Association between visual impairment and depression in patients attending eye clinics: a meta-analysis

Author: Mariacristina Parravano

Geographical coverage: Europe, the US, Asia, Oceania and Africa

Sector: Burden of disease

Sub-sector: Epidemiology

Equity focus: Most included studies focused on older people.

Study population: Adult patients (18 years or older)

Review type: Other review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background: Low vision negatively affects individuals’ quality of life and physical health, and so may be associated with an increase in depression. Depression screening has been recommended as a part of low vision services, with appropriate training of rehabilitation professionals and the use of standardized questions in both high-income and low-middle–income countries. However, no recent reviews or meta-analyses have been published on the prevalence of depression in patients visiting eye clinics and low vision services, regardless of ocular causes or age ranges.

Objectives: To conduct a meta-analysis on the prevalence of depression in patients with visual impairment who regularly visit eye clinics and low vision rehabilitation services.

Main findings:

Overall, authors found depression to be common (prevalence of 25%) in patients with visual impairment and those aged older than 65 years.

A literature search identified 7,054 studies related to depression in visually impaired individuals. After screening, 45 studies were found relevant, with 27 conducted in eye clinics or low vision centers included in this review. Most studies involved patients over 65 years old, conducted across Europe, the US, Asia, Oceania, and Africa. The studies, which varied in their definitions of visual impairment and depression, were conducted in clinical eye care settings, rehabilitation settings, or other health care settings. The number of participants per study ranged from 53 to 990. The remaining 18 community or population-based studies will be considered in a future review.

Out of 6992 patients (average age 76 years, 60% women) with visual impairment, 1687 had depression, with a median depression proportion of 0.30. The pooled estimate was 0.25, indicating high heterogeneity. No patient characteristics influenced the depression prevalence, except for the inclusion of patients with cognitive impairment. Depression prevalence was high in both clinic-based studies and rehabilitation services, and did not vary by visual impairment severity. However, studies that included patients with cognitive impairment had a higher depression prevalence than those that excluded such patients. The prevalence of depression did not vary significantly across different settings or levels of visual impairment severity.

Results of this review suggest that all primary and specialised eye care professionals, not only those working in low vision services, should have an appropriate knowledge of this topic and adequate clinical experience to decide when and how to investigate the presence of depression in people with visual impairment and eventually refer patients with depression for appropriate treatment. Authors suggest the need for depression screening in patients attending eye clinics who are 65 years or older and have mild to severe visual loss, regardless of comorbidity.

Methodology:

The meta-analysis included cross-sectional studies of adults (18 years or older) from eye care and low vision rehabilitation services. It considered baseline data from randomized controlled trials if representative of visually impaired populations. The studies accepted the authors’ definitions of visual impairment and depression, including validated tools, questionnaires, DSMIII or DSM-IV criteria, and self-reported depressive disorder. Only original research reported in English with sufficient depression prevalence data was included. Studies focusing solely on inherited or congenital eye diseases, review studies, unpublished articles, abstracts, theses, dissertations, and book chapters were excluded.

Authors searched MEDLINE (inception to June 7, 2020) and Embase (inception to June 7, 2020) were searched. Four independent reviewers analysed the results of the search and performed the selection, classification of literature, and data extraction to ensure accuracy. Discrepancies were addressed by discussion or with a fifth reviewer. All included studies subject to methodological critical appraisal using an adapted risk of bias assessment for prevalence studies.

The study used the metaprop command in R software to pool prevalence data, fitting a random-intercept logistic regression model with a maximum-likelihood estimator for tau2. It used a logit transformation of proportions and a Clopper-Pearson CI for individual studies. Heterogeneity between studies was assessed graphically and through a 95% predictive interval. A preplanned heterogeneity investigation was conducted, adding study-level categorical covariates to the model such as age, inclusion of patients with major chronic conditions, types of validated questionnaires or scales used to diagnose depression, and severity of visual loss. Post-hoc subgroup analyses were conducted by sample size. Further subgroup analyses by causes of low vision were not conducted due to the inclusion of people with multiple diseases in the studies. The significance level was set at P < .05, and all P values were 2-sided.

Applicability/external validity: The authors highlight several limitations in the studies that could affect their relevance. These include varying definitions of depression and visual impairment, which may have led to a high level of heterogeneity.

Geographic focus: The search was unrestricted, with studies from Europe, US, Asia, Africa, and Oceania included. However, the number of studies conducted specifically in low- and middle-income countries (LMICs) was not specified. The authors did not explore how the findings might differ across high, middle, and low-income settings, but they emphasized that similar issues are applicable in all contexts.

Summary of quality assessment:

There were several limitations to the approaches to identify, include and critically appraise studies. The search was limited to published material, produced in English and there was no evidence of the reference sections of included studies being reviewed or relevant experts being contacted. In addition, the authors note that the included studies include a range of definitions of visual impairment and depression, which may have contributed to the high heterogeneity identified. While all key tasks were conducted by at least two authors and the statistical analysis used was highly robust, the limited nature of the search would lead us to have a low confidence in the findings of this study.