Purpose: To determine whether dilation status has a clinically meaningful effect on sensitivity in normal subjects undergoing two-color dark-adapted perimetry, which can be useful to assess rod function.
Methods: A perimeter measured naturally and pharmacologically dilated scotopic sensitivities using a test grid consisting of 16 points across the horizontal meridian ranging from 60° temporal to 45° nasal using cyan (500 nm wavelength) or red (650 nm wavelength) stimuli. The primary outcome was average overall sensitivity based on dilation status, which was compared using a linear mixed effect model for each color stimuli. A difference of 2 dB or more was considered clinically significant.
Results: Twenty-nine eyes from 15 subjects (nine female) ages 23 to 63 with no known retinal pathology were included. Pharmacologically dilated eyes were 0.54 dB (95% confidence interval [CI], 0.05 dB to 1.03 dB; P = 0.032) more sensitive to a red stimulus than naturally dilated eyes, but this was not statistically significant after correction for multiple comparisons. Pharmacologically dilated eyes were 0.03 dB (95% CI, -0.20 dB to 0.14 dB; P = 0.734) less sensitive to a cyan stimulus compared to naturally dilated eyes.
Conclusions: These findings show no clinically significant differences in sensitivity of scotopic perimetry in eyes without retinal pathology based on dilation status for both cyan and red stimuli.
Translational relevance: In this study, pharmacological dilation did not have a clinically meaningful effect on sensitivity, suggesting that this is not necessary when using two-color dark-adapted perimetry to assess for rod function.