Impact of cataract surgery on depression and cognitive function: a systematic review and meta-analysis

Author: Pellegrini M, Bernabei F, Schiavi C, Giannaccare G.

Geographical coverage: the United States, China, Japan, Viet Nam, the United Kingdom, Iran, France, Greece and Australia

Sector: Depression, cognitive impairment

Sub-sector: Quality of life

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, a major cause of visual impairment and blindness, is projected to increase with rising life expectancy and ageing populations. Adequate vision is crucial for maintaining both physical and cognitive functioning. Growing evidence indicates that visual impairment in older adults is linked to cognitive decline and depression. In elderly people, depression often coexists with cognitive problems, which worsen health outcomes and increase disability. Cataract surgery offers rapid visual recovery and is well known to improve quality of life; some studies also report additional benefits, such as reduced depression and enhanced cognitive performance. However, findings have been inconsistent, leaving uncertainty about the broader mental-health and cognitive effects of cataract surgery.

Objective:

To identify, evaluate and summarise the available evidence to determine whether cataract surgery results in a significant overall improvement in depression and cognitive impairment.

Main findings:

Sixteen studies (published 1996–2018) involving 1308 patients were included. Five were conducted in the United States, two in China, two in Japan, two in Viet Nam and one each in the United Kingdom, Iran, France, Greece and Australia. Follow-up ranged from one to 12 months. Total quality scores ranged from 11 to 22 (maximum 16 for uncontrolled studies, 24 for controlled studies).

The pooled analysis showed a significant reduction in depressive symptoms after cataract surgery (standardised mean difference, SMD = 0.460; 95 % CI 0.223 – 0.697; p < 0.001). Controlled studies confirmed a greater reduction in depression in the surgery group than in controls (SMD = 0.161; 95 % CI 0.027 – 0.295; p = 0.019). Sensitivity analyses supported these findings, and meta-regression indicated that worse baseline visual acuity predicted greater postoperative improvement in depression.

Cognitive function also improved significantly (overall SMD = 0.254; 95 % CI 0.120 – 0.388; p < 0.001). Controlled studies showed higher cognitive gains in the surgery group than in controls (SMD = 0.188; 95 % CI 0.002 – 0.374; p = 0.04). The effect size for cognition was smaller than for depression, and potential publication bias was detected. Subgroup analyses confirmed consistent cognitive benefits across different assessment tools.

Methodology:

PubMed, Scopus and Web of Science were searched from inception to September 2019 for prospective studies of age-related cataract reporting depression or cognitive impairment before and after surgery. Reference lists of included studies were scanned for additional papers. Two reviewers independently screened studies and extracted data, resolving disagreements through discussion. Missing data were requested from authors. Study quality was assessed with the Methodological Index for Non-Randomised Studies (MINORS). Findings were synthesised using a random-effects meta-analysis. Heterogeneity was assessed with the Cochrane Q-test and I² statistics. Sensitivity analyses removed high-risk studies and each study in turn. Subgroup analysis grouped studies using the same assessment tool. Publication bias was examined with funnel plots and Egger’s test. Meta-regression explored covariate effects on changes in depression and cognition.

Applicability/external validity:

The review noted limitations affecting applicability, including the predominance of non-randomised studies, variation in study design, patient demographics and assessment tools. While results suggest cataract surgery may improve depression and cognition in older patients, methodological differences and potential biases limit generalisability. High-quality randomised trials are needed to confirm these effects across diverse populations and settings.

Geographic focus:

No geographical limits were applied. Included studies were conducted in the United States, China, Japan, Viet Nam, the United Kingdom, Iran, France, Greece and Australia.

Summary of quality assessment:

Overall, there is medium confidence in the conclusions. Searches were comprehensive; inclusion and exclusion criteria were clearly defined; two reviewers independently screened and extracted data; and study quality was assessed with established tools. Characteristics of included studies were documented and meta-analyses appropriately performed, with heterogeneity addressed. However, the search was restricted to English-language articles, and the review did not provide a list of excluded studies.