DARK-ADAPTATION IN EARLY PRIMARY BILIARY-CIRRHOSIS

Background The role of vitamin A in early primary biliary cirrhosis (P BC) remains uncertain. Methods We assessed dark adaptation and assayed vitamin-A-related compounds in 10 patients with early PBC and a group of age- and sex-matched controls. Results In patients compared with c ontrols: (i) mean final light threshold value was 11.8% greater (p < 0 .004), (ii) time taken to see the first light stimulus was longer (2.8 +/- 0.6 vs 1.4 +/- 0.2 min, mean +/- SEM; p < 0.03) and (iii) sensiti vity to light stimuli was impaired after 6 min in the dark (p < 0.03). Three patients had an abnormal final light threshold despite receivin g regular vitamin A; two had a low serum vitamin A. Raised serum bilir ubin and increased age were the most important determinants of impaire d dark adaptation. Conclusions Patients with early PBC have modestly i mpaired dark adaptation, despite standard vitamin A supplementation, a lthough these changes may not have a significant effect on visual func tion. Vitamin A supplementation should be recommended for older patien ts with jaundice, but its effect should be carefully monitored.