Abstract
BACKGROUND/AIMS: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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. TRIAL REGISTRATION NUMBER: NCT06078605.