Factors Associated with Lamina Cribrosa Displacement after Trabeculectomy Measured by Optical Coherence Tomography in Advanced Primary Open Angle Glaucoma

Purpose: To investigate the correlation between corneal biomechanical properties and lamina cribrosa displacement after MMC-augmented trabeculectomy. Methods: Eighty-one primary open angle eyes were imaged before and after trabeculectomy using optical coherence tomography. Corneal biomechanical properties were measured by Ocular Response Analyser before the operation. The anterior lamina was marked in several points in each of four radial scans to evaluate lamina cribrosa depth in response to Intraocular pressure (IOP) reduction. Results: Factors associated with deeper baseline lamina cribrosa were cup-disc ratio (P=0.04), baseline IOP (P= 0.01), corneal hysteresis (P=0.001), and corneal resistance factor (P=0.001). The mean change of lamina cribrosa depth after trabeculectomy was 42 μm (P=0.001) and was positively correlated with the magnitude of IOP reduction (P=0.02), and negatively correlated with age (P=0.04) as well as baseline cup-disc ratio (P=0.05) Eyes with more anterior lamina cribrosa displacement were more likely to experience visual field improvement (defined as ≥ 3 dB gain in mean deviation) after trabeculectomy. (P=0.002) Conclusion: while more advanced baseline optic nerve head structural damage, age, and the magnitude of IOP were associated with larger displacement of lamina cribrosa after trabeculectomy, corneal biomechanics did not predict its behavior. Larger anterior LC movement was associated with visual field mean deviation after the surgery.