NEWS & EVENTS
Retinal Review, Issue 61
Authored by Burton Wisotsky, M.D.
A 31 year old man was referred for a swollen left optic nerve. Past ocular history is unremarkable. He had not had an eye examination in many years. Past medical history is significant for IDDM for 18 years. Blood sugars have been poorly controlled. He see his internist twice a year and his glucose levels are “high”. He does not recall his last HgA1C. The patient went for an eye examination based on recommendation by his medical doctor. He was asymptomatic. He was noted to have optic neuropathy and was referred to Omni for an examination. On examination, VA was OU: 20/20. IOP’s and the SLE were unremarkable. VF testing with a 24-2 program showed mild blind spot enlargement in the right eye and was essentially full in the left (see below). No afferent pupillary defect was noted. DFE is shown below:
The right optic nerve is normal. There is a small cup but it is not a “disc at risk”. There is mild NPDR with a few microaneurysms and mild lipid nasal to the macula. In the left eye there is diffuse optic nerve hyperemia and swelling, most notable on the superior aspect of the optic nerve. The vessels are relatively normal without evidence of engorgement. There are peripapillary hemorrhages but no evidence of active diabetic retinopathy.
The important details of this case are the swollen left optic nerve, normal right optic nerve, normal vasculature, and lack of visual acuity or visual field loss in the affected eye. The differential diagnosis for monocular optic nerve swelling includes compression, demyelination, inflammation, infiltration, ischemia, venous stasis, and other. We can rule out just about every condition based on the patient’s findings. Compression: This can be due to a localized tumor such as an optic nerve glioma or meningioma, or hydrostatic compression due to either pseudotumor or brain tumor with high intracranial pressure. Localized compression can be ruled out because either the visual acuity or the visual field would be abnormal. High intracranial pressure due to either tumor or pseudotumor can cause optic nerve swelling without vision or visual field loss, but it is almost always bilateral.
Demyelination: This is unlikely given that it is much more common in women than men. Secondly, the optic nerve is often normal in appearance (retrobulbar optic neuritis), although the nerve can appear swollen. All patients with optic neuritis however, will have either visual acuity or visual field loss.
Inflammation: Papillitis, or inflammatory optic neuropathy can be associated with systemic or localized inflammation or autoimmune disease. Vision is always reduced.
Infiltration: This is a rare cause of optic neuropathy and can be due to lymphoma or systemic inflammation (autoimmune disease or sarcoidosis). Vision is always affected.
Ischemia: Ischemic optic neuropathy is rare, but can present in younger patients. It is often associated with a “disc at risk” – a small, crowded cup with potential for vascular compression. The nonaffected eye often has these finding. In our patient’s case, the other eye was not a disc at risk; furthermore, visual acuity or visual field is always affected in ischemic optic neuropathy, thus ruling out this condition.
Venous stasis: Patients with CRVO will often have unilateral optic nerve edema. A mild form of CRVO, papillophlebitis, can often have optic nerve swelling, minimal intraretinal hemorrhages, and relatively normal acuity. However, the veins are engorged in this conditiion. Our patient’s veins are relatively normal, thus excluding this condition.
Our patient has diabetic papillopathy. This is a rare condition typically found in young, poorly controlled diabetics. The patient develops optic nerve edema, which is usually segmental, without significant visual acuity or visual field loss. The disease is self limited and the optic nerve swelling usually resolves on its own without sequellae. The patient should be referred to the internist for blood sugar control. We observed our patient and when he returned several months later his acuity was still OU 20/20. The optic nerve edema had fully resolved. There was mild resulting optic nerve pallor (see below). Visual fields remained full.