Shauna Berry

Nonarteritic anterior ischemic optic neuropathy: cause, effect, and management

Nonarteritic anterior ischemic optic neuropathy (NAION) is the most common form of ischemic optic neuropathy and the second most common optic neuropathy. Patients are generally over the age of 50 years with vasculopathic risk factors (eg, diabetes mellitus, hypertension, and obstructive sleep apnea). The exact mechanism of NAION is not fully understood. In addition, several treatment options have been proposed. This article summarizes the current literature on the diagnosis, treatment, and management of NAION.

Ethambutol optic neuropathy

Purpose of review We provide a summary of the epidemiology, clinical findings, management and outcomes of ethambutol-induced optic neuropathy (EON). Ethambutol-induced optic neuropathy is a well-known, potentially irreversible, blinding but largely preventable disease. Clinicians should be aware of the importance of patient and physician education as well as timely and appropriate screening. Recent findings Two of the largest epidemiologic studies investigating EON to date showed the prevalence of EON in all patients taking ethambutol to be between 0.7 and 1.29%, a value consistent with previous reports of patients taking the doses recommended by the World Health Organization (WHO). Several studies evaluated the utility of optical coherence tomography (OCT) in screening for EON. These showed decreased retinal nerve fiber layer (RNFL) thickness in patients with clinically significant EON, but mixed results in their ability to detect such changes in patients taking ethambutol without visual symptoms. Summary Ethambutol-induced optic neuropathy is a well-known and devastating complication of ethambutol therapy. It may occur in approximately 1% of patients taking ethambutol at the WHO recommended doses, though the risk increases substantially with increased dose. All patients on ethambutol should receive regular screening by an ophthalmologist including formal visual field testing. Visual evoked potentials and OCT may be helpful for EON screening, but more research is needed to clarify their clinical usefulness. Patients who develop signs or symptoms of EON should be referred to the ethambutol-prescribing physician immediately for discontinuation or a reduction in ethambutol dosing.

Supraorbital Nerve and Cavernous Sinus Invasion with Poorly Differentiated Carcinoma of Unknown Primary

ABSTRACT A 50-year-old man presented with a 4-month history of right-sided trigeminal neuropathy in the V1 and V2 distribution, right sixth nerve palsy and Horner syndrome. Magnetic resonance imaging (MRI) showed enhancement and thickening along the right ophthalmic nerve and supraorbital nerve and fullness at the right cavernous sinus extending to Meckel’s cave. Evaluation for a primary tumour was negative. Cavernous sinus biopsy showed infiltrating poorly differentiated carcinoma; the patient underwent radiation therapy. To our knowledge this is the only case of poorly differentiated carcinoma involving the supraorbital nerve presenting with trigeminal neuropathy and Horner syndrome in the English ophthalmic literature.

Stabilization of Visual Function After Optic Nerve Sheath Fenestration for Optic Nerve Meningocele

A 10-year-old boy with bilateral colobomatous cavitary disc anomalies presented with a 3-month history of vision loss in his right eye. MRI of the head and orbit revealed bilateral tubular cystic enlargement of the optic nerve/optic sheath complex with thickening of the optic nerves without inflammation or neoplasm, suggestive of bilateral optic nerve meningocele. An optic nerve sheath fenestration was performed OD, and he experienced an improvement and stabilization of vision in his right eye during a 1-year follow-up period. The authors recommend that surgical decompression, particularly optic nerve sheath fenestration, should be considered in cases with progressive vision loss due to optic nerve meningocele.