Exploring the Ocular Biometric Changes after Antimetabolite-Augmented Trabeculectomy in Nigerian Adult Glaucoma Patients

Abstract

Background: Trabeculectomy can induce changes in ocular biometrics, potentially impacting intraocular lens calculation accuracy. While  these effects have been documented, primarily in Caucasian populations, limited data exists on how trabeculectomy affects biometrics in  individuals of African descent, who may exhibit distinct ocular characteristics. 

Aim: To describe changes in ocular biometrics after  antimetabolite-augmented trabeculectomy in an adult Nigerian population. 

Methods: An observational, hospital-based, prospective  study involving 52 adult glaucoma patients with Mitomycin-C augmented trabeculectomy for primary glaucoma at the University College  Hospital, Ibadan. Ocular biometry parameters such as keratometry (K), axial length (AXL), pachymetry (CCT), and lens thickness (LT)  measurements were taken before the surgery, 1 week, and 3 months after surgery. 

Results: The study cohort's mean age (SD) was 49.1  (±14.6) years. In the first postoperative week, the mean baseline AXL values (23.7 ± 0.9) mm decreased (23.4 ± 0.8, P <0.001), mean  baseline Keratometry values (42.9 ±1.3D) increased (43.2 ±1.5D, P =0.004), mean baseline CCT values (543.0 ±44.0 µm) did not differ (544.4  ±55.6 µm, P = 0.57) neither did mean baseline LT values (3.8 ±0.7mm) change (3.9 ±0.8mm, P = 0.57). At the 3rd postoperative month, the mean AXL was shorter (23.5 ±0.8mm, P = 0.007), CCT was thinner (526.3 ±47.5 µm, P <0.001), Keratometry was steeper (43.1  ±1.4D, P =0.02), while the LT value remained unchanged. The change in AXL was affected by age, preoperative refractive status, glaucoma  diagnosis, and degree of reduction of IOP from baseline. There was a positive correlation between thinner pachymetry value and lower  IOP, steeper keratometry, and lower IOP values at the 3rd postoperative month. 

Conclusion: The considerable changes in ocular  biometric parameters following trabeculectomy should be considered in setting target IOP at follow-up and calculating intraocular lens  power for cataract surgery post-trabeculectomy