Efficacy of Filtration Surgery and Risk Factors for Central Visual Field Deterioration in Highly Myopic Eyes with Open-Angle Glaucoma.

Prcis: This study demonstrates the effectiveness of filtration surgery in preserving the central visual field in eyes showing open-angle glaucoma with high myopia, highlighting the necessity of intraocular pressure reduction ≥30% for optimal outcomes.

Purpose: To evaluate the efficacy of filtration surgery in preserving the central visual field (VF) in eyes with open-angle glaucoma (OAG) and high myopia (HM) and identify postoperative intraocular pressure (IOP) targets and factors associated with targeted IOP reduction.

Methods: This retrospective cohort study included 55 eyes (48 patients) with OAG and HM who underwent filtration surgery and were followed up for minimum 3 years. Pre- and postoperative IOP values, mean deviation (MD) values, and MD slopes from Humphrey 10-2 VF tests were assessed. Participants were categorized according to the postoperative MD slope (>-0.5 dB/year or ≤-0.5 dB/year) to evaluate surgical success, defined as IOP reduction of ≥20%, ≥30%, or ≥40% from baseline. Predictors of targeted IOP reduction were identified.

Results: Significant postoperative IOP reductions were observed at all time points ( P <0.001). The mean MD slope improved from -1.53±0.91 to -1.00±1.40 dB/year ( P =0.001). Eyes with MD slope ≤-0.5 dB/year had a longer axial length (AL; P =0.048), more needling procedures ( P =0.003), and higher postoperative IOP at 1 and 2 years ( P <0.001, P =0.021, respectively). Surgical success rates (IOP reduction ≥30% and ≥40%) were higher for eyes with MD slope >-0.5 dB/year ( P =0.006, P =0.003), with no significant difference for IOP reduction ≥20% ( P =0.087). To achieve postoperative MD slope >-0.5 dB/year, minimum 30% IOP reduction was required. If AL was >28.01 mm, 40% IOP reduction was required. AL and needling procedure frequency were significantly associated with IOP reduction ≥30% (odds ratio=1.79 and 2.26; P =0.018 and 0.039, respectively).

Conclusions: Substantial IOP reduction is essential for preserving the central visual field in eyes with OAG and HM, particularly those with AL ≥28.01 mm. Longer AL and frequent needling procedures increase the surgical failure risk.