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

Précis: 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. Preoperative 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/y or ≤-0.5 dB/y) 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, 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, 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.