Defects of the lamina cribrosa in eyes with localized retinal nerve fiber layer loss.

OBJECTIVE: To determine whether focal abnormalities of the lamina cribrosa (LC) are present in glaucomatous eyes with localized retinal nerve fiber layer (RNFL) defects.
DESIGN: Cross-sectional, observational study. PARTICIPANTS: We analyzed 20 eyes of 14 subjects with localized RNFL defects detected by masked grading of stereophotographs and 40 eyes of 25 age-matched healthy subjects recruited from the Diagnostic Innovations in Glaucoma Study at the University of California, San Diego.
METHODS: All eyes had stereoscopic optic disc photography and in vivo LC imaging using enhanced depth imaging optical coherence tomography (EDI-OCT). Two masked graders identified focal LC defects defined by a standardized protocol using 48 radial scan EDI-OCT images. The kappa coefficient was calculated as a measure of the reliability of interobserver agreement. MAIN OUTCOME MEASURES: The number of focal LC defects and the relationship between the location of LC defects and the location of localized RNFL defects.
RESULTS: Of 20 eyes with a localized RNFL defect, 15 (75%) had ≥1 LC defect compared with only 1 of 40 healthy eyes (3%). There were 13 eyes with localized RNFL defects that had 1 LC defect, 1 eye with 2 LC defects, and 1eye with 3 LC defects. The largest area LC defect was present in a radial line EDI-OCT scan corresponding with a localized RNFL defect in 13 of 15 eyes (87%). There was good agreement between graders as to whether an eye had an LC defect (kappa = 0.87; 95% confidence interval [CI], 0.73-1.00; P<0.001) and the location of the largest defect (kappa = 0.72; 95% CI, 0.44-1.00; P<0.001).
CONCLUSIONS: Focal defects of the LC were frequently visible in glaucomatous eyes with localized RNFL defects. Focal abnormalities of the LC may be associated with focal retinal nerve fiber damage.