ON and OFF receptive field processing in the presence of optical scattering

Abstract

The balance of ON/OFF pathway activation in the retina plays a role in emmetropization. A new myopia control lens design uses contrast reduction to down-regulate a hypothesized enhanced ON contrast sensitivity in myopes. The study thus examined ON/OFF receptive field processing in myopes and non-myopes and the impact of contrast reduction. A psychophysical approach was used to measure the combined retinal-cortical output in the form of low-level ON and OFF contrast sensitivity with and without contrast reduction in 22 participants. ON responses were lower than OFF responses (ON 1.25 ± 0.03 vs. OFF 1.39 ± 0.03 log(CS); p < 0.0001) and myopes showed generally reduced sensitivities (myopes 1.25 ± 0.05 vs. non-myopes 1.39 ± 0.05 log(CS); p = 0.05). These findings remained unaffected by contrast reduction (p > 0.05). The study suggests that perceptual differences in ON and OFF signal processing between myopes and non-myopes exist but cannot explain how contrast reduction can inhibit myopia development.

Fig. 1.

Examples of stimuli for (a) OFF polarity at 1.5 cpd and (b) ON polarity at 6 cpd.

Fig. 2.

Example of a trial to test the ON condition at (a) central testing with 1.5 cpd and at (b) peripheral testing with 6 cpd.

Fig. 3.

Contrast sensitivity functions (least-squares mean ± standard error, n = 22 participants) for (a) central testing without scattering; (b) temporal 10° testing without scattering; (c) central testing with scattering and (d) temporal 10° testing with scattering. Asteriks denote significant differences between refractive groups for the same testing condition (* p < 0.05).