UC San Diego

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.