Abstract
Purpose :
Amblyopia, a visual developmental disorder, is traditionally characterized by monocular vision loss. And, the current outcome for successful amblyopia treatment is full recovery of visual acuity of the amblyopic eye. However, accumulating evidence suggests that several visual functions remain impaired in patients with treated amblyopia, including poor contrast sensitivity and stereopsis. Additionally, treated amblyopes may also present residual temporal processing deficits. In previous studies, we observed that amblyopes present deficits in motion extrapolation and motion extrapolation correction. Here, we wanted to investigate whether the motion extrapolation deficits remain when normal visual acuity is restored in adults with unilateral amblyopia.
Methods :
Ten treated adult amblyopes who followed patching therapy and/or optical correction, and 10 control subjects participated in the study. We assessed the motion processing functions using two motion illusion paradigms: the Flash Lag Effect (FLE) and the Flash Grab Effect (FGE). We measured the FLE magnitude under two contrast conditions: 0.2 and 1. And, we assessed the FGE magnitude under two spatial frequencies: low 2 and high 8 c/d. Subjects were tested with left and right eye separately.
Results :
First, we compared the difference of FLE magnitude between control and amblyopic groups. There was no significant difference of FLE under contrast 1 condition between the two groups (F1,18 = 2.15, P = 0.16), but the treated amblyopes exhibited a smaller FLE magnitude under the contrast 0.2 condition when compared to the controls (F1,18 = 4.79, P = 0.042). The difference of FLE between the previous amblyopic eye (pAE) and previous fellow eye (pFE) was not significant (F1,9 = 0.036, P = 0.854). Additionally, we found that amblyopes exhibited a larger FGE either in low or high SF conditions compared to controls (P ≤ 0.031). In amblyopic group, the FGE magnitude of pAE was significantly larger than that of the pFE (F1,9 = 14.2, P = 0.004).
Conclusions :
Our findings showed that the treated amblyopes had an improved motion extrapolation in the high contrast but not in the low contrast condition. However, the full recovery of visual acuity does not restore the motion extrapolation correction, suggesting that a processing delay remains in the treated amblyopic visual system. Alternative approaches may be required to improve temporal vision in amblyopia.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.