Abstract
Purpose: :
To compare performance of ganglion cell/inner plexiform layer (GC/IPL) thickness measurements to macular and retinal nerve fiber layer (RNFL) thickness measures for discrimination of glaucoma patients from normal subjects.
Methods: :
51 normal control eyes (29 subjects) and 49 glaucomatous eyes (39 patients) with a visual field mean deviation (MD) better than –12.0 dB and spherical equivalent >–8.0 D and no other significant ocular pathology were enrolled from the UCLA SD-OCT imaging study. Glaucoma eyes were required to have a reproducible field defect defined as presence of ≥4 test locations on pattern deviation plot with p<5% and an abnormal Glaucoma Hemifield Test. Study eyes underwent a thorough eye exam, biometry, and RNFL/macular imaging (Optic Disc and Macular Cubes 200x200, Cirrus SD-OCT). GC/IPL, macular, and RNFL thickness measurements, respective areas under the ROC curves, (AUCs) and accuracies (average of sensitivity and specificity) were compared.
Results: :
Average (±SD) age and MD were 56.3 (±9.0) and 67.4 (±8.5) years and 0.1 (±1.5) and –3.6 (±3.2) dB in the control and glaucoma groups, respectively (p<0.001 for both). The average (±SD) measurements in the control and glaucoma subjects for the three sets of thickness outcomes were: GC/IPL thickness 81 (±8) vs. 64 (±9), macular thickness 281 (±13) vs. 256 (±14), and RNFL 96 (±11) vs. 67 (±9) microns (p<0.001 for all). Parameters with the highest AUCs were temporal inferior GC/IPL thickness (0.96±0.02), macular outer inferior thickness (0.94±0.02), and inferior quadrant RNFL thickness (0.99±0.01). Covariate-adjusted AUCs and accuracies, corrected for age, axial length, and disc size, were as follows: temporal inferior GC/IPL thickness 0.98 (95% CI: 0.96-1.00)/93%, outer temporal macular thickness 0.96 (95% CI: 0.93-0.99)/88%, and inferior quadrant RNFL 0.99 (95% CI: 0.98-1.00)/94%.
Conclusions: :
Performance of GC/IPL measurements approximates that of RNFL thickness for detection of early perimetric glaucoma. Our findings suggest that macular ganglion cell loss occurs concurrent with appearance of early glaucomatous field loss.
Keywords: imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • clinical (human) or epidemiologic studies: systems/equipment/techniques