Clinical

Endothelial dysfunction may underlie interferon-related retinopathy

Last Updated: 2007-01-10 15:15:18 -0400 (Reuters Health)

NEW YORK (Reuters Health) - The retinopathy that may develop rapidly with high-dose interferon treatment may be caused by impaired vascular function in the retinal microcirculation, ophthalmologists in Japan report.

Up until now, this possibility had not been tested in humans because of the lack of screening tools. Now, as they report in the January issue of Investigative Ophthalmology and Visual Science, Dr. Taiji Nagaoka and associates have used a retinal laser Doppler velocimetry (LDV) system to measure retinal vessel diameter, blood velocity, and other parameters noninvasively.

They used the LDV device to evaluate retinal changes in 36 patients at Asahikawa Medical College with chronic hepatitis C undergoing interferon therapy, whose blood glucose and hypertension were well controlled and in whom anemia and retinopathy were absent prior to treatment.

Interferon 6 million units was administered IM 6 times a week for 2 weeks, then 3 times a week for 22 weeks. Twenty-two patients with viral loads > 10,000 copies/mL were also treated with recombinant interferon alpha-2b and oral ribavirin.

The investigators found that retinal blood velocity, retinal blood flow, and wall shear rate increased significantly in all patients. Twenty-two patients also developed asymptomatic retinopathy.

Decreases in red blood cells, hemoglobin, and hematocrit occurred after starting interferon, which were all associated with increased retinal blood flow. The researchers suggest that retinal capillary blood flow was increased to maintain oxygen levels in the retina.

They also observed that retinopathy was associated with blood velocity and wall shear rate but not changes in vessel diameter. Conversely, vessel diameter increased while the wall shear rate remained unchanged among those without retinopathy.

Thus, Dr. Nagaoka's team suggests, "measuring the retinal circulatory parameters during the early phase of interferon treatment can predict or detect the development and severity of interferon-induced retinopathy."

Invest Ophthalmol Vis Sci 2007;48:368-375.