Causes of optic neuritis vary with geography, requiring different treatments

BRASILIA — Optic neuritis may be a symptom of different systemic problems, depending on an ophthalmologist's geographic location, according to a surgeon speaking here at the Brazilian Congress of Ophthalmology.

Andrew G. Lee, MD, told meeting attendees that the results of the Optic Neuritis Treatment Trial may not be applicable to ophthalmologists worldwide because the population studied is unique to the United States.

"If you're reading our English-language paper and trying to use it in Brazil, it might not be valid," Dr. Lee said. "There are clearly worldwide differences in the application of the Optic Neuritis Treatment Trial." In the United States, 90% of cases of optic neuritis can be attributed to multiple sclerosis (MS), but few areas outside of Europe and Australia share similarly high MS rates, he said.

In contrast to the United States, Brazil has only a "pocket" of MS cases, and many Brazilian optic neuritis cases may instead be caused by infection, Dr. Lee said.

In Brazil, diagnostic techniques and treatments for MS also differ from the United States, he noted.

"If you're from a part of Brazil without multiple sclerosis, you're wasting your time with an MRI," he said, adding that physicians should instead test for likely infections.

Even in the more southern areas of Brazil, where MS is more prevalent, MS often presents in the spine rather than the brain, making an MRI equally inefficient, Dr. Lee said.

If treating a patients with MS, Dr. Lee noted that conventional doses of oral steroids can be more harmful than helpful.

If treating at all, he recommended using high doses of intravenous steroids. However, such treatments may not be cost-effective because most patients improve regardless of whether they receive treatment. Additionally, intravenous steroids have not been proven to improve final visual outcome, he said.