||Andrew G. Lee, MD, Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, TX; Professor of Ophthalmology, Weill Cornell Medicine; Sami Younes, Baylor College of Medicine Class of 2022
||So today we're going to be talking about amblyopia, and you might be asking yourself why would an adult neuro-ophthalmologist need to know about amblyopia. And the problem is,patients who are children who have amblyopia grow up and end up in neuro-ophthalmology clinic. And so, when a patient who's an adult says they have a history of a lazy eye, we'd like not to be a lazy doctor and actually figure out if it really is amblyopia or not. And so in order for me to accept this diagnosis of amblyopia in an adult, we have to have some assurance that it really is amblyopia, which means there has been a disruption in the fusion pathway and the maturation of the visual symptoms system prior to some critical age, say age 7 or so. And that allowed the eye not to form properly a connection with the brain. And there's actually nothing wrong with this eye; it has just never formed a connection properly. And so in an adult patient who says I have a past medical history of a lazy eye, we'd like to know (number one) what was the amblyogenic etiology. And what that means is what was the cause, the genesis, of the amblyopia. And we have very limited causes for amblyopia. You can either be strabismic, so the eye was turned in or turned out. They may have had surgery for that strabismus in childhood or patching. We can have deprivation, which means they have a cataract or corneal opacity or something that was blocking the visual pathway, or ptosis. We can have anisometropia, and anisometropia means see(-opia), the measurement(metr-), the same(iso), and not(an-). So it's not the same measurement between the two eyes. And so if one eye is highly myopic or has a high astigmatism and the other eye doesn't, and we don't correct that refractive error early enough in childhood before the critical age for amblyopia development, that degree of anisometropia is an amblyogenicetiology. And then some people are ametropic, which just means you have a high refractive error (it's not -metropic). But if you didn't get your first pair of glasses until you're 20 or 18 then that's past the critical age of formation. And so one of the first things we want to do is establish that there's been an amblyogenic etiologyin childhood for this. Number two, it has to remain static. So amblyopia is a static process. It really can't keep getting worse and worse and worse. Whatever vision you had in childhood or in the record is what you have, and generally we really shouldn't be worse than count fingers level of vision. So once you start getting the hand motion or if your light perception or no light perception, that really isn't compatible with amblyopia. So even if they say "that's my lazy eye"and the lazy eye happens to be no light perception or light perception, that really probably is not amblyopia. Number three, we want to make sure that there's no organic pathology causing the problem. And even though you can have a small RAPD in amblyopia, like a 0.3 log unit RAPD, if you have a big RAPD, you really should be worried that that is not amblyopia. And if we see optic atrophy, obviously that's not amblyopia. There's an organic cause for them. Or optic disc edema; that's not allowed. And if you have a visual field defect. So in amblyopia we're just gonna have generalized depression of the field. There's actually no defect in the field; it's just a maturation problem. So if we have central scotoma, altitudinal field defect,arcuate,homonymous,any kind of field defect,none of these things are gonna be compatible with amblyopia, which doesn't produce optic neuropathy signs like this. And so really when we're confronted with the lazy eye patient,don't be lazy.In order to establish amblyopia in an adult, start with an established amblyogenic etiology (strabismus, deprivation, anisometropia, or ametropia), prove that its been static over time, make sure its not LP or NLP vision, and look for evidence for an optic neuropathy. And once you've done all that, you've met your obligation for adult amblyopia.