Refractive Modification Induced by Supplemented-MMC Trabeculectomy

Abstract

Purpose : Visual performance of glaucomatous patients depends on at least three factors: the functional damage to the optic nerve, the status of the optical media, and the refractive condition. A limited scientific evidence regarding post-trabeculectomy refractive changes is available. This study research aim is to evaluate changes in intraocular pressure (IOP), refractive outcome and keratometric power in glaucoma patients undergoing mitomycin C (MMC)-supplemented trabeculectomy.

Methods : A retrospective analysis of 51 consecutive cases meeting inclusion criteria was performed. One eye was randomly selected when both eyes were operated. All cases underwent MMC-supplemented trabeculectomy at a glaucoma center in Western Mexico. Primary outcome variables were both refractive and keratometric changes after trabeculectomy in three different follow-up visits (week 1, month 1 and month 3). Additional outcome variables were BCVA, intraocular pressure, perimetric indexes, and post-operative complications.

Results : Mean age of included cases was 57.37 ± 20.12 years (32 female, 19 male). Mean pre-operative IOP (24.15 ± 10.28 mm Hg) reduced significantly after 6 months of surgery (11.86 ± 4.41 mm Hg; P=0.001). Pre-operative BCVA (logMAR) did not change in any of the follow-up visits (P=0.021). Perimetric indexes did not significantly change either in the peri-operative moments. Pre-operative spherical equivalent (1.22 ± 2.76 D) was not modified at the last post-operative visit (1.26 ± 3.30 D, P=0.23). Curvature axis of the steepest curvature radius was modified by the surgical intervention but not to a statistical significant level (86.53 ± 49.6 degrees vs. 91.02 ± 53.07 degrees, P=0.64). Keratometric readings, both the flattest and the steepest ones, did not change when comparison of baseline values was carried out against all follow-up visits (P<0.05)

Conclusions : Trabeculectomy supplemented with MMC did not induce significant changes in refraction and corneal astigmatism in the short-term, in spite of a remarkable amount of IOP reduction. A subtle shift of the astigmatism axis was demonstrated in this restrospective analysis.

This is a 2020 ARVO Annual Meeting abstract.