Differences in Corneal Biomechanics in Nonpenetrating Deep Sclerectomy and Deep Sclerectomy Reconverted into Trabeculectomy

Abstract

Purpose: To evaluate the differences in intraocular pressure (IOP) and in corneal biomechanics in eyes with uneventful nonpenetrating deep sclerectomy (NPDS) in 1 eye and with intended deep sclerectomy reconverted into trabeculectomy (RIT) in the fellow eye of the same patient.

Participants: Forty eyes of 20 patients with both types of glaucoma surgery and more than 6 months of follow-up, and 31 eyes of 50 controls.

Methods: IOP was assessed with Goldmann applanation tonometry (GAT), ocular response analizer (ORA), and dynamic contour tonometer (DCT). Student t test for independent samples and a univariate generalized estimating equations model were used to analyze the results.

Main outcome measures: Overall, no significant differences were found between IOP of NPDS and RIT eyes when measured with 3 tonometers.

Results: Although NPDS showed lower values of IOP measured with GAT and ORA, RIT presented lower IOP if DCT is the chosen tonometry. Biomechanically, NPDS eyes had higher corneal hysteresis (CH) and corneal resistance factor (CRF). When compared with control patients, eyes that underwent glaucoma surgery had lower IOP using GAT, DCT and ORA (P<0.001, 0.315, and 0.260, respectively), and lower CRF (P<0.001).

Conclusions: Eyes with NPDS tended to have higher values of CH and CRF and lower IOP than RIT eyes, as measured with 3 of 4 tonometry methods; these differences did not reach statistical significance.