Comparison of Heidelberg Retinal Tomography and Spectral Domain Optical Coherence Tomography examinations for detection of glaucoma

Introduction
To compare the diagnostic ability of Heidelberg Retina Tomograph 3 and Spectral Domain Optical Coherence Tomography Copernicus in detection of optic disc changes in glaucomatous patients.

Material and methods
Retrospective analysis of 24 eyes of 24 subjects with primary open angle glaucoma. All individuals had complete ophthalmic examination, Heidelberg Retina Tomograph 3 and Spectral Domain Optical Coherence Tomography examinations performed. Measurements in Spectral Domain Optical Coherence Tomography were obtained both automatically (Spectral Domain Optical Coherence Tomography software) and manually. Following diameters were analyzed: disc area, cup area, cup volume, C to D ratio (C/D ratio) and circumpapillary retinal nerve fiber layer thickness.

Results
Disc area, cup area, cup volume were classified as within normal limits more often in Spectral Domain Optical Coherence Tomography printouts than in Heidelberg Retina Tomograph (75%, 63% and 83% in SD-OCT auto, 70%, 57% and 83% in SD-OCT manu vs. 58%, 37% and 33% in Heidelberg Retina Tomograph, respectively). C/D ratio was increased in 23 eyes (96%) in Heidelberg Retina Tomograph compared to 14 eyes (58%) in SD-OCT auto and 12 eyes (52%) in SD-OCT manu. Retinal nerve fiber layer thickness was significantly lower in Spectral Domain Optical Coherence Tomography (both auto and manu 96% vs. 58% in Heidelberg Retina Tomograph). According to the Moorfields Regresion Analysis classification from Heidelberg Retina Tomograph, 21 eyes were diagnosed as glaucomatous (88%).

Conclusions
Although there was poor agreement in optic disc measurements between the two methods, both had high sensitivity in detection of glaucomatous optic disc changes (96% when retinal nerve fiber layer thickness measured by Spectral Domain Optical Coherence Tomography compared to 88% for Moorfield regresion analysis in Heidelberg Retina Tomograph). The sensitivity of diagnostic ability increases when both, Heidelberg Retina Tomograph and Spectral Domain Optical Coherence Tomography are performed.