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Xiang Fan, Lingling Wu; Applications of Isolated-check Visual Evoked Potential in Early -Stage of Open-angle Glaucoma Patients. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5845.
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© ARVO (1962-2015); The Authors (2016-present)
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.
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.
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).
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.
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