Abstract
Purpose: :
Vitamin A deficiency and night blindness occur in chronic liver disease but studies of dark adaptation impairment and response to vitamin A administration are limited. This prospective study aimed to 1) measure dark adaptation in patients with chronic liver disease and vitamin A deficiency 2)compare symptoms of night blindness with measured dark adaptation 3)explore relationships between dark adaptation and vitamin A, zinc and severity of illness and 4) quantify improvements in dark adaptation after intramuscular administration of vitamin A.
Methods: :
Twenty patients (15 M, 5 F mean age 51 years) (alcoholic liver disease 10, other parenchymal disease 6, cholestatic disease 4) were selected based on plasma retinol ≤ 0.7 µmol/L (RR 1.6-2.3). There were 15 healthy age-matched controls. Dark adaptation was measured using a SST-1 dark adaptometer with the end-point being final rod sensitivity. Testing continued for 30 minutes. Perception of night vision was assessed by questionnaire. Eight patients received aqueous retinyl palmitate (50,000 IU) and were restudied one month later.
Results: :
Eight (40%) patients had impaired dark adaptation. Most (75%) did not perceive a problem. No relationships were identified between measured dark adaptation and retinol, retinol binding protein, zinc or severity of illness. Dark adaptation was improved by 2.9 dB ± 3.4 dB (p=0.05) at one month.
Conclusions: :
Impaired dark adaptation was commonly present and also under-perceived in patients with chronic liver disease and vitamin A deficiency. Dark adaptation improved after vitamin A, allowing light of half the previous intensity to be seen.
Keywords: vitamin A deficiency • photoreceptors: visual performance • perception