5-Methoxypsoralen increases the sensitivity of the retina to light in humans

The acute effect of 5-methoxypsoralen (5-MOP) on the sensitivity of the retina to visible light in humans has been studied in 11 healthy volunteers 2 h after administration of 5-MOP or placebo given at 09.00 h. Retinal sensitivity was evaluated by electroretinography at 11.00 h. 5-MOP significantly increased the sensitivity of the retina to light under photopic conditions and in the early stages of the dark adaptation period, as observed under scotopic conditions. The findings suggest that melatonin is involved in these changes.