Posterior displacement of the lamina cribrosa in normal-tension and high-tension glaucoma.

PURPOSE

To compare the in vivo lamina cribrosa position in patients with normal-tension glaucoma (NTG) and high-tension glaucoma (HTG).

METHODS

The comparative cross-sectional study included three age- and sex-matched groups: 26 eyes of 26 NTG patients, 26 eyes of 26 HTG patients and 25 eyes of 25 healthy controls. Serial horizontal B-scan images of the optic nerve head were obtained from each eye using enhanced depth imaging optical coherence tomography. Mean and maximum lamina cribrosa depths were measured in 11 equally spaced horizontal B-scans. Statistical analysis was conducted to compare lamina cribrosa depth among the three groups and to correlate lamina cribrosa depth with age, retinal nerve fibre layer (RNFL) thickness and visual field (VF) mean deviation (MD). The area under the receiver operating characteristic curve (AUC) for lamina cribrosa depth was calculated.

RESULTS

Mean and maximum lamina cribrosa depths were significantly greater in HTG than in NTG eyes, and in NTG than in normal eyes in all 11 scans (all p < 0.05). The AUCs of the averaged mean and averaged maximum lamina cribrosa depths in HTG eyes (0.977 and 0.988, respectively) were significantly greater than those in NTG eyes (0.735 and 0.765, respectively; both p < 0.01). Lamina cribrosa depth was found to have a negative correlation with age in HTG eyes; however, the same association was not found in NTG or controls. Neither RNFL thickness nor VF MD was significantly correlated with lamina cribrosa depth in each group.

CONCLUSIONS

The lamina cribrosa is more posteriorly located in HTG than in NTG eyes, as well as in NTG eyes compared with healthy controls. The lamina cribrosa depth can help differentiate HTG from normal eyes, but it does not reach a good level of diagnostic accuracy for detecting NTG.