The relationship between motor fusion and stereoacuity in adults with normal binocular single vision

Abstract

ABSTRACT Purpose: To explore the relationship between motor fusion and stereoacuity in adults with normal binocular single vision. Method: A sample of 31 adult participants was recruited by convenience sampling. The inclusion criteria included age 18–40 and no history of uncorrectable vision loss or strabismus. Examinations included visual acuity, orthoptic assessment and non-cycloplegic autorefraction (Canon RK-F2). Stereoacuity was performed using Precision Vision’s Real Depth Stereo Test, Frisby Stereo Test, Titmus Stereo Fly Test and TNO. Prism fusion ranges were performed at 33 cm and 6 m, using an accommodative target. Written informed consent was obtained from all participants prior to the examination. Results: Participants had a mean age of 23.16 ± 2.48 years, were 80.6% female and 71% had myopia. Most were orthophoric (58.1%) at distance fixation and exophoric (67.7%) at near fixation. There was a moderate and significant correlation between distance and near convergence by prism fusion ranges (r = 0.64, p < .001). There was a moderate negative correlation between near convergence by prism fusion and stereoacuity using the Real Depth Stereo Test (r = −0.42, p = .018) and Frisby Stereo Test (r = −0.52, p = .003). However, there was no correlation between near convergence by prism fusion with Titmus (r = 0.19, p = .36) or TNO (r = −0.31, p = .1). Near divergence fusion range was not significantly correlated to any stereoacuity test (all p > .05). Conclusion: There was a significant relationship between convergence fusion range and stereoacuity measured using the Frisby and Real Depth stereo tests in this population of adults with normal binocular single vision.