Comparison of the Diagnostic Ability of Retinal Nerve Fiber Layer Thickness Measured using Time Domain and Spectral Domain Optical Coherence Tomography in Primary Open Angle Glaucoma

Purpose:To evaluate and compare the diagnostic ability of retinal nerve fiber layer (RNFL) thickness measurements using time domain (Stratus) and spectral domain (Cirrus HD) optical coherence tomography(OCT).in preperimetric and early primary open angle glaucoma (POAG). Methods:A total of 62 eyes from 62 normal subjects,47 eyes from 47 early perimetric damage POAG patients and 30 eyes from 30 preperimetric glaucoma patients were chosen in the study.All the subjects underwent peripapillary RNFL thickness measurements using Stratus OCT and Cirrus HD-OCT on the same day by a single trained operator.The RNFL thickness measured by Stratus OCT and Cirrus HD-OCT was statistically compared using paired t-tests.The relationship between RNFL thickness measured by two OCT instruments was evaluated using Pearson’s correlation coefficient.Areas under the receiver operating characteristic curves (AROC) were calculated and compared. Results:RNFL thickness measured using Stratus OCT was generally thicker than that using Cirrus HD-OCT(P<0.05). A highly significant correlation between the two OCT instruments measurements was found in four quadrants and average RNFL thickness measurements (P<0.001). The average RNFL thickness of Cirrus HD-OCT had significantly(P=0.006) higher diagnostic ability (AROC=0.951) than that of Stratus OCT(AROC=0.881) in preperimetric glaucoma. There were no significant differences between the AROCs for other RNFL thickness parameters from Cirrus HD-OCT and Stratus OCT in preperimetric and early glaucoma(P>0.05). Conclusion: Significant differences and an excellent correlation were noted in terms of RNFL thickness measurements using Stratus OCT and Cirrus HD-OCT. Cirrus HD-OCT presented higher diagnostic ability for preperimetric glaucoma.