New Metamorphopsia in a Fellow Eye With Dry AMD
A 66-year-old retired teacher presents with a 5-day history of new metamorphopsia in the left eye. The right eye has known dry age-related macular degeneration with many intermediate drusen. Acuity is 6/7.5 OD and 6/9 OS. Amsler grid testing shows a central distortion in the left eye. Dilated fundus examination of the left eye shows a shallow subretinal fluid elevation with a small pigment epithelial detachment and a few retinal hemorrhages. OCT shows central retinal thickness of 312 micrometres, subretinal hyperreflective material, and disruption of the ellipsoid zone. The right macula has drusen without fluid. She has hypertension treated with amlodipine and takes aspirin 81 mg daily. She asks whether she can simply monitor at home with the Amsler grid and whether the aspirin should be stopped.
1. Interpret the examination and OCT findings. What is the most likely diagnosis and what is the urgency?
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The left eye shows new metamorphopsia, subretinal fluid, a pigment epithelial detachment, retinal hemorrhage, and subretinal hyperreflective material on OCT. In a 66-year-old with drusen in the fellow eye, this is most consistent with conversion from dry to neovascular age-related macular degeneration. The hemorrhage and subretinal hyperreflective material argue against simple central serous chorioretinopathy, although central serous chorioretinopathy can produce subretinal fluid; age and drusen also favour neovascular AMD. The urgency is high. Anti-VEGF treatment should be arranged promptly, ideally within days, because persistent exudation causes irreversible photoreceptor and retinal pigment epithelium damage. Amsler grid monitoring is not appropriate as the sole plan now that exudation is present. The fellow eye with drusen also warrants monitoring because it is at risk for conversion.
2. Explain why her visual acuity is only mildly reduced despite active exudation, and what this implies about using acuity alone to decide treatment.
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Visual acuity is only 6/9 because the foveal centre may still be relatively spared, or because the fluid and distortion are extrafoveal. Acuity is a high-contrast measure of a small central area and can remain good while photoreceptors are displaced or damaged nearby. Metamorphopsia is often a more sensitive symptom of outer retinal distortion. OCT shows ellipsoid-zone disruption and subretinal hyperreflective material, which are structural markers of risk. This is why treatment decisions in neovascular AMD use OCT and symptoms, not acuity alone. Waiting for acuity to fall would allow irreversible loss. If acuity were the only trigger, this patient might be observed inappropriately while her photoreceptors were being damaged.
3. Address her two questions: home Amsler monitoring and aspirin. Give a reasoned answer rather than a simple yes or no.
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Amsler monitoring is useful for detecting new distortion between visits, but it is not a substitute for urgent assessment when symptoms have already changed. She should be seen and treated now, and then use the Amsler grid daily on each eye as a warning system. Aspirin at 81 mg is not a proven cause of neovascular AMD progression, and stopping it could increase cardiovascular risk. The decision should be made with her cardiologist or primary care physician, not unilaterally in the eye clinic. I would explain that the priority is anti-VEGF treatment and that aspirin can usually continue unless there is a specific contraindication. If she has a history of gastrointestinal bleeding or another reason for aspirin, that should be addressed separately, but fear of AMD progression alone is not a reason to stop.