Pathologic Optic Disc Cupping
- Thinning of optic disc neuroretinal rim so that optic disc appears pathologically cupped (excavated)
- Usual cause is glaucoma
- Glaucoma causes slow death of optic nerve axons and their supporting glia partly because of chronically high intraocular pressure
- Visual fields eventually become constricted, but only when neuroretinal rim is very thinned
- Intraocular pressure must be controlled to forestall worsening of vision
- Enlarged cup to disc ratio (optic disc cup diameter greater than ½ of optic disc diameter)
- Physiologically large optic disc cups, BUT...neuroretinal rim is not thinned and cup is not vertically elongated
- Coloboma of optic disc, BUT...this is congenital abnormality
- Tilted disc of myopia, BUT...features of tilting give this away
- Non-glaucomatous optic neuropathy, BUT...there will be non-ophthalmoscopic clues to this diagnosis
- Distinguishing pathologic optic disc cupping from physiologically large cups, coloboma, and myopic tilt may be difficult by ophthalmoscopy alone
- Identify pathologic optic disc cupping by ophthalmoscopy
- Do not try to distinguish between one cause and another
- Refer to ophthalmologist non-urgently
- Undetected glaucoma can progress to marked and irreversible vision loss
- Control of intraocular pressure is often effective at arresting or slowing down progression of glaucoma