Does Cataract Extraction Significantly Affect Intraocular Pressure of Glaucomatous/ Hypertensive Eyes? Meta-Analysis of Literature

Author: Pasquali A, Varano L, Ungaro N, Tagliavini V, Mora P, Goldoni M, Gandolfi S.

Geographical coverage: Not reported

Sector: Cataract extraction

Sub–sector: Intraocular lens

Equity focus: Not reported

Study population: Patients with cataract

Review type: Effectiveness review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background: Cataract and glaucoma—two leading causes of visual impairment worldwide—frequently coexist in older adults. Co‑management presents clinical challenges, particularly in controlling intra‑ocular pressure (IOP) while preserving visual function. Cataract extraction, one of the most commonly performed and cost‑effective ophthalmic procedures, may influence IOP regulation, especially in individuals with glaucoma or ocular hypertension. As IOP is the only modifiable factor in glaucoma management, understanding its behaviour after surgery is essential. Although numerous studies have explored this interaction, variations in study design, patient characteristics and glaucoma sub‑type have produced inconsistent findings. A systematic evaluation is therefore required to clarify the impact of cataract surgery on IOP control.

Objective:

To examine the association between cataract surgery and subsequent changes in IOP—the only modifiable factor in glaucoma.

Main findings:

The review included 34 studies—11 retrospective and 23 prospective. In primary open‑angle glaucoma (POAG), cataract extraction produced significant IOP reductions of 2.44 mmHg (95 % CI 1.73–3.14; p < 0.00001) at six months, 2.71 mmHg (95 % CI 1.70–3.72; p < 0.00001) at 12 months and 3.13 mmHg (95 % CI 1.98–4.29; p < 0.00001) at 24 months.

The pooled analysis across all glaucoma types showed average IOP reductions of 6.81 mmHg (95 % CI 4.06–9.55; p < 0.0001) at six months, 7.03 mmHg (95 % CI 4.26–9.81; p < 0.0001) at 12 months and 6.52 mmHg (95 % CI 3.84–9.21; p < 0.0001) at 24 months. Sub‑group analysis demonstrated a significant reduction at 12 months in pseudo‑exfoliation glaucoma (−5.30 mmHg; 95 % CI 2.22–8.36) and at 24 months in ocular hypertension (−2.27 mmHg; 95 % CI 0.11–4.44).

Methodology:

Searches were carried out in MEDLINE, Embase and the Cochrane Library for studies involving adults and reporting pre‑ and post‑phacoemulsification IOP values. Eligible English‑language studies published up to 1 April 2021 were included.

Identified articles were screened against predefined criteria and data were extracted manually. Study quality was appraised with the SIGN checklist, and a random‑effects meta‑analysis was performed. Heterogeneity was assessed with the Cochrane Q‑test and I² statistic, and publication bias with funnel plots and Egger’s test.

Applicability/external validity:

The review did not explicitly discuss external validity but highlighted the need for further research into mechanisms and variables influencing IOP reduction. The authors suggested integrating phacoemulsification into management algorithms for additional glaucoma sub‑groups—mirroring its established role in angle‑closure glaucoma—while acknowledging surgical risks.

Geographic focus:

No geographical limits were applied, although the review did not report the distribution of the included studies.

Summary of quality assessment:

Overall confidence in the review conclusions is low. Searches and inclusion criteria were clearly described and risk of bias was assessed with an established tool. Study characteristics were well documented and meta‑analytic methods appropriately applied. However, the search was limited to English‑language papers, the review omitted a list of excluded studies, and it did not specify how many reviewers independently screened and extracted data. Reference‑list checking and quality‑based subgroup analyses were also absent.