Effects of benzodiazepines on saccadic eye movements: A systematic review and meta-analysis

Benzodiazepines are commonly prescribed psychotropic drugs with anxiolytic, sedating, hypnotic, and anticonvulsant effects. They impair saccadic eye movements in prosaccade tasks, particularly peak velocity, but the extent of the effects on different saccadic parameters remains unclear. Therefore, we conducted a systematic review and meta-analyses on the effects of different benzodiazepines on peak velocity (k (number of included studies) = 30, k_ES (number of included effect sizes) = 45, N (number of participants) = 444), latency (k = 12, k_ES = 17, N = 221) and amplitude gain (k = 5, k_ES = 8, N = 113). Furthermore, we performed meta-analyses and dose-dependent meta-regressions of lorazepam effects on peak velocity (k = 13, k_ES = 19, N = 257) and latency (k = 8, k_ES = 12, N = 187). We found a robust and large effect on peak velocity (standardised mean change (SMCC)) = -1.064, 95% CI (confidence intervals) [-1.287, -0.84]), a less consistent, medium sized effect on latency (SMCC = 0.706, 95% CI [0.285, 1.127]), and a medium sized, but non-significant, effect on gain (SMCC = -0.581, 95% CI [-1.226, 0.064]). These findings confirm the sensitivity of saccadic eye movements to modulation of gamma-aminobutyric acid (GABA) through benzodiazepines and point to the peak velocity in particular as a biomarker for sedative effects in pharmacological research in healthy adults.