Investigation of visual perception in keratoconus patients through event-related potentials

This study aims to examine the neurocognitive responses to facial and face-like visual stimuli in individuals with keratoconus. Based on the hypothesis that visual perception may be affected not only peripherally but also at the central level, the impact of keratoconus on visual cognition was investigated using EEG. The study specifically focused on the ERP components N170 and VPP, which are sensitive to face perception. A total of 34 individuals diagnosed with keratoconus and 34 healthy controls participated in the study; after applying artifact control and data quality criteria, EEG data from 30 keratoconus patients and 27 healthy controls were included in the analyses. Participants were presented with images of faces and face pareidolia, and the brain responses to these stimuli were analyzed in terms of latency and amplitude. Assumptions of normal distribution were evaluated using the Shapiro-Wilk test and skewness-kurtosis values. Independent samples t-tests were used for group comparisons. The results indicated a significant increase in latency in both N170 and VPP components in the keratoconus group (p <0.05). These findings demonstrate that neural ERP responses related to face perception are altered in terms of timing in keratoconus patients. Correlation analyses between ERP responses and individuals' visual acuity levels in the keratoconus group revealed no significant relationship. This suggests that the observed differences in brain responses may stem not from visual acuity levels but from deeper perceptual processing mechanisms. The findings indicate that keratoconus can induce perceptual effects not only at the optical but also at the central nervous system level. When considered alongside previously reported psychiatric symptoms in individuals with keratoconus, these delays in face perception may be associated with both perceptual and psychological mechanisms.