Association of optic nerve head prelaminar schisis with glaucoma.

Abstract: Purpose To compare the frequency of observing optic nerve head (ONH) prelaminar schisis by optical coherence tomography (OCT) in glaucoma and glaucoma suspect (GL/S) eyes versus healthy control (HC) eyes and to assess its association other markers of glaucoma severity. Methods This cross-sectional study included 298 eyes of 150 GL/S patients and 88 eyes of 44 HC. OCT scans were obtained by SPECTRALIS (Heidelberg Engineering GmbH), including 24 radial B-scans, each comprised of 768 A-lines spanning 15o, centered on the ONH. Two reviewers masked to all other clinical, demographic and ocular information, independently graded the OCT scans for the presence of ONH prelaminar schisis on a 4-point scale: 0 (none) to 3 (severe). The probability of ONH schisis was compared between groups and against demographic and ocular factors, including structural and functional measures of glaucoma severity. Results The frequency and severity of ONH prelaminar schisis were greater in GL/S than in HC (p=0.009). Among the GL/S group, 165 eyes (55.4%) had no visible schisis (Grade-0), 71 (23.8%) had Grade-1, 46 (15.4%) had Grade-2 and 16 (5.4%) had Grade-3 schisis. Among HC eyes, 59 (67.0%) had Grade-0, 24 (27.3%) had Grade-1, 5 (5.7%) had Grade-2, none had Grade-3. ONH schisis was more common in eyes with thinner MRW and a deeper cup. Conclusions ONH prelaminar schisis may be a sign of glaucomatous deformation and reflect ongoing pathophysiological damage. ONH prelaminar schisis can impact OCT image segmentation and diagnostic parameters, resulting in substantial overestimation of the true rim tissue thickness and underestimation of cup depth.