| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York |
| Transcript |
"So, today we're going to be talking about how OPA1, which is the optic atrophy gene for dominant optic atrophy, can show up in adults, and can be mistaken for or be combined with possible primary open-angle glaucoma, or mistaken for juvenile open-angle glaucoma. And normally, you'd think you'd be able to tell these things apart. However, they share some similarities, and then I'll highlight the differences and show you how this comes to be. So normally, when you have primary open-angle glaucoma, the course is like a painless progressive loss. You might be able to arrest the course and change it to a step-wise thing by modifying the intra-ocular pressure, but primary open-angle glaucoma is a chronic disease that slowly gets worse over years. Now obviously, you can modify the slope of this line by changing it with surgery, like trabeculectomy or shunt tube, but basically the course is slowly progressive loss over years. In primary open-angle glaucoma however, that's your peripheral field. So when we have visual field loss in the periphery, but it tends to spares the papillomacular bundle, which means the visual acuity is spared. In contrast, patients with OPA1 dominant optical atrophy have a central scotoma instead of the nerve-fiber layer defect, because they have central loss from the papillomacular bundle. It's usually bilateral and symmetric. And so, the main differentiating feature is the acuity is decreased, and patients with OPA1 have a slow decrease and then it stays the same. So normally, they either just show up as 20/40 to 20/200 and it doesn't change at all, or it gets worse a little bit and then it stays the same. So, the course and the tempo of primary open-angle glaucoma looks different than the course of OPA1. The reason there's overlap is it can occur in younger patients and be mistaken for juvenile open-angle glaucoma. You need to establish over time that there's change in the cupping for glaucoma. So in glaucoma, the cup-to-disk ratio will slowly be increasing over the time course, and the field will be slowly decreasing over that time period. In OPA1, the cup-to-disk ratio starts off bad and just stays bad. It's usually a very shallow cupping to the temporal rim, but it can be, like, cup-to-disk 0.7, 0.8, or really any number of cupping. It slopes to the temporal rim, and the differentiating feature is going to be the rim pallor. So, the remaining rim is normal. Now in glaucoma, the pressure is 35 or 30. Well, that's glaucoma. But in patients who have OPA1 who are mistaken for glaucoma, they're gonna be mistaken usually for normal tension glaucoma or patients with borderline glaucomas. So the main differentiating features between OPA1-related cupping and primary open-angle glaucoma-related cupping are: they both cup, but the rim is pale in OPA1. The central vision is decreased in OPA1. It doesn't usually progress over their, the whole, lifetime to no light perception: it usually stops somewhere between 20/40 and 20/200. The pressure is normal, and we cannot establish an increase in cup-to-disk ratio over time. Those are the features that suggest this person, who has what looks like glaucomatous cupping, actually is harboring OPA1." |
