The magnitude of visual impairment worldwide is estimated to be 285 million people, out of which 39 million are blind, and 246 million have low vision.1 Most of these visually impaired people are aged 50 years or more. The number of visually impaired people in India is estimated at 62 million, of which eight million have severe sight impairment.2 Worryingly, the number of elderly persons is rising and so the burden of sight loss is expected to increase.3
Cataract is the commonest disease cause of curable blindness the world over and represents a significant problem throughout India. Government authorities and voluntary organisations are targeting cataract, but much still needs to be done (figure 1). The other major cause of sight loss is uncorrected refractive error where, again, much work needs to be done. Taking these two causes into account, over 80% of visual impairment among elderly persons in India is either avoidable or treatable.
Figure 1: Cataract is a major problem in India
Classification of visual impairment
The World Health Organization (WHO) classification of visual impairment is the standard tool for both epidemiology and health management and for clinical intervention. WHO classify sight loss into four categories based upon visual acuity (VA):4
- Category 0; mild or no visual impairment: vision is equal to or better than 6/18 using Snellen chart measurement
- Category 1; moderate vision impairment: vision is worse than 6/18 but equal to or better than 6/60
- Category 2; severe vision impairment: vision is worse than 6/60 but equal to or better than 3/60
- Category 3; blindness: vision is worse than 3/60. Revised WHO definitions further subdivide this category
Moderate and severe vision impairments are grouped together as ‘low vision’. Blindness is also used as a descriptor if the visual field is less than 10 degrees from the point of fixation. WHO categories are based on the VA of the better eye in the presenting vision without pinhole. The presenting VA provides a better understanding of refractive need and it is important to recognise uncorrected refractive error, particularly for epidemiological surveys and for planning.
Epidemiology of vision impairment
There are four aspects of epidemiology of vision impairment that are useful to consider and which influence the determination of appropriate public health control measures. They are:
- Magnitude; how many persons are affected?
- Distribution; where is it?
- Determinants; what are the main causes?
- Control; what can be done about it?
As already stated, the magnitude of visual impairment worldwide is estimated to be 285 million people, out of which 39 million are blind, and 246 million have low vision.1 Globally, the distribution of visual impairment is uneven, with 90% in low- and middle-income countries. The lowest prevalence is in higher-income countries and in Latin America. Prevalence data allows health workers to identify the number of blind and visually impaired people in their region. Globally, 82% of all blind people are aged 50 years and over. The importance of childhood blindness lies in the number of years a child has to live with that blindness. Blindness is more in women (64%) than in men (36%).
The risk of blindness through cataract is closely linked to poverty, and eye care services need to be accessible to all. One risk factor for an increase in global visual impairment in future is the increasing population growth, from approximately three billion people in 1960 to a projected figure of nearly 10 billion by 2060. A second risk factor is the increase in number of people aged over 60 especially in low and middle-income countries.
Treatment strategies for cataract and refractive errors can be implemented at local level, together with the strengthening of eye care services and easy access to these services. Diabetic retinopathy and glaucoma are chronic diseases, and patients need to be screened and treated as early as possible to prevent visual impairment.
In India, while ophthalmologists undertake cataract surgery, qualified optometrists correct refractive errors, mainly with spectacles but also with contact lenses. Myopia is also corrected by ophthalmologists with elective refractive surgery. More recently, ophthalmologists have been using low dose atropine therapy for myopia management, while some optometrists are doing the same but with orthokeratology.
Vision 2020: the Right to Sight
With the launch in 1999 of a global initiative called Vision 2020: the Right to Sight, it was envisaged that, over a period of 20 years, 100 million people could be treated or prevented from going blind. This was by way of a partnership between WHO and the International Agency for the Prevention of Blindness (IAPB).
There has, indeed, been a global decrease in the number of blind people, from 45 to 39 million, and a reduction in the prevalence of vision impairment, from 5% to 4.2%. This is despite a global population increase of half a billion to 6.7 billion and a rise of 18% in the number of people aged over 50. The impact of sight restoration is felt by individuals and the community.
World Sight Day
World Sight Day is an annual day of awareness held on the second Thursday of October to focus global attention on blindness and vision impairment. This year, it will take place on October 14th.5 On this day, non-governmental organisations, professional bodies, educational and research institutions, and hospitals work together to raise public awareness about, and influence governments on, blindness and visual impairment as major international public health issues.
Understanding cataract output
While there is no clear method of preventing the lens from clouding as part of the ageing process, cataract patients who are not yet blind (with less than 3/60 visual acuity) need to be identified and treated. Cataract surgery is both effective and relatively simple. The challenge is to ensure that all people who need surgery can access it.
Usually, the definition of a cataract case is one where the visual acuity is less than 6/60. The minimum cataract surgical rate needs to be equal to the incidence, or the number of new cases in a given time, so as to prevent any negative impact on the cataract backlog. Currently, the target is to simultaneously reduce the backlog and to treat new cases. It is important to remember that cataract surgery is possible at any stage of the disease and with whatever acuity, and should be an option where the vision loss interferes with the everyday life of an individual.
Managing barriers
Cataract surgical rate has remained low in developing countries. That not enough patients are coming for surgery may be due to a lack of awareness about the treatment or inaccessibility of the treatment facility. Another reason may be a belief that the sight loss is a normal part of the ageing process. Cost may be still another barrier. Where the distance from a hospital is a challenge for the rural population, outreach programmes are the best way to reach patients.
Easier access to alternative care, for example over the counter sales of homoeopathic or ayurvedic herbal eye drops, is also a challenge in India, especially when there exists a fear or mistrust of surgery. Health education and improved affordability helps in these cases.
There needs to be adequately trained manpower to manage an operating theatre, and the clinic and related facilities need to be fully equipped. Community based health workers, who make referral to the eye unit, also have an important role in managing barriers.
Managing cataract outcome
Sustainability of cataract services is affected by efficient surgical services, high output, patient confidence, and low-cost surgery. Quality of cataract surgery can be measured by patient satisfaction, what the patients are able to do before and after surgery, and the measurement of vision in the operated eye before and after surgery.
In 2005, a poor outcome (less than 6/60 post-operative acuity) was found in between 21% and 53% of operated eyes. This was due to widespread use of intracapsular extraction and subsequent problems from aphakia and breakage of spectacles. Since then, intraocular lens (IOL) implantation has become the norm in cataract surgery and these improvements in surgical techniques have contributed to much lower rates of poor outcome.
As per WHO guidelines, the outcome is good if VA after surgery is equal to or better than 6/18 in the operated eye. It is borderline if acuity is worse than 6/18 but equal to or better than 6/60. And any acuity less than 6/60 is classified as a poor outcome.
Causes of poor outcome include inappropriate selection of patients for surgery, surgical complications, failure to provide spectacles to correct post-operative refractive error, and sequelae or late post-operative complications. These include posterior capsular opacification (figure 2). To minimise poor outcomes, corrective action needs to be taken at every step whenever needed.
Figure 2: Posterior capsular opacification is a common cause of poor outcome of cataract treatment
Managing cost of cataract services
The cost of cataract surgery may be calculated by the following formula;
When fewer operations are undertaken, the cost per cataract is high. The greater the number of operations undertaken, the lower the cost. Cost containment is achieved by:
- Increasing the number of cataract operations
- Reducing the cost of surgery; by negotiating bulk prices for consumables, generic drugs and IOLs, or even using low-cost technologies
The IAPB publishes a standard list for purchasing consumables and this can be found at www.iapb.standardlist.org.
It is important that clinical standards and outcome are not compromised by cost recovery, and non-clinical facilities can vary significantly. Cost-cutting can be achieved a number of ways, for example by charging fees to richer patients to subsidise the poorer, by raising money from a hospital canteen for relatives or by selling eye drops and spectacles. Many eye units run by NGOs, non-profit organisations that operate independently of any government, still depend on government subsidy. Insurance schemes are another option for paying for surgical treatment.
High volume cataract surgery; the Aravind model
Aravind Eye Hospital developed a replicable model to deliver high quality eye care, regardless of a patient’s ability to pay, by cross-financing the service and by service efficiency. Aravind’s focus was on those affected by cataract but were not accessing care. The approach included awareness creation, diagnosis, service delivery, and follow-up.6 This took the form of outreach screening camps which were organised by local communities. At these camps, comprehensive eye examinations were carried out, glasses and medicines were prescribed, and those requiring cataract surgery were transported to one of the base hospitals.
Further investigations were then carried out and, on the following day, patients were operated and transported home the day after. After five weeks, the Aravind team went back to the campsite for follow up. Through outreach and vision centres, Aravind undertakes about 100,000 cataract procedures each year. Additionally, another 100,000 pay for treatment and 50,000 are subsidised for their surgery, taking the total of cataract treatments to 250,000 per year. This requires Aravind Eye Hospital to perform 750 to 1,500 surgeries each day.
This is possible through detailed, daily micro-planning and by ensuring adequate staffing, supplies, and equipment, including sterilised surgical instruments. Each surgeon operates on two tables, supported by two dedicated scrub nurses and a third nurse on rotation, thus minimising the wait for patients and replacement equipment. This process, combined with a highly motivated workforce, has ensured a high output.
At Aravind, quality systems are built on the foundation of standardised protocols, good medical records and an organisational focus that fosters a culture of continuous improvement. There are close to 400 doctors in the system, with about half of them in training. Standardisation is enforced using simple techniques, such as the use of checklists. The scheduling of patients matches the complexity of the case to the surgeon’s skills and experience, with trainees and junior doctors handing simpler cases and the more skilled surgeons handling the challenging cases.
Every day, a sample of patients gives feedback on their experience and satisfaction through a structured questionnaire and focus group discussions. Staff members collect and record data relating to quality of care which is analysed and reviewed.
Aravind’s purpose to eliminate needless blindness has resulted in policies such as:
- No one will be turned away for want of money
- Accessibility; reaching out proactively those who are not accessing care
- Equity; core aspects of care around safety, outcome, and maintaining patient dignity are the same, regardless of a patient’s paying capacity
- Financial sustainability; maintained by a simple formula of keeping the costs lower than the revenues. Aravind chose its income to come predominantly from patient services to ensure sustainability.
Reflecting the paying capabilities, the Aravind pricing covers the full range of treatments charged at market rates for paying patients while offering a negative price for the rural poor. Negative pricing means that Aravind can spend money on patients in the community and enable access by funding transport. The patients coming to the hospital can self-select whether to be seen at the paying or free facility. Improved ambiance and facilities, such as air conditioning, are what the paying patients pay for. The same clinical quality is insured for both groups by rotating the staff within the two facilities.
The focus on equity also gave birth to Aurolab, which makes available good quality IOLs at a low cost.7 Costs are kept to a minimum by focusing on productivity, eliminating waste, and efficiently managing bottlenecks. Costs are further reduced through a leveraging scale, completing the entire care cycle, including surgery, in a single visit and rationalising the number of follow-up visits. This approach has helped Aravind’s finances to remain robust, not only covering the costs of free care and subsidised care, but also financing the building of new hospitals and purchase of equipment.
Refractive error
In public health, refractive error is defined as vision of less than 6/18 which can be corrected by refraction or by pinhole. Correctable myopia is defined as -1.00DS or more, correctable hyperopia is +3.00DS or more, and it is essential to correct astigmatism of 1.50DC or more. In children under 15, refractive error is higher in urban areas than in rural settings.
India and China are most affected by uncorrected refractive error. There is lack of refraction services and limited affordability of spectacle correction, particularly in rural communities. Sometimes, low importance is assigned to spectacles and, occasionally, there is an aversion to spectacle wear, especially in younger girls.
Twenty percent of the total population is a reasonable estimate of refractive error prevalence for planning refractive error services in India. Community education is important in identifying the demand. Refraction equipment and spectacle dispensing equipment are necessary to deliver comprehensive services. A range of lenses and frames, too, needs to be stocked. The priority age group to be targeted at least once is of children aged 12 to 14 years. School vision testing is an important strategy to address refractive error needs in children.
Team work needed in eye care
Historically, ophthalmologists have been engaged in multiple roles in the delivery of eye care. However, to reduce avoidable blindness, allied eye care professionals are needed in India and their roles will need to be developed, and individuals trained and deployed to work alongside and support ophthalmologists (figure 3). This is essential if blindness in India is to one day be managed.
Figure 3: Managing blindness in India requires a multidisciplinary approach
- Dr Narendra Kumar, BAMS, DROpt, PGCR is Editor, Optometry Today and a clinician at Ophthacare Eye Centre, Janakpuri, New Delhi.
References
- http://www.emro.who.int/control-and-preventions-of...
- Pascolini D, Mariotti SP. Global estimates of visual impairment: 2010. British Journal of Ophthalmology, 2012; 96: 614-18
- United Nations. World Population prospects: Key findings and advanced tables, 2015 revision. Available from: https://esa.un.org/unpd/wpp/publications/files/key...
- https://www.who.int/blindness/Change%20the%20Defin...
- https://www.iapb.org/world-sight-day
- Ravilla T, Ramasamy D. Efficient high-volume cataract services: the Aravind model. Community Eye Health. 2014;27(85):7-8
- https://aurolab.com
