  Purpose: To evaluate nerve fiber layer (NFL) reflectance for glaucoma
diagnosis using a large dataset. Methods: Participants were imaged with 4.9mm
ONH scans using spectral-domain optical coherence tomography (OCT). The NFL
reflectance map was reconstructed from 13 concentric rings of optic nerve
head(ONH) scan, then processed by an azimuthal filter to reduce directional
reflectance bias due to variation of beam incidence angle. The peripapillary
thickness and reflectance maps were both divided into 96 superpixels.
Low-reflectance and low-thickness superpixels were defined as values below the
5th percentile normative reference for that location. Focal reflectance loss
was measured by summing loss, relative to the normal reference average, in
low-reflectance superpixels. Focal thickness loss was calculated in a similar
fashion. The area under receiving characteristic curve (AROC) was used to
assess diagnostic accuracy. Results: Fifty-three normal, 196 pre-perimetric,
132 early perimetric, and 59 moderate and advanced perimetric glaucoma
participants were included from the Advanced Imaging for Glaucoma Study.
Sixty-seven percent of glaucomatous reflectance maps showed characteristic
contiguous wedge or diffuse defects. Focal NFL reflectance loss had
significantly higher diagnostic accuracy than the best NFL thickness parameters
(both map-based and profile-based): AROC 0.80 v. 0.75 (p<0.004) for
distinguishing glaucoma eyes from healthy control eyes. The diagnostic
sensitivity was also significantly higher at both 99% and 95% specificity
operating points. Conclusions: Focal NFL reflectance loss improved glaucoma
diagnostic accuracy compared to the standard NFL thickness parameters.
