Utility of the Modified Isolated-check Visual Evoked Potential Technique in Functional Glaucoma Assessment

Precis: Cortical response to low contrast stimuli, as measured by isolated-check visual evoked potential (icVEP) technology, has the potential to provide functional assessment that may complement standard achromatic perimetry in assessing glaucomatous change. Purpose: To evaluate the utility of modified isolated-check visual evoked potential (icVEP) testing in detecting functional glaucomatous damage. Patients and Methods: Subjects who met pre-determined criteria of controls, glaucoma suspects, pre-perimetric glaucoma, or glaucoma were enrolled in this prospective cross-sectional study from a single tertiary care center. Glaucoma patients were further categorized as early, moderate, advanced, or severe based on Hodapp-Anderson-Parrish criteria. icVEP testing was performed with 10 2-second runs per qualified eye using the EvokeDx testing software. Multivariate statistics were used to calculate signal-to-noise ratios (SNR) and perform outlier analysis. Results: 140 eyes met criteria (mean±standard deviation; age of 63±14▒y, 49% male, logMAR visual acuity 0.11±0.089). There was no significant difference in age, gender, or logMAR visual acuity amongst the groups. Controls had a significantly higher SNR than all other groups (P<0.003), including patients with pre-perimetric glaucoma. Among those with glaucoma, the early glaucoma patients had significantly higher SNR than the moderate, advanced, or severe glaucoma cohorts (P<0.04). The optimal SNR cutoff for differentiating between glaucomatous and non-glaucomatous eyes was 0.95, both with (sensitivity 82%, specificity 76%) and without (sensitivity 82%, specificity 100%) glaucoma suspects included in analysis. Conclusions: icVEP technology has the potential to complement standard achromatic perimetry in functional assessment of glaucomatous defects.