A Systematic Review of the Effects of Second-Eye Cataract Surgery on Motor Function

Author: Sheppard WEA, McCarrick D, Wilkie RM, Baraas RC, Coats RO.

Geographical coverage: Australia, Canada, the UK, Spain, the USA, Turkey, Vietnam, and Sweden

Sector: Cataract surgery

Sub-sector: Motor function

Equity focus: Not reported

Study population: Patients with cataracts

Review type: Effectiveness review

Quantitative synthesis method: Narrative synthesis

Qualitative synthesis method: Not applicable

Background:

Age-related cataracts are the leading cause of preventable blindness in older adults, with their prevalence rising steadily with advancing age. Surgery is the only effective treatment and is widely performed in developed countries. First-eye surgery is typically prioritised, while second-eye surgery (SES) often faces delays due to cost and resource limitations. SES offers functional benefits beyond improved visual acuity, such as better contrast sensitivity, stereopsis, and binocular vision. These improvements are important for tasks such as driving and mobility. However, studies often compare outcomes to pre-surgery levels, which makes it difficult to isolate the specific benefits of SES.

Objective:

To understand the effects of second-eye cataract surgery (SES) on motor function.

Main findings:

The review included 13 studies. Five of the included studies were conducted in Australia, two in Canada, and one each in the UK, Spain, the USA, Turkey, Vietnam, and Sweden.

Objective within-subjects studies showed that SES significantly improved simulated driving performance and mobility, and reduced fall rates when compared to post-first-eye-surgery (FES) levels. For example, SES led to 47% fewer crashes in a driving simulator and a measurable decrease in injurious falls, suggesting functional gains from restoring binocular vision. However, the impact of SES on self-regulation in driving behaviour was less clear, with no significant difference observed after SES.

Between-subjects studies reinforced the positive effects of SES on mobility, as SES groups often performed similarly to healthy controls on tasks involving obstacle navigation and mobility orientation. These results support the view that SES can help restore motor function to levels seen in individuals without cataracts.

Subjective (self-reported) outcomes were more mixed. Some studies noted improvements in specific tasks like sewing and using a computer after SES, but broader measures such as the ability to perform activities of daily living (ADLs) or fall risk reduction did not always show statistically significant benefits beyond FES. Similarly, some self-report data indicated improved driving ability, whereas others showed little to no effect. Overall, the evidence suggests that SES provides tangible benefits to motor function, especially in mobility and fall prevention, although findings vary depending on study design and on whether outcomes were measured objectively or subjectively.

Methodology:

The searches were conducted in PubMed, PsycINFO, CINAHL, and Web of Science to identify empirical studies on patients with age-related cataracts that examined the impact of SES on motor function. Only studies published in English up to 23 October 2020 were included in this review. Two reviewers independently screened the identified studies and extracted the relevant data. Any disagreements were resolved by a third reviewer. The methodological quality of the included studies was assessed using the Mixed Methods Appraisal Tool 2018 (MMAT), and the findings were synthesised narratively.

Applicability/external validity:

The review highlighted a geographic bias towards high-income countries (five of the 13 studies were from Australia, with only one from a low- or middle-income country, Vietnam). In addition, heterogeneity in study designs (only 2 RCTs), outcome measures (e.g., driving simulators vs. self-reports), and participant populations (e.g., age ranges, exclusion of comorbidities) limited direct comparisons. Moreover, the lack of standardised inter-surgery intervals (e.g., varying delays between FES and SES) further restricted clinical applicability. The review emphasised the need for further research to address these issues.

Geographic focus:

The review did not apply any geographical limits. The included studies were conducted in Australia, Canada, the UK, Spain, the USA, Turkey, Vietnam, and Sweden.

Summary of quality assessment:

Overall, there is medium confidence in the review’s conclusions about the effects of second-eye cataract surgery on motor function. The literature search was comprehensive, with clearly defined inclusion and exclusion criteria. Study quality was assessed using valid and reliable tools, and the findings of these assessments were reported. Two reviewers independently screened the articles and extracted the data. Characteristics of the included studies were clearly presented, and the findings were synthesised narratively. However, the review did not provide a list of excluded studies, nor did it report screening the reference lists of the included studies or relevant review articles. Moreover, the search was limited to English-language publications.