This retrospective cohort study analyzes risk factors for central visual loss (CVL) after severe-stage glaucoma surgery. The primary hypothesis is that 1) visual prognosis is determined primarily by early postoperative intraocular pressure (IOP) stability rather than surgical choice, and 2) the nature of risk (hypotony vs hypertension) is modified by baseline visual reserve. We analyzed outcomes in 523 patients with severe-stage glaucoma who underwent trabeculectomy or Ahmed glaucoma valve (AGV) implantation, focusing on the dichotomous risk profile stratified by baseline visual acuity.

Inclusion Criteria:

• 1. Patients who underwent trabeculectomy or Ahmed glaucoma valve implantation at Yonsei Medical Center between January 2005 and October 2024.

  2. Glaucoma patients who underwent static quantitative perimetry (visual field test) before and after surgery.

  3. Patients with a preoperative Mean Deviation (MD) of ≤ -20 dB.

Exclusion Criteria:

• 1. Patients who were unable to undergo visual field testing due to poor preoperative visual acuity.

  2. Patients with central visual field defects caused by retinal or neurological diseases other than glaucoma.

  3. Patients with false-positive or false-negative responses ≥33% on visual field testing.

Patients with severe-stage glaucoma who underwent trabeculectomy or Ahmed glaucoma valve implantation at Gangnam Severance Hospital, Yonsei University College of Medicine, between January 2005 and October 2023, with at least 1-year follow-up data available.