Reversal of lamina cribrosa displacement and thickness after trabeculectomy in glaucoma

Abstract

Purpose: To investigate the response of the lamina cribrosa (LC) and prelaminar tissue to glaucoma surgery using spectral-domain optical coherence tomography (SD-OCT) and to determine the factors influencing such responses.

Design: Observational case series.

Participants: Thirty-five eyes of 35 primary open-angle glaucoma patients who underwent trabeculectomy.

Methods: Patients were imaged using a 10 × 15-degree rectangle covering the optic disc using SD-OCT. About 65 B-scans covering the optic discs were obtained using enhanced depth imaging SD-OCT before surgery, after 1 week, and 1, 3, and 6 months postoperatively. The pre- and postoperative magnitude of the LC displacement (distance from the Bruch's membrane opening plane to the level of anterior LC surface) and the thickness of LC and prelaminar tissue were determined on 7 to 13 selected B-scan images in each eye.

Main outcome measures: The amount of reduction in the LC displacement and changes in the thickness of LC and prelaminar tissue.

Results: Intraocular pressure (IOP) was decreased from 27.2 ± 8.9 mmHg (range, 14-47) to 10.5 ± 3.4 mmHg (range, 6-21) at postoperative month 6. The amount of posterior displacement of the LC was significantly decreased from a mean preoperative level of 614.58 ± 179.57 to 503.90 ± 142.67 μm at postoperative month 6 (P<0.001). The thicknesses of the LC and prelaminar tissue were significantly increased at postoperative month 6 (P<0.001 and P = 0.048, respectively). The magnitude of the reduction in the LC displacement was significantly associated with younger age (P<0.001), greater percent IOP reduction (P = 0.019), and greater preoperative LC displacement (P = 0.024). None of the factors was associated with the amount of LC or prelaminar tissue thickening.

Conclusions: A significant reduction in the posterior displacement and increase in the thickness of the LC and prelaminar tissue were demonstrated after glaucoma surgery using enhanced depth imaging SD-OCT of the optic nerve head. The amount of reduction in the LC displacement was associated with younger age, larger baseline LC displacement, and greater IOP reduction.