No abstract

Thirty-one Cystic Fibrosis patients were investigated for clinical and biochemical evidence of Vitamin A deficiency. All had been prescribed oral pancreatic enzyme replacements and twice the recommended daily requirement of Vitamin A (5000IU). None were aware of any ocular symptoms, but 3 out of 31 (10 per cent) were found to have frank conjunctival xerosis and six (19 per cent) to have abnormal dark adaptation. There was no correlation between the above findings and abnormal liver function or clinical disease severity. All patients with cystic fibrosis should have regular Vitamin A estimations with ophthalmological assessment if serum levels fall below 30 microgram/dl.

In a series of asymptomatic patients with primary biliary cirrhosis there was a significant impairment of dark adaptation thresholds as compared with a control group. Vitamin A levels were abnormally low in only two of the patients and these two both showed high dark adaptation thresholds. The electrooculogram was reduced in only the most severely affected case. It is suggested that visual function tests should be performed alongside vitamin A level measurements before deciding on treatment.

No abstract

The use of vigabatrin is associated with a reduction of the ERG cone b-wave amplitude and oscillatory potentials which correlates with visual field loss. The Arden ratio is reduced in subjects taking vigabatrin but may recover after cessation. However, visual loss may persist in the presence of a recovered EOG. These findings suggest further effects of the drug than those mediated by GABA receptors, and support the contention that the cause of the field loss may be at least in part due to retinal effects. Possible mechanisms are discussed.