Abstract
Purpose:
To investigate the effect of spatial frequency (SF) on accommodation in near-detection threshold tests in emmetropes and myopes.
Methods:
Twelve emmetropic (EMM) and thirteen myopic (MYO) adults were recruited. Sine wave Gabor targets of 2, 4, 6, 8, 12, 16 cpd spatial frequencies were presented from a tablet computer at 40 cm. The horizontal and vertical grating targets were presented in contrast-descending random order. Subjects were asked to choose the direction of gratings with a gamepad. Detection thresholds for each spatial frequency were determined by the mean value of three measurements of the contrast sensitivity function. While each grating was presented with a measured detection threshold, accommodation responses were recorded continuously using the Grand Seiko WAM-5500 autorefractor for 30 seconds at 5 Hz.
Results:
Detection thresholds were lowest for 16 cpd and highest for 4 cpd (EMM: F=70.45, p<0.001; MYO: F=79.14, p<0.001). EMMs and MYOs had similar detection thresholds (p>0.1). The average accommodative responses to detection threshold contrast targets of two groups were -1.96±0.07D (EMM) and -1.96±0.03D (MYO). In the emmetropic group, accommodative responses to targets of 2 and 4 cpd were higher compared to other SFs (F=2.37, p=0.05), but not in myopes. Emmetropes had smaller variations of accommodation (AMF, defined as SD of accommodative response) than myopes for 12cpd (t=-4.763, p=0.001). In the myopic group, AMF of 8cpd was lowest, while in the emmetropic group, AMF of 12cpd was lowest.
Conclusions:
Emmetropic and myopic adults had similar contrast sensitivity functions for near presentations. Accommodative responses in emmetropes seem more sensitive to near-detection threshold grating targets than in myopes.
Keywords: 478 contrast sensitivity •
404 accommodation