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.
A noninflammatory, usually bilateral protrusion of the cornea, the apex being displaced downward and nasally. It occurs most commonly in females at about puberty. The cause is unknown but hereditary factors may play a role. The -conus refers to the cone shape of the corneal protrusion. (From Dorland, 27th ed)
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)
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)
Refraction of LIGHT effected by the media of the EYE.
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)
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.
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.
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.
Diseases of the cornea.
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.
Partial or total replacement of all layers of a central portion of the cornea.
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.
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.
Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.
A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.

Zernike representation of corneal topography height data after nonmechanical penetrating keratoplasty. (1/329)

PURPOSE: To demonstrate a mathematical method for decomposition of discrete corneal topography height data into a set of Zernike polynomials and to demonstrate the clinical applicability of these computations in the postkeratoplasty cornea. METHODS: Fifty consecutive patients with either Fuchs' dystrophy (n = 20) or keratoconus (n = 30) were seen at 3 months, 6 months, and 1 year (before suture removal) and again after suture removal following nonmechanical trephination with the excimer laser. Patients were assessed using regular keratometry, corneal topography (TMS-1, simulated keratometry [SimK]), subjective refraction, and best-corrected visual acuity (VA) at each interval. A set of Zernike coefficients with radial degree 8 was calculated to fit two model surfaces: a complete representation (TOTAL) and a representation with parabolic terms only to define an approximate spherocylindrical surface (PARABOLIC). The root mean square error (RMS) was calculated comparing the corneal raw height data with TOTAL (TOTALRMS) and PARABOLIC (PARABOLICRMS). The cylinder of subjective refraction was correlated with the keratometric readings, the SimK, and the respective Zernike parameter. Visual acuity was correlated with the tilt components of the Zernike expansion. RESULTS: The measured corneal surface could be approximated by the composed surface 1 with TOTALRMS < or = 1.93 microm and by surface 2 with PARABOLICRMS < or = 3.66 microm. Mean keratometric reading after suture removal was 2.8+/-0.6 D. At all follow-up examinations, the SimK yielded higher values, whereas the keratometric reading and the refractive cylinder yielded lower values than the respective Zernike parameter. The correlation of the Zernike representation and the refractive cylinder (P = 0.02 at 3 months, P = 0.05 at 6 months and at 1 year, and P = 0.01 after suture removal) was much better than the correlation of the SimK and refractive cylinder (P = 0.3 at 3 months, P = 0.4 at 6 months, P = 0.2 at 1 year, and P = 0.1 after suture removal). Visual acuity increased from 0.23+/-0.10 at the 3-month evaluation to 0.54+/-0.19 after suture removal. After suture removal, there was a statistically significant inverse correlation between VA and tilt (P = 0.02 in patients with keratoconus and P = 0.05 in those with Fuchs' dystrophy). CONCLUSIONS: Zernike representation of corneal topography height data renders a reconstruction of clinically relevant corneal topography parameters with a marked reduction of redundance and a small error. Correlation of amount/axis of refractive cylinder with respective Zernike parameters is more accurate than with keratometry or respective SimK values of corneal topography analysis.  (+info)

Changes in corneal wavefront aberrations with aging. (2/329)

PURPOSE: To investigate whether corneal wavefront aberrations vary with aging. METHODS: One hundred two eyes of 102 normal subjects were evaluated with videokeratography. The data were decomposed using Taylor and Zernike polynomials to calculate the monochromatic aberrations of the cornea for both small (3-mm) and large (7-mm) pupils. RESULTS: For a 3-mm pupil, the amount of total aberrations (Spearman rank correlation coefficient r(s) = 0.145; P = 0.103) and spherical-like aberrations (r(s) = -0.068; P = 0.448) did not change with aging, whereas comalike aberrations exhibited a weak but statistically significant correlation with age (r(s) = 0.256; P = 0.004). For a 7-mm pupil, total aberrations (r(s) = 0.552; P < 0.001) and comalike aberrations (r(s) = 0.561; P < 0.001) significantly increased with aging, but spherical-like aberrations showed no age-related changes (r(s) = 0.124; P = 0.166). Simulated pupillary dilation from 3 mm to 7 mm caused a 38.0+/-28.5-fold increase in the total aberrations, and the extent of increases significantly correlated with age (r(s) = 0.354; P < 0.001). Pupillary dilation influenced the comalike aberrations more in the older subjects than in the younger subjects (r(s) = 0.243; P = 0.006), but such age dependence was not found for spherical-like aberrations (r(s) = 0.141; P = 0.115). CONCLUSIONS: Comalike aberrations of the cornea correlate with age, implying that the corneas become less symmetrical along with aging. Spherical-like aberrations do not vary significantly with aging. Pupillary dilation markedly increases wavefront aberrations, and those effects are more prominent in older subjects than in younger subjects.  (+info)

Evaluation of corneal thickness and topography in normal eyes using the Orbscan corneal topography system. (3/329)

AIMS: To map the thickness, elevation (anterior and posterior corneal surface), and axial curvature of the cornea in normal eyes with the Orbscan corneal topography system. METHODS: 94 eyes of 51 normal subjects were investigated using the Orbscan corneal topography system. The anterior and posterior corneal elevation maps were classified into regular ridge, irregular ridge, incomplete ridge, island, and unclassified patterns, and the axial power maps were grouped into round, oval, symmetric bow tie, asymmetric bow tie, and irregular patterns. The pachymetry patterns were designated as round, oval, decentred round, and decentred oval. RESULTS: The thinnest point on the cornea was located at an average of 0.90 (SD 0. 51) mm from visual axis and had an average thickness of 0.55 (0.03) mm. In 69.57% of eyes, this point was located in the inferotemporal quadrant, followed by the superotemporal quadrant in 23.91%, the inferonasal quadrant in 4.35%, and the superonasal quadrant in 2.17%. Among the nine regions of the cornea evaluated (central, superotemporal, temporal, inferotemporal, inferior, inferonasal, nasal, superonasal, and superior) the central cornea had the lowest average thickness (0.56 (0.03) mm) and the superior cornea had the greatest average thickness (0.64 (0.03) mm). The mean simulated keratometry (SimK) was 44.24 (1.61)/43.31 (1.66) dioptres (D) and the mean astigmatism was 0.90 (0.41) D. Island (71.74%) was the most common elevation pattern observed in the anterior corneal surface, followed by incomplete ridge (19.57%), regular ridge (4.34%), irregular ridge (2.17%), and unclassified (2.17%). Island (32.61%) was the most common topographic pattern in the posterior corneal surface, following by regular ridge (30.43%), incomplete ridge (23. 91%), and irregular ridge (13.04%) patterns. Symmetric bow tie was the most common axial power pattern in the anterior cornea (39.13%), followed by oval (26.07%), asymmetric bow tie (23.91%), round (6. 52%), and irregular (4.53%) patterns. In the pachymetry maps, 47.83% of eyes had an oval pattern, and round, decentred oval, and decentred round were observed in 41.30%, 8.70%, and 2.18% of eyes, respectively. CONCLUSION: The information on regional corneal thickness, corneal elevation and axial corneal curvature obtained with the Orbscan corneal topography system from normal eyes provides a reference for comparison with diseased corneas. The Orbscan corneal topography system is a useful tool to evaluate both corneal topography and corneal thickness.  (+info)

Proposed classification for topographic patterns seen after penetrating keratoplasty. (4/329)

AIMS: To create a clinically useful classification for post-keratoplasty corneas based on corneal topography. METHODS: A total of 360 topographic maps obtained with the TMS-1, from 95 eyes that had undergone penetrating keratoplasty (PKP), were reviewed independently by two examiners in a masked fashion, and were categorised according to a proposed classification scheme. RESULTS: A high interobserver agreement (88% in the first categorisation) was achieved. At 12 months post-PKP, a regular astigmatic pattern was observed in 20/85 cases (24%). This was subclassified as oval in three cases (4%), oblate symmetric bow tie in six cases (7%), prolate asymmetric bow tie in six cases (7%), and oblate asymmetric bow tie in five cases (6%). An irregular astigmatic pattern was observed in 61/85 cases (72%), subclassified as prolate irregular in five cases (6%), oblate irregular in four cases (5%), mixed in seven cases (8%), steep/flat in 11 cases (13%), localised steepness in 16 cases (19%), and triple pattern in three cases (4%). Regular astigmatic patterns were associated with significantly higher astigmatism measurements. The surface asymmetry index was significantly lower in the regular astigmatic patterns. CONCLUSIONS: In post-PKP corneas, the prevalence of irregular astigmatism is about double that of regular astigmatism, with a trend for increase of the irregular patterns over time.  (+info)

Reassessment of the corneal endothelial cell organisation in children. (5/329)

AIM: To assess uniformity of the corneal endothelial cell mosaic in children. METHODS: 36 healthy children (5-11 years old, 16 boys, 20 girls) were assessed by specular microscopy. Endothelial cell density (ECD) was calculated from measured cell areas, and the number of sides/cell noted. RESULTS: Average values for ECD and cell areas were 3987 cells/mm(2) (95% CI 3806 to 4168 cells/mm(2)) and 278 (SD 85) mm(2) respectively, with normal distribution (COV 28. 2%, range 17.4 to 39.2%) and with the average percentage of six sided cells being 66.6% (8.8%). Cell area was positively correlated to number of cell sides (p <0.01, r(2)=0.993), but the percentage of six sided cells was negatively correlated to ECD (p <0.01, r=0.493). CONCLUSION: A high ECD occurs in children, but this does not mean there is a high percentage of "hexagons".  (+info)

Pterygium-induced corneal astigmatism. (6/329)

BACKGROUND: Previous work has suggested an association between increasing size of pterygium and increasing degrees of induced corneal astigmatism. OBJECTIVES: To assess the quantitative relation between pterygium size and induced corneal astigmatism using a computerized corneal analysis system (TMS II) and slit-lamp beam evaluation of pterygium size, and to conclude whether corneal astigmatism is an early indication for surgical intervention. METHODS: We evaluated 94 eyes of 94 patients with unilateral primary pterygium of different sizes, using TMS II and slit-lamp beam measurements of the size of the pterygium (in millimeters) from the limbus to assess parameters of pterygium size with induced corneal astigmatism. Best corrected visual Snellen acuity was performed. RESULTS: Primary pterygium induced with-the-rule astigmatism. Pterygium extending > 16% of the corneal radius or 1.1 mm or less from the limbus produced increasing degrees of induced astigmatism of more than 1.0 diopter. Significant astigmatism was found in 16.16% of 24 eyes with pterygium of 0.2 up to 1.0 mm in size, in 45.45% of 22 eyes with pterygium of 1.1 up to 3.0 mm in size (P < or = 0.0004), and in 100% of 3 eyes with pterygium of 5.1 up to 6.7 mm in size (P = 0.0005). We found that visual acuity was decreased when topographic astigmatism was increased. CONCLUSIONS: When primary pterygium reaches more than 1.0 mm in size from the limbus it induces with-the-rule significant astigmatism (> or = 1.0 diopter). This significant astigmatism tends to increase with the increasing size of the lesion. Topographic astigmatism tends to be improved by successful removal of the pterygium. These findings suggest that early surgical intervention in the pterygium may be indicated when the lesion is more than 1.0 mm in size from the limbus.  (+info)

Effect of disagreement between refractive, keratometric, and topographic determination of astigmatic axis on suture removal after penetrating keratoplasty. (7/329)

BACKGROUND/AIMS: Post-keratoplasty astigmatism can be managed by selective suture removal in the steep axis. Corneal topography, keratometry, and refraction are used to determine the steep axis for suture removal. However, often there is a disagreement between the topographically determined steep axis and sutures to be removed and that determined by keratometry and refraction. The purpose of this study was to evaluate any difference in the effect of suture removal, on visual acuity and astigmatism, in patients where such a disagreement existed. METHODS: 37 cases (from 37 patients) of selective suture removal after penetrating keratoplasty, were included. In the first group "the disagreement group" (n=15) there was disagreement between corneal topography, keratometry, and refraction regarding the axis of astigmatism and sutures to be removed. In the second group "the agreement group" (n=22) there was agreement between corneal topography, keratometry, and refraction in the determination of the astigmatic axis and sutures to be removed. Sutures were removed according to the corneal topography, at least 5 months postoperatively. Vector analysis for change in astigmatism and visual acuity after suture removal was compared between groups. RESULTS: In the disagreement group, the amount of vector corrected change in refractive, keratometric, and topographic astigmatism after suture removal was 3.45 (SD 2.34), 3.57 (1.63), and 2.83 (1. 68) dioptres, respectively. In the agreement group, the amount of vector corrected change in refractive, keratometric, and topographic astigmatism was 5.95 (3.52), 5.37 (3.29), and 4.71 (2.69) dioptres respectively. This difference in the vector corrected change in astigmatism between groups was statistically significant, p values of 0.02, 0.03, and 0.03 respectively. Visual acuity changes were more favourable in the agreement group. Improvement or no change in visual acuity occurred in 90.9% in the agreement group compared with 73.3% of the disagreement group. CONCLUSIONS: Agreement between refraction, keratometry, and topography was associated with greater change in vector corrected astigmatism and was an indicator of good prognosis. Disagreement between refraction, keratometry, and topography was associated with less vector corrected change in astigmatism, a greater probability of decrease in visual acuity, and a relatively poor outcome following suture removal. However, patients in the disagreement group still have a greater chance of improvement than worsening, following suture removal.  (+info)

Corneal topography by keratometry. (8/329)

AIMS: To investigate the ability of a telecentric keratometer to describe the asphericity and curvature of convex ellipsoidal surfaces and human corneas. METHODS: 22 conicoidal convex surfaces and 30 human corneas were examined by conventional keratometry. Additional keratometric measurements were made when the surface was tilted in the horizontal plane relative to the instrument optical axis. This resulted in a series of radius measurements derived from different regions of the surface. These measurements were used to determine the apical radius and the p value of the horizontal meridian of each surface. The results were compared with those derived from measurements using the EyeSys videokeratoscope and form Talysurf analysis. The method was repeated on 30 human corneas and the results compared with those of a videokeratoscope. RESULTS: For the aspheric buttons, the keratometric and the EyeSys results tended to give higher values for both apical radius and the p values than those of the Talysurf analysis. The best agreement was between the Talysurf and the keratometer where the results were not significantly different. For the human corneas, the apical radii were significantly different comparing the keratometer with the videokeratoscope but the p values were not significantly different. CONCLUSION: The keratometric method for assessing curvature and asphericity appears to hold promise as a method for quantifying the corneal topography.  (+info)

While there is no cure for keratoconus, there are several treatment options available to help manage the condition. These include eyeglasses or contact lenses, specialized contact lenses called rigid gas permeable (RGP) lenses, and corneal transplantation in severe cases. Other treatments that may be recommended include phototherapeutic keratectomy (PTK), which involves removing damaged tissue from the cornea using a laser, or intacs, which are tiny plastic inserts that are placed into the cornea to flatten it and improve vision.

Keratoconus is relatively rare, affecting about 1 in every 2,000 people worldwide. However, it is more common in certain groups of people, such as those with a family history of the condition or those who have certain medical conditions, such as Down syndrome or sickle cell anemia. It typically affects both eyes, although one eye may be more severely affected than the other.

While there is no known cause for keratoconus, researchers believe that it may be linked to genetics, environmental factors, or a combination of both. The condition usually begins in adolescence or early adulthood and can progress over several years. In some cases, keratoconus can also be associated with other eye conditions, such as cataracts, glaucoma, or retinal detachment.

Astigmatism can occur in people of all ages and is usually present at birth, but it may not become noticeable until later in life. It may also develop as a result of an injury or surgery. Astigmatism can be corrected with glasses, contact lenses, or refractive surgery, such as LASIK.

There are different types of astigmatism, including:

1. Corneal astigmatism: This is the most common type of astigmatism and occurs when the cornea is irregularly shaped.
2. Lens astigmatism: This type of astigmatism occurs when the lens inside the eye is irregularly shaped.
3. Mixed astigmatism: This type of astigmatism occurs when both the cornea and lens are irregularly shaped.

Astigmatism can cause a range of symptoms, including:

* Blurred vision at all distances
* Distorted vision (such as seeing objects as being stretched out or blurry)
* Eye strain or fatigue
* Headaches or eye discomfort
* Squinting or tilting the head to see clearly

If you suspect you have astigmatism, it's important to see an eye doctor for a comprehensive eye exam. Astigmatism can be diagnosed with a visual acuity test and a retinoscopy, which measures the way the light enters the eye.

Astigmatism is a common vision condition that can be easily corrected with glasses, contact lenses, or refractive surgery. If you have astigmatism, it's important to seek professional treatment to improve your vision and reduce any discomfort or strain on the eyes.

Myopia can be caused by a variety of factors, including:

1. Genetics: Myopia can run in families, and people with a family history of myopia are more likely to develop the condition.
2. Near work: Spending too much time doing close-up activities such as reading or using digital devices can increase the risk of developing myopia.
3. Poor posture: Slouching or leaning forward can cause the eye to focus incorrectly, leading to myopia.
4. Nutritional deficiencies: A diet lacking in essential nutrients such as vitamin D and omega-3 fatty acids may contribute to the development of myopia.
5. Eye stress: Prolonged eye strain due to excessive near work or other activities can lead to myopia.

Symptoms of myopia include:

1. Difficulty seeing distant objects clearly
2. Headaches or eye strain from trying to focus on distant objects
3. Squinting or rubbing the eyes to try to see distant objects more clearly
4. Difficulty seeing in low light conditions
5. Blurry vision at a distance, with close objects appearing clear.

Myopia can be diagnosed with a comprehensive eye exam, which includes a visual acuity test, refraction test, and retinoscopy. Treatment options for myopia include:

1. Glasses or contact lenses: These corrective lenses refract light properly onto the retina, allowing clear vision of both close and distant objects.
2. Laser eye surgery: Procedures such as LASIK can reshape the cornea to improve its curvature and reduce myopia.
3. Orthokeratology (ORTHO-K): A non-surgical procedure that uses a specialized contact lens to reshape the cornea while you sleep.
4. Myopia control: This involves using certain treatments or techniques to slow down the progression of myopia in children and young adults.
5. Multifocal lenses: These lenses have multiple focal points, allowing for clear vision of both near and distant objects without the need for glasses or contact lenses.

In conclusion, myopia is a common vision condition that can be caused by a variety of factors and symptoms can include difficulty seeing distant objects clearly, headaches, and eye strain. Treatment options include glasses or contact lenses, laser eye surgery, ORTHO-K, myopia control, and multifocal lenses. It is important to consult an eye doctor for a comprehensive evaluation and to determine the best course of treatment for your specific case of myopia.

1. Keratoconus: This is a progressive thinning of the cornea that can cause it to bulge into a cone-like shape, leading to blurred vision and sensitivity to light.
2. Fuchs' dystrophy: This is a condition in which the cells in the innermost layer of the cornea become damaged, leading to clouding and blurred vision.
3. Bullous keratopathy: This is a condition in which there is a large, fluid-filled bubble on the surface of the cornea, which can cause blurred vision and discomfort.
4. Corneal ulcers: These are open sores on the surface of the cornea that can be caused by infection or other conditions.
5. Dry eye syndrome: This is a condition in which the eyes do not produce enough tears, leading to dryness, irritation, and blurred vision.
6. Corneal abrasions: These are scratches on the surface of the cornea that can be caused by injury or other conditions.
7. Trachoma: This is an infectious eye disease that can cause scarring and blindness if left untreated.
8. Ocular herpes: This is a viral infection that can cause blisters on the surface of the cornea and lead to scarring and vision loss if left untreated.
9. Endophthalmitis: This is an inflammation of the inner layer of the eye that can be caused by bacterial or fungal infections, and can lead to severe vision loss if left untreated.
10. Corneal neovascularization: This is the growth of new blood vessels into the cornea, which can be a complication of other conditions such as dry eye syndrome or ocular trauma.

These are just a few examples of the many different types of corneal diseases that can affect the eyes. It's important to seek medical attention if you experience any symptoms such as pain, redness, or blurred vision in one or both eyes. Early diagnosis and treatment can help prevent complications and preserve vision.

Myopia occurs when the eyeball is too long or the cornea is too steep, causing light to focus in front of the retina instead of directly on it. Hyperopia is the opposite, where the eyeball is too short or the cornea is too flat, causing light to focus behind the retina. Astigmatism is caused by an irregularly shaped cornea, which causes light to focus at multiple points instead of one. Presbyopia is a loss of near vision that occurs as people age, making it harder to see close objects clearly.

In addition to these common refractive errors, there are other, less common conditions that can affect the eyes and cause blurred vision, such as amblyopia (lazy eye), strabismus (crossed eyes), and retinal detachment. These conditions can be caused by a variety of factors, including genetics, injury, or disease.

Refractive errors can have a significant impact on daily life, affecting everything from work and school performance to social interactions and overall quality of life. Fortunately, with the help of corrective lenses or surgery, many people are able to achieve clear vision and lead fulfilling lives.

While corneal topography relies on reflected light from the front (anterior) of the cornea, a technique called corneal ... Computerized corneal topography can be employed for diagnostics. It is, in fact, one of the exams the patients have to undergo ... Corneal Topography measuring and modifying the cornea - Schanzlin 1992, page 4-5 Gullstrand A (1909). "Procedure of rays in the ... Corneal topography, also known as photokeratoscopy or videokeratography, is a non-invasive medical imaging technique for ...
Corneal pachymetric topography. Ophthalmology 101:432-438, 1994. Reinstein DZ, Silverman RH, Raevsky T, Simoni GJ, Lloyd HO, ... Arc-scanning very high-frequency ultrasound for 3-D pachymetric mapping of the corneal epithelium and stroma in laser in situ ... This system allowed demonstration of the importance of arc-scanning for corneal analysis and led to the subsequent development ... Epithelial and corneal thickness measurements by high-frequency ultrasound digital signal processing, Ophthalmology, 101: 140- ...
The gold standard diagnostic test for PMD is corneal topography. However, it may not be as specific as corneal pachymetry, ... Pellucid marginal degeneration is diagnosed by corneal topography. Corneal pachymetry may be useful in confirming the diagnosis ... if corneal topography is used for diagnosis, it should be in conjunction with clinical findings of peripheral, inferior corneal ... Corneal topography may show a "crab claw-like" appearance, a finding that is seen in both keratoconus and in pellucid marginal ...
Kiely PM, Carney LG, Smith G (October 1983). "Menstrual cycle variations of corneal topography and thickness" (PDF). American ... Leach NE, Wallis NE, Lothringer LL, Olson JA (May 1971). "Corneal hydration changes during the normal menstrual cycle--a ...
... anterior corneal) astigmatism is measured through the use of techniques such as keratometry and corneal topography. One method ... Corneal topography may also be used to obtain a more accurate representation of the cornea's shape. An autorefractor or ... Corneal Topography and Imaging at eMedicine Graff, T (1962). "Control of the determination of astigmatism with the Jackson ... "Classification of normal corneal topography based on computer-assisted videokeratography". Archives of Ophthalmology. 108 (7): ...
"Corneal topography and Schirmer testing in eyes with the Hudson,-,Stahli line". Eye. 16 (3): 267-70. doi:10.1038/sj.eye.6700028 ... Fleischer ring - corneal iron depositions in keratoconus Ophthalmology Myron Yanoff, Jay S. Duker Edition 3, illustrated ... 321 It lies in the corneal epithelium. Usually it has about 0.5 mm in thickness and is 1-2 mm long. It is generally horizontal ...
Is the future of refractive surgery based on corneal topography or wavefront? "Ocular Surgery News". August 1, 2000, page 26. ... Both the depth of the corneal incisions and the degree of central corneal flattening correlated with the laser energy applied. ... Those with Fuchs' corneal endothelial dystrophy, corneal epithelial basement membrane dystrophy, retinal tears, autoimmune ... or corneal topography machine, to measure their surface contour. Using low-power lasers, a topographer creates a topographic ...
Corneal topography indices after corneal collagen crosslinking for keratoconus and corneal ectasia One-year results. J Cat ... Refractive Corneal Surg. 1994;10:571-574. Hersh PS, Schwartz-Goldstein B. Summit PRK Topography Study Group. Corneal topography ... "Corneal topography indices after corneal collagen crosslinking for keratoconus and corneal ectasia: One-year results". Journal ... Summit PRK Topography Study Group. Corneal topography of phase III excimer laser photorefractive keratectomy: Optical zone ...
The corneal thickness from mild (> 506 μm) to advanced (< 446 μm). Increasing use of corneal topography has led to a decline in ... A more definitive diagnosis can be obtained using corneal topography, in which an automated instrument projects the illuminated ... The corneal transplant surgeon trephines a lenticule of corneal tissue and then grafts the donor cornea to the existing eye ... Maguire LJ, Bourne WM (August 1989). "Corneal topography of early keratoconus". American Journal of Ophthalmology. 108 (2): 107 ...
Treating Manifest Refractive Astigmatism Versus Topography-Measured Anterior Corneal Astigmatism". Journal of Refractive ... "Clinical outcomes after topography-guided LASIK: comparing results based on a new topography analysis algorithm with those ... customized laser refractive surgery and corneal cross-linking propagation and most innovations, reducing corneal transplants ... "Combining corneal crosslinking and PRK shows increasingly good results in keratoconus". American Academy of Ophthalmology. 2010 ...
"Evaluation of corneal thickness and topography in normal eyes using the Orbscan corneal topography system". Br J Ophthalmol. 83 ...
"Evaluation of corneal thickness and topography in normal eyes using the Orbscan corneal topography system". The British Journal ...
Corneal topography may also be used to obtain a more accurate representation of the cornea's shape. An autorefractor or ... It is typically characterized by an aspherical, non-figure of revolution cornea in which the corneal profile slope and ...
The specific application of UVA for each patient takes into account the refractive error and corneal topography. The major ... PiXL is a high-fluence corneal collagen cross-linking administered in a customizable pattern and intensity in order to flatten ... or steepen the cornea through corneal strengthening. ...
In ophthalmology, corneal topography is used as a technique for mapping the surface curvature of the cornea. In tissue ... Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and ... In human anatomy, topography is superficial human anatomy. In mathematics the concept of topography is used to indicate the ... Topographers are experts in topography. Cartography Digital elevation model Fall line (topography) Geomorphology Global Relief ...
Corneal and Retinal Topography: computerized tests that maps the surface of the retina, or the curvature of the cornea. ...
Corneal topography and pachymetry are used to screen for abnormal corneas. Furthermore, some people's eye shape may not permit ... Customized Transepithelial No-touch (C-TEN) is an innovative strategy for corneal surgery that avoids any corneal manipulation ... such as corneal topography. While refractive surgery is becoming more affordable and safe, it may not be recommended for ... It involves cutting a flap in the cornea and pulling it back to expose the corneal bed, then using an excimer laser to ablate ...
Corneal topography is considered a more quantitative test, and for purposes of aligning a toric IOL, most surgeons use a ... which is calculated by the internal programming of the corneal topography machine, to determine the astigmatic meridian on the ... including manifest refraction or corneal topography. Manifest refraction is the familiar test where the eye doctor rotates ... It is believed to have a lesser effect on corneal endothelium. The main complication with this type is their tendency to cause ...
GWAS studies found that TMEM248 SNP rs4718428 is associated with corneal topography, and another SNP rs6971897 is associated ... with corneal thickness. GRCh38: Ensembl release 89: ENSG00000106609 - Ensembl, May 2017 GRCm38: Ensembl release 89: ...
He has also done extensive research in corneal crosslinking and topography-guided PRK for keratoconus, procedures he introduced ... Stein R: Applications of Corneal Crosslinking, Refractive Eyecare for Ophthalmologists, Ethis Publishing, March 2010. "The Best ...
... have demonstrated the ability of OCT systems to depict pathology within the cornea as well as disorders of corneal topography. ... Direct corneal elevation measurements using multiple delay en face optical coherence tomography. J Biomed Opt. 2008 Sep-Oct;13( ... High-speed optical coherence tomography of corneal opacities. Ophthalmology. 2007 Jul;114(7):1278-85. Plesea et al. ...
As the inflammation is reduced, the stroma appears to be thin and the corneal topography changes to show an area of depression ... The corneal response to the treatment appears to be as expected until the four-day mark where the corneal inflammation and ... It could also show corneal oedema which leads to thickening the corneal by up to 30%. Extensive conjunctival injection, which ... corneal abrasion and infectious corneal ulcer. In order to diagnosis Christmas Eye, it's essential to take a look at the ...
A modern development of the concept is found in corneal topography, in which analysis of the reflected image is passed to a ... The automated instrument can produce colour-coded contour maps of the eye's topography or even three-dimensional visualisations ... If the patient is suffering from astigmatism or from a corneal dystrophy, the rings will be distorted. ...
Corneal topography is a non-invasive medical imaging technique for mapping the anterior curvature of the cornea, the outer ... corneal transplantation, and preservation of grafts from cadaver eyes and tissue therapy; he founded the Filatov Institute of ... as well as the first microkeratome and corneal microlathe Tadeusz Krwawicz (1910-1988) (Poland), in 1961, developed the first ...
... however corneal topography is a practical test (technique) as the condition worsens. Pterygium should be differentiated from ... "Facts About the Cornea and Corneal Disease , National Eye Institute". The National Eye Institute (NEI). May 2016. Archived from ... Other conditions that can look similar include a pinguecula, tumor, or Terrien's marginal corneal degeneration. Prevention may ... as it invades the cornea with the potential of obscuring the optical center of the cornea and inducing astigmatism and corneal ...
Central corneal power can be measured by keratometry or corneal topography. Corneal radius of curvature relates to corneal ... which uses the pre-LASIK corneal power for the calculation of the ELP, and the post-LASIK corneal power for the calculation of ... corneal topographers) cannot obtain accurate measurements in eyes that have undergone corneal refractive surgery. Most manual ... The central corneal power is the second important factor in the calculation formula. To simplify the calculation, the cornea is ...
... computerized corneal topography, endothelial microscopy, ultrasound pachymetry, b-scan sonography, keratometry and ... Corneal cross-linking with riboflavin (vitamin B2) and UV-A light is a surgical treatment for corneal ectasia such as ... Corneal Collagen Cross-Linking on National Keratoconus Foundation website. Corneal Collagen Cross-Linking on EyeWiki from the ... "Corneal collagen crosslinking: A clinical update". "Corneal cross-linking" (PDF). Moorfields Eye Hospital NHS Foundation Trust ...
Rabinowitz, YS; McDonnell, PJ (1989). "Computer-assisted corneal topography in keratoconus". Refractive & Corneal Surgery. 5 (6 ... custom topography-guided transepithelial PRK combined with corneal collagen cross-linking, or corneal transplant. When cross- ... Abnormal corneal topography compromises of keratoconus, pellucid marginal degeneration, or forme fruste keratoconus with an I-S ... "Post-LASIK ectasia treated with intrastromal corneal ring segments and corneal crosslinking". Digital Journal of Ophthalmology ...
It is also the principle used in corneal pachymetry, the mapping of corneal topography, done prior to refractive eye surgery ...
Corneal topography Corneal tomography Treatment options include contact lenses and intrastromal corneal ring segments for ... corneal collagen cross-linking to strengthen a weak and ectatic cornea, or corneal transplant for advanced cases. "Corneal ... Corneal ectatic disorders or corneal ectasia are a group of uncommon, noninflammatory, eye disorders characterised by bilateral ... Although some investigations might needed for confirming the diagnosis and to differentiate different types of corneal ectatic ...
... applications of corneal Crosslinking 1999 World's first wavefront-guided laser treatment on the human eye 2002 First topography ... His work and research interests include corneal surgery, especially refractive corneal surgery, surgery of the anterior segment ... He habilitated at the Free University of Berlin in 1987 with his scientific paper "Refractive corneal surgery" and was ... Eyes 1988 World's first Holimum YAG laser PRK thermokeratoplasty 1989 First clinical studies on PRK 1995 Invention of Corneal ...
In 79% of these cases, sealers did not check the corneal reflex to ensure that the seals were dead prior to hooking or skinning ... There are also words referring to seasons, topography, place names, legends, and kinship relationships based on the seal. One ... of the sealers recorded on the four videotapes failed to palpate the skull or check the corneal reflex before proceeding to ... including checking for a corneal reflex and bleeding animals immediately after clubbing." In 2005, the World Wildlife Fund (WWF ...
"Fast Facts, Geography, Topography". navajobusiness.com. Retrieved 27 July 2017. Comerford, Kevin. "Checkerboard Reservation, ... Other symptoms include corneal anesthesia and scarring, acral mutilation, cerebral leukoencephalopathy, failure to thrive, and ...
"CXL, topography-guided, customized ablation Tx for keratoconus and post-LASIK". Archived from the original on 2016-03-10. " ... He performs complex corneal collagen and cross-linking (CXL) procedures for keratoconus patients, combined with excimer laser ... He went on to complete his post-doctoral fellowship training in corneal transplantation, cataract surgery and laser refractive ... In 2015, Wallerstein and Cohen launched a new laser vision procedure called Laser PresbyVision™, a corneal-based treatment ...
1-15 Corneal topography Gullstrand-Painlevé coordinates Optical aberration Perceptual paradox Slit lamp Gullstrand, Allvar ( ...
Sun XC, Bonanno JA (2003). "Identification and cloning of the Na/HCO(3-) cotransporter (NBC) in human corneal endothelium". Exp ... 2003). "Identification of membrane topography of the electrogenic sodium bicarbonate cotransporter pNBC1 by in vitro ...
Corneal pachymetry Corneal reflex Corneal tattooing Corneal topography Eye disease Keratometry List of keratins expressed in ... For corneal epithelial diseases such as Stevens Johnson Syndrome, persistent corneal ulcer etc., the autologous contralateral ( ... There is a global shortage of corneal donations, severely limiting the availability of corneal transplants across most of the ... The most common corneal disorders are the following: Corneal abrasion - a medical condition involving the loss of the surface ...
A young man endured bilateral corneal burns to the eye area when an e-cigarette exploded near his chest. A man died when his ... Evans SE, Hoffman AC (May 2014). "Electronic cigarettes: abuse liability, topography and subjective effects". Tobacco Control. ... or corneal abrasion; multiple routes of exposure resulted in eye irritation or pain, vomiting, red eye or conjunctivitis, ...
"Topography of the layer of rods and cones in the human retina". Acta Ophthalmologica. 13 (Suppl. 6): 11-103. doi:10.1111/j.1755 ... Other optical causes are astigmatism or more complex corneal irregularities. These anomalies can mostly be corrected by optical ...
However, it was not until computerized corneal topography became available during the 1990s that it became possible to apply ... In June 2002, the FDA granted approval for overnight wear of a type of corneal reshaping called "Corneal Refractive Therapy" ( ... 2001 Aug;108(8):1389-99 Macsai, M.D., Marian S. (January 2005). "Corneal Ulcers in Two Children Wearing Paragon Corneal ... Each patient presented with a bacterial corneal ulcer after wearing CRT contact lenses for less than 6 months. In the first ...
... tomography Elastography Electrical impedance tomography Optoacoustic imaging Ophthalmology A-scan B-scan Corneal topography ...
Beneath the outer layer is the corneal layer (stratum corneum), which is thickened and flexible. Under the corneal layer is ... "Quantifying surface topography of biological systems from 3D scans". Methods in Ecology and Evolution. 12 (7): 1265-1276. doi: ... Chromatophores in the dermis yield coloration when light shines through the corneal layer of the epidermis. There are many ...
... , Keratoconus Research ... Simultaneous Topography-guided PRK Followed by Corneal Collagen Cross-linking for Keratoconus. George D. Kymionis, MD, PhD; ... Reaching functional vision consists of improving UCVA and BSCVA and normalization of corneal topography, which indicates that ... One-year follow-up of corneal confocal microscopy after corneal cross-linking in patients with post laser in situ ...
Corneal Topography WW 220 Cosmetic Techniques. Surgical (General) WO 600 Skin WR 650. Specific location, by site. Used for ... Epithelium, Corneal WW 220 Family Relations. Children WS 105.5.F2. Ethnology GN 480-480.65. Relations to health see Family ...
Corneal Topography * Female * Follow-Up Studies * Humans * Incidence * Italy / epidemiology * Keratoconus / diagnosis ...
CORNEAL TOPOGRAPHY. Preoperative topography shows minimal astigmatism in the left eye of the patient described in the case ... Corneal shape and power analysis. Screening for corneal irregularities us-ing topography, tomography, or other advanced imaging ... Corneal topography (Fig. 1) and biometry were obtained in preparation for cataract surgery in the left eye. ... Corneal refractive surgery. Cataract patients who have had previous corneal refractive surgery present a challenge. Given that ...
The corneal topography unit aids in the diagnosis and treatment of corneal disorders. ... Corneal topography. The ability to see the contour of the cornea, the transparent portion of the outer coat of the eyeball is ... The corneal topography unit projects a series of light rings onto the surface of the cornea. The separation between the rings ... The keratometer offers a limited evaluation of the cornea and is greatly enhanced by the corneal topography unit. The UIC Eye ...
Computer mapping of the cornea (corneal topography). *Schirmers test for eye dryness ... Corneal tissue engineering: new applications for corneal stromal stem cells (Doctoral dissertation, UCL (University College ... Kataguiri P, Kenyon KR, Batta P, Wadia HP, Sugar J. Corneal and external eye manifestations of systemic disease. In: Yanoff M, ... Early and late clinical landmarks of corneal dystrophies. Exp Eye Res. 2020;198:108139. PMID: 32726603 pubmed.ncbi.nlm.nih.gov/ ...
The surgical technique involves the creation of a hinged lamellar corneal flap, after which an excimer laser is used to make a ... Corneal Topography and the Corneal Modeling System. Mediguide Ophthalmology. 1991. 6:1-5. ... Screening for Corneal Topography Abnormalities before Refractive Surgery. Ophthalmology. 1994. 101:147-52. ... Topography-modified refraction (TMR): adjustment of treated cylinder amount and axis to the topography versus standard clinical ...
Corneal Topography. *Neuro-Ophthal Imaging. *Low Vision Aids. *Biometry. TSTC. Imaging Module. Smartphone Anterior Segment ...
Socioeconomic factors were more consistent predictors of keratoconus severity and corneal transplantation compared with ... Trends in Corneal Topography and Tomography Imaging for Keratoconus Management. Kong AW, Ahmad TR, Turner ML, Barnett J, Kaur G ... Corneal Cross-linking in Thin Corneas: 1-Year Results of Accelerated Contact Lens-Assisted Treatment of Keratoconus. Knyazer B ... The natural history of corneal topographic progression of keratoconus after age 30 years in non-contact lens wearers. Gokul A, ...
... corneal diseases and LASIK. He is an adjunct professor for several Colleges of Optometry, and routinely mentors optometry ...
Neural network classification of corneal topography. Preliminary demonstration.. Maeda N; Klyce SD; Smolek MK. Invest ...
Corneal topography by keratometry (1 August, 2000) Free W A Douthwaite, W T Evardson ... Corneal transplantation: how successful are we? (1 August, 2000) Free A WALDOCK, S D COOK ... Amniotic membrane transplantation for severe neurotrophic corneal ulcers (1 August, 2000) Free Hong-Jeng Chen, Renato T F Pires ... Cell subpopulations in failed human corneal grafts (1 August, 2000) Free D F P LARKIN ...
The pinhole test should be used in patients with corneal diseases such as keratoconus to determine whether optical aberrations ... whether the correction of residual defocus and irregular astigmatism might improve the visual acuity in patients with corneal ... P. Kanclerz, R. Khoramnia, and X. Wang, "Current developments in corneal topography and tomography," Diagnostics, vol. 11, no. ... Before hybrid lens fitting, a slit lamp examination, corneal topography, and anterior segment optical coherence tomography were ...
Corneal curvature measurement. *Corneal topography. *Retinal nerve fiber layer measurement. *Retinal thickness and topography ...
Corneal topography (including back surface). *Dry eye. *Pupil size. *Corneal thickness. *Wavefront analysis ...
CORNEAL TOPOGR. Entry Term(s). Topography, Corneal Videokeratography NLM Classification #. WW 220. Previous Indexing. Cornea/ ... Corneal Topography Preferred Term Term UI T058792. Date01/01/1999. LexicalTag NON. ThesaurusID NLM (1998). ... Corneal Topography Preferred Concept UI. M0029345. Scope Note. The measurement of curvature and shape of the anterior surface ... Topography, Corneal Term UI T058791. Date12/16/1996. LexicalTag NON. ThesaurusID NLM (1998). ...
Corneal Topography 100% * Acoustic Microscopy 51% * Crystalline Lens 46% * Eye 45% * Anterior Chamber 39% ...
... and corneal shape measurements with topography and/or tomography. Changes of these parameters should be measured over time. For ... with slight inferior corneal steepening. After only 2 years following the initial evaluation, corneal steepening had increased ... Fortunately, corneal collagen cross-linking is FDA-approved and has been shown in hundreds of clinical trials to effectively ... Because progression of keratoconus can occur in any patient, it is important that clinicians follow the corneal shape of ...
In terms of diagnosis, the advent of corneal topography, and more recently corneal tomography, has increased the ability of ... Management of corneal ectasia after LASIK with combined, same-day, topography-guided partial transepithelial PRK and collagen ... Steepening of the posterior corneal surface. *Thinning and/or an increase in the rate of corneal thickness change from the ... These devices can measure both anterior and posterior corneal surfaces, produce a corneal thickness map, and reconstruct the ...
I believe that patient education is key, so I often rely on visual aids in the clinic, especially irregular corneal topography ... My first priority is to measure corneal topography and wavefront aberrometry at the initial cataract consultation. There are ... As their corneal health improves (or doesnt), the lens choice becomes clearer. Typically, the more visits that are required to ... If the patient is interested in a presbyopia-correcting or even a toric IOL but the cornea demonstrates corneal staining and ...
For refractive corneal and refractive cataract, surgeons management of astigmatism is extremely important when it comes to ... which is best done with either topography or tomography. Nonetheless, the increasing prevalence of astigmatism in the interval ... To me, as a refractive corneal/cataract surgeon, this is a big drawback of the findings. In order to treat astigmatism (in ... He specializes in corneal and cataract surgery as well as laser refractive surgery. ...
A straightforward corneal implant provides the near vision patients want. ... Tests are the same as LASIK: corneal topography, corneal tomography, and optical or ultrasound pachymetry, as well as ... The corneal flap is then replaced.. I have performed about 50 Raindrop procedures, and the outcomes have been excellent. ... The surgeon makes a flap using a femtosecond laser at 30% of the corneal thickness, somewhat deeper than a standard LASIK flap ...
ESHE-6000 - Corneal Topography. *Measuring method: Placido cone. *Coverage:10.91mm(Diameter) ...
Corneal Topographies Topographies, Corneal Topography, Corneal Videokeratography - Related but not broader or narrower Concept ... Corneal Topographies. Topographies, Corneal. Topography, Corneal. Videokeratographies. Videokeratography. Tree number(s):. ... Corneal Topography - Preferred Concept UI. M0029345. Scope note. The measurement of curvature and shape of the anterior surface ... This measurement is often applied in the fitting of contact lenses and in diagnosing corneal diseases or corneal changes ...
CORNEAL TOPOGR. Entry Term(s). Topography, Corneal Videokeratography NLM Classification #. WW 220. Previous Indexing. Cornea/ ... Corneal Topography Preferred Term Term UI T058792. Date01/01/1999. LexicalTag NON. ThesaurusID NLM (1998). ... Corneal Topography Preferred Concept UI. M0029345. Scope Note. The measurement of curvature and shape of the anterior surface ... Topography, Corneal Term UI T058791. Date12/16/1996. LexicalTag NON. ThesaurusID NLM (1998). ...
search information related to IOL, biometry, corneal topography. Theres Nothing Here.... We cant find the page youre looking ...
Prior to that, Ram founded Tomey Technology Inc., that pioneered the corneal topography imaging technology that is now a ... Ram co-developed an innovative corneal implant device for presbyopia and licensed the technology to (venture funded) Acufocus, ...
A corneal topography exam allows the doctor to detect signs of corneal diseases and irregular corneal conditions such as:. * ... A contact lens exam may include a corneal topography exam and a tear film evaluation, in addition to tests performed during a ...
2005). Curvature sensor for the measurement of the static corneal topography and the dynamic tear film topography in the human ...
  • To present the results after simultaneous photorefractive keratectomy (PRK) followed by corneal collagen cross-linking (CXL) for progressive keratoconus. (keratoconuscanada.org)
  • Twelve patients (14 eyes) with progressive keratoconus were prospectively treated with customized topography-guided PRK with the Pulzar Z1 (wavelength 213 nm, CustomVis) immediately followed by corneal collagen CXL with the use of ribofl avin and ultraviolet A irradiation. (keratoconuscanada.org)
  • Keratoconus is a progressive corneal disorder that can lead to severe vision deterioration through the development of irregular astigmatism and corneal scarring. (keratoconuscanada.org)
  • The irregular astigmatism in keratoconus can be confronted with the use of customized laser ablations that restore the refractive properties of the anterior corneal surface. (keratoconuscanada.org)
  • The application of customized topography-guided surface ablation has been reported in patients with stable or subclinical keratoconus with promising visual outcomes.6-8 The disadvantage of ablative procedures is that tissue removal might lead to further destabilization of corneal biomechanics and progression of the ectatic disorder. (keratoconuscanada.org)
  • In this case series, we present a new technique and the results of simultaneous customized topography-guided surface ablation followed by CXL in patients with keratoconus. (keratoconuscanada.org)
  • Inclusion criteria were progressive keratoconus, hard contact lens and full spectacle correction intolerance, expected central corneal thickness (CCT) after PRK 400 μm, and no other corneal pathological signs. (keratoconuscanada.org)
  • Outcomes included severe keratoconus at presentation (steep keratometry ≥52 diopters), disease progression (≥0.75 diopters increase from the first to the most recent clinical visit), and corneal transplantation. (nih.gov)
  • Trial rigid lens fitting is considered the best approach to determine whether the correction of residual defocus and irregular astigmatism might improve the visual acuity in patients with corneal disorders including keratoconus. (hindawi.com)
  • The pinhole test should be used in patients with corneal diseases such as keratoconus to determine whether optical aberrations associated with the disease cause their visual impairment. (hindawi.com)
  • The development of interventions such as cornea crosslinking, photorefractive keratectomy, intrastromal corneal ring segment implantations, and combined treatment provide clinicians with a range of treatment options for visual rehabilitation in patients with keratoconus [ 2 - 4 ]. (hindawi.com)
  • 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. (nih.gov)
  • Fortunately, corneal collagen cross-linking is FDA-approved and has been shown in hundreds of clinical trials to effectively halt progression of keratoconus in most patients by strengthening the cornea, which stabilizes and often improves the corneal shape. (ophthalmologytimes.com)
  • Because progression of keratoconus can occur in any patient, it is important that clinicians follow the corneal shape of patients with keratoconus over time, to help identify progression. (ophthalmologytimes.com)
  • Despite extensive knowledge regarding the diagnosis and management of keratoconus and ectatic corneal diseases, many controversies still exist. (lww.com)
  • Corneal Collagen Crosslinking - a procedure used for the treatment of early to moderate keratoconus and other types of ectasia that can happen after refractive surgery. (columbiadoctors.org)
  • He gave two talks about corneal inlays for the treatment of presbyopia and corneal ring segments for the treatment of keratoconus. (doctorawwad.com)
  • Conclusions: The 揃harat� Protocol to arrest keratectasia progression and improve corneal regularity is a safe and efficacious alternative as a keratoconus management option. (who.int)
  • A hard contact lens trial may help determine the contribution of corneal aberrations to the patient's decreased vision, although visual disturbances are often the result of the combined effects of the lens and cornea. (aao.org)
  • The ability to see the contour of the cornea, the transparent portion of the outer coat of the eyeball is an important tool in the identification of corneal disorders. (uic.edu)
  • The keratometer offers a limited evaluation of the cornea and is greatly enhanced by the corneal topography unit. (uic.edu)
  • The corneal topography unit projects a series of light rings onto the surface of the cornea. (uic.edu)
  • For corneal shape, comparison maps, also called difference maps, can help highlight areas of the cornea that change shape over time. (ophthalmologytimes.com)
  • The difference map demonstrated that the steep part of the cornea became steeper, and the flap part of the cornea flattened further, resulting in a significant worsening of irregular corneal astigmatism that resulted in loss of best-corrected vision. (ophthalmologytimes.com)
  • If the patient is interested in a presbyopia-correcting or even a toric IOL but the cornea demonstrates corneal staining and irregular topography, I am hyper-aggressive in optimizing the ocular surface. (crstodayeurope.com)
  • In my experience, these patients, if compliant, will quickly separate into two groups: those who return with a cornea that is almost completely normalized (objectively and topographically) and those who return with ongoing corneal pathology. (crstodayeurope.com)
  • Typically, the more visits that are required to normalize the cornea and topography, the less willing I am to implant a diffractive IOL. (crstodayeurope.com)
  • Phototherapeutic keratectomy (PTK) - surgery which can treat recurrent corneal erosions, remove some corneal scarring, and treat certain cornea dystrophies. (columbiadoctors.org)
  • Average central corneal thickness is about 550 µm, increasing to about 700 µm in the periphery. (medscape.com)
  • The surgeon makes a flap using a femtosecond laser at 30% of the corneal thickness, somewhat deeper than a standard LASIK flap. (crstoday.com)
  • INTRODUCTION: Corneal thinning and changes in the corneal thickness profile are major symptoms of corneal ectasia. (bvsalud.org)
  • Preoperative topography shows minimal astigmatism in the left eye of the patient described in the case example. (aao.org)
  • What about posterior corneal astigmatism? (medscape.com)
  • For refractive corneal and refractive cataract, surgeons' management of astigmatism is extremely important when it comes to delivering outcomes. (medscape.com)
  • In order to treat astigmatism (in cataract surgery), it is important to quantify the amount and regularity of corneal astigmatism, which is best done with either topography or tomography. (medscape.com)
  • Screening for corneal irregularities us-ing topography, tomography, or other advanced imaging is recommended in patients considering MF-IOL correc-tion. (aao.org)
  • Evaluations should typically include uncorrected and best-corrected visual acuity, refraction, and corneal shape measurements with topography and/or tomography. (ophthalmologytimes.com)
  • Tests are the same as LASIK: corneal topography, corneal tomography, and optical or ultrasound pachymetry, as well as evaluation for dry eye including tear osmolarity and meibography. (crstoday.com)
  • Each patient underwent a standard ophthalmological examination (visual acuity, tonometry, slit lamp examination, fundus biomicroscopy), a corneal topography with OCULUS Keratograph 5M, and an anterior segment optical coherence tomography with RTVue-100. (bvsalud.org)
  • Therefore, they have been also successfully used to treat other corneal ectasias, including irregular corneas following photorefractive surgery, penetrating keratoplasty, and corneal dystrophies [ 10 - 12 ]. (hindawi.com)
  • I believe that patient education is key, so I often rely on visual aids in the clinic, especially irregular corneal topography images, to demonstrate how keratopathy affects the accuracy of IOL calculations. (crstodayeurope.com)
  • The surgical technique involves the creation of a hinged lamellar corneal flap, after which an excimer laser is used to make a refractive cut on the underlying stromal bed. (medscape.com)
  • Pallikaris developed the technique of performing the excimer laser corrective ablation in the corneal stromal bed under a hinged flap. (medscape.com)
  • We decided to compare, using atomic force microscopy (AFM), the roughness of the corneal stromal bed, after a femtosecond lasers device flap was created with or without an excimer myopic ablation. (bvsalud.org)
  • Descemet's stripping endothelial keratoplasty (DSEK) - a partial corneal transplant to treat for corneal edema or swelling. (columbiadoctors.org)
  • Besides the indices automatically generated by the software of the device, we measured the following custom parameters: partial corneal area (PCA), partial chamber area (PCA), and an index that reflects the relation between the two (CpC). (bvsalud.org)
  • He has been published several times and lectures nationally on various topics including OSD, dry eye, cataract surgery, pharmacology, corneal diseases and LASIK. (aaopt.org)
  • AIM: To determine the diagnostic value of newly developed custom anterior segment OCT indices in diagnosing corneal ectasia. (bvsalud.org)
  • PATIENTS AND METHODS: Two sets of patients were included in the current study - healthy controls in the first and patients with corneal ectasia in the second, 80 eyes per group of 43 patients each. (bvsalud.org)
  • Early and late clinical landmarks of corneal dystrophies. (medlineplus.gov)
  • We analyzed visual outcomes, Scheimpflug topography, and corneal haze evaluation. (who.int)
  • Burratto's original work involved performing a corrective excimer laser ablation on the back of a resected disc of corneal tissue. (medscape.com)
  • Mittal, Vikas Abstract: Purpose: Outcome of topography?guided excimer laser ablation in conjunction with accelerated, high?fluence cross?linking in corneal ecstatic disease using the NIDEK CXIII equipped with CATz algorithm from the FinalFit software棓Bharat Protocol. (who.int)
  • He specializes in corneal and cataract surgery as well as laser refractive surgery. (medscape.com)
  • Among the growing number of options that are intended to decrease spectacle dependence-including mono-vision, mini-monovision, accommoda-tive IOLs, corneal inlays, and bioptic re-finements-multifocal IOLs (MF-IOLs) continue to play an important role. (aao.org)
  • 2005). Curvature sensor for the measurement of the static corneal topography and the dynamic tear film topography in the human eye . (city.ac.uk)
  • RGP lenses have the benefit of masking corneal irregularities, thus providing a regular anterior refractive surface [ 10 ]. (hindawi.com)
  • Campos, Mauro Abstract: Purpose: Compare the safety and efficacy of wavefront?guided photorefractive keratotomy (PRK) 6 months after cross?linking (CXL) to wavefront?guided PRK alone for refractive correction in patients with bilateral asymmetric corneal topography. (who.int)
  • The workhorse of my evaluation is the OPD-Scan III (Nidek) to assess corneal aberration profiles and Placido disc mires. (crstodayeurope.com)
  • Jose Barraquer is generally credited with much of the early work leading to corneal lamellar refractive procedures as they are currently practiced. (medscape.com)
  • Characterizing corneal aberrations is helpful when selecting IOLs. (aao.org)
  • Analysis of corneal aberrations may guide the decision to implant a mono-focal IOL with aspheric offsets (zero or negative) to neutralize spherical aberrations. (aao.org)
  • There are many devices that provide topography and concomitant measurement of higher-order aberrations in one capture that are excellent. (crstodayeurope.com)
  • Logistic regression was used to evaluate factors associated with severity at presentation and corneal transplantation. (nih.gov)
  • Corneal transplantation: how successful are we? (bmj.com)
  • However, as currently practiced, it is perhaps best thought of as photorefractive keratectomy (PRK) performed under a flap instead of on the corneal surface. (medscape.com)
  • The corneal flap is then replaced. (crstoday.com)
  • A straightforward corneal implant provides the near vision patients want. (crstoday.com)
  • A contact lens exam may include a corneal topography exam and a tear film evaluation, in addition to tests performed during a comprehensive eye exam. (advantagedental.com)
  • 11. Neural network classification of corneal topography. (nih.gov)
  • As their corneal health improves (or doesn't), the lens choice becomes clearer. (crstodayeurope.com)
  • For patients at high risk of progression, cross-linking should be considered as a first step to prevent worsening of the corneal shape, which can lead to permanent visual loss. (ophthalmologytimes.com)
  • AFM imaging of the remaining corneal stroma was performed. (bvsalud.org)
  • MF-IOLs should not be placed in eyes with significant oph-thalmic comorbidities such as retinop-athy, corneal disease, uveitis, and optic neuropathy. (aao.org)
  • Two patients in the CXL + PRK group presented corneal haze. (who.int)
  • Nonsurgical and surgical treatments for these conditions, including the use of corneal cross-linking and corneal transplantations, were presented in a stepwise approach. (lww.com)
  • Ten different square areas of 20 µm x 20 µm at the central area of the stroma of each corneal sample were studied. (bvsalud.org)
  • Conversely, if he had used indentation tonometry, it would not have considered the misclassification resulting from the presence of a thin central corneal (1). (cdc.gov)