Abstract
Purpose :
Based on poor conjunction search performance in individuals with amblyopia, it is speculated that these individuals would have difficulties in their day-to-day activities. We investigated visual search performance in this cohort with real world images.
Methods :
A real world image was displayed on a computer screen along with a search target. Participant was asked to find the search target within the displayed image and click on it. Two groups of children participated: controls (monocular visual acuity 20/25 or better) and patients having anisometropic amblyopia (anisometropia ≥ 1.5 D and interocular visual acuity difference ≥2 lines). Three viewing conditions (binocular, dominant eye, and non-dominant (or amblyopic) eye) were tested in a random order. In each of these conditions 30 images were presented. Dominant eye in the control group was determined using the Porta test. Search performance was assessed using integrated performance (IP) that accounts for both accuracy and time taken. Eye movements were tracked with Eyelink1000. Saccade count, run count (number of repeated viewing) and average fixation duration were analysed.
Results :
23 patients (mean age: 10 ± 0.6 years) and 13 controls (10 ± 0.9 years) participated. Dominant eye visual acuity was comparable between the two groups (p=0.54). The mean interocular-visual acuity difference in patients was logMAR 0.35±0.03. As expected, patients had the worst search performance [IP=0.14 ± 0.01] in the amblyopic eye. However, their performance was also significantly (p<0.03) poor in both binocular [IP=0.19 ± 0.01] and dominant eye [IP= 0.18 ± 0.02] when compared to the controls’ binocular [IP =0.26 ± 0.02] and dominant eye IP=0.25± 0.03] viewing conditions. While the average fixation duration between patients and controls were comparable (p=0.9), the saccade (patients=20.1 ± 1.5, controls=15 ± 1.1, p=0.03) and run counts (patients=8.2 ± 0.77, controls=6.1 ± 0.4, p=0.03) were significantly more in patients.
Conclusions :
Despite having normal acuity in the dominant eye, children with anisometropic amblyopia show a visual search deficiency for real world images. This is similar to the performance observed in conjunction search, which requires feature binding. The poor visual search performance could be due to deficiencies in higher cortical functions rather than low-level visual functions. More run counts to revisit the same image areas suggests deficiency in visual coding.
This is a 2021 ARVO Annual Meeting abstract.