Abstract
Purpose :
One-eyed (uniocular) individuals are devoid of binocular cues for estimating 3D depth information. Given this, does their monocular depth vision develop differently from those with intact binocularity? If so – how, and does this development co-vary with their age, gender, and onset/duration of uniocularity? These questions were addressed in this study using a depth-related visuomotor task that emulates complex activities of daily living
Methods :
45 uniocular cases (7-37 years) and 46 age-similar controls performed three variants of a buzz-wire task with and without head restraint, in random order. Each 33.5 cm buzz-wire had 5 horizontal turns, designed to require accurate depth perception. Task accuracy and speed were calculated from the frequency of contact between the hoop and wire (signalled by audio buzzes) and the total task duration (adjusting for the time spent in error), respectively, all from objective video recordings of the task. Participants’ head movements were analysed using face-tracking software.
Results :
Similar suboptimal task accuracy was noted within both the uniocular group [median (25th – 75th IQR): 0.31errors/sec (0.25 – 0.38errors/s)] and monocular viewing of controls [0.33errors/s (0.28 – 0.41errors/s); p=0.16], relative to binocular viewing [0.15errors/s (0.09 – 0.22errors/s); p<0.01]. The uniocular group [1.05cm/s (0.81 – 1.46cm/s)] also exhibited similar slower speed to that of monocular viewing controls [1.16cm/s (0.97 – 1.44cm/s); p=0.39], however under binocular viewing, the controls moved statistically significantly faster [1.55cm/sec (1.31– 1.87cm/s); p<0.01]. The uniocular group exhibited significantly larger head movement compared to the monocular viewing of controls, however, the task performance remained unchanged with and without head restraint (p>0.12) and the demographic covariates (p>0.07). These variables were uncorrelated across cohorts (rho=0.16 – 0.36; p>0.06), reflecting the absence of a speed-accuracy trade-off in the task performance
Conclusions :
Functional depth vision of one-eyed humans was equivalent to binocular controls deprived of stereoscopic disparity cues by viewing monocularly. These results imply that extended experience with monocular depth cues does not compensate for the permanent loss of binocularity in complex dynamic depth-related visuomotor activities.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.