| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (RK) Baylor College of Medicine, Houston, Texas |
| Transcript |
Today I'm going to be talking about dominant optic atrophy, DOA, and DOA is usually from OPA-the optic atrophy gene, and there area number of these. Number one is the most common, but there's number one, and number three, and all sorts of different numbers ,but really the number one is the most common cause of the dominant optic atrophy. It comes to us, you know, usually in a child, and usually it's noticed first at school age because the kid doesn't know that their vision isn't what it's supposed to be. So if you're 20/50, but you were born 20/50,you really don't notice that until you get to school, and sometimes it doesn't present until later because the visual demand is higher as you're getting further and further along in school. So, a kid might think they're normal up until school age and the key and differentiating features of the OPA one are it's bilateral, so we really shouldn't be making the diagnosis if it is only in one eye. And the field defect is usually central scotoma or cecocentral scotoma, but it can be any nerve fiber layer type field defect, and it's very hard to test the field on a kid, so that even a teenager might have a trouble with doing the Humphrey visual field, which requires some effort, so you probably should do a couple fields on the person before you judge whether they have a central/cecocentral scotoma or just diffuse generalized depression. And the rest of the exam should be normal including the intraocular pressure, but one of the curious things about autosomal dominant optic atrophy is it produces cupping, and so that can look like glaucoma. So it's a pseudo-glaucomatous cupping, and the cup to disk ratio is typically greater than 0.5 in these people. And they have the same thing as glaucoma: they have this peripapillary atrophy or might have this grayish crescent around the nerve, and they have saucerization of the disc so it's very shallow cupping to the to the rim and then the remaining rim is pale. So, that's different than glaucoma. So, the things that suggest that is not glaucoma are number one, it's a kid, and so glaucoma in a kid outside of congenital glaucomas would be rare. Number two, their intraocular pressure is going to be normal. Number three, their field is not a glaucomatous field, it's like a central scotoma or a cecocentral scotoma, as opposed to the inferior nasal step and the arcuate-type field defects of glaucoma. And number four, their central acuity is going to be affected, as opposed to glaucoma, which is not affecting the central acuity until very, very late. There's going to be rim power, and that rim power is going to be seen on the OCT as papillomacular bundle nerve fiber layer loss. So the retinal nerve fiber layer will be thinner right in the temporal portion which is the papillomacular bundle. So that's going to be seen ophthalmoscopically as temporal pallor in the rim, and it can cause pseudo-glaucomatous cupping greater than 0.5 cup to disk ratio. So, if you've got a kid with decreased acuity, central scotoma, saucerization, rim power, bilateral, symmetric, because it's usually dominant we want to get the family history. And so if, if we'd like to have three generations: passing from male to male or male to female in an autosomal dominant pattern. So OPA1 is autosomal dominant. And the main reason to test this person is to end the cycle of testing and to give the patient a diagnosis. Also it affects the other family members, so they have to undergo genetic counseling. About 20%of these people have OPA1 plus-they have other stuff, other nerves that are involved: a hearing loss or they might have other neurologic symptoms, but most of the patients it's just isolated optic atrophy. Most of the time the vision hovers around 20/50. That's probably 40%of the cases. And then another 40%between20/50and,say,20/100,and then less than 20%of the cases are less than 20/200vision.So,you can reliably tell these people that they're not going to go completely blind-that we usually end up in a range of useful vision still that can be low vision. And the OPA1,even though it's a nuclear gene, codes for mitochondrial fusion proteins, so we'd probably like to avoid the mitochondrial stimulants, and we'd like to tell them a little bit about the prognosis and to watch out for OPA plus |
