Aniseikonia: A condition in which the ocular image of an object as seen by one eye differs in size and shape from that seen by the other.Vision Tests: A series of tests used to assess various functions of the eyes.Lenses: Pieces of glass or other transparent materials used for magnification or increased visual acuity.Epiretinal Membrane: A membrane on the vitreal surface of the retina resulting from the proliferation of one or more of three retinal elements: (1) fibrous astrocytes; (2) fibrocytes; and (3) retinal pigment epithelial cells. Localized epiretinal membranes may occur at the posterior pole of the eye without clinical signs or may cause marked loss of vision as a result of covering, distorting, or detaching the fovea centralis. Epiretinal membranes may cause vascular leakage and secondary retinal edema. In younger individuals some membranes appear to be developmental in origin and occur in otherwise normal eyes. The majority occur in association with retinal holes, ocular concussions, retinal inflammation, or after ocular surgery. (Newell, Ophthalmology: Principles and Concepts, 7th ed, p291)Ocular Physiological Phenomena: Processes and properties of the EYE as a whole or of any of its parts.Diagnosis, Computer-Assisted: Application of computer programs designed to assist the physician in solving a diagnostic problem.Vision, Binocular: The blending of separate images seen by each eye into one composite image.Lenses, Intraocular: Artificial implanted lenses.
Physiology - Latest research and news | NatureAssociations of aniseikonia with metamorphopsia and retinal displacements after epiretinal membrane surgery. *Y Ichikawa*, Y ...
Grady M. Hughes, MD | Swedish Medical Center Seattle and IssaquahGrady M. Hughes, MD is a specialist in Ophthalmology who has an office at 1600 East Jefferson Street Suite 202 in Seattle, WA and can be reached at 206-320-5686.
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Extração do cristalino transparente e uso de lente intraocular tórica SN60T5 AcrySof Toric em ceratocone grau 2Predicting refractive aniseikonia after cataract surgery in anisometropia. J Cataract Refract Surg. 2008;34(8):1353-61. [ Links ...
Anisometropic amblyopia | definition of anisometropic amblyopia by Medical dictionaryThis induces a sufficient difference in image size (aniseikonia) that the two images cannot be fused. To avoid confusion, the ...
Vision GlossaryAniseikonia- a difference in the size or shape of two visual images when the images should be the same size and/or shape. ...
Anise seed | definition of anise seed by Medical dictionaryLooking for online definition of anise seed in the Medical Dictionary? anise seed explanation free. What is anise seed? Meaning of anise seed medical term. What does anise seed mean?
Ophthalmology | Ophthalmologist: OPTICS and RefractionANISEIKONIA ( 1 ) Arcus senilis ( 1 ) Basal cell carcinoma ( 1 ) CORNEAL OEDEMA ( 1 ) Cornea guttata ( 1 ) EMBRYONIC LAYERS ( 1 ...
Sight Blindness Seeing and Vison Problems... aniseikonia. The brain can eliminate double vision by ignoring all or part of the image of one of the eyes. The area of a ...
All 12-letter words containing Letters A, A, O, S and SANALYSATIONS ANAMORPHISMS ANAMORPHOSES ANAMORPHOSIS ANAPLASMOSES ANAPLASMOSIS ANASTOMOSING ANASTROZOLES ANISEIKONIAS ...
Accommodative Intraocular Lens (Frontier Vision)The accommodative intraocular lens 1 include an optical section 10 of a lens, and a lens supporting section 20 provided at the peripheral portion of the optical section 10. The lens supporting section 20 includes one end portion 201 connected to the peripheral portion of the optical section 10 via
Patent US6969403 - Accommodative intraocular lens - Google PatentsA two-optic accommodative lens system. The first lens has a negative power and is located posteriorly against the posterior capsule. The periphery of the first optic contains a pair of clasps. The second optic is located anteriorly to the first optic and is of a positive power. The peripheral edge of the second optic contains a pair of locking arms that fit into the clasps contained on the periphery of the first optic to lock the second optic onto the first optic, but allow for rotation of the arms within the clasps. Hinge structures on the locking arms allow the second optic to move relative to the first optic along the optical axis of the lens system in reaction to movement of the ciliary muscle.
AniseikoniaLandolt CMicromirror device: Micromirror devices are devices based on microscopically small mirrors. The mirrors are Microelectromechanical systems (MEMS), which means that their states are controlled by applying a voltage between the two electrodes around the mirror arrays.Epiretinal membraneComputer-aided diagnosis: In radiology, computer-aided detection (CADe), also called computer-aided diagnosis (CADx), are procedures in medicine that assist doctors in the interpretation of medical images. Imaging techniques in X-ray, MRI, and Ultrasound diagnostics yield a great deal of information, which the radiologist has to analyze and evaluate comprehensively in a short time.Binocular vision: Binocular vision is vision in which creatures having two eyes use them together. The word binocular comes from two Latin roots, bini for double, and oculus for eye.Intraocular lens power calculation: The aim of an accurate intraocular lens power calculation is to provide an intraocular lens (IOL) that fits the specific needs and desires of the individual patient. The development of better instrumentation for measuring the eye's axial length (AL) and the use of more precise mathematical formulas to perform the appropriate calculations have significantly improved the accuracy with which the surgeon determines the IOL power.
(1/16) Saccade amplitude disconjugacy induced by aniseikonia: role of monocular depth cues.
The conjugacy of saccades is rapidly modified if the images are made unequal for the two eyes. Disconjugacy persists even in the absence of disparity which indicates learning. Binocular visual disparity is a major cue to depth and is believed to drive the disconjugacy of saccades to aniseikonic images. The goal of the present study was to test whether monocular depth cues can also influence the disconjugacy of saccades. Three experiments were performed in which subjects were exposed for 15-20 min to a 10% image size inequality. Three different images were used: a grid that contained a single monocular depth cue strongly indicating a frontoparallel plane; a random-dot pattern that contained a less prominent monocular depth cue (absence of texture gradient) which also indicates the frontoparallel plane; and a complex image with several overlapping geometric forms that contained a variety of monocular depth cues. Saccades became disconjugate in all three experiments. The disconjugacy was larger and more persistent for the experiment using the random-dot pattern that had the least prominent monocular depth cues. The complex image which had a large variety of monocular depth cues produced the most variable and less persistent disconjugacy. We conclude that the monocular depth cues modulate the disconjugacy of saccades stimulated by the disparity of aniseikonic images. (+info)
(2/16) Disconjugate oculomotor learning caused by feeble image-size inequality: differences between secondary and tertiary positions.
In order to examine the minimum value of image-size inequality capable of inducing lasting disconjugacy of the amplitude of saccades, six normal emmetropic subjects were exposed for 16 min to 2% image size inequality. Subjects were seated at 1 m in front of a screen where a random-dot pattern was projected and made saccades of 7.5 and 15 deg along the horizontal and vertical principal meridians and to tertiary positions in the upper and lower field. During the training period, compensatory disconjugacy of the amplitude of the saccades occurred for the principal horizontal and vertical meridians; such increased disconjugacy persisted after training, suggesting learning. In contrast, for horizontal saccades to or from tertiary positions made in the upper and lower field, no consistent changes in the disconjugacy occurred, either during training or after the training condition. In an additional experiment, three subjects read sequences of words with the 2% magnifier in front of their dominant eye: in such a task, horizontal saccades to or from tertiary positions at the upper or lower field showed appropriate and lasting disconjugacy for two of the three subjects. We conclude that even a 2% image size inequality stimulates oculomotor learning, leading to persistent disconjugacy of saccades. The small disparity created by the image-size inequality is thus compensated by the oculomotor system rather than tolerated by the sensory system (e.g. by enlarging the Panum's area). (+info)
(3/16) Differences in tests of aniseikonia.
The New Aniseikonia Test (NAT), a hand-held direct-comparison test using red/green anaglyphs, has several potential advantages as a screener. We compared the validity of the NAT to that of the Space Eikonometer in three experiments: (1) aniseikonia was induced by calibrated size lenses in a double-blind study of 15 normal subjects; (2) habitual aniseikonia was measured with both instruments in four patients; and (3) eight of the normal subjects were retested with a computer-video simulation of the NAT. The NAT underestimated induced aniseikonia by a factor of 3 in the normal subjects and underestimated habitual aniseikonia in four patients. The Space Eikonometer correctly measured the magnitude of induced aniseikonia in the normal subjects. The simulation test did not show underestimation in the eight normal subjects. We could not attribute the NAT's underestimation of aniseikonia to the red/green anaglyph method, printing error, psychophysical method, or the direct-comparison test format. We speculate that the NAT induces a different sensory fusion response to aniseikonia than do the other tests, and that this altered sensory fusion response diminishes measured aniseikonia. We conclude that the NAT is not a valid measure of aniseikonia. (+info)
(4/16) Aniseikonia associated with epiretinal membranes.
AIMS: To determine whether the computerised version of the new aniseikonia test (NAT) is a valid, reliable method to measure aniseikonia and establish whether aniseikonia occurs in patients with epiretinal membranes (ERM) with preserved good visual acuity. METHODS: With a computerised version of the NAT, horizontal and vertical aniseikonia was measured in 16 individuals (mean 47 (SD 16.46) years) with no ocular history and 14 patients (mean 67.7 (14.36) years) with ERM. Test validity was evaluated by inducing aniseikonia with size lenses. Test reliability was assessed by the test-retest method. RESULTS: In normal individuals, the mean percentage (SD) aniseikonia was -0.24% (0.71) horizontal and 0% (0.59) vertical. Validity studies revealed mean (SD) 0.990 (0.005) horizontal and 0.991 (0.004) vertical correlation coefficients, 0.985 (0.111) horizontal and 0.989 (0.102) vertical slope. Repeatability coefficients were 1.04 horizontal and 0.88 vertical. Aniseikonia in patients with ERM ranged from 4% to 14%. Eight patients showed 2% or more size difference between horizontal and vertical meridians. CONCLUSIONS: The aniseikonia test used in this study can be considered a simple, fast, valid and reliable method to measure the difference in image size perceived by each eye. Aniseikonia does occur in symptomatic patients with ERM. The effect of ERM on image size is heterogeneous across the retinal area affected. (+info)
(5/16) Validity and repeatability of a new test for aniseikonia.
PURPOSE: The Aniseikonia Inspector 1.1 (AI) is a new software product to measure aniseikonia using red-green anaglyphs. The purpose of this study was to test whether the AI is a valid and reliable test. METHODS: There were two groups of sample subjects: one at risk of aniseikonia, with anisometropia greater than or equal to 1.00 D (n= 29), and a control group (n= 45). The validity was studied by comparing the measured aniseikonia with the aniseikonia simulated with size lenses. The reliability was estimated by the Bland-Altman statistical method. RESULTS: The results showed that the AI underestimated aniseikonia and that the underestimation was greater in the horizontal than in the vertical direction. The reliability was low, with biases that were clinically insignificant, but the 95% limits of agreement were around +/-2%. The behavior of the test was similar in both groups of subjects. CONCLUSIONS: The reliability of the AI is only moderate, and professionals are therefore warned to use the results of this test with caution. (+info)
(6/16) Effect of aniseikonia on fusion.
Physiological aniseikonia is the basis of stereopsis but beyond certain limits it becomes an obstacle to fusion. It is not well established as to how much aniseikonia can be tolerated by the fusional mechanism. Different tests under different testing conditions have given a wide range of variation. On the synoptophore we had observed tolerance upto 35% aniseikonia in some cases. Under more physiological conditions on a polaroid dissociation stereoprojector we observed lesser baseline fusional vergences but tolerance in about 70% of the cases upto 30% aniseikonia while 25% could tolerate even 35% aniseikonia. However we realise that these indicate the maximal potential and not the symptom free tolerable limits. (+info)
(7/16) Magnifications of single and dual element accommodative intraocular lenses: paraxial optics analysis.
(8/16) The effect of lens-induced anisometropia on accommodation and vergence during human visual development.
Can't get a comfortable prescription! Where should I look next?
- Basic problem is that after a handful of prescriptions I still haven't gotten something comfortable. Here are my old numbers (which I wore for 4 years, but which started giving me problems after I went without correction of any sort for ~8 months): OD -3.25 -1.25 x30 OS -0.75 -3.00 x0 Here are my new numbers: OD -4.00 -1.50 x30 OS 0.75 -3.00 x0 So the left lens has been kept identical, right lens has both increased cylindrical and spherical correction with identical axis. I've gone back to the optometrist for a recheck and ended up adding 5 degrees to both the OS and OD and tried all four combinations, each causing a strange new variety of strain and peripheral distortion. The nature of it hasn't seemed to make much sense, either. For instance, I add 5 degrees to the right eye and the left eye starts to feel strange, or add 5 degrees to both eyes and I start to feel a kind of deadness on one side of my visual field. Only thing I haven't tried yet, with this doctor, is lowering the cylindrical/spherical correction on the OD (-3.75 -1.00 or something like that). I'm not really getting diplopia, just trouble reading, scanning, and visuospatial confusion that doesn't go away after a week. My eyes are diverging and I have a feeling that I'm going to need to find a doctor that can at least address the disparity. My current doctor might not be the answer; I heard him say that he chose some nondescript high index material for the left side and polycarb for the right, with the simple rationale that for lenses with very low cylindrical, high index material doesn't affect the lens thickness enough to justify the extra cost. He also did not measure my P.D. Aren't both of these things important to take under consideration for cases of possible aniseikonia? Knapp's law and matching materials, at the very least? What sort of optometrist should I look for, how concerned should I be about the material used for the lenses (I've never SEEN so much chromatic distortion out of the corners of a lens as out of this polycarb right lens, and I'm not making this up) and what are some other possible culprits?
- As your optometrist, I would likely decrease the power in your right eye (maybe even down to a -3.50) to maintain the balance between the eyes. Your eyes are used to the balance they used to have so new glasses may be disrupting that. I would ask you new doc to 'trial-frame' the lenses so you can try different Rx's BEFORR you buy. I do this all the time with great results. Changing the axis 5 degrees here and there will do nothing. I would find a new optomtrist. This is entirely an optometrist's domain and we study for these things for 4 years, including things like convergence/divergence. Ophtalmologists take something like a one monht course on refractions (finding the prescription) so come see us (the specialists in this) and just find a new doc. Good Luck and pass along my info to them :)
Closer to finding comfortable eyeglasses. What next?
- So I'm astigmatic in one eye and myopic in the other. I'm getting closer to glasses that don't drive me nuts, but I'm not quite there. It seems that I'm VERY sensitive to small changes (probably because I do a lot of visually-oriented detail work,) which has perhaps made things more difficult. Here's the most comfortable old prescription I've been able to use: OD: -3.00 -1.50 x20 OS: -0.75 -3.00 x175 Unfortunately, they've always given me this strange, glassy-eyed impossible to concentrate feeling.. My newer glasses have been worse in terms of strain, but without the glassy-eyedness. Those numbers were like so: OD: -4.00 -1.50 x25 OS: -0.75 -3.00 x175 Before dropping that doctor I asked him to low the OD back down to -3.25 -1.50 x25, and it made no difference to the strain. I learned that he'd used polycarb in the OD and high index in the OS so I suspected this to be the culprit and ran. Why you'd use materials with different optical properties in somebody already at risk for aniseikonia boggles my mind. So I recently went to a handful of different optometrists looking for some answers, competence, and a new prescription and chose only one to order a new pair of glasses. He was one of only two doctors who insisted I was overcorrected on the OS, as opposed to undercorrected. My current glasses look like this: OD: -3.75 N OS: N -3.00 x175 The simple fact was that I could still see 20/20 without any spherical correction in that eye at all. The result was quite satisfying and much more comfortable than the old one. The new doctor also dropped the cylindrical in the OD, which he admitted I *did* need. The reason it's not there is that, after seeing that I was feeling a lot of subjective difference in binocular comfort between 25 and 28 degrees in that eye, he decided that it may have hurt more than it helped, and decided to get rid of it. This was a BIG mistake, as now that eye can't get a clear image even at close distances and it is extremely distracting when using both eyes. Unfortunately, although the most comfortable OD I've ever had by far is -3.00 -1.50 x20, several doctors (including, ironically, my current one who left me with an even blurrier OD) heavily discourages me because it's less than what I need. Moreover, computer and subjective results at the office both place me at closer to x28, even though I can swear from old lenses that x20 is just a little bit crisper somehow. Perhaps I'd be willing to split the difference. There's also something else: For the OS, I've noticed that at 180 it ends up being blurry on the left part of the lens at at 175 it goes blurry on the right, suggesting to me that the angle that would give me enough leeway for lens distortion (and which is also probably the most correct angle) would be about 177 or 178. But from my experience, nobody will believe that anything less than 5 degrees makes any difference at all. Some doctors/labs even seem to round to the nearest multiple of five. So basically, the best balance of crispness and comfort would seem to be yielded by the following prescription: OD: -3.00 -1.50 x24 (or x20 if I want to just copy the old lens and leave it at that) OS: N -3.00 x177 But am I crazy or what? I feel like the most irritating patient alive. How should I be approaching this? My current doctor already switched me from 180 to 175 on the OD because 180 created constant blurriness while reading and even then he was surprised it made any difference at all. Plus, he'd already discouraged keeping the spherical in the OD so low. What do some other professionals think?
- Just come in for an exam. I can help.