Comparison of quantitative imaging devices and subjective optic nerve head assessment by general ophthalmologists to differentiate normal from glaucomatous eyes.

PURPOSE

To compare the ability of subjective assessment of optic nerve head (ONH) and retinal nerve fiber layer (RNFL) by general ophthalmologists and by a glaucoma expert with objective measurements by optical coherence tomography (Stratus OCT, Carl Zeiss Meditec Inc), confocal scanning laser ophthalmoscope (HRT III; Heidelberg Engineering, Heidelberg, Germany), and scanning laser polarimetry (GDx enhanced corneal compensation; Carl Zeiss Meditec Inc, Dublin, CA) in discriminating glaucomatous and normal eyes.

METHODS

Sixty-one glaucomatous and 57 normal eyes of 118 subjects were included in the study. Three independent general ophthalmologists and 1 glaucoma expert evaluated ONH stereophotographs. Receiver operating characteristic curves were constructed for each imaging technique and sensitivity at fixed specificity was estimated. Comparisons of areas under these curves (aROCs) and agreement (k) were determined between stereophoto grading and best parameter from each technique.

RESULTS

Best parameter from each technique showed larger aROC (Stratus OCT RNFL=0.92; Stratus OCT ONH vertical integrated area=0.86; Stratus OCT macular thickness=0.82; GDx enhanced corneal compensation=0.91; HRT3 global cup-to-disc area ratio=0.83; HRT3 glaucoma probability score numeric score=0.83) compared with stereophotograph grading by general ophthalmologists (0.80) in separating glaucomatous and normal eyes. Glaucoma expert stereophoto grading provided equal or larger aROC (0.92) than best parameter of each computerized imaging device. Stereophoto evaluated by a glaucoma expert showed better agreement with best parameter of each quantitative imaging technique in classifying eyes either as glaucomatous or normal compared with stereophoto grading by general ophthalmologists. The combination of subjective assessment of the optic disc by general ophthalmologists with RNFL objective parameters improved identification of glaucoma patients in a larger proportion than the combination of these objective parameters with subjective assessment of the optic disc by a glaucoma expert (29.5% vs. 19.7%, respectively).

CONCLUSIONS

Diagnostic ability of all imaging techniques showed better performance than subjective assessment of the ONH by general ophthalmologists, but not by a glaucoma expert. Objective RNFL measurements may provide improvement in glaucoma detection when combined with subjective assessment of the optic disc by general ophthalmologists or by a glaucoma expert.