Which of the following conditions can cause unilateral optic disc edema?

• A. Thyroid Eye Disease
• B. Glaucoma
• C. Diabetic retinopathy
• D. Age-related macular degeneration

Answer: (A)

Unilateral optic disc edema points to a localized optic nerve problem rather than a generalized rise in intracranial pressure. Thyroid Eye Disease can cause compressive optic neuropathy when the orbital tissues, including enlarged extraocular muscles, crowd the optic nerve behind the globe. This compression disrupts axoplasmic flow and leads to swelling of the optic nerve head on the affected side, producing unilateral disc edema and potential vision changes.

The other conditions listed don’t usually produce this finding. Glaucoma mainly causes cupping and progressive neuroretinal loss due to elevated intraocular pressure rather than edema of the disc. Diabetic retinopathy affects the retina and macula, with retinal edema, hemorrhages, and hard exudates—not the optic disc swelling described. Age-related macular degeneration targets the macula and does not cause optic disc edema.