The Cirrus HD OCT is a new spectral domain OCT. Even though its resolution and speed are much better than the previous time domain Stratus OCT, its diagnostic power for glaucoma detection and judgement of disease progression should be directly compared with Stratus OCT. In the present study, we will review the data of peripapillary retinal nerve fiber layer thickness measurement using the Cirrus HD OCT and Stratus OCT. Their discriminating ability for diagnosis of glaucoma and judgement of disease progression will be compared using the ROC curves and Cohen's kappa.