Differential Diagnosis of Gradual Visual Loss. (a) Painful
| Cause | Features |
|---|---|
| Optic neuritis | Subacute but rapid profound visual loss, with gradual recovery over six weeks. May be pain on eye movements particularly convergence. RAPD, if unilateral, and reduced colour vision. Central or centrocecal visual field defect – central and including blindspot. May be history of multiple sclerosis. |
| Corneal epitheliopathy: herpes keratitis | Pain, watering, photophobia. Stains with fluorescein dye. Corneal sensation will be reduced. |
| Scleritis | Deep ache, beefy redness of the eye (best seen in daylight), which does not blanch with topical application of phenylephrine drops. May be a history of connective tissue disease, for example rheumatoid disease. |
| (b) Painless | |
| Cause | Features |
|---|---|
| Keratoconus, corneal dystrophies | Blurring of vision and loss of acuity. |
| Cataract | Blurring of vision, foggy vision, glare and dazzle, gradual onset. No distortion. |
| Post-cataract surgery: cystoid macular oedema, posterior capsule opacification | Macula oedema: central smudge in vision that develops 4–6 weeks post-cataract surgery. |
| Age-related macular degeneration (dry) | Decreased vision with loss of clarity – may be some distortion. |
| Diabetic maculopathy (exudative, ischaemic) | Decreased visual acuity and blurry vision. |
| Macular problems: epiretinal membrane, macular hole | Decreased vision with loss of clarity – some distortion likely. |
| Compressive optic neuropathy | Tends to be unilateral. Insidious visual field loss that may become apparent when the good eye is covered. Can also be due to thyroid orbitopathy. As it is an optic neuropathy there will be an RAPD and variable loss of colour vision with associated field loss. |
| Drug-related: maculopathy, optic neuropathy | Decreased visual acuity and blurry vision. |