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Adaptive optics (AO), which was first used in astronomical telescopes, is a technology used to improve the performance of optical systems by reducing the effect of wavefront distortions. For the past few years, AO has been used in glaucoma research to visualize the lamina cribrosa,1,2 retinal ganglion cells3 and retinal nerve fiber bundles (RNFBs).4,5 Takayama et al. conducted a prospective, cross-sectional study comparing the RNFB width between glaucoma patients and normal controls using AO scanning laser ophthalmoscopy (SLO) and concluded that RNFB width was significantly smaller in the glaucoma group than in the controls. They also demonstrated that RNFB narrowing corresponded to RNFL thinning and visual field defects. The usage of RNFB width as a parameter to evaluate glaucomatous damage was suggested in a previous article by Kocaoglu et al.4 using AO optical coherence tomography (OCT). A good correlation between retinal nerve fiber layer (RNFL) thickness measured by OCT and RNFB width measured by AO SLO in normal eyes was demonstrated in the authors' previous article.5 AO is certainly a promising technology in glaucoma diagnostics, but there are hurdles that should be overcome to be used in clinical practice. Current AO SLO captures only a small portion of the fundus (3.0 x 1.9 degrees in the present study) and it is timeconsuming to create a montage using numerous AO SLO images to evaluate one eye. Additionally, a better parameter should be invented than RNFB width. In the present study, RNFB was significantly thinner in the glaucomatous eyes than in the normal eyes only in 3 of 12 clock hour locations. As shown in Figure 3, RNFL thickness appears to be more useful in discriminating glaucoma from normal than RNFB width.