Claire Manley¹, Peter Bex¹, Lotfi Merabet²; ¹Northeastern University, ²Massachusetts Eye and Ear Infirmary, Harvard Medical School

Cerebral visual impairment (CVI) is a brain-based visual disorder associated with early damage and maldevelopment of retrochiasmal visual processing pathways and areas. Individuals with CVI often face difficulties with tasks such as visual search, navigation, scene recognition, reading, and driving, requiring more time and cognitive effort compared to typically developing individuals. A common feature among these tasks is the need to divide visual attention between central and peripheral vision, reflecting the functional field of view (FFV). We assessed the FFV in 10 participants with CVI (meanAge=24.09 years, SD=11.08) and 6 control participants (meanAge=20.00 years, SD=5.00). Two characters (“X”s and “O”s), one foveal and one peripheral (4°, 8°, 16°), were presented at size and duration combinations determined by a QuestPlus algorithm. In a 2AFC task, participants indicated whether the characters were the same or different. The area under the curve (AUC) for target size and duration decreased with eccentricity and was higher for the control group (mean = 0.78, SD = 0.09) (Figure 1.1) compared to the CVI group (mean=0.63, SD=0.14) [F(1,46)=20.84, p= 0.00004] (Figure 1.2, Figure 2). For duration, there was a significant effect of group [F(1,46)=25.37, p=9.459e-06], but not of eccentricity [F(1,44)=0.7204, p=0.4925]. The CVI group required longer durations for accurate identification (meanCVI=0.15, SD=0.08; meanControls=0.05, SD=0.04). For target size, however, there were significant effects of both group [F(1,46) = 15.56, p = 0.0003] and eccentricity [F(1,45)=16.55, p=0.0002]. The CVI group required larger target sizes across eccentricities (meanCVI=0.57, SD=0.32; meanControls=0.29, SD=0.18). This suggests that for both groups, target size must increase with eccentricity for accurate identification. However, processing time does not significantly increase with greater eccentricity. This research highlights the perceptual deficits experienced by individuals with CVI. In the periphery, they require more time and larger stimuli to accurately perceive information in parallel with stimuli in the central visual field.