Agent useful for uveitic cystoid macular edema

"The burden of uveitic CME is quite considerable. More than 30% of all patients with uveitis will develop CME, and it is a leading cause of loss of vision and blindness in these patients. Unlike some of the other causes of decreased vision in uveitis, such as cataracts, vitreous debris, or epiretinal membranes, the loss of vision here may not be reversible if the edema isn't cleared in a certain amount of time," said Dr. Butler, assistant professor of Ophthalmology, Johns Hopkins University School of Medicine, Wilmer Eye Institute, Baltimore.

Interferon alpha is a species-specific cytokine produced by all cells in the body but predominantly by WBC. It has antiviral, antiproliferative, and immunomodulatory activity. The FDA has approved interferon alpha-2b for chronic hepatitis, leukemia and lymphomas, and solid tumors such as melanoma. Its use in patients with CME is currently off-label.

Early success of interferon alpha in ocular inflammatory disease was demonstrated in patients with Behçet's disease complicated by sight-threatening posterior or panuveitis.¹ Fifty patients were treated and had a 92% response rate, with significant improvements in mean visual acuity by week 24 of treatment. In this study, 58 eyes were affected by CME, and there was 100% resolution in these eyes, Dr. Butler explained.

More recently, other researchers have looked at dose-escalating forms of interferon regimens to minimize the side effects of interferon alpha when treating refractory Behçet's uveitis.² They found low-dose and dose-escalating interferon alfa-2a therapy similarly effective, with a 95% response rate in 37 patients.

Another study was done in patients with noninfectious severe posterior uveitis and panuveitis of various etiologies (i.e., not solely Behçet's disease).³ Results showed an 83% response rate to therapy with interferon alpha in 12 patients. In the 14 eyes with CME included in this study, there was also 100% resolution. Side effects were common, however.

A pilot study was done in 15 eyes in eight patients with non-Behçet's uveitic CME.⁴ Thirteen of these eyes had a response to systemic interferon alfa-2a with 100% resolution within 2 to 4 weeks. In two patients with non-response or a lost response, antibodies against interferon were present initially or had developed during the study. Of the 11 eyes that continued to be treated over 6 months, the central macular thickness changed from 551 to 143 µm, and mean BCVA (logMAR) improved from +0.80 to +0.42.

In a follow-up study,⁵ researchers conducted an interventional case series in 24 consecutive patients (40 eyes) for a mean duration of 36 months. Their results were similar, with 62.5% of patients having 100% response and another 25% meeting their strict "partly effective" criteria.