Institution: University of California Berkeley
Poster Title: The appearance of isolated and crowded stimuli in amblyopia
Abstract: Amblyopia is a neurodevelopmental disorder characterized by reduced visual acuity (VA) in one or both eyes. Amblyopic observers perceive stimuli distorted (e.g., thinner strokes, blurred, indefinite edges). Additionally, stronger and more extensive crowding (i.e., impaired target identification due to neighboring stimuli) has been found in the central visual field of observers with amblyopia. Here, we investigated the appearance of isolated and crowded (by black bars) high contrast letters in amblyopia. Observers (16 controls, 14 persons with amblyopia) were presented with 5 letters monocularly (either to the dominant/fellow eye (DE/FE) or non-dominant/amblyopic eye (NDE/AE)). Letters were presented at 1.0 and 1.5 x observersÂ’ VA threshold to the fovea for 500 ms. Observers were instructed to recreate target appearance by selecting squares on a 9x9 square-grid interface used to create the letter targets. Results showed that observers' responses were most similar to the target for stimuli 1.5 x the VA threshold (vs. 1.0 x threshold size), for isolated (vs. flanked) targets and for controls (vs. observers with amblyopia). No crowding differences were found between groups. The responsesÂ’ similarity to the target between the FE and AE of observers with amblyopia showed no differences. Surprisingly, response-target similarity was lower for controlsÂ’ DE, compared to the NDE. The captured appearance of the targets showed distortions in shape (e.g., straight line elements depicted as curves), fusion of elements (e.g., connecting the flanking bars), as well as truncation and extension of elements. The current results reveal characteristics of target appearance and highlight appearance differences between normal and amblyopic visual perception when controlling for VA differences.