Abstract
Purpose :
To determine whether isolated-check visual evoked potential (icVEP) could detect visual function abnormalities in early-stage of open-angle glaucoma (OAG), and to explore the potentials and relating factors of diagnosing by icVEP.
Methods :
Forty-four OAG patients with early-stage of visual field loss detected by standard automated perimetry (Humphrey Field Analyzer, 30-2 SITA program) and twenty-six control observers were included in a cross sectional study. Low-contrast bright isolated-checks were luminace-modulated against a static background at 10 Hz in order to drive preferentially the magnocellular ON pathway. Visual evoked potentials were recorded during 1-s epochs of stimulation and responses at the stimulus frequency were measured. Artifact rejection features ensured that eight valid runs were obtained per eye. Optical coherence tomography (Spectralis SD-OCT, Heidelberg Engineering, Heidelberg, Germany) was used to detect and confirm retinal nerve fiber layer (RNFL) defects for OAG patients. Signal-to-noise ratios (SNR) were derived based on a multivariate statistic. Eyes that yielded an SNR≤1 were considered as abnormal. Receiver-operating-characteristic (ROC) curve analysis was used to estimate the accuracy of group classification. Correlations between SNR and relating factors were analyzed.
Results :
By SNR criterion of 1, icVEP had the sensitivity of 68% and the specificity of 95% for diagnosing early-stage of OAG with 81% of classification accuracy. However, ROC curve analysis implied that SNR criterion of 0.93 could reach the sensitivity of 66% and the specificity of 100%, which produced the highest classification accuracy (82%). Thickness changing of RNFL in the temporal superior quadrant on OCT showed significant correlated with SNR (p<0.05, r=0.370). Amount of abnormal test points in central 11°visual field (pattern deviation, P<0.5%) was significantly negative correlated with SNR (p<0.05, r=-0.332).
Conclusions :
The icVEP could detect glaucomatous visual function abnormalities in about 70% of eyes with early-stage OAG with specificity about 95%. The severity of SNR correlated with both the the decreases of RNFL thickness detected by OCT and severity of central 11°visual field loss to some extent. Above results suggested the icVEP could be a potential objective visual function test for early glaucoma.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.