Diagnostic Evaluation Of Optical Coherence Tomography In Glaucoma Suspect Eyes

Objectives:1. To determine the effect of demographic and ocular variables on optic nerve head and retinal nerve fiber layer (RNFL) thickness measurements using spectral-domain optical coherence tomography(OCT) in healthy population.2. To compare the OCT parameters and to identify which measurements are best able to differentiate between healthy and glaucoma suspect eyes.3. To calculate and validate the diagnostic ability of the linear discriminant function (LDF) based on the parameters obtained using OCT for discriminating between healthy and glaucoma suspect eyes.Methods:1. A total of119volunteers at Tianjin medical university eye hospital from January2011to September2012were retro-spectively enrolled in this study, which included20eyes with ocular hypertension (OHT),22eyes with pre-perimetric glaucoma (PG),17perimetrically unaffected eyes of patients with glaucoma in the fellow eye (FE),60eyes of age matched healthy individuals. All participants underwent complete ophthalmic examinations. The effect of gender, laterality, axial and age on the topograph of ONH and RNFL were analyzed.2. The ONH and RNFL parameters were compared among the four study groups. The areas under the receiver operating curves (AUC) and the standard error were calculated for single parameters.3. The discriminant function were established by integrate OCT parameters with high diagnostic values in healthy and glaucoma suspect eyes. Receiver operating characteristic (ROC) curve were plotted and compared with the parameters measured using OCT.Results:1. There were no difference between men and women and right and left eyes in all ONH and RNFL parameter(r=-1.10～1.27, P>0.05). 2. There was significant positive correlation between axial length and rim area, disc area(r=0.83,0.36, P<0.05) Correlation analysis also showed significantly negative correlation between RNFL thickness and axial length as well as age.(r=-0.76～-0.88, P<0.05)3. Comparative analysis of OCT parameters revealed statistically significant differences in all ONH parameters, except for DA and CV; statistically significant differences were found in all RNFL parameters, except for RNFL thickness at8’ and9o’clock.4. The average RNFL thickness obtained the highest AUC values in the whole glaucoma suspect group (AUC=0.828). The vertical C/D had the best diagnostic accuracy among the ONH parameters (AUC=0.775).5. The discriminant function was:LDF=-10.91+1.076XI-3.124X2+0.025X3+0.028X4+0.011X5+0.013X6+0.014X7(X1:RA, X2:vertical C/D, X3:mRNFL, X4:inferior RNFL, X5, X6, X7:6,7,11o’ Clock RNFL), the AUC values of the LDF was0.901.Conclusions:1. In normal population, there is significant correlation between age or axial length and the OCT parameter. These factor can impair the efficacy of the OCT, thus greatly affecting the accuracy of the measurements.2. Using OCT parameters to discriminate glaucoma suspect eyes from control showed promising results in our studies.3. RNFL parameters presented with better discriminatory abilities than ONH parameters in our study.4. Compared with the OCT-provided parameters, the linear discriminant analysis improved the ability to differentiate between normal and glaucomatous eyes in Chinese population.