Abstract
Purpose: :
To evaluate the ability of short duration transient VEP (SD-tVEP) to discriminate between healthy eyes and eyes with early to advanced glaucomatous visual field loss.
Methods: :
We tested 30 normal eyes of 30 subjects and 45 eyes of 45 glaucoma patients. Normal eyes had 20/30 or better visual acuity and normal 24-2 SITA Standard visual fields (VF). Glaucoma was staged as early, moderate and advanced (15 eyes each). Synchronized single-channel SD-tVEPs were recorded using the Diopsys NOVA-FP (Fixed Protocol) System (Diopsys, Inc. Pine Brook,NJ). Each eye was stimulated with a 15% and 85% Michelson contrast checkerboard pattern. Test duration was 30 seconds/eye. Each resulting test resulted in a low and high contrast VEP response. Each response was evaluated for overall waveform quality, N75 and P100 latency, and the amplitude difference of the P100 and N75. Asymmetries between OS and OD latencies and amplitudes were evaluated. The sensitivity and specificity was calculated for the entire population and for each category.
Results: :
The specificity was 86.2%. For all eyes, the sensitivity was 89.6%; the PPV was 91.5% and the NPV 83.3%. For the early glaucoma eyes, the sensitivity was 80%, the PPV was 86.2% and the NPV 80%. For the moderate stage eyes the sensitivity was 100%, the PPV was 66.7% and the NPV 100%. For the advanced stage eyes the sensitivity was 94.7%, the PPV was 81.8% and the NPV 96.2%.
Conclusions: :
Short-duration transient VEP was able to objectively measure visual field loss and discriminate between healthy and glaucomatous eyes. In addition, it showed good differentiation between early, moderate and advanced glaucoma.
Keywords: electrophysiology: clinical