Risk counseling important for cataract candidates with history of optic neuropathy

An optic neuropathy resembling nonarteritic ischemic optic neuropathy (NAION) may occur after apparently uncomplicated cataract extraction at a rate higher than would be expected in the general population, said Neil R. Miller, MD. Dr. Miller is professor-ophthalmology, neurology, and neurosurgery, and Frank B. Walsh Professor of Neuro-Ophthalmology, The Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore.

The rate of optic neuropathy in the first 6 months after cataract extraction is estimated to be about 52 per 100,000 cases. According to results of the Ischemic Optic Neuropathy Decompression Trial, patients with unilateral NAION have about a 15% to 20% 5-year risk of the same event in a fellow eye. Cataract extraction increases this risk two to eight times, Dr. Miller said.

It is thought two types of NAION can occur post-cataract extraction: an immediate event that may be associated with elevated intraoperative IOP and a delayed type that may be more related to the same risk factors as NAION.

Judicious control of IOP during surgery may reduce the risk of the immediate type of post-cataract extraction optic neuropathy. However, there appears to be no way to prevent the delayed event.

"We need to talk to our patients," Dr. Miller urged. "Patients who developed an optic neuropathy after first eye cataract surgery should be told there is an increased risk of this event if cataract extraction is performed in the fellow eye. Those patients with spontaneous NAION in one eye should also be told they have an increased risk following cataract extraction in the fellow eye."