ABSTRACT
Purpose
Our goal was to explore the longitudinal association between vision-related variables and incident depressive symptoms in a community-dwelling sample of older adults and to examine whether sex, education, or hearing loss act as effect modifiers.
Methods
A 3-year prospective cohort study was performed using data from the Canadian Longitudinal Study on Aging consisting of 30,097 individuals aged 45–85 years. Visual acuity was evaluated with habitual distance correction using an illuminated Early Treatment of Diabetic Retinopathy Study chart. Visual impairment was defined as binocular presenting visual acuity worse than 20/40. Incident depressive symptoms was defined using a cut-off score of 10 or greater on the Center for Epidemiologic Studies Depression scale. Participants were asked if they had ever had a physician diagnosis of age-related macular degeneration (AMD), glaucoma, or cataract. Multivariable Poisson regression was used.
Results
Of 22,558 participants without depressive symptoms at baseline, 7.7% developed depressive symptoms within 3 years. Cataract was associated with incident depressive symptoms (relative risk = 1.20, 95% confidence interval 1.05, 1.37) after adjusting for age, sex, income, education, partner status, smoking, level of comorbidity, hearing loss, and province. Visual impairment, AMD, and glaucoma were not associated with incident depressive symptoms. No effect modification was detected.
Conclusions
Our longitudinal data confirm that the risk of depressive symptoms is higher in those who report ever having a cataract. Further research should confirm this and interventions should be considered.
Introduction
Vision loss is very common in old age due to uncorrected refractive error and age-related eye diseases like cataract, age-related macular degeneration, glaucoma, and diabetic retinopathy.Citation1 Some older adults are able to adapt well to vision loss adopting a resilient attitude and positive coping skills. However, other older adults struggle to accept and adapt to their vision loss and are at risk of depression.Citation2 The presence of depression may complicate efforts to manage and treat eye disease.Citation3,Citation4
Many cross-sectional studies have identified an association between visual impairment or eye disease and depression.Citation5–10 However, cross-sectional studies are limited because they cannot establish temporality of the vision loss and the onset of depression. As such, they cannot rule out reverse causality such that depression might aggravate the proper care for vision problems thereby exacerbating vision loss. Some longitudinal studies, which can establish temporality, have been done although the results are somewhat conflicting.Citation11–16 For example, five studies have found that visual impairment is not associated with incident depressive symptoms,Citation11Citation17–20 while five other studies have reported a positive association.Citation12,Citation13,Citation21–23 Furthermore, few of the longitudinal studies have examined effect modifiers to indicate whether some groups of people are at a greater risk of depressive symptoms after losing vision than others. One cross-sectional study that did examine effect modification found that people with cataract and lower education had a higher prevalence of depressive symptoms than those with cataract and higher education.Citation9 Other differences might be seen by sex or the loss an additional sensory system like hearing, both of which are risk factors for depression,Citation24Citation25
The Canadian Longitudinal Study on Aging is a large, population-based cohort study with data on over 30,000 middle-aged and older adults.Citation26 We utilized this dataset to examine the association between visual impairment or eye disease and the 3-year incidence of depressive symptoms and to determine whether sex, education, or hearing loss modifies any of the associations.
Methods
Study population
A prospective study of community-dwelling older adults was performed using data from rounds 1 and 2 of the Canadian Longitudinal Study on Aging (CLSA) Comprehensive cohort consisting of 30,097 individuals.Citation26 The sampling strategy used in the CLSA Comprehensive cohort consisted of provincial healthcare registration databases and random digit dialing of landline telephones. Stratified random sampling was used to ensure participants met the specified demographic distributions (i.e. age, sex, urban-rural) required from each province. To be able to participate, participants had to be aged between 45 and 85 years, community-dwelling, cognitively unimpaired at baseline, speak English or French, and provide written informed consent. Exclusion criteria included being a full-time member of the Canadian Armed Forces, residing on a federal First Nations reserve or settlement, living in a long-term care institution, or not being a permanent resident or Canadian citizen.
Study design
The baseline assessment included a home visit and a data collection site visit done between December 2011 and July 2015. The 11 data collection sites are located in Victoria, Vancouver, Surrey, Calgary, Winnipeg, Hamilton, Ottawa, Montreal, Sherbrooke, Halifax and St. John’s. All CLSA Comprehensive Cohort study personnel received standardized training on data collection procedures in order to ensure that participant assessments were standardized across the data collection sites. Follow-up data were obtained between July 2015 and December 2018 in a home visit and a visit to a data collection site. The follow-up rate was very high at 92%. Research Ethics Board approval was received in July 2010 from all affiliated sites. Ethics approval from the University of Ottawa was received for the present analysis in May 2019.
Data collection
Visual impairment and eye disease
Baseline visual acuity was measured by trained study personnel at the data collection site using an illuminated Early Treatment of Diabetic Retinopathy Study (ETDRS) letter chart and its standard protocol.Citation27 Visual acuity was evaluated at a 2-meter distance from the ETDRS chart using habitual distance correction (i.e. wearing normal corrective lenses for distance vision). Acuity scores from participants were converted to logMAR units. Baseline visual impairment was defined as presenting binocular acuity worse than 20/40 (0.301 logMAR), as is standard in North American studies.Citation28 For cataract, participants were asked if a doctor has ever told them that they have or had a cataract. If they said yes, they were asked if they currently have a cataract. If they said no, it was assumed to have been removed. For AMD, participants were asked if a doctor has ever told them that they have macular degeneration. For glaucoma, participants were asked if a doctor has ever told them that they have glaucoma.
Depression
The Center for Epidemiologic Studies Depression scale (CES-D10) was used to measure depressive symptomatology.Citation29 The CES-D10 consists of 10 items covering depressive symptomatology experienced during the past week and includes 4 response categories ranging from “rarely” to “all of the time”. The instrument takes approximately three minutes to administer; scores range from 0–30 with a score of 10 or greater indicating that a participant has screened positive for depressive symptoms. Incident depressive symptoms were present in those who had a score of 10 or higher at follow up and had previously scored less than 10 at baseline
Demographic, health, and lifestyle data
Demographic data including age, sex, education, income, and marital status were collected at baseline during the in-home visit using the interviewer-administered questionnaire. Participant education level was determined by asking, “What is the highest degree, certificate or diploma you have obtained?”. In order to assess household income, participants were asked, “What is your best estimate of the total household income received by all household members, from all sources, before taxes and deductions, in the past 12 months?”. Self-reported marital status was dichotomized into partnered (married/living with a partner) and not partnered (single, never married or lived with a partner, widowed, divorced, or separated).
Regarding health, hearing was assessed by asking participants, “Is your hearing, using a hearing aid if you use one, excellent, very good, fair or poor?”. For use in our analyses, participant responses were dichotomized into two categories: good, very good, or excellent versus fair or poor. Participants were asked if they had ever received a physician diagnosis of 9 chronic conditions which included diabetes, heart disease, stroke, osteoarthritis of the knee or hip, peripheral vascular disease, asthma, back problems, and Parkinson’s disease. As is often done in aging research, a comorbidity score was created based on the total number of the 9 chronic conditions listed above.Citation30 Scores range from 0–9, with higher scores reflecting a greater number of chronic conditions present among participants.
Smoking status was classified as either current, never, or former based on participant responses to the interview questions “Have you smoked at least 100 cigarettes in your life?” and “At the present time, do you smoke cigarettes daily, occasionally (at least once in last 30 days), or not at all (not in last 30 days)?”. A current smoker was defined as a person who reported smoking at least 100 cigarettes and currently smokes daily or occasionally while a former smoker was someone who reported smoking at least 100 cigarettes in life but had not smoked in the last 30 days.
Statistical analysis
Those with and without incident depressive symptoms were compared for visual, demographic, health, and lifestyle factors at baseline. Multiple Poisson regression was used to assess the association of vision-related variables at baseline with incident depressive symptoms adjusting for potential confounding variables including age, sex, household income, level of education, marital status, smoking status, number of chronic conditions, and province.Citation31 These variables were chosen based on previous research showing their importance to vision or depressive symptoms.Citation11,Citation12 Given prior reports of a nonlinear association between age and depressive symptoms,Citation32 age was modeled both linearly and nonlinearly while examining Akaike’s information criteria to determine the optimal fit to the data. Effect modification was tested by adding product terms into regression models. Statistical significance was considered to be P < .05. As recommended by the CLSA, sampling weights and strata variables were incorporated into all analyses. This was done using the SVY commands in STATA SE Version 16 (College Station, Texas).
Results
Descriptive
Of the 27,643 out of 30,097 who returned to follow-up after 3 years (92%), 23,451 did not have depressive symptoms at baseline and were therefore eligible for the development of incident depressive symptoms (). Our analysis consisted of 22,558 people after excluding those who were missing depressive symptoms data at follow-up. Of the 2,454 who did not return to follow-up, 974 died (40%) and 967 withdrew (39%) with the remaining 513 (21%) either unable to be contacted or unable to complete data collection. Participants who were lost to follow-up were older, had lower education, lower household income, were more likely to smoke, to be unpartnered, and had higher comorbidity scores compared to those with who were not lost to follow-up (P < .05).
Figure 1. Flow chart of participants included in the analysis
Of the 22,558 in our analysis cohort, the mean age of participants, after correction for the complex survey design, was 59.2 years (SD = 9.6) and 49.0% were female. Overall, at baseline, 5.1% of participants in the cohort had visual impairment, 20.2% reported ever having had a cataract diagnosis, 2.8% reported a diagnosis of macular degeneration, and 3.6% reported a diagnosis of glaucoma.
Baseline characteristics of the cohort by depressive symptoms status are presented in . The incidence of depressive symptoms was 7.7% after accounting for the complex survey design. Those who developed depressive symptoms were more likely to report a previous diagnosis of cataract, AMD, and glaucoma, were older, more likely to be female, had lower levels of education, lower total household incomes, were more likely to be current smokers, unpartnered, and had higher levels of comorbidity compared to those who did not develop depressive symptoms.
Table 4. Summary of studies that have examined cataract and depression
Table 1. Descriptive statistics of those with and without incident depression
Visual impairment and depressive symptoms
As shown in , visual impairment was not associated with incident depressive symptoms after adjustment (relative risk (RR) = 0.94, 95% CI 0.75,1.17). No interactions were found with sex, education, or hearing loss. Factors that were associated with a higher risk of incident depressive symptoms included female sex (RR = 1.51, 95% CI 1.35, 1.69), lower household income (e.g. RR = 2.19, 95% CI 1.69, 2.83) for those earning less than 20,000 CAD per year, lower education levels (RR = 1.19, 95% CI 1.03, 1.39 for those with less than a Bachelor’s degree), current smoking (RR = 1.60, 95% CI 1.35, 1.91), higher levels of comorbidity (RR = 1.31, 95% CI 1.25, 1.37), and hearing loss (RR = 1.27, 95% CI 1.09, 1.48).
Table 2. Vision/eye disease variables and incident depression during the 3-year follow up from four separate Poisson regression models
Age-related eye disease and depressive symptoms
Having or having had cataract was associated with an increased risk of becoming depressed after adjustment (RR = 1.20, 95% CI 1.05, 1.37) (). Adjusting for presenting binocular visual acuity did not alter the association between cataract and incident depressive symptoms (RR = 1.24, 95% CI 1.09, 1.41). By contrast, AMD was not associated with an increased risk of becoming depressed (RR = 1.22, 95% CI 0.97, 1.53) after adjustment for demographic, lifestyle, and health variables () nor was there a statistically significant association between a self-report of glaucoma and the incidence of depressive symptoms (RR = 1.10, 95% CI = 0.90, 1.36) (). No interactions were found between eye disease and sex, education, or hearing loss. To further describe the association with cataract, age and sex-stratified analyses are presented in . Like Chen et al,Citation16 no differences by age or sex were found.
Table 3. Age and sex-stratified analysis for cataract
Discussion
We did not find that visual impairment or that the self-report of AMD or glaucoma increased the 3-year risk of incident depressive symptoms. However, we did find that the self-report of a diagnosis of cataract was related to incident depressive symptoms. The association with cataract was unaltered by adjusting for visual acuity indicating the association is primarily explained by other unknown factors.
Our results confirm a previously demonstrated longitudinal association between a prior diagnosis of cataract and incident depressive symptoms (). Cataract is a treatable condition. It is unclear from our data if our association is found primarily in those who currently have a cataract in the eye or rather just in those who have already had surgery or in both groups equally. Chen et al recently reported that a diagnosis of cataract was associated with a greater risk of incident depressive symptoms, both in those who had cataract surgery (HR = 1.65, 95% CI 1.54, 1.76) and in those who did not (HR = 2.14, 95% CI 2.03, 2.27).Citation16 Two cross-sectional papers also support our findings. Eramudugolla et al found that the self-report of having or having had a cataract was associated with greater depressive symptoms (OR = 1.40, 95% CI 1.07, 1.81).Citation10 Wang et al found that currently having a cataract in the eye, as measured using the Lens Opacities Classification System III scheme, was associated with depressive symptoms (OR = 1.33, 95% CI 1.08, 1.70) despite adjusting for presenting visual acuity.Citation9 Cataract-related factors besides visual acuity that might affect depressive symptoms include difficulty with glare sensitivity or contrast sensitivity, fear of cataract surgery, difficulty doing visual tasks, or complications with obtaining surgery such as long wait times or uncovered surgical costs. The stress from cataract may serve as a “tipping point” for some people so that even when the cataracts are removed, the depression does not subside.Citation33 There may additionally be stress related to postoperative treatment recommendations and possible surgical complications. Furthermore, Wang et al identified an interaction such that the association between cataract and depressive symptoms was even stronger in those with lower education (P-value for interaction = 0.03).Citation9 We did not find an interaction between cataract and education in the CLSA data nor did we find any interactions with sex or hearing loss.
As noted, we did not find that visual impairment was associated with incident depressive symptoms. Our results are in agreement with five prior longitudinal studies which found visual impairment and self-reported sight problems were not associated with the onset of depressive symptoms.Citation11,Citation17–20 The most comprehensive examination was by Zheng et al who used latent growth curve modeling to examine 4 rounds of data from the Salisbury Eye Evaluation. They found, similar to us, that visual acuity at baseline was not associated with worsening depressive symptoms although it was associated with baseline depressive symptoms. They also found that depressive symptoms at baseline were associated with worsening visual acuity over time indicating that reverse causality could be at least partially driving cross-sectional associations. The mechanism for this association could be that depressive symptoms may lead to worse compliance with recommended treatment regimens for eye conditions.Citation3,Citation4
Our results are in contrast to five past studies that found visual impairment to be associated with incident depressive symptoms.Citation12 For example, in Australia, Hong et al found that people with best-corrected visual acuity worse than 6/12 had a higher 5-year odds of incident depressive symptoms using a questionnaire called the Mental Health Index (OR = 3.06, 95% CI 1.72, 5.44) although they did not see an association at 10 years (OR = 1.29, 95% CI 0.84, 1.98).Citation12 Brown and Barrett found that visual impairment was a significant predictor of an increase in depressive symptoms over 3-years of follow-up in an American cohort of 1,221 people from the 1980’s (β = 0.29, P = .01).Citation21 Frank et al using the National Health and Aging Trends Study data reported that the self-report of vision loss was associated with the risk of developing depressive symptoms (HR = 1.33, 95% CI 1.15, 1.55). In a retrospective cohort study of 21,995 people using Quebec health administrative records, Tournier et al found that a diagnosis of moderate or severe visual impairment was associated with a higher adjusted risk of incident depression after excluding those with a history of depression in the two years prior to the index date (hazard ratio (HR) = 1.38, 95% CI 1.25, 1.91 for blindness or severe visual impairment and HR = 1.30, 95% CI 1.18, 1.44 for moderate visual impairment).Citation13 Finally, in a retrospective cohort study of people enrolled in the Korean National Health Insurance Service, Choi et al found that those people meeting the legal definition of visual impairment had increased risks of a diagnosis of depression after adjusting for potential confounding factors (Hazard ratio (HR) = 1.19, P = .002).Citation22 As these last two studies relied on diagnosis codes, those people with visual impairment or depression who had not sought clinical care were not included. The validity of the diagnosis codes for visual impairment and depression is not known.
We did not find that self-reported AMD was related to the incidence of depressive symptoms. This was not in agreement with two prior longitudinal studies. A 2-year prospective cohort study of low vision rehabilitation patients by Heesterbeek et al indicated that AMD was associated with the incidence of depressive symptoms using a linear mixed model (β = 0.12, 95% CI 0.04, 0.21) while visual acuity was not.Citation19 It should be noted that 56% of the sample was lost to follow-up, which could lead to bias. Also, a U.S. study by Wysong et al using Medicare claims data found an association between AMD and the incidence of depression, although the effect size was extremely small and perhaps not clinically significant (HR = 1.06, 95% CI 1.02, 1.09).Citation15 We must note that when we adjusted for age in a linear fashion, AMD was associated with incident depressive symptoms in our data. However, we found that age was non-linearly associated with incident depressive symptoms and thus modeling age as a linear term would have led to residual confounding and did not fit the data as well. Heesterbeek et al modeled age in a non-linear fashion while Wysong et al modeled age in a linear fashion.
We did not find a statistically significant association between glaucoma and the incidence of depressive symptoms. Most studies assessing the association between glaucoma and depressive symptoms were cross-sectional or case-control studies.Citation7,Citation34,Citation35 One longitudinal study, a retrospective population-based cohort study conducted by Chen et al using the Taiwan National Health Insurance Research Database, reported conflicting findings to ours in that patients with glaucoma had a significantly higher risk of depression (adjusted HR = 1.71, 95% CI 1.54–1.89) as compared to those without.Citation14 Relying on medical records, as in Chen et al, or the use of the self-report of glaucoma, as we did, may result in misclassification since many people are undiagnosed.Citation36
A strength of this research was that this population-based, longitudinal dataset allowed us to measure the incidence of depressive symptoms, to determine the temporality of the vision loss/eye disease and the onset of depressive symptoms, and to adjust for a large number of potentially confounding variables. We appropriately modeled the non-linear association between age and incident depressive symptoms and we examined potential effect modification. A limitation of this work is the use of self-reported data on the presence of eye disease. In particular, we are unable to determine which people who reported cataract had had cataract surgery because of substantial missing data for that question (57% missing). Furthermore, the validity of self-reported data on eye disease is known to be limited.Citation37,Citation38 This probably resulted in non-differential misclassification and attenuated results. However, the prevalence of self-reported eye diseases that we report in the CLSA (20% cataract, 2.8% AMD, 3.6% glaucoma) are similar to the prevalence of eye diseases in the US using an ophthalmic exam (17% cataract, 1.86% open-angle glaucoma, 1.47% AMD)Citation39–41 although we found higher prevalences of AMD and glaucoma. Also, selection bias is always possible when doing aging research if the association between vision loss and depressive symptoms is different in those who did not participate. We are reassured that the 3-year incidence of depressive symptoms in those 65 and older in the CLSA (9%) is similar to the 3-year incidence of depressive symptoms in NuAge, a population-based study of adults ages 65 and older in Quebec (12%).Citation42 It should be noted that depression is a relapsing and remitting condition.Citation43 Thus, the 3-year follow-up period may have missed some cases of depression. Finally, our results may not be generalizable to those excluded from the CLSA sampling frame which includes full-time members of the Canadian Armed Forces, those residing on a federal First Nations reserve or settlement, those living in a long-term care institution, those who are not a permanent resident or Canadian citizen, those not fluent in English or French, and those with cognitive impairment.
To summarize, these data indicate that the risk of depressive symptoms is 20% higher in those who reported a previous diagnosis of cataract. Depressive symptoms are a very common problem in the population with almost 8% of the population developing it within 3 years. Its presence may complicate efforts to treat eye disease.Citation3,Citation4 Further research should confirm our finding. If confirmed, efforts should be made to address depressive symptoms in those with cataract. Strategies to decrease depressive symptoms include greater screening and targeted interventions in high-risk groups.Citation44,Citation45
Acknowledgments
This research was made possible using the data/biospecimens collected by the Canadian Longitudinal Study on Aging (CLSA). Funding for the Canadian Longitudinal Study on Aging (CLSA) is provided by the Government of Canada through the Canadian Institutes of Health Research (CIHR) under grant reference: LSA 94473 and the Canada Foundation for Innovation. This research has been conducted using the CLSA dataset, Baseline Comprehensive Dataset version 4.0, Follow-up 1 Comprehensive Dataset version 1.0, under Application Number 190212. The CLSA is led by Drs. Parminder Raina, Christina Wolfson and Susan Kirkland. The opinions expressed in this manuscript are the author’s own and do not reflect the views of the Canadian Longitudinal Study on Aging. No potential conflict of interest was reported by the authors.
Disclosure statement
The authors report no conflict of interest
Data availability
Data are available from the Canadian Longitudinal Study on Aging (www.clsa-elcv.ca) for researchers who meet the criteria for access to de-identified CLSA data.
Additional information
Funding
References
- Flaxman SR, Bourne RRA, Resnikoff S, et al. Global causes of blindness and distance vision impairment 1990-2020: a systematic review and meta-analysis. Lancet Glob Health. 2017;5(12):e1221–e1234. doi:10.1016/S2214-109X(17)30393-5.
- Reinhardt JP, Boerner K, Horowitz A. Personal and social resources and adaptation to chronic vision impairment over time. Aging & Mental Health. 2009;13(3):367–375. doi:10.1080/13607860902860912.
- Friedman DS, Okeke CO, Jampel HD, et al. Risk factors for poor adherence to eyedrops in electronically monitored patients with glaucoma. Ophthalmology. 2009;116(6):1097–1105. doi:10.1016/j.ophtha.2009.01.021.
- Chen AJ, Hwang V, Law PY, Stewart JM, Chao DL. Factors Associated with Non-compliance for Diabetic Retinopathy Follow-up in an Urban Safety-Net Hospital. Ophthalmic Epidemiol. 2018;25(5–6):443–450. doi:10.1080/09286586.2018.1504311.
- Brody BL, Gamst AC, Williams RA, et al. Depression, visual acuity, comorbidity, and disability associated with age-related macular degeneration. Ophthalmology. 2001;108(10):1893–1900. doi:10.1016/S0161-6420(01)00754-0. discussion 1900-1891.
- Casten RJ, Rovner BW, Tasman W. Age-related macular degeneration and depression: a review of recent research. Curr Opin Ophthalmol. 2004;15(3):181–183. doi:10.1097/01.icu.0000120710.35941.3f.
- Mabuchi F, Yoshimura K, Kashiwagi K, et al. High prevalence of anxiety and depression in patients with primary open-angle glaucoma. J Glaucoma. 2008;17(7):552–557. doi:10.1097/IJG.0b013e31816299d4.
- van der Aa HP, Comijs HC, Penninx BW, van Rens GH, van Nispen RM. Major depressive and anxiety disorders in visually impaired older adults. Invest Ophthalmol Vis Sci. 2015;56(2):849–854. doi:10.1167/iovs.14-15848.
- Wang H, Sun HP, Wang P, Xu Y, Pan CW. Cataract and Depressive Symptoms among Older Chinese Adults. Optom Vis Sci. 2016;93(12):1479–1484. doi:10.1097/OPX.0000000000000960.
- Eramudugolla R, Wood J, Anstey KJ. Co-morbidity of depression and anxiety in common age-related eye diseases: a population-based study of 662 adults. Front Aging Neurosci. 2013;5:56. doi:10.3389/fnagi.2013.00056.
- Zheng DD, Bokman CL, Lam BL, et al. Longitudinal relationships between visual acuity and severe depressive symptoms in older adults: the Salisbury Eye Evaluation study. Aging & Mental Health. 2016;20(3):295–302. doi:10.1080/13607863.2015.1008985.
- Hong T, Mitchell P, Burlutsky G, Gopinath B, Liew G, Wang JJ. Visual impairment and depressive symptoms in an older Australian cohort: longitudinal findings from the Blue Mountains Eye Study. British J Ophthalmol. 2015;99(8):1017–1021. doi:10.1136/bjophthalmol-2014-306308.
- Tournier M, Moride Y, Ducruet T, Moshyk A, Rochon S. Depression and mortality in the visually-impaired, community-dwelling, elderly population of Quebec. Acta Ophthalmol. 2008;86(2):196–201. doi:10.1111/j.1600-0420.2007.01024.x.
- Chen YY, Lai YJ, Wang JP, et al. The association between glaucoma and risk of depression: A nationwide population-based cohort study. BMC Ophthalmol. 2018;18(1):146–147. doi:10.1186/s12886-018-0811-5.
- Wysong A, Lee PP, Sloan FA. Longitudinal incidence of adverse outcomes of age-related macular degeneration. Arch Ophthalmol. 2009;127(3):320–327. doi:10.1001/archophthalmol.2008.613.
- Chen PW, Liu PP, Lin SM, Wang JH, Huang HK, Loh CH. Cataract and the increased risk of depression in general population: a 16-year nationwide population-based longitudinal study. Sci Rep. 2020;10(1):13421. doi:10.1038/s41598-020-70285-7.
- Prince MJ, Harwood RH, Thomas A, Mann AH. A prospective population-based cohort study of the effects of disablement and social milieu on the onset and maintenance of late-life depression. The Gospel Oak Project VII. Psychol Med. 1998;28(2):337–350. doi:10.1017/S0033291797006478.
- Forsell Y. Predictors for Depression, Anxiety and psychotic symptoms in a very elderly population: data from a 3-year follow-up study. Soc Psychiatry Psychiatr Epidemiol. 2000;35(6):259–263. doi:10.1007/s001270050237.
- Heesterbeek TJ, HPA VDA, GHMB VR, Twisk JWR, van Nispen RMA. The incidence and predictors of depressive and anxiety symptoms in older adults with vision impairment: a longitudinal prospective cohort study. Ophthalmic Physiol Opt. 2017;37(4):385–398. doi:10.1111/opo.12388.
- Harris T, Cook DG, Victor C, DeWilde S, Beighton C. Onset and persistence of depression in older people - Results from a 2-year community follow-up study. Age Ageing. 2006;35(1):25–32. doi:10.1093/ageing/afi216.
- Brown RL, Barrett AE. Visual impairment and quality of life among older adults: an examination of explanations for the relationship. J Gerontol. 2011;66 B(3):364–373. doi:10.1093/geronb/gbr015.
- Choi HG, Lee MJ, Lee SM. Visual impairment and risk of depression: A longitudinal follow-up study using a national sample cohort. Sci Rep. 2018;8(1):2083–2084. doi:10.1038/s41598-018-20374-5.
- Frank CR, Xiang X, Stagg BC, Ehrlich JR. Longitudinal associations of self-reported vision impairment with symptoms of anxiety and depression among older adults in the United States. JAMA Ophthalmol. 2019;137(7):793–800. doi:10.1001/jamaophthalmol.2019.1085.
- Heine C, Browning CJ. Mental health and dual sensory loss in older adults: a systematic review. Front Aging Neurosci. 2014;6:83. doi:10.3389/fnagi.2014.00083.
- Rorsman B, Grasbeck A, Hagnell O, et al. A prospective study of first-incidence depression. The Lundby study, 1957-72. Br J Psychiatry. 1990;156(3):336–342. doi:10.1192/bjp.156.3.336.
- Raina P, Wolfson C, Kirkland S, et al. Cohort Profile: the Canadian Longitudinal Study on Aging (CLSA). Int J Epidemiol. 2019;48(6):1752–1753j. doi:10.1093/ije/dyz173.
- Ferris FL 3rd, Kassoff A, Bresnick GH, Bailey I. New visual acuity charts for clinical research. Am J Ophthalmol. 1982;94(1):91–96. doi:10.1016/0002-9394(82)90197-0.
- Aljied R, Aubin MJ, Buhrmann R, Sabeti S, Freeman EE. Prevalence and determinants of visual impairment in Canada: cross-sectional data from the Canadian longitudinal study on aging. Can J Ophthalmol. 2018;53(3):291–297. doi:10.1016/j.jcjo.2018.01.027.
- Andresen EM, Malmgren JA, Carter WB, Patrick DL. Screening for depression in well older adults: evaluation of a short form of the CES-D (Center for Epidemiologic Studies Depression Scale). Am J Prev Med. 1994;10(2):77–84. doi:10.1016/S0749-3797(18)30622-6.
- Guralnik JM. Assessing the impact of comorbidity in the older population. Ann Epidemiol. 1996;6(5):376–380. doi:10.1016/S1047-2797(96)00060-9.
- McNutt LA, Wu C, Xue X, Hafner JP. Estimating the relative risk in cohort studies and clinical trials of common outcomes. Am J Epidemiol. 2003;157(10):940–943. doi:10.1093/aje/kwg074.
- Kessler RC, Foster C, Webster PS, House JS. The relationship between age and depressive symptoms in two national surveys. Psychol Aging. 1992;7(1):119–126. doi:10.1037/0882-7974.7.1.119.
- van de Leemput IA, Wichers M, Cramer AO, et al. Critical slowing down as early warning for the onset and termination of depression. Proc Natl Acad Sci U S A. 2014;111(1):87–92. doi:10.1073/pnas.1312114110.
- Wilson MR, Coleman AL, Yu F, Fong Sasaki I, Bing EG, Kim MH. Depression in patients with glaucoma as measured by self-report surveys. Ophthalmology. 2002;109(5):1018–1022. doi:10.1016/S0161-6420(02)00993-4.
- Jampel HD, Frick KD, Janz NK, et al. Depression and mood indicators in newly diagnosed glaucoma patients. Am J Ophthalmol. 2007;144(2):238–244. doi:10.1016/j.ajo.2007.04.048.
- Quigley HA, Broman AT. The number of people with glaucoma worldwide in 2010 and 2020. Br J Ophthalmol. 2006;90(3):262–267. doi:10.1136/bjo.2005.081224.
- Linton KL, Klein BE, Klein R. The validity of self-reported and surrogate-reported cataract and age-related macular degeneration in the Beaver Dam Eye Study. Am J Epidemiol. 1991;134(12):1438–1446. doi:10.1093/oxfordjournals.aje.a116049.
- Patty L, Wu C, Torres M, Azen S, Varma R. Los Angeles latino eye study G. Validity of self-reported eye disease and treatment in a population-based study: the Los Angeles Latino Eye Study. Ophthalmology. 2012;119(9):1725–1730. doi:10.1016/j.ophtha.2012.02.029.
- Friedman DS, Wolfs RC, O’Colmain BJ, et al. Prevalence of open-angle glaucoma among adults in the United States. Arch Ophthalmol. 2004;122(4):532–538.
- Congdon N, Vingerling JR, Klein BE, et al. Prevalence of cataract and pseudophakia/aphakia among adults in the United States. Arch Ophthalmol. 2004;122(4):487–494.
- Friedman DS, O’Colmain BJ, Munoz B, et al. Prevalence of age-related macular degeneration in the United States. Arch Ophthalmol. 2004;122(4):564–572.
- Gougeon L, Payette H, Morais J, Gaudreau P, Shatenstein B, Gray-Donald K. Dietary patterns and incidence of depression in a cohort of community-dwelling older Canadians. J Nutrition, Health Aging. 2015;19(4):431–436. doi:10.1007/s12603-014-0562-9.
- Mueller TI, Leon AC, Keller MB, et al. Recurrence after recovery from major depressive disorder during 15 years of observational follow-up. Am J Psychiatry. 1999;156(7):1000–1006.
- van der Aa HP, van Rens GH, Comijs HC, et al. Stepped care for depression and anxiety in visually impaired older adults: multicentre randomised controlled trial. BMJ. 2015;351:h6127. doi:10.1136/bmj.h6127.
- Kamga H, McCusker J, Yaffe M, et al. Self-care tools to treat depressive symptoms in patients with age-related eye disease: a randomized controlled clinical trial. Clin Exp Ophthalmol. 2017;45(4):371–378. doi:10.1111/ceo.12890.