Neurovisual impairment: A frequent complication of alpha-interferon treatment in chronic viral hepatitis

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Abstract
Following our earlier observation of clinically evident optic tract neuropathy in patients receiving low-dose interferon (IFN) therapy, we prospectively evaluated 53 consecutive patients treated for chronic hepatitis B or C with a median dose of 3 MU of IFN-a2b thrice weekly. Measurements included routine ophthalmologic evaluation and recordings of visual evoked responses (VER), electro-retinograms (ERG), visual acuity, and visual fields, before, at the end of IFN treatment, and at follow-up visits. Baseline P100 latencies of VERs (base-VER) were abnormally prolonged in 24 patients (32 of 106 eyes, 30.2%); age was the only significant covariate associated with increased risk for an abnormal base-VER by multiple logistic regression (relative risk [RR] 5.3 per each 5-year increase in age). In 45 patients (74 eyes) with normal baseline P100 latencies, the end-of-treatment VERs (end-VER) were significantly prolonged compared with baseline, becoming abnormal in 11 (15 of 74 eyes, 20.3%) (138.8 ± 8.7 vs. 117.7 ± 5.2 ms, P < .001). This subgroup had older age (59.1 ± 11.0 vs. 47.5 ± 15.3, P = .007) and reduced visual sensitivity compared with their own pretreatment measurements (24.5 ± 1.6 vs. 23.0 ± 1.2db, P = .019). Changes of end-VERs by age had a sigmoid distribution with a steep increase of values beyond the 5th decade (R2 = .326, P < .001). In a logistic regression model, significant predictors of abnormal end-VERs were, patients’ age (RR 5.6 per each 5-year increase), presence of hepatitis B virus (HBV) infection (RR 15.1 compared with hepatitis C virus [HCV] infection) and serum cholesterol levels above 240 mg% (RR 7.1 compared with values <240 mg%). Subconjunctival hemorrhages were seen in 2 cases and funduscopic examination revealed cotton wool spots in one other. ERG recordings and the P100 amplitude remained unchanged. After stopping IFN, the treatment-associated neurovisual abnormalities reversed to normal in 7 patients (10 of 15 eyes) and persisted in 5 (5 of 15 eyes, 33.3%) for up to 37 (median 7.3) months observation, all patients remaining clinically asymptomatic. In conclusion, subclinical neurovisual impairment is a frequent, largely unrecognized complication of low-dose IFN therapy, and patients with chronic hepatitis B and older age appear to be most susceptible. This apparently innocuous complication is long lasting, possibly irreversible in some patients, with yet undetermined consequences on visual function.