More than 250 million people are blind or visually impaired worldwide and 90% live in low- and middle-income countries.1 Due to India's large population and high prevalence of eye disease, it is home to more individuals with blindness and VI than any other countries2 and the number affected is projected to increase due to aging of the population. In India, vision impairment has been associated with increased falls, depression, social isolation, and decreased independence and vision-related quality of life (VRQOL).3–7 Although up to 85% of patients who receive low vision services may experience improved functioning and VRQOL,8–11 low vision services are available to <10% of the Indian population.12
Low vision services can include the prescription of low vision aids, orientation and mobility therapy, adaptive techniques, and occupational therapy. Typically, a plan for low vision rehabilitation is developed around an individual patient's goals, impairments, and type(s) of vision loss (eg, visual acuity, peripheral fields, contrast sensitivity).13 A rehabilitation plan should also be responsive to the local culture and environment, since in different settings disabilities may cause distinct functional limitations due to variable factors like local occupational demands and environmental challenges.14
Accordingly, it is important for local practitioners to understand the clinical and demographic factors that are associated with specific impairments in patients with low vision. A study by Brown et al identified the prevalence and risk factors for 13 different concerns in patients with low vision in the United States.15 They found that difficulty reading was by far the most common impairment, followed by driving, using assistive devices, in-home activities, lighting and glare, and social interactions. Some concerns varied as a function of age, visual acuity, or sex of the patient. However, as the authors pointed out, these results may not be applicable to settings beyond the United States. To our knowledge, few studies from India have investigated the factors associated with specific functional limitations in low vision,11,16–18 and they focused on a highly specific population,17,18 a single disease,16 or were limited by a predefined set of survey questions.11
In the current study, we sought to determine the most common functional concerns of patients with different ocular diagnoses seeking low vision care in South India. We also identified clinical and demographic factors predictive of each concern. These data may help practitioners and researchers design informed treatment plans and new interventions that are responsive to the needs of Indians with low vision.
Ethical approval for this study (Project Code RES2016034CLI) was provided by the Institutional Review Board of AECS, India (Chairperson Dr. R. Venkata Ratnam) on August 20, 2016. All participants provided informed consent to participate in this study and it adhered to the tenets of the Declaration of Helsinki.
Consecutive new patients seen in the low vision clinic at AECS in Madurai, India from September 2016 to March 2017 were informed of the study and offered the opportunity to participate. Participants in this study were new to the low vision service and were either referred internally from other AECS doctors, referred from other medical providers in the community, or were self-referred. The low vision service at AECS provides a standard low vision examination and evaluation, and offers a range of optical low vision devices.
The primary ocular diagnosis for each participant was determined by the examining ophthalmologist and presenting visual acuity (PVA) was measured for each eye on a logMAR chart. Detailed ocular diagnoses were categorized as acquired retinal disease, congenital pathology, glaucoma, high refractive error, neuro-ophthalmic disease, retinal dystrophy, or other diseases. The most common types of acquired retinal disease were age-related macular degeneration (20/92, 21.7%) and retinal detachment (10/92, 10.9%), whereas other less common diagnoses included conditions such as central serous chorioretinopathy, and macular scar. Acquired retinal diseases were grouped together due to the small number of participants with each individual diagnosis. The anatomic site of low vision was noted according to the World Health Organization Eye Examination Record.19
Additional data were recorded by a trained interviewer, including age, sex, educational attainment, and occupation. Participants were asked, “because of your vision, do you face any difficulties in your life?” Up to 3 responses to this question were recorded and served as the primary outcome variable. The free-text responses of participants were assigned to one of the following 12 impairment categories, based on post-hoc review of responses: color identification; computers; cooking; driving; face identification; mobility; night vision; pain; reading and writing; school/work difficulty; socioemotional problems; and watching television. To classify participant responses, 2 independent coders classifying each free-text statement and disagreements were adjudicated by a third coder.
On initial review of the study data, the difficulties that participants faced in their lives could not be determined for 194 (41%) participants because data were missing or recorded answers were vague (eg, “seeing problem”). Therefore, the same interviewer attempted to contact each of these participants by telephone to obtain complete data. Ultimately, complete data were available for 419 of the 470 (89.1%) participants enrolled in the study.
Pearson's chi-squared tests and analysis of variance were used to compare differences in age, sex, educational attainment, occupation, number of functional impairments, and PVA in the better-seeing eye by ocular diagnosis category. The proportion of participants reporting each impairment was stratified by ocular diagnosis category (for impairments reported by >1 participant). Multivariable logistic regression was used to model the odds of reporting each impairment as a function of age, sex, and PVA in the better-seeing eye. Education and occupation were not included in these models because there were too few participants in some levels of those variables to do so. Logistic models were run for each impairment category endorsed by ≥30 participants, because logistic models with <10 events per predictor variable have a high risk of bias due to large sample variance estimates.20 Negative binomial regression was used to test the association of age, sex, highest education, occupation, and PVA in the better-seeing eye with the number of functional impairments cited. Analyses were conducted using Stata version 14 (Stata Corp, College Station, TX). All statistical tests were 2-tailed with a significance threshold of P ≤ 0.05.
Characteristics of the study sample stratified by primary ocular diagnosis are presented in Table 1. We included 419 patients, 65.2% of whom were male with a mean age of 42.0 years old. The most common ocular diagnoses were retinal dystrophy (35.8%) and acquired retinal disease (22.0%), which together comprised more than half of the sample. Ocular diagnoses varied significantly as a function of age (P < 0.001), educational attainment (P = 0.001), occupation (P < 0.001), and PVA in the better-seeing eye (P < 0.001), but not sex (P = 0.67). Table 2 presents the classification of participants according to the anatomic site of their low vision.
Most participants (n = 242, 57.8%) endorsed a single impairment, although 26.0% did not cite any difficulty due to their vision, and 16.2% noted 2 to 3 difficulties (Fig. 1). The number of difficulties did not differ significantly by diagnosis (P = 0.69), age (P = 0.93), sex (P = 0.31), highest education (P = 0.13), occupation (P = 0.82), or PVA in the better-seeing eye (P = 0.60). Figure 2 illustrates the proportion of participants who endorsed each functional limitation. The most common difficulty was reading (37.7%), followed by mobility (19.9%), and facial identification (13.8%), whereas all other impairments were cited by <10% of respondents.
Table 3 presents functional difficulties stratified by ocular diagnosis. The only significant association was between night vision difficulty and ocular diagnosis (P < 0.001); of the 30 participants who endorsed night vision problems, 23 (76.7%) had a diagnosis of retinal dystrophy. Other functional difficulties were not more common in any specific eye disease.
Multivariable logistic models were used to test the association between functional impairments and age, sex, and PVA in the better-seeing eye. The results of these models are presented in Figure 3. Each 10-year increase in age corresponded to 20% increased odds of difficulty with facial recognition [odds ratio (OR) = 1.20, 95% confidence interval (CI) = 1.01, 1.43, P = 0.03) and 22% decreased odds of night vision difficulty (OR = 0.78, 95% CI = 0.60, 1.00, P = 0.05). Worse PVA was associated with greater odds of reporting a mobility problem (OR = 2.87, 95% CI = 2.09, 3.93, P < 0.001). No other statistically significant associations were detected in these models.
Blindness and VI are the second leading cause of years lived with disability in India.2 Nonetheless, a 2011 report found that only ≤10% of the Indian population had access to low vision services.12 Additional research, training, and capacity building are needed to improve the provision of low vision services in India and to attend to the needs of an aging population. The current study makes several important contributions to this effort. First, to our knowledge this is the only Indian study to describe the day-to-day difficulties that are common in different ocular diagnoses among those seeking low vision services. In addition, the study provides practical data on clinical and demographic factors that are associated with specific functional limitations.
In the current study, reading was the most common functional difficulty, affecting 37.7% of those presenting for low vision care. In a study from the United States, reading was also the most important functional difficulty and affected 66.4%.15 The higher prevalence of reading difficulty in the United States was likely due to the high proportion of macular disease, and differences in literacy and cultural, environmental, and occupational demands between India and the United States. The second and third most commonly cited functional difficulties in the US study were driving and assistive device use, respectively. Neither of these issues were commonly cited by Indian patients with low vision. Although this study did not ask about past and current driving behaviors, automotive vehicle ownership is low in India and access to assistive devices is poor.21,22 These findings further underscore the importance of local studies to understand how the experience of living with eye disease varies from place to place.
It was surprising to learn that there were few associations between ocular diagnosis and functional difficulty. Based on prior reports,23,24 it was anticipated that eye diseases like glaucoma and retinal dystrophy that cause peripheral field loss would be strongly associated with mobility difficulty. As the extent of peripheral field loss was not known in this study, it is possible that a measure of the extent visual field loss (eg, mean deviation) would be associated with mobility difficulty. In addition, visual acuity was not associated with tasks like reading and facial identification that require good central vision. It is possible that some participants may have successfully adapted to vision loss or adopted compensatory strategies, and therefore did not express difficulty performing tasks that would otherwise be challenging. It is notable, however, that age was significantly associated with greater difficulty recognizing faces and that worse PVA was significantly associated with mobility difficulty; these may be important considerations for low vision providers in India. Finally, the functional difficulties of those with congenital and acquired pathologies did not seem to differ, despite the possibility that individuals with congenital vision loss might be more likely to develop compensatory strategies.
About one-quarter of the study sample did not cite any difficulty in their daily lives due to vision impairment. This may have been the case if patients were referred because a medical provider or family member believed that they could benefit from low vision care or if they were inappropriately referred for low vision services. It is important to understand patients’ perceptions and experiences with low vision services in India, a topic that should be addressed in future qualitative or mixed-methods studies.
There were several limitations to this study. Several of the disease categories contained individuals with >1 ophthalmic diagnosis and this could have obfuscated associations between functional difficulties and specific disease states. As it was not possible to perform robust and valid analyses on diagnostic categories containing a small number of individuals, some diagnoses were grouped together (eg, acquired retinal diseases) and this may have biased the results away from detecting significant associations. Likewise, we did not perform analyses based on a classification using the anatomic site of low vision because nearly all cases (96.9%) were assigned to only four anatomic sites. A larger sample may have permitted more in-depth analyses of the impact of education and occupation on functional difficulties among individuals with diverse low vision diagnoses. There were also a number of strengths to this study. To our knowledge, this is the first study to provide a comprehensive assessment of functional difficulties in a large and diverse sample of patients seeking low vision services in India. This study also provides data that can be easily compared with previous studies from other settings to discern differences between populations.
In summary, the results of this study support the expansion of low vision services in India targeted to common functional concerns like reading, mobility, and facial identification. However, these results do not support the use of ocular diagnosis for this purpose. Additional research is needed to better understand the effectiveness of low vision interventions for individuals with different conditions and functional concerns in India. Addressing the functional needs of patients with low vision in India is an important step toward decreasing vision-related disability and promoting independence and well-being for an aging population.
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