Temporal Characteristics of Visual Processing in Amblyopia

Purpose: Amblyopia affects not only spatial vision but also temporal vision. In this study, we aim to investigate temporal processing deficits in amblyopia.

Methods: Twenty amblyopic patients (age: 27.0 ± 5.53 years, 15 males), and 25 normal observers (age: 25.6 ± 4.03 years, 15 males) were recruited in this study. Contrast thresholds in an orientation discrimination task in five target-mask stimulus onset asynchronies (SOA) conditions (16.7 ms, 33.4 ms, 50.0 ms, 83.4 ms, and ∞/no noise) were measured. An elaborated perceptual template model (ePTM) was fit to the behavioral data to derive the temporal profile of visual processing for each participant.

Results: There were significant threshold differences between the amblyopic and normal eyes [(1,43) = 10.6, = 0.002] and a significant group × SOA interaction [(2.75,118) = 4.98, = 0.004], suggesting different temporal processing between the two groups. The ePTM fitted the data well ( test, all s > 0.50). Compared to the normal eye, the amblyopic eye had a lower template gain ( = 0.046), and a temporal window with lower peak and broader width (all s < 0.05). No significant correlation was found between the observed temporal deficits and visual acuity in amblyopia (s > 0.50). Similar results were found in the anisometropic amblyopia subgroup. No significant difference was found between the fellow eyes of the monocular amblyopia and the normal eyes.

Conclusion: Amblyopia is less efficient in processing dynamic visual stimuli. The temporal deficits in amblyopia, represented by a flattened temporal window, are likely independent of spatial vision deficits.