Separating Deficits: First-Order vs. Second-Order Temporal Perception in Anisometropic Amblyopia

Previous research has indicated that the processing of first-order and second-order stimuli in the amblyopic eye (AE) is compromised, yet whether its diminished temporal perception is distinct from its impaired first-order spatial perception remains unclear. This study evaluates the contrast and modulation sensitivity of first-order and second-order sinusoidal grating stimuli across six temporal frequencies in eight anisometropic amblyopes and ten normal subjects. Results revealed that the AE exhibited deficits in first-order temporal perception and carrier detection compared to both its fellow eye (FE) and the control eyes (CE) of normal subjects. For second-order temporal perception, tested under two conditions with identical or balanced carriers, the AE showed impaired perception with identical carriers but no significant deficits with balanced carriers. The FE performed normally in all tasks compared to the CE. These findings suggest that the reduced second-order temporal perception in amblyopia may stem from underlying impairments in first-order spatial perception.