Effects of nicotinamide supplementation in normal-tension glaucoma: a crossover placebo-controlled randomised clinical trial.

Abstract

The neuroprotective effect of nicotinamide (NAM) supplementation has been demonstrated in both animal models and clinical trials. We conducted a trial to assess whether oral NAM improves retinal function in normal-tension glaucoma (NTG) participants receiving intraocular pressure (IOP)-lowering therapy. Fifty-three NTG participants (untreated IOP ≤18 mm Hg) were enrolled in a double-masked, placebo-controlled crossover randomised clinical trial. Participants were randomly assigned to receive either oral placebo or NAM, followed by crossover without a washout period. Each treatment was administered for 12 weeks (NAM/placebo 1 g/day for 6 weeks, then 2 g/day for the subsequent 6 weeks). Retinal function was evaluated using full-field electroretinography and visual field testing. After 12 weeks, the amplitude changes of the photopic negative response in peak-to-trough (PhNRPT) and the B-wave were significantly greater in the NAM group (3.121±3.968 and 2.112±3.220 μV, respectively) compared with the placebo group (0.996±4.190 and 0.305±3.279 μV, respectively; p=0.045 and p=0.032). PhNRPT improved beyond twice the 95% coefficient of variation in 29.0% of the NAM group and 19.3% of the placebo group. No significant intergroup differences were observed in changes in mean deviation, pattern SD or visual field index after 12 weeks. Oral NAM supplementation in NTG participants induced functional improvement, as measured by PhNRPT and B-wave amplitude. Given that NTG is characterised by lower IOP, which may show a weaker correlation with electrophysiological activity and a slower progression rate compared with high-tension glaucoma, further long-term studies are needed to clarify the effects of NAM in this population. NCT06078605.