & In Focus 1993;1(1):1)

Ocular wavefront aberrations in patients with macular diseases. (1/53)

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Aberration control and vision training as an effective means of improving accommodation in individuals with myopia. (2/53)

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Study of ocular aberrations with age. (3/53)

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The effect of the asphericity of myopic laser ablation profiles on the induction of wavefront aberrations. (4/53)

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Measurement of the time course of optical quality and visual deterioration during tear break-up. (5/53)

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Detection of subclinical keratoconus by using corneal anterior and posterior surface aberrations and thickness spatial profiles. (6/53)

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Corneal aberrations and visual acuity after laser in situ keratomileusis: femtosecond laser versus mechanical microkeratome. (7/53)

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Estimation of the depth of focus from wavefront measurements. (8/53)

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Purpose: To correlate subjective visual performance responses with through-focus retinal image quality (RIQ) metrics obtained on presbyopic participants fitted with single vision (SV) and multifocal (MF) contact lenses.. Methods: Thirteen presbyopic participants (50.2 ± 3.5 years, SE: +1.38 to -5.50D) who needed adds of +1.00 or +1.25D were fitted bilaterally with AirOptix Aqua™ SV and AirOptix Aqua™ MF lenses [Alcon, USA]. Using the EyeMapper, a global aberrometer, on-axis ocular wavefront aberration profiles with lenses were captured. Five independent repeats were performed under natural pupils. Additionally, participants pupil sizes were measured at different illumination conditions (scotopic (0 Lux), mesopic (80 Lux) and photopic (300 Lux)) using a custom-built instrument. Post-processing routines in Matlab using the 6th order Zernike polynomial (z1 to z28) obtained from the EyeMapper yielded through-focus retinal image quality metrics (visual Strehl Ratio in the Fourier domain) over ...
Purpose: : To investigate the incidence of high order ocular aberrations (HOAs) in relationship with age, sex, race, and eye dominance pre- and post-LASIK. Methods: : Wavefront exams were uniformly randomly selected from 10 clinical studies in the United States and Canada. All 335 patients (635 eyes) had undergone LASIK for myopia, hyperopia, or presbyopia. Ages ranged from 21 to 65 (43±11). The cohort comprised 50.7% females and 49.3% males. The racial makeup of the cohort was 90.7% Caucasian, 7.8% unknown, 0.9% Black, and 0.6% Asian/Pacific. Pre- and post-Op wavefront maps were compared and analyzed. Exams with wavefront maps smaller than 5 mm were excluded. Maps larger than 5 mm were scaled to 5 mm for comparison purposes. Results: : No statistical difference in pre-and post op HOAs was found between male and female subjects or in HOAs between pre- and post-op dominant and non-dominant eyes. However, Asian subjects had statistically significantly more HOAs pre-operatively than non-Asian ...
Coherence-gated wavefront sensing (CGWS) allows the determination of wavefront aberrations in strongly scattering tissue and their correction by adaptive optics. This allows, e.g., the restoration of the diffraction limit in light microscopy. Here, we develop a model, based on ray tracing of ballistic light scattered from a set of discrete scatterers, to characterize CGWS performance as it depends on coherence length, scatterer density, coherence-gate position, and polarization. The model is evaluated by using Monte Carlo simulation and verified against experimental measurements. We show, in particular, that all aberrations needed for adaptive wavefront restoration are correctly sensed if circularly polarized light is used.. © 2007 Optical Society of America. Full Article , PDF Article ...
All extended optical systems with aberrations suffer from anisoplanatism effect. In this presentation we investigate anisoplanatism in human eye. For that purpose we use a reference source (beacon) obtained by focusing of a dim laser beam on the retina and consider increasing the retina resolution within anisoplanatic angle by means of ideal wavefront corrector and a real bimorph flexible one. The numerical simulations of isoplanatic patch size of human retina were made for different beacon positions and based on the aberrations measured by means of custom wavefront-guided aberrometer. We found out that in particular human eye the existence of optimal correction directions is possible. As the behavior of Zernike coefficients varies from subject to subject the existence of optimal correction angle is a feature of a particular eye. We also estimated the contribution of low-order and high-order aberrations in anisoplanatism effect for the subjects we measured. We found out that aberrations with ...
An apparatus and method for characterizing an energy beam (such as a laser) with a two-dimensional wavefront sensor, such as a Shack-Hartmann lenslet array. The sensor measures wavefront slope and irradiance of the beam at a single point on the beam and calculates a space-beamwidth product. A detector array such as a charge coupled device camera is preferably employed.
It would be technically possible to create a custom wavefront ablation map that would be designed to overcorrect sphere, however the effect would be limited and quite possibly counterproductive. Any excimer laser surgery will affect Higher Order Aberrations (HOA). Sphere and cylinder are Lower Order Aberrations (LOA). Current wavefront guided systems do well at reducing the amount of increased HOA during surgery, but they do not reliably and predictably reduce HOA or even keep HOA at the same level. Surgery to overcorrect sphere would undoubtedly increase HOA even more than surgery to correct sphere to plano (no refractive error). Overcorrection with todays systems may provide the desired "quantity" of overcorrection of sphere, but would very likely decrease the "quality" of vision by increasing HOA ...
Wavefront LASIK is suitable for those patients with moderate to severe refractive errors (a high level of short sightedness). It can also treat patients with poor night vision.. Your suitability for Wavefront will be assessed in the usual way during your consultation. ...
Looking for INTRALASE + Wavefront? Choose from 8 clinic(s) offering INTRALASE + Wavefront treatment in 10 countries. Get quotes fast & choose the best.
Every eye possesses a number of aberrations. However, in a KC patients eye, there are approximately five to six times the numbers of high-order aberrations (HOAs) than in a healthy eye. Using this technology to detect and assess the HOAs, it was found that in a KC cornea, it is possible to detect at a very early stage a much higher value of vertical coma aberrations compared with a normal eye. By using this technology, it is possible to study and understand the characteristics of the quality of the image on the retina, thereby understanding its impact on the patients visual quality ...
The volume Wavefront Optics for Vision Correction is written for vision-research scientists, ophthalmic device engineers and clinicians who are workin
DISCUSSION. Over the last few years, the impact of higher order aberrations on visual development and emmetropization has been the source of much debate. Brunette et al. described significant levels of higher order aberrations in children, but these higher order aberrations tended to decrease with growth, possibly as part of emmetropization(8). Studies have shown that lower order aberrations are responsible for about 90% of the quality of retinal images and that the remaining 10% is a combination of the effects of various higher order aberrations(9). However, higher order aberrations do not interact with each other in a linear algebraic manner(10,11); in fact, the effects of the different aberrations tend to compensate for each other(4,12). According to the work of Kelly et al., corneal optical aberrations are often compensated by internal ocular aberrations; therefore, the measurement of corneal wavefront aberrometry alone may produce inaccurate information about the retinal image quality(12). ...
To investigate wavefront aberrations in the entire eye and in the internal optics (lens) and retinal image qualities according to different lenticular opacity types and densities. Forty-one eyes with nuclear cataract, 33 eyes with cortical cataract, and 29 eyes with posterior subcapsular cataract were examined. In each group, wavefront aberrations in the entire eye and in the internal optics and retinal image quality were measured using a raytracing aberrometer. Eyes with cortical cataracts showed significantly higher coma-like aberrations compared to the other two groups in both entire eye and internal optic aberrations (P = 0 ...
When the contact lens is well centered, the central flattening - just as the laser refractive procedure - induced spherical aberration. If the contact lens has lateral or vertical displacement, it will induce horizontal or vertical coma just as with decentration of laser ablation. The spherical aberration and coma are the main high-order aberrations for patients following orthokeratology. The measure of optical quality with modulation transfer function shows the retinal image quality get worse after orthokeratology as compared to only high-order aberrations ...
We have employed ptychographic coherent diffractive imaging to completely characterize the focal spot wavefield and wavefront aberrations of a high-resolution diffractive X-ray lens. The ptychographic data from a strongly scattering object was acquired using the radiation cone emanating from a coherently illuminated Fresnel zone plate at a photon energy of 6.2 keV. Reconstructed images of the object were retrieved with a spatial resolution of 8 nm by combining the difference-map phase retrieval algorithm with a non-linear optimization refinement. By numerically propagating the reconstructed illumination function, we have obtained the X-ray wavefield profile of the 23 nm round focus of the Fresnel zone plate (outermost zone width, Δr = 20 nm) as well as the X-ray wavefront at the exit pupil of the lens. The measurements of the wavefront aberrations were repeatable to within a root mean square error of 0.006 waves, and we demonstrate that they can be related to manufacturing aspects of the ...
Contents: What is sports vision; Basics of sports vision; Designing a sports vision program; Sports Vision training exercises; Sport Specific Sports Vision training exercises
Alignment of optical components is one of the important requirements in any optical system. Decentration of a component, like a lens, in the path of the beam, would introduce aberrations of various types. This would affect the measurement accuracy in the optical system such as an interferometer. In this work, we have analyzed the influence of decentration of an optical component on the wavefront in an optical system. The various aberrations caused due to the shifting of the axis of a lens in the path of an optical wavefront have been measured using a Shack Hartmann Wavefront Sensor and their influence studied. One of the lenses in the optical system is moved or decentered in transverse direction by 500 μm in steps of 50 μm. Decentration was done for all four quadrants. For each step, wavefront data is been taken and data was analyzed. Defocus, horizontal coma, vertical coma and spherical aberration were analyzed, apart from peak-to-valley and RMS values. Results showed that the error ...
The MTF at 50lp/mm (FineVision/AT Lisa/PanOptix) at the far focus was 0,373/0,399/0,400 (3mm aperture) and 0,512/0,311/0,243 (4.5mm aperture). At the intermediate focus, the MTF was 0,162/0,147/0,153 (3mm aperture) and 0,092/0,125/0,137 (4.5mm aperture). The MTF at the near focus was 0,229/0,192/0,404 (3mm aperture) and 0,217/0,212/0,169 (4.5mm aperture). The Strehl ratio was 0,335/0,298/0,370 (3mm aperture) and 0,243/0,180/0,270 (4.5mm aperture) at the far focus. At intermediate distances, the Strehl ratio was 0,189/0,185/0,162 (3mm aperture) and 0,099/0,097/0,114 (4.5mm aperture). The Strehl ratio was 0,305/0,283/0,464 (3mm aperture) and 0,177/0,181/0,155 (4.5mm aperture) at the near focus ...
Optical correction methods, devices, and systems reduce optical aberrations or inhibit refractive surgery induced aberrations. Error source control and adjustment or optimization of ablation profiles or other optical data address high order aberrations. A simulation approach identifies and characterizes system factors that can contribute to, or that can be adjusted to inhibit, optical aberrations. Modeling effects of system components facilitates adjustment of the system parameters.
Optical correction methods, devices, and systems reduce optical aberrations or inhibit refractive surgery induced aberrations. Error source control and adjustment or optimization of ablation profiles or other optical data address high order aberrations. A simulation approach identifies and characterizes system factors that can contribute to, or that can be adjusted to inhibit, optical aberrations. Modeling effects of system components facilitates adjustment of the system parameters.
The International Congress on Wavefront & Presbyopic Refractive Correction Congress invites you to join leaders in the field of visual optics, refractive surgery and adaptive optics for two full days of lectures, debates and discussion. Learn from experts from around the globe the latest advances in refractive, multi-focal IOLs and extended depth of focus lenses, SMILE, binocular vision and more. ...
An apparatus for determining the objective refraction of a patients eye includes a transparent window and a wavefront measurement device that determines aberrations in a return beam from the patients eye after the beam passes through a corrective test lens in the apparatus. The wavefront measurement device outputs an instant display representative of the quality of vision afforded the patient through the test lens. The display can be a representation of a Snellen chart, convoluted with the optical characteristics of the patients vision, an overall quality of vision scale or the optical contrast function, all based on the wavefront measurements of the patients eye. The examiner may use the display information to conduct a refraction examination and other vision tests without the subjective response from the patient.
Sports vision training allows athletes to practice eye exercises to improve their sight and in turn, performance in sports. Learn more from our eye doctors!
A vision training system according to the present invention is computer based and is self-advancing and self-directed. The system is operable in two modes, a diagnostic mode and a therapeutic exercise mode. Therapeutic exercises are automatically tailored for a subject based upon the subjects test results in the diagnostic mode. The system has particular application for subjects who suffer from near point visual stress, but is not limited thereto.
My myopia is -8.5 on the right eye and -6.75 on the left eye. Does this mean I am not a good candidate for the Wavefront? That is what my surgeon is doing, and having read this now I am concerned I am not a good candidate. I went in last week for my pre-op consultation and had to do the wavefront scans twice because they didnt get a good scan the first time. Should I be concerned about this ...
In this thesis, we have analyzed the accuracy and stability aspects of weak boundary and interface conditions (WBCs) for high order finite difference methods on Summations-By-Parts (SBP) form. The numerical technique has been applied to wave propagation and flow problems.. The advantage of WBCs over strong boundary conditions is that stability of the numerical scheme can be proven. The boundary procedures in the advection-diffusion equation for a boundary layer problem is analyzed. By performing Navier-Stokes calculations, it is shown that most of the conclusions from the model problem carries over to the fully nonlinear case.. The work was complemented to include the new idea of using WBCs on multiple grid points in a region, where the data is known, instead of at a single point. It was shown that we can achieve high accuracy, an increased rate of convergence to steady-state and non-reflecting boundary conditions by using this approach.. Using the SBP technique and WBCs, we have worked out how ...
The result, enhanced image quality regardless of the amount of lens power correction required. Biomedics 55 Premier was found in a recent clinical study to be a lens design which effectively controlled spherical aberration in the lens and human eye. Spherical aberration is the inability of a lens to focus light on a common point. With Biomedics 55 Premier, its ability to control aberration produces a contact lens that provides clearer, crisper, sharper vision. Also, a new thinner patented edge design provides unsurpassed wearing comfort compared to other contact lenses. Better vision and better comfort, Biomedics 55 Premier is the clear choice ...
We asked whether spatial coding in the visual system is matched to the native blur specific to an individuals HOAs by investigating long-term adaptation to the blur produced by the optics of the eye. Adaptive Optics allow us to cancel the natural aberrations of all subjects, exposing observers to identical aberration patterns and ensuring that any difference across subjects would arise from their own neural processing and their prior neural adaptation. Retinal blur was manipulated by projecting degraded images with known HOAs where realistic blur of different amounts and forms was computer simulated (we used convolved images with the optical point spread function to represent the retinal image quality) using real aberrations from a population. Our results provide strong evidence that spatial vision is calibrated for the specific blur levels present in each individuals retinal image as, for the majority of observers, the level of blur perceived as best-focused was closely predicted by the ...
The basic requirements for the artificial star are that it be bright for a better signal-to-noise ratio in the wavefront sensor and small in size for better accuracy in determining the wavefront distortions. Furthermore, to better sample the atmospheric turbulence, the artificial star should be put as high up in the atmosphere as possible. All of these requirements can be met by using a laser with its wavelength tuned to the sodium D2 line. With such a laser, a small, bright, artificial sodium star can be generated in the mesospheric sodium layer which lies at about 90 kilometers above sea level ...
Hastings Triplet Achromatic Lenses used to reduce or eliminate pincushion distortion and chromatic and spherical aberrations are available at Edmund Optics
12 effeects Form. Due to preexisting conjunctival scarring, tra- beculectomy surgery in these eyes is often technically difficult and GDI surgery is frequently preferred 4. Int J Antimicrob Agents 2003; 21(4)364в391 Page 196 59 Antimicrobial Resistance in Helicobacter and Campylobacter 861 п180.Dolin, P.
Abstract , References , Similar Articles , Additional Information Abstract: This paper is concerned with the development of high order methods for the numerical approximation of one-dimensional nonconservative hyperbolic systems. In particular, we are interested in high order extensions of the generalized Roe methods introduced by I. Toumi in 1992, based on WENO reconstruction of states. We also investigate the well-balanced properties of the resulting schemes. Finally, we will focus on applications to shallow-water systems. ...
Implementation of PSF engineering using a fabricated squbic phase mask to reduce the effect of spherical aberration in 3D wide field fluorescence imaging. [Abstract #52] ...
The high optical quality of the Baader narrowband filters guarantees no loss in sharpness or contrast. Each substrate is fine-optically polished plane parallel to deliver a smooth and accurate 1/4 wavefront over the entire surface. This special custom p
The aim of this study was to use a Shack-Hartmann clinical aberrometer (COAS, Wavefront Sciences Ltd) to evaluate the variability of low- and higher-order aberration measurement of the eye. Using the wave aberration polynomial determined for a full-size pupil we compared the Zernike expansion coefficients for a smaller, 3 mm pupil derived by two methods: first, by re-calculating the wave aberration coefficients to the reduced sampled points corresponding to that pupil ("direct" method), and, second, by using a matrix method to reconstruct a new set of coefficients appropriate for the reduced pupil ("scaling" method) (see figure 1).. Our results suggest that, for full-size pupil, the efficiency of the measurements varies across x and y pupil position: where the wavefront is larger, measurement variance is higher, especially near the margins of the pupil, where increased standard deviation results to higher wave-aberration error. Some of this increased variance may have been due to poorer image ...
Looking for online definition of posterior surface of elbow in the Medical Dictionary? posterior surface of elbow explanation free. What is posterior surface of elbow? Meaning of posterior surface of elbow medical term. What does posterior surface of elbow mean?
Laser in situ keratomileusis is a successful procedure for the treatment of low to moderate myopia.. Advances over the last decade have allowed LASIK to also correct higher order wavefront aberrations. In low myopia, there seem to be a minor effect of such wavefront-guided treatment. However, it remains to be established whether there is a beneficial effect in higher degrees of myopia.. The study aims to determine whether myopic subjects (-6 to -10 diopters) with higher-than-average preoperative higher-order aberrations have benefit of wavefront-guided treatment. Subjects are randomized to wavefront-guided treatment in one eye, and conventional treatment in the other. ...
CHAPTER 3. WAVEFRONT ABERROMETRY (77 pages) Description: Wavefront aberrometry is the technology used in wavefront science. This discussion addresses the principles of the technology and its applications in clinical vision care. Course Outline: 1. Wavefront Aberrometry A. Basic Principles 1. Measures points of the Zernike in a given pupil diameter 2. Uses adaptive optics a. Lenslet array b. Diffraction grating c. Pixel optics 3. Infrared laser beams measure points B. Instruments 1. Shack-Hartmann aberrometer a. Lenslet array b. Simultaneous delivery of beams c. Limited number of points measured d. Popular system with excimer lasers 2. Ray tracing aberrometry a. Lenslet array b. Delivers beams one at a time c. More points measured d. Slower than Shack-Hartmann 3. Tscherning aberrometry a. Similar to ray tracing b. Subjective responses from patient 4. Dynamic spatial skiascopy a. Purely diagnostic instrument b. Uses Scheiners disk principle for measuring c. Measures
The Shack-Hartmann or Hartmann-Shack wavefront sensors are particular forms of the Hartmann sensor and are the most commonly used in adaptive optics. The traditional Hartmann screen in the pupil is replaced by an array of small lenslets at a conjugate to an image of the pupil or deformable mirror. Each lenslet forms an independent image of the incoming wavefront. Shifts in the positions of these images can be shown by simple geometric optics to be proportional to the mean wavefront gradient over each lenslet. The measurement range or dynamic range of a conventional Shack-Hartmann sensor is normally limited by the sub-aperture size of the detector plane, in which each spot should remain. In order to overcome this restriction, several methods, such as modified unwrapped algorithm or a spatial-light modulator as a shutter, have been proposed. We first simulated the image forming of a conventional Shack-Hartmann wavefront sensor for highly aberrated spherical aberrations through computer simulation, ...
However, as the eye ages from the young adulthood (20-30 years) to the elderly (60-80 years) it becomes more aberrated on average. In particular, the spherical aberration (SA) of the eye tends to increase in older eyes. Similarly, a significant increment of horizontal coma and other third-order aberrations has been reported. In a previous work (Artal et al., 2002), we showed that a progressive disruption of the corneal-internal aberrations balance was the primary source of increment of ocular aberrations in older eyes. However, the underlying causes of this mechanism remain unclear. To answer the question, it is necessary to improve our understanding about how ocular aberrations are generated and how the compensation mechanism works. Ocular aberrations may have an intrinsic origin related to the shape of the surfaces or the profile of the refractive index, or an angular origin associated with the alignment of the optical components. The combination of intrinsic factors makes the cornea of a ...
Flash Focus: Vision Training in Minutes a Day is a new video game for Nintendo DS. Its designed to improve hand-eye coordination, focus, and peripheral
Athletes with from concussions are getting help through the use of a regimen known as vision training, and a facility in Overland Park is one of the few places where its already available.
Heal Mind, Body and Spirit in a caring atmosphere! Learn how to heal yourself with private and group sessions and workshops, encompassing counseling, hypnotherapy,. The Rapid Healing Technique, Eye-Robics (the Bates Method of Vision Training) and Laying on of Hands.
The relative contributions of optical aberrations of the cornea and the crystalline lens to the final image quality of the human eye were studied. The aberrations of the entire eye were obtained from pairs of double-pass retinal images, and the aberrations of the cornea were obtained from videokeratographic data. Third-order spherical aberration and coma were significantly larger for the cornea than for the complete eye, indicating a significant role of the lens in compensating for corneal aberrations. In a second experiment retinal images were recorded in an eye before and after we neutralized the aberrations of the cornea by having the subjects wear swimming goggles filled with saline water, providing a direct estimate of the optical performance of the crystalline lens.. © 1998 Optical Society of America. Full Article , PDF Article ...
A method of and apparatus for improving vision and the resolution of retinal images is described in which a point source produced on the retina of a living eye by a laser beam is reflected from the retina and received at a lenslet array of a Hartmann-Shack wavefront sensor such that each of the lenslets in the lenslet array forms an aerial image of the retinal point source on a CCD camera located adjacent to the lenslet array. The output signal from the CCD camera is acquired by a computer which processes the signal and produces a correction signal which may be used to control a compensating optical or wavefront compensation device such as a deformable mirror. It may also be used to fabricate a contact lens or intraocular lens, or to guide a surgical procedure to correct the aberrations of the eye. Any of these methods could correct aberrations beyond defocus and astigmatism, allowing improved vision and improved imaging of the inside of the eye.
Definition of posterior surface of tibia. Provided by Stedmans medical dictionary and Drugs.com. Includes medical terms and definitions.
TY - JOUR. T1 - Estimation and prediction for spatial generalized linear mixed models using high order Laplace approximation. AU - Evangelou, Evangelos. AU - Zhu, Zhengyuan. AU - Smith, Richard L. PY - 2011/11. Y1 - 2011/11. N2 - Estimation and prediction in generalized linear mixed models are often hampered by intractable high dimensional integrals. This paper provides a framework to solve this intractability, using asymptotic expansions when the number of random effects is large. To that end, we first derive a modified Laplace approximation when the number of random effects is increasing at a lower rate than the sample size. Second, we propose an approximate likelihood method based on the asymptotic expansion of the log-likelihood using the modified Laplace approximation which is maximized using a quasi- Newton algorithm. Finally, we define the second order plug-in predictive density based on a similar expansion to the plug-in predictive density and show that it is a normal density. Our ...
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This newer form of LASIK is more precise than standard LASIK. Its also more expensive. Before surgery, the doctor creates a detailed map of your eyes using an aberrometer. This records even the tiniest imperfections in the cornea. In theory, this method gives better results and better vision. And in some studies, wavefront patients reported…
PureVision 2 HD has design advances for improved comfort and breathability. PureVision 2 HD contact lenses are designed to reduce spherical aberration across the entire power range. PureVision 2 with High Definition Optics design at -1.00D reduces spherical aberration better than other lenses. These lenses are packaged in a unique solution featuring poloxamine - a moisturizing surfactant - designed to deliver outstanding comfort on insertion ...
A network optimization algorithm was used to find wavetip paths (Figure 2B⇑ and 2C⇑). First, a directed graph was constructed in which a node represented every eligible active sample in the most-reentrant route (ie, the route with the largest ratio of activations to activated electrodes) through the wavefront graph component. The edges of this graph connected each active sample with all of the active samples in the succeeding timestep. Each edge was then weighted with the distance between the electrodes associated with the active samples connected by the edge. The graph therefore defined all possible paths that contain one active sample in each timestep. The length of any path was simply the sum of the weights of the edges along the path. A hypothetical wavefront containing 6 active samples in 3 timesteps is illustrated in Figure 2B⇑. The graph and associated edge weights constructed from this wavefront are shown in Figure 2C⇑.. The shortest path through such a graph is our desired ...
Dr. Gregory Pamel is one of the first surgeons in the Northeast to offer the latest FDA approved LASIK technology, Contoura™ Vision Topography Guided LASIK in NYC. Call now!
Wooptix focuses on the transfer to the community of our technology for the diagnosis, understanding and evaluation of eye diseases and their treatments.
Immersing themselves in a research environment can provide teachers with a new perspective when they return to the classroom. Program participants have reported that the stress of adapting to the labs - of absorbing seemingly overwhelming amounts of information in short periods of time - helps them to better appreciate their students difficulties. The experience also teaches them that they dont need to know everything, Silverstein explained. It gives them the confidence to say to a student, "Thats a good question. I dont really know the answer, but lets see how we can find it ...
... with Eye Tracking and Vision Training following Screening and Eye Testing. International Squads Teams or local Amateur Level want improve Vision Performance
Title: Seeing By Moving: The Motor Side of visual perception. February 22nd, 2017 4:10 PM, MRB III room 1220. Sponsored by the Vanderbilt Vision Training Grant. Thomas W. Gardner, M.D., M.S. ...
There are 695 nine-letter words containing A, O and V: AASVOGELS ABSOLVENT ABSOLVERS ... WAVEFORMS WAVEFRONT WRAPOVERS. Every word on this site can be played in scrabble. Build other lists, starting with or ending with letters of your choice.
The Tcal data was fit to a high order polynomial. You can download the fit parameters here: ALFA_POLY_FITS.tar.gz. The tar file contains some explanatory notes as well as the Fortran program which calculated the fit parameters. In the table below, the files with the label Tcal_1 refer to the measurements taken on tJD 53228, and Tcal_2 refer to the measurements taken on tJD53278. ...
Cleanergis has capabilities for characterizing some of the potential microorganisms for Enzyme studies. The proteins have been expressed for being potential as high order enzymes. These studies are aimed at cloning, expression, and purification of
i have suggested to my stepson( in the chicago suburb areas) where he mows large hoas to try using embark around the areas he weedeats and edges. as...
PURPOSE: To manufacture and test a set of phase plates for the calibration of ocular aberrometers and apply it to the calibration of an ocular laser ray tracing aberrometer. METHODS: The set of phase plates is made by a greyscale single-mask photosculpture in photoresist method. Each plate induces a given amount of a particular aberration (Zernike) mode. The set contains two subsets: 1) pure Zernike modes to test the accuracy among different orders (from 3rd to 7th, approximately 0.3 to 0.4 μm); and 2) plates having different amounts of the same mode, 3rd order coma ranging from 0.11 to 0.47 μm. After manufacturing, the plates were tested twice, as a crosscheck, measuring the aberration pattern of each plate with a Mach-Zehnder interferometer and a single-pass Hartmann-Shack wavefront sensor. The set was then applied to the calibration of an ocular double-pass laser ray tracing aberrometer. RESULTS: Close agreement was found between the three types of measurement. The maximum difference ...
Purpose: The aim was to assess the visual impact of ocular wavefront aberrations, corneal thickness, and corneal light scatter prospectively after performing a Descemet stripping automated endothelial keratoplasty (DSAEK) in humans. Methods: Data were obtained prospectively from 20 eyes preoperatively and at 1, 3, 6, and 12 months post-DSAEK. At each visit, the best spectacle-corrected visual acuity and visual acuity with glare (brightness acuity testing) were recorded, and ocular wavefront measurements and corneal optical coherence tomography (OCT) were performed. The magnitude and the sign of individual Zernike terms [higher-order aberrations (HOAs)] were determined. Epithelial, host stromal, donor stromal, and total corneal thicknesses were quantified. The brightness and intensity profiles of OCT images were generated to quantify light scatter in the whole cornea, subepithelial region, anterior and posterior host stroma, interface, and donor stroma. Results: The mean best spectacle-corrected visual
Other possible mechanisms could be involved in the compensation we found. One is the possible effect on the aberration of the posterior corneal surface. It should be noted that what we referred to as "internal ocular optics" also includes the posterior surface of the cornea (Guirao & Artal, 2000). The difference in refractive index between the cornea and the aqueous humor is about 10% of the difference of indexes between air and cornea. It is, therefore, unlikely that the posterior corneal surface makes a significant contribution to the aberrations. However, if the posterior surface of the cornea has a shape similar to the first surface, because the refractive index change is opposite, a small amount of first-surface aberration could be compensated. Precise measurements of both corneal surfaces would allow determination of the posterior surfaces exact role in the aberrations. A decentration of the eyes pupil could also explain part of the balance obtained between cornea and internal surfaces. ...
Vision training uses methods (often exercises) for the treatment of a variety of conditions, some of which are not directly related to ocular problems. Patients are selected for treatment in different ways from those used for orthoptic eye exercises. Conditions such as dyslexia (a type of learning disorder) and poor academic performance may be better treated by educational therapists. Vision training may, in fact, delay getting educational assistance to those who need it. Vision training visits may be daily or 2-3 times weekly and continue for months or even years. Such treatments are often expensive and time-consuming. There is little scientific evidence that vision training exercises cure the conditions such as dyslexia, myopia and learning difficulties. Some improvement may result from the one-on-one attention given to a child with a learning disability which can be attained more readily through remedial exercises given by qualified educators ...
0029] The exemplary measurement system 10 includes a wavefront measurement device 20, such as a wavefront aberrometer, and an imaging assembly 25. Imaging assembly 25 captures an image of the eye at substantially the same time (so that the eye does not move between the image and the measurement) that the wavefront measurement device 20 directs a beam 30 toward the eye of a patient in a diagnostic procedure under the direction of a computer system 35. Measurement device 20 and imaging assembly 25 may be optically coupled to optics 40, which directs a measurement beam 30 to the eye 15A, an image from the eye to the imaging assembly, and a measurement image from the eye back to the measurement device. The computer system 35 optionally determines a desired corneal flap geometry based on the images generated by the measurement system 10, often with the input of a system operator. The computer may store the corneal flap geometry, wavefront measurements and images of the patients eye. One or more ...
In astronomy, the light emitted by an object travels through the vacuum of space and then the turbulent atmosphere before arriving at a ground based telescope. By passing through the atmosphere a series of turbulent layers modify the lights wave-front in such a way that Adaptive Optics reconstruction techniques are needed to improve the image quality. A novel reconstruction technique based in Artificial Neural Networks (ANN) is proposed. The network is designed to use the local tilts of the wave-front measured by a Shack Hartmann Wave-front Sensor (SHWFS) as inputs and estimate the turbulence in terms of Zernike coefficients. The ANN used is a Multi-Layer Perceptron (MLP) trained with simulated data with one turbulent layer changing in altitude. The reconstructor was tested using three different atmospheric profiles and compared with two existing reconstruction techniques: Least Squares type Matrix Vector Multiplication (LS) and Learn and Apply (L + A).
Below are the results of VISXs clinical study used to gain FDA approval. ICON Eyecare in Denver, owns the most advanced laser systems available in the U.S. the NIDEK EC5000, the Wavefront VISX STAR S4T Excimer, and the Intralase lasik. Icons goal is to provide you with as much information as you can so you can make the proper choice regarding your eye care. Because we own both the NIDEK and VISX systems you can trust that we only provide accurate information.
The reconstruction of 1-H MRSI data and analysis of the resulting arrays of spectra combines fourier transforms and apodization with automated methods of spectral processing to provide data that can be interpreted by visual inspection or quantified to generate maps of the spatial distribution of different metabolites (62). The first step is to apply an apodization function to the k-space-free induction decays and perform a fourier transform to produce k-space spectra. The next step is to reconstruct the spatial dependence of the data. For spiral or irregular k-space sampling, the approach is to first re-grid the k-space data onto a rectangular array (59-61). For conventional phase encoding, this step is unnecessary. To center the data at the most appropriate spatial location, it is possible to phase-weight the k-space array with the appropriate voxel shift. This is followed by applying any required spatial apodization and then performing the spatial fourier transformations. The resulting array ...
Professor Dr. Theo Seiler made the case for WaveLight, stating that "SuperVision" was not the main goal, but that correcting almost everyone to 20/15 was probably good enough, while the use of wavefront was most useful for correction of problematic eyes. Wavefront corrects both refraction and aberration. Some of the problems remaining are to achieve centration of the treatment -- aligning the measurement and the treatment, while adjusting for cyclotorsion -- the difference from measuring while sitting and treating while the patient is lying down. He reported on his patients with at least three months followup, achieving no loss of more than 1 line of vision, but getting an increase in RMS error on average of 1.44±0.74, a 44% increase, a suboptimal result. (Is this due to the effect of the LASIK flap?) Standard LASIK results in a 5-25 times increase. What was accomplished, 15% of the patients treated with waveguided ablation achieved 20/10, compared to only 5% of standard LASIK patients; 45% ...
For those who ve reached the age when reading a newspaper means holding it at arm s length or fumbling for reading glasses, wavefront-optimized lens technology may offer a better solution.
The formation of somites, during embryonic development, is highly regulated both temporally and spatially. The main effectors of this regulation are a set of cyclic genes, that display an oscillating pattern of expression, and a morphogenetic gradient, which constitutes the wavefront of differentiation. Wilts the oscillating behavior of the cyclic genes requires a certain instability at the mRNA level, the wavefront gradient is formed by the slow degradation of mRNA. Our aim is the study and characterization of the mechanisms that regulate mRNA stability in this context. Using Zebrafish as a model organism, we are combining bioinformatic and biochemical approaches with in vivo studies ...
The high order spectral element approximation of the Euler equations is stabilized via a dynamic sub-grid scale model (Dyn-SGS). This model was originally designed for linear finite elements to solve compressible flows at large Mach numbers. We extend its application to high-order spectral elements to solve the Euler equations of low Mach number stratified flows. The major justification of this work is twofold: stabilization and large eddy simulation are achieved via one scheme only. Because the diffusion coefficients of the regularization stresses obtained via Dyn-SGS are residual-based, the effect of the artificial diffusion is minimal in the regions where the solution is smooth. The direct consequence is that the nominal convergence rate of the high-order solution of smooth problems is not degraded. To our knowledge, this is the first application in atmospheric modeling of a spectral element model stabilized by an eddy viscosity scheme that, by construction, may fulfill stabilization ...
Optical quality transparent conductors such as bodies, films and coatings formed from substituted and unsubstituted polyanilines in nonconductive substrates such as polymers or polymer plus solvents with protonic acid are disclosed as are methods of forming such conductors from fluid forms of the polyaniline/substrate/acid mixtures.
When measuring the form errors of precision optics with an interferometer, calibration of the reference wavefront is of central importance. In recent years, ball averaging, or random ball testing, has emerged as a robust method for calibrating spherical reference wavefronts in converging beams.. Read More for more information CLICK HERE. ...
An optical vortex is a point on an optical wavefront where there is a null of intensity and the phase is undefined. When the phase is defined over the range 2 pi radians, as is commonly done, the phase surrounding the ...
We present an improved design of a wavelength-tunable single-mode laser array based on a high order surface grating with non-uniformly spaced slots. The laser ...
Lowell T. Ku, M.D. of Dallas IVF explains why it is important to avoid conception of high order multiples, and gives specific information as to the guidelines for responsible
The Cost curve plots the normalized expected cost of the classifier as a function of the skew (fraction of positive examples multiplied by the cost of misclassifying a positive example) of the data on which it is deployed. Lines and points on the cost curve correspond to points and lines on the ROC curve of the classifier. ...
THUMBS UP to Stephanie Gutmann for her in-depth freelance piece in the Jan. 1-Jan. 8 Weekly Standard which examined intimidation of the press in the Israeli-Palestinian media war.
Advanced computerized optical diagnostic equipment is revolutionizing eye care in the 21st century. Refraction is no exception. Traditionally, the refraction of the eye was given with spherical and cylindrical lens powers assumed to be valid across the entire pupil. However, using wavefront sensing, adaptive optics, and new treatment technologies, higher-order aberrations can be measured across the pupil and then modified or eliminated. Research has clearly shown that there are many applications involving these aberrations with diagnosis, treatment, and management of disorders, such as myopia, corneal disorders, presbyopia, cataract, and intraocular lens application and the dynamic changes in refractive state and retinal image quality produced by tear film thinning and accommodation. There are also many related questions that need to be answered regarding the natural stimulus for focusing, the patients perception of the aberrations and their correction, and vision simulation with computational ...
The patients will have a comprehensive eye examination once they express an interest in the study. This includes a slit lamp examination of the front of the eye and a dilated fundoscopic examination of the back of the eye. if there is any pathology noted that would exclude the patient from the study, then we will inform the patient and make an appropriate referral. If the patient is deemed appropriate for the study after a comprehensive examination included computerized videokeratography, then they can be enrolled. The patient will undergo bilateral simultaneous eye surgery. Which eye is treated with a wavefront-guided excimer laser and which eye is treated with wavefront-optimized will be randomized so there is a 50% chance for either eye to receive one treatment. The patients will be seen on the day of surgery, post op day one, post op day 4-7, one month, three months, six months and one year. The patient will receive topical antibiotics in each eye for one week following the procedure. LASIK ...
Lots of ophthalmologic cosmetic surgeons are currently supplied the next evolution in LASIK surgical treatment, which they called Customized LASIK. The general treatment used to correct refractive mistakes coincides as is used for conventional LASIK treatments, with the enhancement of wavefront devices made use of to map the distinct surface area of the clients eye. The wavefront tool passes a narrow ray check out here of light through the systems as well as into the eye, measuring any optical distortions that result as the light leaves back out the eye. Any kind of abnormalities recognized are after that fed back right into the system so that the laser can automatically deal with for aberrations on the surface of the eye. Proponents of Personalized LASIK case that the use of wavefront modern technology allows cosmetic surgeons to deal with greater order aberrations that could add to low-light aesthetic disruptions such as halos as well as glare not corrected by conventional LASIK, eyeglasses, ...
1) Vision Training Grant - John Clark, Director. Multidisciplinary training in basic science and clinical aspects of vision research is conducted at both the pre- and post-doctoral levels. Faculty in 9 departments in the School of Medicine and the School of Arts and Sciences are preceptors for pre- and post-doctoral trainees in structural biology, cell and molecular biophysics, visual function and systems neurobiology using a variety of model systems in vertebrate animals and selected cell and organ culture systems. Vision training will emphasize modern technological approaches to clinical problems in the visual system in both normal and abnormal conditions. Interdisciplinary interactions that will develop new understanding of the scientific basis for important clinical problems in vision are encouraged.. 2) Development Biology Training Grant - David Raible Director. The program provides graduate work in developmental biology and supporting areas, including training in teaching, scientific ...
Id customized Lasik with Leahey two yrs in the past. The end result: 1 eye is ideal, another terrible. I get problems generally. I hate holding eyes opened and take into consideration my determination to acquire this accomplished with Alan on a regular basis. He certainly counts my case as successful, for the reason that Im twenty/twenty on equally eyes. What these numbers tend not to inform you is that the two eyes are so different that I have trouble correcting my eyesight Despite having Eyeglasses. The bad eye has a solid astigmatism through the Lasik and has a fuzzy double impression ...
Long range object identi¯cation needs visual identi¯cation over large distances. However, atmospheric turbulence does hinder long range imaging. Therefore it is crucial to compensate the visual artifacts due to atmospheric turbulence. In this paper we propose a new method to compensate these turbulence e®ects, thus enabling identi¯cation at larger distances. Our method is based on applying phase diversity imaging by a wavefront modulator in free-running mode. As we have no feedback loop, we can simultaneously compensate turbulence for multiple isoplanatic angles. The wavefront modulator generates several images with known additional wave front aberrations. This extra information allows us to locally estimate the optimal wave front aberration and thus the optimal - turbulence free - image can be derived. This paper provides results on simulated data showing that this method performs well under realistic turbulence and noise conditions. Furthermore the robustness of the proposed method is ...
A lens having a semipermeable transparent sheath with opposite anterior and posterior portions joined at their edges and forming a closed interior space between themselves. A body of liquid is provided within the sheath and fills the interior space and constitutes an optical lens whose anterior and posterior surfaces are bounded by the anterior and posterior portions of the sheath, respectively, thus defining the anterior and posterior surfaces of the lens. A substance is provided in the body of liquid for producing within the interior space a concentration which is greater than the concentration of a liquid medium in association with which the lens is to be used, in consequence of which when the lens is in contact with such medium, the interior space will be kept filled with liquid under the influence of osmosis which causes the flow of liquid from the exterior of the sheath to the interior thereof whenever the interior space is less than full thereby maintaining the shape of the lens.
Looking for online definition of Aberrations in the Medical Dictionary? Aberrations explanation free. What is Aberrations? Meaning of Aberrations medical term. What does Aberrations mean?
Beamlines on synchrotrons worldwide need a lot of specific components in order to carry out specialised and state of the art experiments. Scintillators are essential components which make X-rays visible so they can be detected with CCD or CMOS cameras.. The sub-micrometre resolution and high image contrast demanded by todays experiments require scintillator films with thicknesses in the range 1-20 μm as well as providing high optical quality and uniformity. Thin scintillators minimise degradations due to focusing defects, diffraction and spherical aberrations, therefore boosting the image contrast and spatial resolution. But the sophisticated techniques required to grow such crystals and their high specificity means that very thin single crystal film scintillators are not commercially available.. In April 2010, the ESRF established a unique liquid phase epitaxy facility for single crystal film scintillators. Liquid phase epitaxy is a technique whereby scintillating crystal layers are grown on ...
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IN DEPTH VISION in AUBURN is a referral-based developmental optometry practice specializing in vision therapy, sports vision training and neuro-optometric rehabilitation.
An interesting piece of research, available on the website of the US National Institutes of Health, came to my attention recently. It was published in December, 2015. It is part of a growing body of research validating the efficacy of Vision Training. Im posting it here because it also includes some practical exercises which might inspire you to try them yourself. If you are a strabismic, make sure the risk of double vision or other adverse side effects is under control by talking to a qualified Behavioral Optometrist. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4723179/ The Effects of Sports Vision…Read more … ...
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Providing multi-focal visual correction includes determining a plurality of visual conditions to which an eye is to be exposed, determining effects of the visual conditions on a pupil of the eye, and determining a target wavefront profile on the basis of the effects.
The RMS block computes the root mean square (RMS) value of each row or column of the input, or along vectors of a specified dimension of the input.
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LASIK which is customised according to the patients own optical (eye) aberrations is called custom-vue LASIK or wavefront guided LASIK.. What are optical aberration?. Optical aberration are the natural defects in the refractive state/mechanism of the eye due to which the patient cannot focus and see objects clearly. There are different types of optical aberrations. Lower order aberrations are rectified in a normal LASIK but for significant higher order aberrations, wavefront guided LASIK is required.. What is done in custom-vue LASIK or wavefront guided LASIK?. Firstly, the patients eyes are scanned to find out its optical aberrations. Then, this data is fed into the LASIK machine, where the computer generates the laser for rectifying these errors, according to the individual optical aberrations, during LASIK surgery.. Do all cases require custom-vue LASIK or wavefront guided LASIK?. This depends upon the type of optical aberrations present in ones eye. For lower order aberrations normal ...
This thesis is about our peripheral vision. Peripheral vision is poor compared to central vision, due to both neural and optical factors. The optical factors include astigmatism, defocus and higher order aberrations consisting mainly of coma. Neurally, the density of ganglion cells decreases towards the periphery, which limits the sampling density. The questions that this thesis attempts to answer are how much and under which circumstances correction of optical errors can improve peripheral vision. For this, an adaptive optics system has been constructed with a wavefront sensor and a deformable mirror working in closed loop to perform real-time correction of optical errors. To investigate vision, psychophysical routines utilizing Bayesian methods have been evaluated and modified for peripheral vision to handle the presence of aliasing, fixation instability and rapid fatigue.. We found that correcting both refractive errors and higher order aberrations improved peripheral low-contrast resolution ...
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Irreversible ischemic myocardial cell injury developes in an increasing number of cells as the duration of coronary occlusion is prolonged. The present study quantitates myocardial necrosis produced by 40 minutes, 3 hours, or 6 hours of temporary circumflex coronary occlusion (CO) followed by 2 to 4 days of reperfusion, or by 24 or 96 hours of permanent circumflex ligation in pentobarbital anesthetized open chest dogs. After 40 minutes of ischemia, myocyte necrosis was subendocardial but with increasing duration of coronary occlusion, irreversible injury progressed as a wavefront toward the subepicardium. Transmural necrosis was 38 +/- 4% after 40 min, 57 +/- 7% after 3 hours, 71 +/- 7% after 6 hours and 85 +/- 2% after 24 hours of ischemic injury. These results document the presence of a subepicardial zone of ischemic but viable myocardium which is available for pharmacologic or surgical salvage for at least three and perhaps six hours following circumflex occlusion in the dog. ...
The Q value, which reflects corneal asphericity, is negative for most eyes and not related to the degree of myopia [3]. However, conventional surgery could make the cornea undergo a pathological topographical change, from its initially prolate shape (Q , 0) with a steeper central area and flat peripheral area to an oblate shape (Q , 0) with a flat center and steep periphery [4-6]. Q value guided surgery aimed to minimize changes of the corneal anterior surface asphericity in order to reduce the spherical aberration, which impacts mostly on visual quality.. Most of previous papers about Q value guided ablation were focused on short or medium-term study, correcting low myopia or medium myopia, or comparing aspheric and conventional spheric ablation. Then what about correcting high myopic astigmatism? How the parameters of the anterior corneal surface changed following Q value guided LASIK and LASEK?In the present study, Q value guided LASIK and LASEK showed good efficacy, safety, and ...
First in 2006 for its Spherical Aberration Management and Wavefront technologies. And again in April 2010 for KeraSoft, ... and wavefront technologies, as well as lenses for persons suffering from keratoconus and corneal trauma. In 2001, UltraVision's ... Spherical Aberration Management technology received the Award for Innovation in British Optics from the Worshipful Company of ...
Any phase aberration can be approximated by a set of discrete tilts. By sampling an array of lenslets, all of these tilts can ... Shack-Hartmann sensors are used to characterize eyes for corneal treatment of complex refractive errors. Recently, Pamplona et ... It is a wavefront sensor commonly used in adaptive optics systems. It consists of an array of lenses (called lenslets) of the ... Each is focused onto a photon sensor (typically a CCD array or CMOS array or quad-cell). The local tilt of the wavefront across ...
Customized Wavefront-guided refractive corneal laser treatments are designed to reduce existing aberrations and to help prevent ... The distance in micrometers between the actual wavefront and the ideal wavefront is the wavefront aberration, which is the ... However, the amount of increase in aberrations are less than conventional Lasik. Corneal optical aberrations after ... Other lower-order aberrations are non- visually significant aberrations known as first order aberrations, such as prisms and ...
June 2009). "Higher-order aberrations due to the posterior corneal surface in patients with keratoconus". Investigative ... "Characterizing the wave aberration in eyes with keratoconus or penetrating keratoplasty using a high-dynamic range wavefront ... The corneal transplant surgeon trephines a lenticule of corneal tissue and then grafts the donor cornea to the existing eye ... In the USA, corneal transplants (also known as corneal grafts) for keratoconus are usually performed under sedation as ...
"Characterizing the wave aberration in eyes with keratoconus or penetrating keratoplasty using a high-dynamic range wavefront ... Coma is also a common temporary symptom of corneal injuries or abrasions, in which case the visual defect gradually resolves as ... In optics (especially telescopes), the coma, or comatic aberration, in an optical system refers to aberration inherent to ... Aberration in optical systems Zernike polynomials US a coma-correcting meniscus lens 4571036, Gebelein, Rolin J. & David Shafer ...
Combined corneal topography and corneal wavefront data in the treatment of corneal irregularity and refractive error in LASIK ... LASIK induced aberrations: Comparing corneal and whole eye measurements. Optometry and Vision Science. 2015 Apr;92(4):447-455. ... Conservation of corneal tissue with wavefront-guided laser in situ keratomileusis. Journal of Cataract and Refractive Surgery. ... Optimized and wavefront guided corneal refractive surgery using the Carl Zeiss Meditec platform: the WASCA aberrometer, CRS- ...
Ocular aberrations are generally measured using a wavefront sensor, and the most commonly used type of wavefront sensor is the ... Customized Corneal Ablation: The Quest for SuperVision. SLACK, Inc. pp. 11-32. ISBN 1-55642-625-9. "Improved Adaptive Optics ... Ocular aberrations are caused by spatial phase nonuniformities in the wavefront exiting the eye. In a Shack-Hartmann wavefront ... Ocular aberrations are distortions in the wavefront passing through the pupil of the eye. These optical aberrations diminish ...
Barakat, R. (1980). "Optimum balanced wave-front aberrations for radially symmetric amplitude distributions: Generalizations of ... rescaling and decentering for different pupils and evaluation of corneal aberrations". J. Opt. Soc. Am. A. 9 (3): 209-221. ... Tyson, R. K. (1982). "Conversion of Zernike aberration coefficients to Seidel and higher-order power series aberration ... The first modal aberration (piston) is also known as the Wigner semicircle distribution. In precision optical manufacturing, ...
Shack-Hartmann wavefront sensor and its inverse can also be used to characterize eye aberrations in a higher level of ... such as if the corneal curvature tends towards a cylindrical shape. The angle between that meridian and the horizontal is known ... "NETRA: Inverse Shack-Hartmann Wavefront Sensor using High Resolution Mobile Phone Display". Vitor F. Pamplona, Ankit Mohan, ...
Higher-order aberrations after corneal collagen crosslinking for keratoconus and corneal ectasia. J Cat Refract Surg 2012; 38: ... Wavefront analysis and Scheimpflug imagery in diagnosis of anterior lenticonus. J Cat Refract Surg 2010;36:850-853. Van De ... Corneal thickness changes after corneal collagen crosslinking for keratoconus and corneal ectasia: One-year results. J Cat ... Corneal topography indices after corneal collagen crosslinking for keratoconus and corneal ectasia One-year results. J Cat ...
... higher order Aberrations of the eye, complications post-corneal transplant and pellucid degeneration. Injuries to the eye such ... Wavefront guided and other custom optics are then imported and incorporated into the virtual lens design. The virtual design is ... In comparison to corneal contact lenses, scleral lenses bulge outward considerably more. The space between the cornea and the ... Sclerals may also be used in people with eyes that are too sensitive for other smaller corneal-type lenses, but require a more ...
The astigmatic meridian can also be identified using corneal wavefront technology or paraxial curvature matching. One of the ... Belluci R. An Introduction to Intraocular Lenses: Material, Optics, Haptics, Design and Aberration. In: Güell JL (ed): Cataract ... It is believed to have a lesser effect on corneal endothelium. The main complication with this type is their tendency to cause ... A toric IOL is a type of toric lens used to correct preexisting corneal astigmatism at the time of cataract surgery. This ...
The amount of aberration due to astigmatism is proportional to the square of the angle between the rays from the object and the ... Corneal topography may also be used to obtain a more accurate representation of the cornea's shape. An autorefractor or ... The combination of surface or wavefront error precision requirements and part aspect ratio drives the degree of back support ... This form of aberration occurs even when the optical system is perfectly symmetrical. This is often referred to as a " ...
"Characterizing the wave aberration in eyes with keratoconus or penetrating keratoplasty using a high-dynamic range wavefront ... Coma is also a common temporary symptom of corneal injuries or abrasions, in which case the visual defect gradually resolves as ... Optical aberration. Defocus. Tilt. Spherical aberration. Astigmatism. Coma. Distortion. Petzval field curvature. Chromatic ... In optics (especially telescopes), the coma, or comatic aberration, in an optical system refers to aberration inherent to ...
... Ning Lu, Fangyu ... S. Amano, Y. Amano, S. Yamagami et al., "Age-related changes in corneal and ocular higher-order wavefront aberrations," ... Y. Wang, J. J. Xu, X. H. Sun, R. Chu, H. Zhuang, and J. C. He, "Dynamic wavefront aberrations and visual acuity in normal and ... R. Montés-Micó, A. Cáliz, and J. L. Alió, "Wavefront analysis of higher order aberrations in dry eye patients," Journal of ...
Corneal aberrations were positively correlated with ocular aberrations for the RMS of third- to sixth-order aberrations, third- ... Preoperative corneal aberrations, and 3-month postoperative corneal and total ocular aberrations were calculated and compared. ... Intraindividual comparative study of corneal and ocular wavefront aberrations after biaxial microincision versus coaxial small- ... Intraindividual comparative study of corneal and ocular wavefront aberrations after biaxial microincision versus coaxial small- ...
Purpose: : To evaluate the ability of wavefront aberrations of the anterior and posterior corneal surface in order to classify ... Analysis of Corneal Wavefront Aberrations for Classification of Keratoconus, Pellucid Marginal Degeneration and Normal Eyes ... Analysis of Corneal Wavefront Aberrations for Classification of Keratoconus, Pellucid Marginal Degeneration and Normal Eyes ... Analysis of Corneal Wavefront Aberrations for Classification of Keratoconus, Pellucid Marginal Degeneration and Normal Eyes. ...
... and corneal aberrations of small incision lenticule extraction (SMILE) with a triple centration technique and corneal wavefront ... Comparison of Corneal Aberrations (μm) Between Eyes With High Astigmatism Treated by Corneal Wavefront-Guided Transepithelial ... Comparison of Corneal Aberrations (μm) Between Eyes With High Astigmatism Treated by Corneal Wavefront-Guided Transepithelial ... Comparison of Corneal Aberrations (. μ. m) Between Eyes With High Astigmatism Treated by Corneal Wavefront-Guided ...
Corneal curvature and corneal height data were used to analyze the corneal aberrations. Wavefront aberrations in the whole eye ... tested for wavefront aberrations in the anterior corneal surface and the whole eye using a corneal topographer and a wavefront ... Myopic versus hyperopic eyes: axial length, corneal shape and optical aberrations. Compensation of corneal aberrations by the ... He JC Gwiazda J Thorn F Wave-front aberrations in the anterior corneal surface and the whole eye. J Opt Soc Am A Opt Image Sci ...
... with a two-dimensional wavefront sensor, such as a Shack-Hartmann lenslet array. The sensor measures wavefront slope and ... Combination advanced corneal to topography/wave front aberration measurement. US6497483. 6 Mar 2002. 24 Dic 2002. Alcon, Inc.. ... Wavefront aberration measuring instrument, wavefront aberration measuring method, exposure apparatus, and method for ... Wavefront aberration measuring instrument, wavefront aberration measuring method, exposure apparautus, and method for ...
Corneal onlays and wavefront aberration correction to enhance vision. US7776086. 30 Abr 2004. 17 Ago 2010. Revision Optics, Inc ... Corneal optic formed of degradation resistant polymer. US20060241751 *. 28 Jun 2006. 26 Oct 2006. Marmo J C. Corneal onlays and ... Insertion system for corneal implants. US8668735. 22 Oct 2012. 11 Mar 2014. Revision Optics, Inc.. Corneal implant storage and ... Corneal implant retaining devices and methods of use. US9345569. 22 Oct 2012. 24 May 2016. Revision Optics, Inc.. Corneal ...
Wavefront Aberrations From Corneal Ectasia After Laser in situ Keratomileusis Demonstrated by InterWave Aberrometry J Bradley ... LADARWave Wavefront Measurement in Normal Eyes Maria Regina Chalita, MD; Josel Finkenthal, COA; Meng Xu, MS; Ronald R Krueger, ... Wavefront-guided Surface Ablation With Prophylactic Use of Mitomycin C After a Buttonhole Laser in situ Keratomileusis Flap ... Ocular higher-order aberrations in individuals screened for refractive surgery Renato Ambrósio, Jr, MD ...
Corneal topography and ocular wavefront aberrations were also measured.. RESULTS: The study enrolled 51 eyes of 41 patients. ...
aberration correction applied to anterior segment disorders including corneal disorders (e.g., keratoconus, wounds, wound ... However, using wavefront sensing, adaptive optics, and new treatment technologies, higher-order aberrations can be measured ... aberration correction/induction applied to myopia development, cataract, presbyopia. *wavefront technologies for investigating ... surgical correction of wavefront errors (cornea, corneal graft, and intraocular lens implants) ...
To investigate the changes of corneal topography and high-order wavefront aberration (WA) after femtosecond laser assisted ... laser-assisted clear corneal incision for cataract removal on corneal topography and high-order wavefront aberration. Search ... Edemization of the corneal incision, which was not requested after femtosecond laser CCI, was always needed after manual CCI in ... Manifest refraction, simulated keratometry (Ksim), corneal curvature at the site of CCI and high-order WA at 3.5 and 6.0 mm ...
Corneal wavefront aberrations were obtained using a rotating Scheimpflug Camera (Pentacam HR, Oculus, Wetzlar, Germany). The ... In terms of correlations between corneal biomechanics and corneal aberrations, previous studies found that the corneal ... T. Oshika, S. D. Klyce, R. A. Applegate, H. C. Howland, and M. A. El Danasoury, "Comparison of corneal wavefront aberrations ... J. Qu, F. Lu, J. Wu et al., "Wavefront aberration and its association with intraocular pressure and central corneal thickness ...
Stimuli for Accommodation/Wavefront Aberration. Robert McPeek, PhD. Neural Mechanisms Underlying Attention and Visually-Guided ... Corneal Diseases. Jordan Pola, PhD. The Control of Smooth Pursuit Eye Movement ...
Post-DSAEK Optical Changes: A Comprehensive Prospective Analysis on the Role of Ocular Wavefront Aberrations, Haze, and Corneal ... Post-DSAEK Optical Changes: A Comprehensive Prospective Analysis on the Role of Ocular Wavefront Aberrations, Haze, and Corneal ... Post-DSAEK Optical Changes: A Comprehensive Prospective Analysis on the Role of Ocular Wavefront Aberrations, Haze, and Corneal ... Post-DSAEK Optical Changes: A Comprehensive Prospective Analysis on the Role of Ocular Wavefront Aberrations, Haze, and Corneal ...
Masking effect of the epithelium on corneal wavefront aberrations in the virgin cornea and after myopic LASIK. Poster Details. ... Comparison of the corneal anterior surface wavefront (AW) and stromal surface wavefront (SW) in virgin eyes and after myopic ... spherical aberration was much greater (p. Conclusions: In virgin eyes, spherical aberration is similar for the SW and AW, ... In virgin eyes, there was no statistically significant difference (p=0.210) in spherical aberration (AW 0.231µm, SW 0.196µm) or ...
... and determining a target wavefront profile on the basis of the effects. ... For example, a wavefront aberration map can be estimated from a map of corneal topography. Thus, the wavefront aberration map ... and determining a wavefront-correction profile on the basis of the target wavefront profile and the wavefront aberration map. ... the wavefront aberration map W(ρ,θ) represents a deviation of a wavefront 200 from a reference surface 202 over a pupil area ...
Can custom (wavefront) lasik correct higher order aberration not caused by corneal curvature? Safe to have the procedure in ... Wavefront crs attempts to treat the entire wavefront measured through all the optical media of the eye, which would include the ... LASIK and Wavefront: Retinal lattice found in the periphery of many moderate and high myopes should not contribute to your ...
PRK Surgery: Get Rid Of Corneal Aberrations and Discard Glasses. 11th May 2010 ... Recovering from Wavefront LASIK Surgery. 14th May 2010. Wavefront™ LASIK is a custom LASIK procedure that uses sophisticated ... Wavefront™ is a safe and effective form of laser eye surgery, and is usually received well ... Read ,. Author: Penelope Stone ... If you are suffering from a corneal deformation or with myopic problem in ,PRK surgery can be the best solution for you. Photo ...
Next Document: Wavefront aberrations in eyes with decentered ablations.. © 2009-2018 BioMedSearch.com. All rights reserved ... Corneal Diseases / surgery. Corneal Topography. Corneal Transplantation*. Descemet Membrane / surgery*. Endothelium, Corneal / ... Epithelium, Corneal / pathology*. Female. Humans. Male. Middle Aged. Vision, Ocular / physiology*. Visual Acuity / physiology. ... Anterior and posterior corneal elevation data were decomposed into a set of Zernike polynomials up to the 8th order within a ...
... higher-order corneal aberrations can increase depth of focus in eyes with a history of corneal refractive surgery." ... Wavefront-guided PRK shows promise for postkeratoplasty astigmatism Editors Choice Week in review: Orion prosthesis, Eyer ... It also led to a better understanding of higher-order corneal aberrations and how they can be used to increase depth of focus ... predictably lower some aberrations and predictably produce some aberrations," he said. "There is an upside of increased HOAs. ...
25221766 - Corneal astigmatism change and wavefront aberration evaluation after cataract surgery: .... 22176876 - Predicting ...
... aberration analysis is essential to achieve higher visual quality after refractive surgery. Keywords: Corneal wavefront ... Evaluation of anterior corneal surface aberrations according to normal corneal topography is important. In this study, ... An Investigation of Aberration Components and their Associated Factors in Quintuple Normal Corneal Topographic Patterns in the ... showed that there is a significant relationship between corneal topographic patterns and corneal anterior surface aberrations, ...
Preliminary investigation of corneal wavefront aberration following femtosecond laser clear corneal incision for cataract ...
Corneal wavefront aberrations were measured using i-Trace (Tracey Technologies Corp. Houston, TX). All examinations were ... Effect of diquafosol three per cent ophthalmic solution on tear film and corneal aberrations after cataract surgery. Clin Exp ... transection of the corneal nerves by corneal incision, use of topical anesthetics, and preservatives in topical eye drops. In ... Houston, TX). The unit of those is μm. The value of total higher order aberration at postoperative 3 months will be compared ...
What was your dilated pupil size and your prescription and your corneal thickness? Did you have higher-order aberrations? How ... What type of surgery did you have? LASIK, LASEK, etc? what technology? all-laser, wavefront custom, etc? ... My corneal thickness is 622-625 micron...which was funny to hear, since they were like well the range is 480-600, and the ... Glasses would not correct this aberrations, only the residual refractive errors. My expectation is not so much what I see on ...
  • The results were fascinating in that primary topography-guided procedures provided better outcomes for these primary eyes than routine wavefront-optimised procedures for visual quality including night driving. (springer.com)
  • At my practice, we have achieved superb outcomes in these patients using ORange intraoperative wavefront aberrometer (WaveTec Vision, Aliso Viejo, CA). If this technology is not available, I recommend printing a topographic map and drawing a line through the middle of the skewed axes to use as a landmark. (crstoday.com)
  • There are three principal factors that limit the finest details an eye can see: optical (due to scattering, diffraction, chromatic and monochromatic aberration), retinal and neural factors (limiting visual acui (mais) ty to an approximate maximum of 20/10 or 2.0). (worldwidescience.org)
  • If you are suffering from a corneal deformation or with myopic problem in ,PRK surgery can be the best solution for you. (articlealley.com)
  • Several mechanisms may explain the increase in the amount of higher-order aberrations with conventional eximer laser refractive procedures: a change in corneal shape toward oblateness or prolateness (after myopic and hyperopic ablations respectively), insufficient optical zone size and imperfect centration. (wikipedia.org)
  • Despite the large inter-subject variability, the population average of the root mean square for all aberrations (excluding defocus) remained constant for accommodative levels up to 3.0 D. Even though aberrations change with accommodation, the magnitude of the aberration change remains less than the magnitude of the uncorrected aberrations, even at high accommodative levels. (arvojournals.org)
  • The IOP and central corneal thickness (CCT) were measured with a noncontact tonometer and a pachymeter, respectively. (arvojournals.org)
  • Elevation of the stromal surface was calculated for each eye by subtracting the epithelial thickness profile (from Artemis VHF digital ultrasound scanning) from the anterior corneal surface elevation data (from Orbscan II). (escrs.org)
  • To estimate repeatability and comparability of central corneal thickness (CCT) and keratometry measurements obtained by four different devices in healthy eyes. (hindawi.com)
  • When it comes to determining corneal thickness, ultrasound pachymetry is regarded as the gold standard, because of its high degree of reproducibility [ 5 ]. (hindawi.com)
  • My corneal thickness is 622-625 micron. (usaeyes.org)
  • What was your dilated pupil size and your prescription and your corneal thickness? (usaeyes.org)
  • The purpose of this study is to evaluate the accuracy of the WaveLight FS200 femtosecond laser, as assessed by 1 day and 1 month post-operative optical coherence tomography (OCT) anterior segment corneal measurements compared to pre-operative flap thickness target. (clinicaltrials.gov)
  • We have designed and built a binocular Hartmann-Shack wave-front sensor using a single microlens array and camera for real-time aberration measurement of both eyes in an open-view configuration. (um.es)
  • 8 ‐ 10 ] It follows that the analysis of the total wavefront aberrations of the eye would provide the most direct and complete measurement of retinal image quality and therefore can be directly related to visual performance. (pubmedcentralcanada.ca)
  • The setup provides a large dynamic range and simultaneous measurements of convergence, pupil size, accommodation, and aberrations. (um.es)
  • In general, the increase in overall wave aberration with pupil size has been reported to increase to approximately the second power of the pupil radius. (wikipedia.org)
  • Elevation data were imported into VolPro (Sarver & Assoc.) to calculate the AW and SW aberrations for a 6mm analysis zone. (escrs.org)
  • In virgin eyes, there was no statistically significant difference (p=0.210) in spherical aberration (AW 0.231µm, SW 0.196µm) or coma (AW 0.233µm, SW 0.235µm), but HORMS was statistically significantly lower (p=0.003) for the AW (0.446µm) than the SW (0.515µm). (escrs.org)
  • The tubal corneal (TC) distance significantly influences corneal endothelial cell density (ECD), according to a study. (eyeworld.org)
  • In the EX-PRESS group, however, these aberrations were no longer significantly different from the baseline at month 2 ( P = 0.36). (springer.com)
  • The coma aberration significantly increased when the pterygium size was 45% or larger in 1.0 and 3.0 mm diameters and over 25-30% in 5.0 mm diameter. (biomedcentral.com)
  • Results: Compared to preoperative values, corneal density significantly increased at 1 month and decreased over time in both groups. (isrs.org)
  • Current clinical approaches to reduce corneal fibrosis are only partially effective and carry significant side effects, while PPARγ ligands are already clinically available as "insulin sensitizers" for diabetes. (rochester.edu)
  • Pubmed ID: 14691158 To investigate the effects of alcohol and mitomycin C (MMC) on cultured corneal fibroblast of the rabbit to determine the safety of this compound for clinical use. (jove.com)
  • The next article will deal with the peculiarities of the wavefront analysis, as well as with some of the clinical and surgical applications to the day-to-day ophthalmic practice. (worldwidescience.org)
  • 4 KAMRA Intracorneal Inlay Characteristics 8,400 holes for oxygen and nutrition flow 3.8mm diameter 1.6mm central aperture 5 µm thick First developed in 2002 Currently in FDA clinical trials Made from PVDF (PolyvinylideneFluoride) The AcuFocus corneal inlay is designed with a tiny aperture and a small opening in the center, which creates a pinhole effect. (docplayer.net)
  • Wavefront has been evolving as a clinical science in eye care for the past 20 years now. (wcea.education)
  • I published this textbook in 2009 with the goal of converting the complex mathematical and optical physics of wavefront science into understandable clinical, diagnostic and non-surgical and surgical corrective approaches for day-to-day practitioners' use. (wcea.education)
  • Using next-generation analysis technology, PathFinder II provides probabilities for 5 different corneal conditions by comparing topography exams to an extensive clinical database. (myeyeequipment.com)
  • An apparatus and method for characterizing an energy beam (such as a laser) with a two-dimensional wavefront sensor, such as a Shack-Hartmann lenslet array. (google.es)
  • 2. The apparatus of claim 1 wherein said apparatus comprises a Shack-Hartmann wavefront sensor. (google.es)
  • 20. The method of claim 19 wherein the method employs a Shack-Hartmann wavefront sensor. (google.es)
  • A Shack-Hartmann (or Hartmann-Shack) wavefront sensor (SHWFS) is an optical instrument used for characterizing an imaging system. (wikipedia.org)
  • Since only tilts are measured the Shack-Hartmann cannot detect discontinuous steps in the wavefront. (wikipedia.org)
  • Shack-Hartmann sensors are used to characterize eyes for corneal treatment of complex refractive errors. (wikipedia.org)
  • While Shack-Hartmann sensors measure localized slope of the wavefront error using spot displacement in sensor plane, Pamplona et al. (wikipedia.org)
  • Wave aberrations were measured with a Shack-Hartmann wavefront sensor (SHWS) in the right eye of a large young adult population when accommodative demands of 0, 3, and 6 D were presented to the tested eye through a Badal system. (arvojournals.org)
  • In virgin eyes, spherical aberration is similar for the SW and AW, although there is still an overall HORMS reduction produced by the epithelium over the SW. (escrs.org)
  • Causes of corneal scarring include almost any disruption to normal corneal structure and function, whether from infection, corneal surgery, corneal transplantation, ocular trauma (chemical or physical) or corneal dystrophies. (rochester.edu)
  • PURPOSE OF REVIEW: Corneal transplantation is successful in the short-term, but the long-term prognosis has not improved over the past 20 years. (edu.au)
  • The auto keratometer provides conventional keratometry and novel corneal surface descriptors such as APP (Average Pupil Power) and ECCP (Effective Central Corneal Power) which aid in the calculation of the correct IOL power for post-operative corneas. (nidek.com)
  • To comprehensively assess the precision and agreement of anterior corneal power measurements using 8 different devices. (plos.org)
  • Repeatability and reproducibility of corneal power measurements were assessed based on the intrasession and intersession within-subject standard deviation (Sw), repeatability (2.77Sw), coefficient of variation (COV), and intraclass correlation coefficient (ICC). (plos.org)