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Interferon treatment for hepatitis C causes changes in retinal blood flow, study shows
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Patients treated with interferon for chronic hepatitis C experienced a significant increase in retinal blood flow as early as 2 weeks after initiating therapy, a prospective study found. Retinal vascular endothelial dysfunction may be associated with interferon-induced retinopathy, the study authors said.
Taiji Nagaoka, MD, PhD, and colleagues at Asahikawa Medical College in Japan evaluated interferon's effects on retinal microcirculation in 36 patients with chronic hepatitis C. The researchers used laser Doppler velocimetry to measure retinal blood velocity, retinal blood flow (RBF) and wall shear rate (WSR), an index of physiological stress on retinal vessels.
Their results are published in the January issue of Investigative Ophthalmology & Visual Science.
Dr. Nagaoka and colleagues found that all patients had significant increases in retinal blood velocity, RBF, and WSR at 2 weeks' follow-up (P < .0001).
Between 2 to 16 weeks after initiating interferon treatment, 22 patients (61%) developed asymptomatic retinopathy. Retinal hemorrhage was seen in 18%, cotton-wool spots in 41% and both retinal hemorrhage and cotton-wool spots in 41%. In patients with retinopathy, blood velocity and WSR increased, but vessel diameter remained unchanged.
In the 14 patients who did not develop retinopathy, vessel diameter, blood velocity and RBF increased significantly, but WSR remained unchanged, according to the study authors.
Patients with retinopathy showed statistically greater increases in vessel diameter (P = .008), blood velocity (P = .04) and WSR (P = .007) compared to patients without retinopathy. Multivariate logistic regression analysis showed that only age and change in WSR at 2 weeks were significant risk factors for interferon-induced retinopathy.
"The increased WSR in patients with retinopathy indicates that retinal vascular endothelial dysfunction may be associated with [interferon]-induced retinopathy, because wall shear stress should be constant under physiologic conditions," the authors said.
Retinopathy resolved in all patients within 1 month after discontinuing interferon. No patients had a recurrence after their retinopathy resolved, and none experienced other ocular complications.
"The current results suggest that both hepatologists and ophthalmologists should be aware of the importance of the evaluation of retinal circulation in patients with chronic hepatitis C who receive interferon treatment," the authors said.