Abstract
Purpose :
Compare VEP and SD-OCT in glaucoma suspect or glaucoma patients, aiming to explore the efficiency of VEP to detect early visual electrophysiological functional change before structural damage of optic nerve and ganglion cell complex, indirectly understand glaucoma pathophysiological sequence between ganglion cells and optic nerve axons bundles.
Methods :
Glaucoma-suspect or glaucoma patients in the clinic were tested with OCT for optic nerve (ON) and ganglion. VEP was also obtained in these patients. Total 56 patients, 105 eyes were used for data analysis, missing data was due to patient’s incoorperation or technical difficulties. Data results were analysed and expressed as sensitivity and specificity comparing VEP (positive/negative) results reference to OCT for both ON and ganglion. The Kappa value was also used to compare the agreement between two tests.
Results :
VEP compared to OCT, the sensitivity and specificity for both ON and ganglion are less than 80% ( sensitivity for ON and ganglion is 70% and 74%; specificity for ON and ganglion is 65% and 65%). The Kappa value is between 0.2 to 0.6 (0.37 for ON and 0.36 for ganglion) indicating fair agreement. This result is not as expected i.e., to have VEP more sensitive to detect early glaucoma as a functional test. This inconsistence results could be due to technical variations, or there is a missing link between OCT detectable structural change and the electric physiological change of visual response. The possibale technical variations can be further studied by comparing two testers using Kappa value to identify the consistence of VEP test.
Conclusions :
Current study indicates that OCT imaging study is one of the most efficent clinical study in glaucoma diagnosis and progress monitor. The current preliminary result indicated possible missing link from optic nerve functional impairment to detectable structural change in glaucoma progress. For example how does lamela cribrosa change cause optic nerve damage; how is ganglion cells apoptosis triggered by axon damage and how does axon transport affect glaucoma pathogenesis. This study indirectly support the hypothesis in glaucoma pathophysiological sequential process, i.e., optic nerve axon damage causes retrospective damage to ganglion cell complex.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.