Effect of Phaco-trabeculectomy versus Phacoemulsification on Refractive Outcome - A Prospective Observational Study

Abstract

Purpose: To compare the refractive outcomes of phaco-trabeculectomy versus phacoemulsification.

Methods: This prospective observational study included 75 eyes, 42 eyes with cataract and glaucoma that underwent phaco-trabeculectomy, and 33 eyes with cataract that underwent phacoemulsification. The primary outcome measures were the assessment of mean prediction refractive error and absolute mean prediction refractive error, measured during biometry with a target refraction of more than -1 diopter.

Results: The mean age of the study population was 60.3 ± 4.5 years (SD) in the phaco trabeculectomy group (Group 1) and 64.24 ± 3.2 years (SD) in the phacoemulsification group (Group 2). The mean prediction error in group 1 was -0.21 + 0.88 diopters, and in group 2, it was -0.24 + 1.42 diopters, with absolute mean prediction errors of 0.72 + 0.68 diopters in group 1 and 0.71 + 0.97 diopters in group 2. A statistically significant shift in myopic and hyperopic prediction error was noted for 0 to 1 diopter, and a change above one diopter was not substantial.

Discussion: This discussion examines the challenges associated with refractive outcomes following combined cataract and glaucoma filtration surgery. The study found considerable variability in achieving the target refraction, with prediction errors generally within one diopter, consistent with other research. The study's limitations, including a short follow-up period and variations in surgical techniques, are acknowledged as possible factors that may contribute to refractive errors and astigmatism.

Conclusions: The predicted refractive errors in both groups were similar, with equal myopic and hyperopic shifts noted, and a statistically significant change was observed from 0 to 1 diopter.

Keywords: BCVA = Best Corrected Visual Acuity; D = Diopter; IOL = Intraocular Lens; Kolmogorov-Smirnov = A statistical test for the distribution pattern (not an abbreviation but refers to a statistical test); MMC = Mitomycin C; P = Probability (used in statistical analysis); SD = Standard Deviation; SE = Spherical Equivalent; SPSS = Statistical Package for the Social Sciences; SRK-T = Sanders-Retzlaff-Kraff; absolute mean prediction error; mean prediction error; phacoemulsification; phacotrabeculectomy; refractive outcomes.

Graph 1

Histogram with Bell curve showing distribution of prediction error among phacotrabeculectomy group (n=42)

Graph 2

Histogram with Bell curve showing distribution of prediction error among phacoemulsification group (n=33)