Spotlight on Toxic and nutritional deficiency optic neuropathies

Toxic and nutritional deficiency optic neuropathies are fairly uncommon in the United States. They are usually the result of drug toxicity. Due to the effects of these conditions on mitochondria and cellular energy production, these entities share many signs and symptoms. Awareness of the hallmark findings of these entities as well as an increased index of suspicion in patients with chronic disease will assist the clinician with diagnosis.

In this article, Dr. Michelle Wang of the Southern California Permanente Medical Group and Dr. Peter Quiros of the Doheny Eye Center UCLA and the David Geffen School of Medicine discuss manifestations, etiology, diagnosis, and management of toxic and nutritional deficiency optic neuropathies.

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Spotlight on Leber hereditary optic neuropathy

Leber hereditary optic neuropathy is a maternally inherited bilateral optic neuropathy that typically affects teenage males with acute vision loss first in one eye and then the other within days or weeks. The etiology involves a point mutation in the mitochondrial DNA at 1 of 3 main loci: 11778, 14484, or 3460. There are some distinctive changes in the ocular fundus appearance at various stages of the process that make specific diagnosis possible clinically. At the time the patient presents with vision loss, there is apparent swelling of the optic disc but there is no leakage of fluorescein dye as is usually present with other forms of optic nerve head swelling. Other distinctive changes include small peripapillary telangiectatic vessel changes that go away shortly after the acute phase and retinal venous tortuosity that may persist indefinitely as a marker.

In this article, Dr. James Goodwin of the University of Illinois at Chicago updates progress on developing a virus vector delivering DNA restorative therapy for patients with Leber hereditary optic neuropathy, citing a phase I clinical trial that demonstrated safety and even some visual improvement in a few subjects. He also reviews an OCT-based imaging study in which thinning of the retinal ganglion cell layer and the retinal nerve fiber layer were demonstrated prior to vision loss, which may provide a basis for early intervention to prevent vision loss when it becomes available..

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Spotlight on Ischemic optic neuropathy

In this clinical summary, Dr. Howard Pomeranz of Hofstra North Shore-LIJ School of Medicine reviews ischemic optic neuropathy, a common cause of sudden visual loss in patients over 50 years of age. The most common form of this condition, called nonarteritic anterior ischemic optic neuropathy, occurs in the context of “vasculopathic” risk factors, particularly diabetes, hypertension, or hypercholesterolemia. In some patients, giant cell arteritis is the cause of ischemic optic neuropathy (arteritic ischemic optic neuropathy). Arteritic ischemic optic neuropathy is a true visual emergency because the second eye may become involved within days if giant cell arteritis is not treated promptly. Less commonly, the ischemic optic neuropathy may be posterior. Rare causes of non-arteritic ischemic optic neuropathy include associations with surgery (cataract surgery, spinal surgery, cardiac, and transplant surgeries), sleep apnea, and phosphodiesterase inhibitors.

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