Temporal Characteristics of Visual Processing in Amblyopia

Abstract

PurposeAmblyopia affects not only spatial vision but also temporal vision. In this study, we aim to investigate temporal processing deficits in amblyopia.MethodsTwenty 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.ResultsThere were significant threshold differences between the amblyopic and normal eyes [F(1,43) = 10.6, p = 0.002] and a significant group × SOA interaction [F(2.75,118) = 4.98, p = 0.004], suggesting different temporal processing between the two groups. The ePTM fitted the data well (χ2 test, all ps > 0.50). Compared to the normal eye, the amblyopic eye had a lower template gain (p = 0.046), and a temporal window with lower peak and broader width (all ps < 0.05). No significant correlation was found between the observed temporal deficits and visual acuity in amblyopia (ps > 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.ConclusionAmblyopia 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.

Decomposing the Response Time in Amblyopia: A Drift Diffusion Model Analysis

“…When viewing stimuli with same strength, the drift rate would be smaller because of the higher internal noise in the amblyopic visual system. 53 – 55 This could explain the linear relationship between the visual acuity and the RT deficits in the amblyopic eye reported in other studies. 14 , 20 On the other hand, it suggests that the drift rate can be compensated by increasing the stimulus strength, as confirmed by our finding of no difference in the drift rate or accumulation time between the AE and NDE.…”

Temporal synchronization elicits enhancement of binocular vision functions

“…This loss of balance can dramatically decrease the binocular summation, as is modeled and reported by the gain control and other theories. 13 , 36 , 55 , 56 , 57 …”

“… 2 , 13 , 14 , 15 An important example of ocular imbalance is amblyopia, a developmental condition resulting from the abnormal development of the visual system in the early stages of life, 16 characterized by a unilateral decrease in various spatial resolution dysfunctions, 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 the presence of spatial crowding, 25 and reduced temporal functions. 24 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 Indeed, various studies have shown that binocular imbalance in the spatial or stimulus energy domain is associated with lower binocular summation, 13 , 15 , 38 , 39 , 40 which is restored by adjusting the contrast or stimulus energy of the two eyes. 39 , 41 …”

Noise Generation Methods Preserving Image Color Intensity Distributions

“…P e l l i and F a r e l l [5] explain that comparing sensitivity to stimulus characteristics with and without background noise allows separating the observer's ability of information processing from the observer's intrinsic noise. Visual noise, added to images is widely used to explore visual system characteristics in different diseases such as amblyopia [6], X-linked retinoschisis [7], glaucoma [8], age-related changes of visual functions [9] neural variability between children with Autism Spectrum Disorder and typical development, e.g., [10,11].…”