Unlike macular degeneration, glaucoma and diabetic retinopathy can affect the retina outside of the macula. They are diseases that have a wide range of presentations, so patients will present with a wide variety of visual volumes. But there are some things that they will all have in common:
- They should all involve some degree of contrast and luminance impairment, along with acuity loss, so in many ways they should be similar to macular degeneration. (For now, I treat them in pretty much the same way in the clinic, and it seems to work pretty well).
- Diabetic macular oedema would be expected to involve the fovea, so we’d expect more acuity loss.
- Glaucoma patients tend to respond well to stronger task lighting, but the optimal level seems to be not as bright as that for macular degeneration.
- Diabetic retinopathy patients often have more glare sensitivity, especially if they have media opacities. Cataract extractions will help, but the increased risk of retinopathy worsening after cataract surgery makes it a difficult decision. Yellow filters can help minimise glare while improving contrast at high illumination, and electronic magnifiers will be helpful with reversed contrast.
Just as we see a variety of classic patterns of glaucomatous field loss (arcuate, temporal wedge, nasal step, etc), could we find some classic impaired visual volumes? I’d love to analyse the VV (and OVV) of 20 or so glaucoma patients and see if patterns emerge.
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