A 63-Year-Old Woman With Decreased Vision

Rod Foroozan, MD


April 03, 2018

Case Diagnosis

Funduscopy showed a marked asymmetry in the optic disc cup size, with focal tissue loss inferiorly of the right optic disc. There was no optic disc pallor. The cupping of the optic disc, in the absence of optic disc pallor, was suggestive of glaucoma as the cause. The superior visual field defect in the right eye was consistent with the cupping of the right optic disc. The OCT of the RNFL showed thinning in the right eye compared with the left eye, also consistent with the optic disc cupping. In addition, there was asymmetry of the IOP, with a slightly greater IOP in the right eye.

Nonarteritic anterior ischemic optic neuropathy (NAION) typically occurs in patients who have small optic discs with small cups. NAION occurs in the absence of systemic symptoms and more commonly in those aged 50 years and older. Optic disc edema must be present in the acute phase for there to be symptomatic vision loss. This patient's optic disc cup in both eyes was relatively larger than that typically seen in NAION. In addition, there was no evidence of optic disc edema or pallor.

There was no evidence of optic disc drusen in either eye. Drusen typically occurs in optic discs with small cups. Drusen can be buried underneath the optic disc or be on the surface of the optic disc, where they are more likely to be visible, and are more commonly bilateral than unilateral. They occur more commonly in white persons.

These findings were not suggestive of dominant optic atrophy (DOA), a hereditary optic neuropathy with an autosomal dominant inheritance pattern. The responsible genetic abnormality most commonly involves the OPA 1 gene on chromosome 3. The OPA 1 gene and its protein product, a dynamin-related GTPase, are involved in mitochondrial metabolism. From a clinical standpoint, most patients have bilateral, symmetric vision loss, while other organ systems are relatively spared. Other findings may include sensorineural hearing loss, ptosis, and ophthalmoplegia (DOA plus). Involvement of other OPA genes may be associated with additional systemic abnormalities. The onset of vision loss frequently begins in the teenage years, a much earlier time than in this patient, and progressively worsens slowly over the years. Central or cecocentral visual field defects occur as the papillomacular bundle is preferentially affected, resulting in temporal optic disc pallor. As the optic neuropathy progresses, there is often an excavation of the temporal neuroretinal tissue of the disc.

Clinical Course

Two weeks later, the IOP was 15 mm Hg in the right eye and 12 mm Hg in the left eye, confirming the asymmetry in the pressures. Latanoprost in the right eye (1 drop per day) was suggested. The patient returned 2 months later, and the IOP was 13 mm Hg in the right eye and 12 mm Hg in the left eye. Latanoprost was continued, and she was to return in 6 months.


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