Changes in lamina cribrosa and prelaminar tissue after deep sclerectomy

Area of Science:

• Ophthalmology
• Glaucoma Research
• Ophthalmic Surgery

Background:

• Primary open-angle glaucoma (POAG) management often requires surgical intervention to lower intraocular pressure (IOP).
• Nonpenetrating deep sclerectomy (NPDS) is a surgical technique aimed at reducing IOP with a lower risk profile than traditional filtering surgeries.
• Understanding the structural response of the optic nerve head (ONH) to IOP reduction is crucial for predicting long-term visual function.

Purpose of the Study:

• To evaluate the impact of NPDS on the lamina cribrosa (LC) and prelaminar tissue.
• To quantify changes in optic nerve head (ONH) cupping and LC position following IOP reduction after NPDS.
• To correlate IOP reduction with structural changes in the ONH using enhanced depth imaging spectral domain optical coherence tomography (EDI SD-OCT).

Main Methods:

• A prospective study involving 28 eyes of 28 patients with POAG who underwent NPDS.
• High-resolution EDI SD-OCT scans of the ONH were acquired preoperatively and at 1 week, 1 month, and 3 months postoperatively.
• Measurements included the anterior prelaminar tissue surface and anterior/posterior LC surfaces relative to Bruch's membrane opening to assess ONH cupping and LC displacement.

Main Results:

• Post-NPDS, IOP significantly decreased from 18.7 ± 4.3 mmHg preoperatively to 9.1 ± 4.0 mmHg at 1 week, 11.4 ± 3.7 mmHg at 1 month, and 13.1 ± 3.6 mmHg at 3 months (P<0.001).
• ONH cupping showed significant reduction: 22.3% at 1 week, 13.7% at 1 month, and 9.8% at 3 months (P<0.001 for all).
• A slight but significant anterior displacement of the LC was observed at 1 week (4.5%), 1 month (3.8%), and 3 months (3.3%) postoperatively (P<0.05). IOP reduction correlated with reduced cupping and LC displacement.

Conclusions:

• NPDS effectively reduces IOP and leads to significant reversal of ONH cupping.
• The observed cupping reversal is primarily attributed to alterations in prelaminar tissue thickness.
• Changes in the lamina cribrosa's position are less significant compared to the prelaminar tissue response.