Abstract
Purpose :
The purpose of this study is to improve the continuous flash suppression (CFS) method described by (Yang et al. 2010) for use as a tool to evaluate ocular dominance in patients with retinal conditions. Modifications made include: a change in shutter glasses, monitor and increased visual angle of all images.
Methods :
The continuous flash suppression image is a Mondrian subtending a visual angle of 12.9° x 12.9° with a refresh rate of 10Hz. The stimulus image was a face (visual angle 5° x 3.5°). All images were presented on a blank gray background. The CFS display was bordered by a frame of black and white circles (0.33° diameter). Images were presented on a 3D monitor (ASUS VG248QE) at a distance of 66cm and dichoptic presentation was controlled by NVIDIA 3D Vision 2 active shutter glasses. At the beginning of an experiment testing the right eye (RE), the RE views the stimulus at low contrast and the left eye (LE) views the Mondrian at full contrast. As time progresses, the Mondrian decreases in contrast and the stimulus increases in contrast. The time when the orientation (pointing right or left) of the stimulus is first perceptible is recorded; this is the right eye response time (RErt). The same test is done with the LE to measure the left eye response time (LErt). The times are used to calculate the ocular dominance ratio (LErt/RErt). An ocular dominance ratio (ODR) less than 1 corresponds to LE dominance and greater than 1 corresponds to RE dominance. Volunteers (N = 22) were recruited and gave informed consent as approved by the UC Riverside Human Research Review Board.
Results :
Overall, the results are very similar to those obtained in the original work. Of the participants 64% were RE dominant and 36% were LE dominant. 27% of participants demonstrated strong (ODR>1.2 or ODR<0.8) ocular dominance. However, our test-retest reliability was higher (r = 0.76) than in the previous study (r = 0.52).
Conclusions :
Increasing the visual angle and changing equipment improved the reliability of the CFS method. We think this is most likely due to the increased visual angle, as this made it easier to determine the orientation of the face once it became visible. Measurement of ocular dominance shows promise as a clinical decision-making tool in monocular retinal conditions and monovision correction due to its speed and ease of use.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.