Eye Diseases in Hot Climates John Sandford-Smith, Saul Rajak
Chapter Notes

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People don't go blind by the million; they go blind one by one, each with their own sadness and loss.
The eye is a truly amazing structure. Rays of light from the outside world enter the eye and are converted into electrical impulses that are transferred along visual pathways to the brain, which uses this information to generate a picture of the world – to allow us to see. The eyes provide about half the total sensory input from the entire body into the brain. There is, however, one small defect in the visual image produced by the healthy eye: the ‘blind spot’. This is a small area in our field of vision where we are unable to see. It corresponds to where the optic nerve leaves the eye. Remarkably, our brain creates appropriate images to fill in the blind spot, so that we are not even aware of it. Unfortunately there is a very large ‘blind-spot’ in worldwide ophthalmology. This is the tragedy of avoidable blindness in poor countries. Approximately 285 million people worldwide are visually impaired. About three quarters of this is treatable or avoidable. And just as in the eye, we cover over this blind spot and ignore it. Medical science, governments and health care workers largely neglect the millions of blind and visually impaired people worldwide. Indeed, that is the only reason why they are blind.
The aim of this book is to focus on this ‘blind spot’. It describes eye diseases and eye care in poor countries and in particular those diseases which cause treatable and preventable blindness.
The diseases of hot climates have traditionally been called ‘tropical’ diseases, although some hot countries are not exactly in the tropics, which is the 2region of the earth surrounding the equator. There are two important features about these areas with hotter climates. Firstly, some diseases may be influenced directly by the heat, humidity and solar radiation. For example, this climate encourages the growth and multiplication of bacteria, fungi and other micro-organisms that cause corneal infections and the insects and other carriers that cause many infective diseases. Secondly, and more importantly, a look at the world map will show that most hot countries are also poor (Figure 1.1). Poverty is associated with poor hygiene, poor nutrition, poor provision of and access to healthcare, civil wars and poor management of natural disasters, all of which are devastating for healthcare.
In the last few decades, countries with poor economies have been referred to in several ways, such as the Third World, developing countries, resource poor countries/settings, low income countries/settings. Each of these terms has problems.
  • The ‘Third World’ has complex political implications related to colonialism and the Cold War in the past. ‘Third’ is a rather derogatory term, which relates to ‘third class’ and ‘third rate’ and is therefore not a suitable description of poor countries.
  • ‘Developing countries’ is complimentary and optimistic, but is sometimes simply not true. In many war torn or badly governed countries the economic and health situation is not improving or may even be getting worse.
  • ‘Resource poor countries/settings’ is also often untrue, as some of the poorest countries have some of the highest levels of natural resources, but the money that they generate does not reach most of the population.
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Figure 1.1: UN world poverty map. The size of each country is proportional to its poverty compared to the rest of the world. Therefore Africa and South Asia look much larger than other countries. © Copyright Sasi Group (University of Sheffield) and Mark Newman (University of Michigan).
  • ‘Low-income countries/settings’ is the most accurate description of the sort of countries whose eye care we want to cover in this book, but it is a rather wordy and technical term.
We are therefore left doing a full circle back to the only phrase that accurately and honestly describes the economic situation in many areas: poor countries. We will therefore use this term throughout the book, although it must be emphasised that we are referring to the economic definition of the word ‘poor’ and it is not a reflection on other qualities in the many wonderful poor countries of the world. Also, these countries are often very rich in the culture and the resourcefulness of the people to overcome the difficulties and problems that are thrust on them.
Some diseases, such as trachoma and xerophthalmia (vitamin A deficiency associated eye disease) are seen more frequently because they are caused or worsened by poverty, the heat or the endemic micro-organisms and vectors. Other diseases, such as cataract and glaucoma, are the same as those seen in rich countries, but are seen at a much more advanced stage because of the lack of access to healthcare. Sometimes, e.g. cataract, the disease can still be treated, but other times, e.g. glaucoma, the visual loss is irreversible. Finally, some diseases, such as age-related macular degeneration and retinopathy of prematurity are seen less frequently in poor countries, because the life expectancy of adults is shorter and very premature babies are unlikely to survive.
A summary of some of the ways in which a hot climate and poverty can cause serious and common eye diseases is shown in Table 1.1. However, it is important to remember that for a lot of these diseases many factors interact. For example, corneal ulcers and scars are often much worse in poor countries because of the micro-organisms that live in hot climates, the increased risk of agricultural eye trauma, malnutrition in children, the poor access to healthcare and immunisations and the poor availability of treatments when healthcare is sought. Therefore you will see that some diseases appear several times in Table 1.1.
The World Health Organization (WHO) defines blindness as ‘visual acuity less than 3/60 in the better eye with the best possible spectacle correction or a corresponding visual field loss’. This degree of visual loss prevents the patient from walking about or navigating independently. In addition, the WHO has another category called ‘low vision’. Low vision corresponds to a visual acuity of less than 6/18, but equal to or better than 3/60 in the better eye with the best possible spectacle correction. Such people have a significant visual impairment which often makes working difficult, but they can get around independently.
Table 1.1   Diseases associated with poverty and hot climates
Risk factor
Disease caused or exacerbated by risk factor
Heat and solar radiation
Solar keratopathy
Eyelid tumours (e.g. basal cell carcinoma)
Insect and other disease vectors
Malaria retinopathy
Cutaneous leishmaniasis
Warm and humid climates
Fungal and bacterial keratitis
Allergic conjunctivitis
Vitamin A deficiency associated eye disease
Poor hygiene
Infective conjunctivitis
Leprosy and tuberculosis
Poor access to vaccinations and widespread untreated disease putting others at risk
Vitamin A deficiency associated eye disease
Congenital rubella
Increased risk of ocular trauma
Fungal and bacterial keratitis
Penetrating eye injury
Poor access to healthcare
All diseases
The most recent estimates are that worldwide 246 million people are visually impaired and 39 million blind. About 90% of them live in poor countries, 80% of it is avoidable and 60% are women. In fact, the proportion of women may be greater because women often have less opportunity to seek healthcare and be ‘counted’. The prevalence figures for visual loss are very approximate estimates, as counting the number of blind and visually impaired people is extremely difficult for the following reasons:
  • The majority of the world's eye disease is in poor countries. Many of these people live in remote, rural areas where they are not examined and their eye disease never ‘counted’. Because of the cost and difficulty of reaching these people, the prevalence figures of eye disease and visual loss are all based on samples. These samples are of course all estimates and often underestimate the numbers in the most rural and deprived places, where the level of eye disease is often highest.
  • Visually impaired people often hide their disease. There may be great social stigma attached to visual loss. Therefore, people with eye disease often do not inform their friends and relatives, let alone the health facilities or the researchers conducting prevalence surveys.
  • Although the definition of blindness and visual impairment has been internationally agreed upon on paper, it is often difficult to translate 5this to the ‘real patient’. The classification of whether a person is visually impaired can vary greatly, e.g. in different lighting conditions and with different vision testing charts.
  • Some people are continually becoming visually impaired as their disease progresses and some people's vision is being improved with treatment. The most dramatic example of this is cataract surgery in which a patient can change from being blind to having perfect vision almost immediately after a short operation.
The number of blind people in each region are shown in Table 1.2. Although the actual numbers of blind and visually impaired people are highest in Asia, this is because these are the most populous areas of the world. The highest prevalence of blind people are in some countries of sub-Saharan Africa (Niger, Mauritania, Mali, Chad, Somalia, Ethiopia and Burkina Faso).
Approximately 0.2% of the population in most rich countries are blind, but in poor countries the figure is between 0.5% and 1%. There are good reasons to believe that the difference between the two communities may be much greater than this:
  • Blindness is such a significant handicap in poor and rural communities that blind people have a much shorter life expectancy. This is especially true for blindness starting in infancy, but it is also true for blindness starting at any age.
  • In rich countries, many more people live into old age when the risk of visual loss increases. For example in England, three quarters of the people registered as blind each year are over 70 years.
    Table 1.2   Number of blind and visually impaired people in the world in 2010
    Total population, millions (%)
    Number of blind people, millions (%)
    Number with Low vision millions (%)
    Total number with blindness or low vision, millions (%)
    805 (11.9%)
    5.9 (15%)
    20.4 (8.3%)
    26.3 (9.2%)
    The Americas
    915 (13.6%)
    3.2 (8%)
    23.4 (9.5%)
    26.6 (26.6%)
    Eastern Mediterranean
    580 (8.6%)
    4.9 (12.5%)
    18.6 (7.6%)
    23.5 (23.5%)
    European region
    889 (13.2%)
    2.7 (7%)
    25.5 (10.4%)
    28.2 (28.2%)
    South East Asia (not including India)
    579 (8.6%)
    4.0 (10.1%)
    23.9 (9.7%)
    27.9 (9.8%)
    Western Pacific (not including China)
    442 (6.6%)
    2.3 (6%)
    12.4 (5%)
    14.7 (5.2%)
    1181 (17.5%)
    8.1 (20.5%)
    54.5 (22.2%)
    62.6 (21.9%)
    1345 (20.0%)
    8.2 (20.9%)
    67.3 (27.3%)
    75.5 (26.5%)
    6738 (100%)
    39.4 (100%)
    246.0 (100%)
    285.4 (100%)
    Modified from Pascolini D, Mariotti SP. Global estimates of visual impairment: 2010. Br J Ophthalmol. 2012; 96:614–618.
    6There are many fewer people over the age of 70 years in poor countries. Therefore, the difference in prevalence between rich and poor countries of visual loss in younger people is probably much greater than the overall difference.
  • Blind and visually impaired people in rich countries are registered on national registers. This occurs because they receive social security benefits and additional support such as low vision aids and tools to help them in their home. On the other hand in poor countries, there are often economic and cultural reasons for people to hide their blindness. For example, one of the authors once examined a man who was totally blind. He requested a note to excuse his absence from work. He was employed as a night watchman and certainly did not want his employer knowing his visual acuity level.
Over two thirds of worldwide visual impairment and blindness could be eliminated if the necessary treatment was provided for just refractive error and cataract. The major causes of preventable disease are listed in Box 1.1. There are also some causes of blindness that can neither be prevented nor treated. However, these are much less common in poor countries, either because they are rare, such as congenital abnormalities in children or because in many countries the life expectancy is not long enough for most people to develop these diseases such as degenerative and vascular diseases of the retina. Therefore, these diseases make up a much larger proportion of visual impairment in rich countries, where almost all people with refractive error are able to get glasses, those with cataract get cataract surgery before they are significantly impaired, glaucoma gets detected and treated early, and trachoma and onchocerciasis do not exist (Figure 1.2).
Eye diseases are a major health problem in most of the tropics and, in some places, may be the biggest community health problem of all. Yet there are not nearly enough trained medical staff to tackle this large and challenging problem. It has been said that there are more ophthalmologists in New York than in all of sub-Saharan Africa. In most African countries and in many rural areas of Asia there is less than one trained eye specialist for a million or more people compared to 81 per million in America.
Eye specialists are not only few in number, they are usually very unevenly distributed in most poor countries. They almost all work in the major cities and often treat mainly private and wealthier patients. Most poor countries have very small budgets for health care and very fragmented health systems, and therefore cannot offer attractive salaries or good working conditions to medical staff working in government hospitals. Therefore, most doctors are obliged or choose to work privately, and for specialists this nearly always means practising in the big cities or even leaving their home country to work in a richer country. They are therefore working far away from where most of the visually 7impaired people and the diseases of poverty are located.
In some countries, there may be almost an excess of specialists in the capital cities, and competition for work, but hardly any specialists in the rural areas. Furthermore eye care 8programmes have to compete with more serious life-threatening diseases for the small amount of money in health care budgets.
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Figure 1.2: The major causes of visual impairment.
There have been many large and small scale plans and strategies for addressing eye disease and visual impairment in poor countries. We will discuss the two major recent International Plans – VISION 2020 and Universal Eye Health – as well as a smaller and less prominent but potentially very effective strategy – institutional links between eye units in poor and rich countries.
In 1999 the World Health Organisation (WHO) and the International Agency for the Prevention of Blindness (IAPB) launched a plan called ‘VISION 2020 The Right to Sight’. IAPB is a coalition of many organisations involved in eye care, such as non-governmental organisations, eye care institutions and corporations, all of which are therefore involved in VISION 2020. The aim of VISION 2020 is to eliminate avoidable blindness, as a public health problem, by the year 2020 (as well as being the year 2020, it is also a reference to the assessment of vision, in feet rather than metres; 20/20 which is the same as 6/6 in metres, is ‘normal’ vision). The philosophy of VISION 2020 is that all people have the right to a basic level of healthcare, and this includes the right to sight and not to lose vision from treatable diseases. Therefore, the ultimate goal is that everyone has access to high-quality eye care that is part of a sustainable health system. VISION 2020 hopes to achieve this by providing guidance, support and advocacy for eye care. A summary of the original 1999 action plan is shown in Box 1.2 and described in more detail in the following pages.9
VISION 2020 Action Plan 2006–2011
The VISION 2020 plan was updated in 2006. This plan was based on the same three core principles in Box 1.2, but highlighted the importance of the following ideas:
  • Effective and efficient comprehensive eye health-care needs to be integrated into well-managed national health systems.
  • Human resource, infrastructure and technology must be scaled up in numbers and coverage.
  • Additional activities that must be undertaken:
    • Advocacy and public relations
    • Information
    • Education and communication
    • Community participation.
VISION 2020, where are we now?
As we get closer to the year 2020, it is clear that the ambitious target of eliminating all avoidable blindness by 2020 will not be met. Worldwide, there are now thought to be 39 million blind people and 246 with low vision. In 1999, the estimated figures were 38 million blind and 110 million with low vision. There are probably several reasons for this apparent increase:
  • The ageing population of the world: almost all the commonest causes of visual impairment become increasingly common with age. As the life 10expectancy is increasing in most countries, there will be more visually impaired people.
  • More complete and accurate surveys of eye disease: VISION 2020 has made visual loss a much more prominent issue, and therefore, many more surveys have been conducted. Therefore, the current figures are probably more accurate than the 1999 figures, which are likely to have been an underestimate.
  • New cases: for some eye diseases, the number of cases being treated is little more than the number of new cases going blind, and therefore the overall number does not decrease.
Has VISION 2020 failed? The answer is of course a resounding ‘no’, as VISION 2020 has been responsible for raising the profile of visual loss, for treating many millions of people and for raising money for eye care and eye research. However, the original target of eliminating avoidable blindness by 2020 will not be achieved and there is still an enormous amount to be done.
Integrating eye care into general health services: Universal Eye Health
One of the possible shortcomings of the original VISION 2020 plan was its emphasis on eliminating certain specific diseases. A strategy that focuses on particular diseases is sometimes called a ‘vertical’ plan. In recent years, there has been increased emphasis on seeing eye care as part of general health care services. This is sometimes called a ‘horizontal’ health plan because it covers all aspects of health care.
The aim is still to prevent and treat avoidable blindness, but the method is more through improving eye services as part of the general health care system. The most recent WHO resolution is called ‘Towards Universal Eye Health: A Global Action Plan, 2014–2019’. This WHO resolution, which has been endorsed by the World Health Assembly has the more realistic target for 2019 of aiming to reduce avoidable visual impairment by 25% from the 2010 levels. This plan has several principles, approaches and objectives, which are slightly different from the original 2020 approach. The major ones are:
  1. Integrating eye care services into health care systems at all levels (primary, secondary and tertiary), i.e. a horizontal approach.
  2. A goal of providing good access to rehabilitation services for the visually impaired. Providing rehabilitation services is almost impossible in a ‘vertical’ campaign and individual disease based approach to eye care, but can and should be achieved if patients are receiving eye care in an integrated health system.
  3. Generating more evidence about visual impairment, i.e. the scale of the problem, the causes of visual impairment and what eye care services are available. This evidence can be used to push for greater political and financial commitments.
  4. Addressing the global trend towards more chronic eye diseases related to ageing, which will become an increasingly large proportion of the causes of visual impairment.
  5. The Global Action Plan specifically states that research is important and needs to be funded, because this is how new and more cost-effective 11treatments are developed. Operational research is particularly useful for determining if treatment is actually reaching the people who need it. For example, one trachoma study found that although many hundreds of surgeons had been trained and equipped to do surgery, the majority were doing few or even no trachoma surgeries.
However, in the end, a ‘plan’ is only as good as the commitment and determination of us the eye care workers to put it into action.
‘Links’ refers to partnerships between an eye department in a poor country and one in a rich country. Health institutions in rich countries should not think about just their own population's needs and there are numerous reasons for being involved in the health needs of poor countries. ‘Links’ are an excellent way of joining the respective health systems and should be seen as an obligation rather than a luxury for the following reasons:
  • The ethical obligation: this is the most important reason. It is unacceptable for the wealthy nations to ignore the terrible healthcare provisions of a large proportion of the world's population and the needless visual loss that occurs throughout the poor countries of the world. Never has the phrase ‘turning a blind eye’ been more appropriate.
  • The political obligation: poor countries are unstable and at much greater risk of civil war and extremism. Of course, we cannot prevent this, but assisting poor countries, with major needs such as healthcare and education, may help to create more stability.
  • The ‘brain-drain’ obligation: many doctors and nurses from poor countries emigrate to rich countries. The health systems of rich countries have become dependent on these health care professionals and have not even paid for training them. This has decimated the number working in poor countries, despite the enormous need there and the cost of training them.
  • The mutual benefit: these partnerships do not just benefit the institution in the poor country. It is of enormous value to individual health practitioners and the institutions they work in to see how healthcare is delivered in a poor country. There are some parts of healthcare that are done better in poor countries because of the enormous need. For example, it is normal to conduct 30 or more cataract operations in a day in some units in poor countries. In rich countries it can be a challenge to do more than 12.
  • Personal learning: many health workers from a rich country on seeing the advanced pathology and needless visual loss that patients suffer in poor countries, find their attitudes are changed. They become more humble and understanding and learn the importance of setting priorities.
  • Communicable diseases: the enormous migration around the world has facilitated the spread of diseases such as tuberculosis and ‘flu viruses’. There are big increases in the incidence of some of these diseases in rich 12countries. Treating and controlling them in the poor countries would minimise their spread.
The VISION 2020 LINKS programme is a UK programme that is designed to support the aims of Vision 2020 by setting up institution-to-institution partnerships, mainly in Africa. The programme is already seeing huge benefits to institutions and the people who work in them on both sides of the partnership. Informed partnerships have been established elsewhere in the world, but it hoped that other countries in the world will also set up more formalised partnerships.
The major worldwide causes of blindness can be divided into four groups:
  1. Easily preventable diseases.
  2. Easily treatable diseases.
  3. Less easily preventable and treatable diseases.
  4. Untreatable or unpreventable diseases.
VISION 2020 is targeting the first two groups, although the increase in the ageing population has brought about greatly increased focus on the eye diseases of older people, some of which are untreatable. VISION 2020 has also made it a priority to target childhood blindness, because although often more difficult to prevent or treat, it has an enormous impact on the rest of the child's life and the community they live in.
Easily preventable diseases
This group consists of three diseases which are almost exclusively found in poor countries and particularly, poor countries with hot climates. These diseases are: trachoma, xerophthalmia (vitamin A deficiency associated eye disease) and onchocerciasis. They are all easily preventable, but once blindness has occurred, treatment or restoration of vision is difficult or impossible. Onchocerciasis occurs in just a few areas. Trachoma and xerophthalmia are more widespread in poor countries, although with great variation in prevalence. In the places where they are more prevalent, they can be major causes of blindness. Blinding trachoma can be prevented by improvements in hygiene and living conditions, and blinding xerophthalmia can be prevented by improvements in nutrition.
To prevent blindness from each of these three diseases, there is now also a ‘magic bullet’ treatment. A ‘magic bullet’ is a treatment, which is very effective, needs to be given only once or very infrequently, and has very few side effects. These magic bullets are:
  • Trachoma: azithromycin, an antibiotic, which kills the Chlamydia bacteria which causes the disease.
  • Xerophthalmia: vitamin A capsules, which almost immediately eliminate vitamin A deficiency.
  • Onchocerciasis: ivermectin, a drug that kills filarial worms, which cause the disease.
Easily treatable diseases
Cataract and refractive error are found throughout the world. However, both of these conditions rarely cause severe visual impairment or blindness in rich countries but are by far the commonest causes of visual loss in poor countries where poor medical services simply cannot address the huge number of cases.
Refractive error
People with serious refractive errors need spectacles to see properly. Uncorrected refractive errors are a significant cause of visual impairment, and even ‘blindness’, in places where it is difficult to obtain spectacles. Refractive errors are particularly important because they usually develop in young children, and will therefore affect the education and development and therefore the entire future life of the child.
The surgical treatment of cataract and the cataract surgical rate
Cataracts are quickly and relatively cheaply eliminated with a surgical procedure. This procedure only needs to be done once for each patient. The results can be fantastic, but complications can also occur and the patient left with worse vision than before the operation. However, ‘new’ cataracts are continually developing in patients. This is illustrated in Figure 1.3. If more surgical procedures are being done than new cataracts developing, the number of people blind from cataracts will fall. But if more cataracts are developing than surgeries being conducted, the number of blind people will rise. The ‘cataract surgical rate’ (CSR) is the number of cataract surgeries performed per million people in the population. The CSR helps us to determine if the number of cataract surgeries being done is enough to keep up with new cataracts developing. For example, we know that when the CSR in rich countries was about 3500, surgical output kept up with new cases. However, there are issues that must be considered when targeting a particular CSR for a particular country:
  1. When there is an enormous backlog of cataract – as there is in most poor countries – a very high CSR needs to be aimed for initially to get through the backlog and then the CSR can drop to a level that keeps up with new cases.
  2. As cataract surgical technique and equipment have improved, patients and surgeons have desired cataract surgery at an earlier stage, i.e. when they are less visually impaired. Therefore, the CSR needs to rise unless these people are denied surgery, which practically and ethically is very difficult to do. Therefore, the CSR in rich countries has risen to approximately 5000 in recent years. If the CSR in a poor country is 3500, one might expect cataract blindness to be eliminated. However, it is possible and in fact likely that the less dense cataracts of richer people are being operated on, and poor people with dense, blinding cataracts are still struggling to receive surgery. This is probably the case in India where in the last 30 years the CSR has risen from 500 to approximately 5000, but many millions of poor people remain blind from cataract. Therefore, the CSR needs to be uniformly distributed throughout a 14country, so that there are not pockets of neglected blindness.
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    Figure 1.3: The size of the reservoir represents the number of people already blind with cataract (prevalence). The tap into the reservoir represents the extra number of people going blind each year from cataract (incidence). The taps out of the reservoir represent: (a) the people who have been successfully treated for cataract and recovered their sight, or (b) those who die of old age or disease while still blind.
    This requires an even distribution of well-trained surgeons, and the teams and infrastructure that they require. This is rarely seen in poor countries, where many more eye surgeons are found in major cities.
  3. A high CSR is only of benefit if the outcomes of cataract surgery are good. If there is a high level of complications, the vision of patients who are receiving cataract surgery will not improve and the number of visually impaired people will not reduce as expected.
  4. The world's population is ageing. Therefore, the number of people with cataract is ever-increasing and the CSR must continue to increase with this.
As a result of these problems with the provision of cataract surgery, the prevalence of visually impaired people with cataract has remained fairly static, unlike the other WHO priority diseases, trachoma, xerophthalmia and onchocerciasis which have shown dramatic improvements in recent years.
Non-ophthalmologist cataract surgeons
Many African countries have 1 or less ophthalmologists per million people in the population. In these countries, it is entirely appropriate to train people who are not doctors to do cataract surgery, because otherwise many millions of people will continue to be needlessly blind. A good example of this is the Gambia, a small country in West Africa where the training of cataract 15surgeons who are not doctors is actively encouraged. The Gambia is also the only country in West Africa which is beginning to meet its target of eradicating cataract blindness. The surgical outcomes of well-trained high output nurse cataract surgeons are just as good as that of ophthalmologists. However, like all surgeons, their practice must continue to be periodically supervised and audited by others as well as auditing their own work.
Less easily preventable and treatable diseases
The most important of these are glaucoma, diabetic retinopathy and wet macular degeneration. They are all found throughout the world and in all communities. These are major causes of avoidable blindness but have not been given the same high priority in the VISION 2020 programme because blindness from these causes cannot be prevented quite so easily and they do not cause as much visual loss as cataract and refractive error in poor countries, where the life expectancy is shorter.
About 6 million people are blind from glaucoma. Glaucoma is a disease that causes irreversible damage to the optic nerve (see Chapter 15). However, if the disease is detected in an early stage, surgical or medical treatment may be given to prevent blindness from developing.
Diabetic retinopathy
Diabetic retinopathy is the ophthalmic complication that commonly occurs with diabetes. Once the patient has gone blind, it is not possible to recover the vision. However, if the changes on the retina are detected at an early stage, education and interventions aimed at improving diabetic control as well as laser treatments for the eye can prevent the disease progressing, and even reverse some of the changes if done early enough. There has been an enormous increase in the number of diabetics worldwide, particularly in South Asia, probably because of dietary changes and increased life expectancy in this region. Therefore, diabetic retinopathy has become much more common. Unfortunately, patients need regular examinations to detect retinopathy, as well as good education and then lasers and possibly surgery for treatment. All of these are expensive and inaccessible for much of the world's population.
Age-related macular degeneration (AMD)
Until the last 10 years, AMD has been untreatable. However, the development of anti-vasoendothelial growth factor drugs, which are injected into the eye, has enabled one type – ‘wet’ – of AMD to be treated. The more common ‘dry’ type remains untreatable. The treatment does not reverse the damage, but can stop it progressing, and often needs to be repeated many times. The technology needed to assess the retina before and after treatment, as well as the regular eye examinations and the treatment itself, are unfortunately too expensive for most of the world's population.
Blindness from both glaucoma and diabetic retinopathy can be prevented, but requires screening and surveillance so that they can be detected at an early stage before there has been serious visual loss. Treating wet AMD requires urgent assessment and assessment as soon as the patient develops symptoms in order to be of benefit. Patients may go blind from these 16conditions even in rich countries. Blindness is much more likely in poor countries because of the lack of screening in primary health care and the lack of medical services in general and the lack of resources even when the diseases are detected.
Diseases that cannot be prevented or treated
There are numerous eye diseases that currently cannot be prevented or treated. The most important among these are degenerative and vascular retinal conditions, in particular dry AMD, and retinal vein and artery blockages, which are both relatively common in older people. There are also numerous inherited and congenital diseases of the retina, optic nerve and cornea, such as retinitis pigmentosa, hereditary optic atrophy and corneal dystrophies. Fortunately most of these are rare, but they usually occur in children or young adults and therefore will cause a whole life of visual loss. These diseases that cannot be treated or prevented are the main causes of blindness in rich countries. They are present just as much in poor countries but their significance is less because they are outnumbered by the treatable and preventable causes of blindness. The VISION 2020 programme was not originally focussing on these conditions, but Universal Eye Health has included the very important goal of providing visual aids and assistance to visually impaired people (see above).
Visual loss has enormous effects on home life, social life and working life. It is impossible to accurately calculate the true cost of this for the individual visually impaired person, their community and their country. However, it is clear that the ‘cost’ is enormous. A study in Australia highlighted some of the factors associated with visual loss that are particularly expensive:
Costs that affect rich and poor countries
  • Loss of earnings
  • The cost of people giving care to those with visual loss, and the loss of earnings of the caregivers
  • The personal and emotional cost of suffering and premature death that is associated with visual impairment
  • The medical costs of treating eye disease. For some diseases, the later the disease is detected and treated, the more expensive and less effective the treatment is
Costs that affect mainly rich countries
  • The cost of low vision aids and equipment and home modifications.
  • Welfare payments and taxation benefits.
There are several ways of estimating the precise economic benefits of treating eye disease, which are beyond the scope of this book. However, it is absolutely clear that the treatment of preventable eye disease, and particularly cataract and refractive error, which is relatively cheap and very effective, provides enormous economic benefits to the person, their community and their country. Cataract surgery is undoubtedly the single most cost-effective operation in the world.17
There is an enormous shortage of ophthalmic care workers in poor countries. This limits the potential to roll out even the most carefully designed and run eye-care programmes. Human resource development involves training people to prevent and treat blinding diseases and also supporting them in their work once they are trained. The precise type of workers needed varies with each country, but typically they are:
  • Ophthalmologists: doctors who have specialised in eye care and eye surgery. There are far too few in almost all poor areas of poor countries. Therefore, they may provide complex treatment and surgery and help run programmes, but cannot provide the huge amount of day-to-day care that is required in the community.
  • Optometrists and dispensing opticians: these practitioners have been trained to assess refractive error and dispense appropriate spectacles. The burden of refractive error is huge, and therefore optometrists or eye care workers who have a basic training in this skill are crucial. Optometrists must also know how to detect the early signs of diseases such as glaucoma, diabetic retinopathy and cataract.
  • Ophthalmic nurses and nurses with eye care training: although different countries have nurses with different levels of eye care training, in principle the bulk of eye care can and often is done by nurses. At one end of the spectrum some very specialised ophthalmic nurses are trained to perform cataract surgery and do this to a very high level, while at the other end of the spectrum, general nurses can be trained in some basic eye care and diagnostic skills, e.g. in treating trachomatous infection.
  • Orthoptists: these practitioners have been trained to assess and treat squints and other defects of binocular vision and eye movements. Many of their patients are children, and they are therefore often skilled in measuring visual acuity in children. There are very few specialised orthoptists in most poor countries.
  • Community healthcare workers: many countries train members of the community in specific tasks, e.g. dispensing vitamin A capsules and promotion of face washing and hygiene for trachoma control. These members of the community are a critical part of eye care and often provide a huge amount of eye care at a fraction of the cost of more highly trained professionals. Examples of these workers are health extension workers in Ethiopia, community distributors in onchocerciasis programmes and ‘friends of the eyes’ in The Gambia.
  • Traditional healers: many communities in poor countries have minimal or no access to ‘conventional’ eye care workers. They are dependent on the traditional healers who have been practising long before VISION 2020 and other health plans. They are discussed in more detail on page 24.
  • Managers: despite not being trained as eye care workers, managers are a critical part of an effective and efficient health system. Clinics, 18hospitals and treatment campaigns do not run themselves, and require efficient managers or people delegated with this role. Without them, trained doctors and nurses may be sitting around without the correct equipment, or without the patients being directed to them; a sight seen far too often in poor countries.
The specific set-up of a country or a region's eye care health service will depend on their needs and resources. However, the fundamental principles are that the service should be able to assess and treat as many people as possible, as economically as possible and with an ultimately sustainable service that is part of a universal healthcare system. A critical requirement is that the many people involved in providing healthcare work together as a team. The management of most serious eye diseases of poor countries requires people with many different skills and training, all of whom depend on each other to do their job carefully and thoroughly.
As discussed above, many blinding eye diseases that are common in poor countries are best managed with prevention rather than treatment. These include xerophthalmia, trachoma and onchocerciasis. Other diseases, such as diabetic retinopathy and glaucoma must be detected early in the community through community eye health programmes and then referred for treatment. Therefore, prevention and community health must play a major part in any eye care programme.
There are basic differences between the practice of clinical medicine and preventive medicine. In clinical medicine, the patient visits a health practitioner because they are sick (or concerned that they are sick). The doctor responds to the needs of the patient by trying to treat them and help them get better. Clinical medicine might be described as ‘reactive’, because the patient initiates the process and the health practitioner reacts to this.
In preventive medicine, the medical profession takes the initiative and institutes measures in the community in order to make them healthy or prevent disease. Programmes of vaccination, clean water supply or insect vector control are prime examples. Community health could be described as ‘proactive’. The medical profession makes the first move and the community then makes a response. Curative medicine is almost always less cost effective than preventive medicine, because in curative medicine individual patients are treated, which is time-consuming and expensive, but for preventive medicine, whole communities can be treated, e.g. with clean water or health education. Unfortunately however, most government health spending is directed towards curative rather than preventive medicine and most health practitioners’ time is spent on curative treatment. In poor countries particularly, there are few doctors. These doctors are often so busy treating patients in the big cities, that there is little interest in preventive medicine or community health, especially in rural areas.19
Curative medicine attracts health practitioners for several reasons:
  • Health practitioners get instant satisfaction from treating patients and making them better. For example, the results of a successful cataract operation are very rewarding, whereas preventive medicine is much more long-term and does not bring the thanks and joy of an individual patient.
  • Health practitioners gain status in the community for providing treatment. However, the practitioners who plan and institute preventive medicine campaigns are rarely known by the community, despite saving the sight and even lives of enormous numbers of people.
  • Treating patients gives financial rewards; individual patients will pay a lot of money to clinicians who are able to cure disease. Preventive medicine does not usually give great financial rewards.
Preventive medicine can seem much less attractive than curative medicine. The clinical work is often repetitive and boring, and administration takes up a lot of time. However, there is far more potential to make a major difference to the prevalence of blindness in a community.
Many people think that preventive medicine is the concern of governments and NGOs, and that individuals can do little or nothing to prevent disease. It is true that large preventive medicine campaigns require the involvement of health departments and/or NGOs. However, the individual medical worker can do a lot to help prevent some of the major causes of blindness. For example:
  • Trachoma is a disease of poor hygiene, and health workers can teach and encourage good hygiene.
  • Xerophthalmia is a disease of poor nutrition, and health workers can help to improve nutrition. They can also encourage measles vaccination schemes, which are an important way to prevent blindness from xerophthalmia.
  • A good health practitioner can detect glaucoma or diabetic retinopathy early in the community before it has caused irreversible visual loss.
Health education
Health education forms a vital part of community health. Much eye disease and blindness is caused by poor hygiene or nutrition, or is related to the lifestyle of the community. The only real and lasting solution to these problems will come from within the community itself when people become aware of the importance of good nutrition and hygiene, and healthy living. Health education presents a very different sort of challenge – to win the confidence of communities and their leaders and persuade them to alter some of their traditional customs and ways of life. Health education is most effective when the stimulus for change comes from within the community itself rather than from outside it, i.e. when they understand the importance of the intervention for their own health and well-being. The key concept of health education is ‘ownership’. If the community feels that the health service in some way belongs to them and is for them and they have some part in being responsible for it, then they are much more likely to use it properly, and to respond to suggestions from health care professionals.
20Hospitals, clinics and schools are traditionally used as places for health education. However, nowadays, much more imaginative ways of disseminating health education are being used, such as religious and cultural meetings and events, radio, television and newspapers and even mobile vans that stop in villages and perform educational theatre performances. An example of an increasingly successful health education message is ‘clean faces’ for trachoma control. It is now completely normal for children in the most rural villages to be cleaning their faces, from a newly installed water pump that has been provided in conjunction with the education. Whatever way the education is provided, it must be remembered that the closer any health worker is to the community the more effective they are likely to be. They are likely to be trusted to and listened to and they can repeat their message again and again, as is often required. Unfortunately, it is all too easy for a doctor or even a nurse to be seen as a superior and unapproachable person who dispenses injections and medicines and performs operations and leaves the rural community after just a short time.
This is the third main aim of the VISION 2020 plan; the aim is to provide universal coverage and access to eye care services that are required to prevent and treat visual loss. This requires suitably located primary, secondary and tertiary units for eye care. The infrastructure of eye care must have both a hospital base and a community base which support each other. The community health worker can identify and send the right patients to hospital for treatment. High quality, successful hospital treatment will then encourage and strengthen the acceptance of the community health worker within the community and encourage more patients to attend. There is little point in having lots of teaching hospital eye units in which complex surgery can be done, but no-one to dispense vitamin A capsules in the community and similarly there is little value in having lots of community screeners who can detect cataract, but no operating theatre in the region where cataract extraction surgery can be done. Infrastructure also includes some less obvious components, e.g. providing transport for people to reach eye units, or places for them to stay if they come for trachoma or cataract surgery. Infrastructure goes hand in hand with the human resources development discussed above, as sparkling new clinics and operating theatres are useless without health-care professionals to work in them.
Mobile services: campaigns and outreach surgery
The infrastructure may also require the use of mobile eye care provision. This can take the form of specifically organised campaigns or outreach activity that comes from a larger clinic or health centre. It can be advantageous to take the service closer to the patient for several reasons:
  • Some patients are unable to travel to the permanent clinic because of infirmity, illness, transport costs, lack of an accompanying person 21or responsibilities that they cannot leave such as childcare. Women particularly are often less able to access more distant healthcare.
  • Providing intensive treatment can help to get the best use out of limited staff and resources, as it can allow a large number of people coming for treatment in a short period of time.
There are numerous examples of the success of taking the treatment to the community, e.g. the uptake of trachoma surgery is much higher if the surgery is taken to the villages than when it is done in health centres and hospitals. Similarly mass vaccinations or vitamin A supplement campaigns reach many more people when they are taken to the community. The vertical campaign model of healthcare is often not sustainable. However, outreach that is organised in a pre-existing health centre or hospital and uses the local staff, can be extremely effective, entirely sustainable and still fit within the ‘normal health system’.
Eye care requires specific and sometimes expensive equipment. Good eye care planning and services depend on the appropriate equipment being supplied, serviced and kept up-to-date. This equipment needs to be of high quality, but affordable and durable. In a community clinic, torches, log books and simple stationary may be enough for some screening programmes, while in a hospital surgical equipment and even lasers may be required. Health care and medical treatment is becoming more and more sophisticated and technologically advanced. This is particularly true in ophthalmology where there have been major advances in technology in three particular areas:
  • Lasers: many different lasers are used in ophthalmology. They are now used extensively to treat retinal disease, glaucoma, after cataract surgery and in corneal surgery.
  • Microsurgery: since the widespread usage of the operating microscope and fibre optic illumination, intraocular surgery is now performed with much finer instruments and through small incisions. The equipment required for cataract and retinal surgery has changed dramatically, particularly if the phacoemulsification cataract extraction procedure is used, which uses a complicated, expensive machine that requires regular maintenance.
  • Diagnostic techniques: the diagnosis of eye conditions has been revolutionised by new equipment, such as automated visual field screening for glaucoma, ocular coherence tomography for macular degeneration and diabetic macular disease, ultrasonography for intra-ocular disease and computerised tomography (CT) scanning and magnetic resonance imaging (MRI) for assessing the orbit, optic nerve and brain.
Unfortunately, all this technology is very expensive and even rich countries are finding that they must put cash limits on health care.
There is a difficult and sometimes insoluble balance to be found between the needs of individual patients and doctors, who want the very best and most modern equipment; and the cost of running a whole health system, which 22needs to provide care and preventive measures to as many people as possible. Apart from the cost, modern equipment has other disadvantages:
  • It requires servicing, which can usually only be done by a specialist technician, who often works for the company that made or installed the equipment. Servicing is expensive and often difficult to access.
  • Machines that break down are usually difficult to repair.
  • Some machines require a lot of skill and training to use and then interpret the results.
  • It is often doctors who are trained to do this, and therefore lots of modern equipment is very ‘doctor intensive’.
Ophthalmologists are like all professional people, they want to be up-to-date with the most recent techniques and have the most modern equipment. However, this can make them ‘blind’ to the real needs of the community. Although this does happen in rich countries, it is a much bigger problem in poor countries where there is a huge gap between sophisticated care that is available in the big cities and the lack of access to care of many poor patients in rural areas.
Fortunately in some poor countries, low cost, high quality technology is being developed and produced locally. Perhaps the best example of this is intraocular lenses used during cataract surgery. Until recently, these were only made in factories in the Western World and were very expensive and therefore not accessible to the average citizen of a poor country. They are now made in factories in developing countries, where they cost a fraction of those made in the rich countries and are of similar quality. This has had the further benefit of forcing ‘Western’ manufacturers to reduce their prices. Other examples are eye drops and ointment which can be made in a small hospital pharmacy for a fraction of their commercial price.
Any programme of health care must be cost effective to be of value to poor people. Reducing the cost while maintaining the quality is one of the biggest challenges of health care in poor countries. People often think that cheap medical care is bad medical care. There are indeed a few techniques which need expensive equipment and take a long time to perform. However, most eye problems can be treated simply, quickly and effectively using relatively unsophisticated equipment. It should be possible to provide an eye care service that even the poorest people can afford. Indeed, all the major causes of preventable world blindness, with the exception of diabetic retinopathy, are either treatable or preventable at very reasonable cost. Often the biggest challenge and greatest expense of healthcare in poor countries is not the cost of the actual treatment, but the cost of providing a nationwide service and reaching people in remote, rural areas.
There are now many excellent hospitals in the world which are outstanding examples of how to provide reasonable quality services at much reduced costs. There are various models of hospitals and programmes that are providing cost-effective care. Although each model is different they all seem to follow the same principles:23
  • They see large numbers of patients which lowers the unit cost for each patient, so that the more work that is done, the cheaper it becomes.
  • They are not run for profit, and patients who can pay little or nothing are not discriminated against or turned away.
  • All patients receive the same treatment. Some hospitals and clinics use a ‘cost recovery’ system in which patients who can afford to pay for some or all of their treatment, do pay. Although they receive the same treatment as other non-paying patients, they may receive some benefits such as better accommodation. Some units can be completely financially self-sufficient with this system.
  • The cost of hospital equipment and medication has been greatly reduced by manufacturers based in poor countries, in particular, India and China.
In rich countries, there is a fairly similar pattern of eye disease throughout the country. There may be some racial differences but overall the blindness rates are fairly similar. However, in poor countries there may be quite marked differences in diseases between one area and another. The following are some examples of this:
  • Trachoma is common all over the tropics. However, it is much more severe and disabling in dry, desert areas with many flies, than in the tropical rain forests. Some poor countries are almost free of trachoma, while others are seriously affected.
  • Xerophthalmia and corneal ulcers in children varies widely depending on the local dietary habits and intake and even customs like how early babies are weaned.
  • Onchocerciasis used to be very common in the Savannah Belt of West Africa with many people blind but was much less common in the coastal areas. Much of this has changed, thanks to the onchocerciasis control program, but there are still pockets of active disease, causing blindness throughout Africa.
Because eye diseases can vary so much from area to area, any plans for treatment and prevention must be carefully planned and flexible. For example, in xerophthalmia causing corneal ulceration and blindness in young children, it may be appropriate to solve this problem by nutritional advice in one area, adding vitamin A to the food in another and measles vaccination in yet another.
When a patient is visually impaired or blind and no treatment is possible, many health practitioners feel that this is the end of their responsibility and there is little more they can do. However, for the patient it means the beginning of a new and very difficult period in their life and they need all the help, support and encouragement that are available. With appropriate support and low vision aids, a severely visually impaired person can have a full working, home and social life. But without these, they can easily become a recluse. It is a responsibility of the health practitioner who sees the blind 24or visually impaired patient, to help them access any support that is available to them. Most countries have some sort of low vision and rehabilitation for blind or visually impaired people. These are usually run by appropriately trained staff. In rich countries, these services are usually very effective and allow the patient to get vision aids, improvements in their home, and social security benefits. However in poor countries there are many more blind people, a great shortage of trained rehabilitation care workers and of equipment for aiding people with sight loss.
There are three words with a slightly different meaning that are used to describe people who have difficulty in seeing well: visual impairment, disability and handicap.
  • Visual impairment refers to the actual loss of vision that has happened to the patient.
  • Disability refers to what a person is unable to do because they are visually impaired.
  • Handicap is the personal, social and economic loss that comes because of the disability.
The purpose of rehabilitation is to help the patient to come to terms with their visual impairment, and to try to overcome and prevent as much as possible the disability and handicap.
Examples of aids and support for people with visual impairment
The United Nations has listed five principles in the care and rehabilitation of disabled people: independence, participation (in society), care, self-fulfilment and dignity. The following are a few examples of what can be done to help people with visual impairment to achieve these goals:
  • Visual aids and magnifiers that can help make the best use of the patient's limited vision.
  • Training in particular occupations or activities that may help the person become economically self-sufficient and may help them to be busy and engage with other people.
  • Mobility training can help people to move around with confidence, and training in skills for living can increase their independence. Without this, one blind person sometimes means that two people are unable to be productive, if the blind person requires someone else in the family to lead him around and look after him.
  • Special education can be given to children, even in a normal school. If blind children are educated, they can be expected to continue on to university.
  • Social activities can help a blind person to feel valued rather than a helpless outcast.
In all communities there are people who treat and attempt to heal patients by traditional methods. There are many different types of traditional healing, such as the use of herbs, homeopathy, or acupuncture or in some cases 25spiritual methods such as divination. There are also traditional methods of surgery, in particular, the operation of couching for cataract, or other techniques like applying cautery to the skin. Those of us trained in orthodox ‘western’ medicine tend to be dismissive of these alternative healers. If we have seen children's eyes destroyed by some toxic medication given for conjunctivitis or someone blinded after couching for cataract, we will probably feel both totally opposed to these methods and superior to the traditional healers, with some justification. Modern orthodox medicine is rightly proud of its rigorous training and scientific method. However, we need to look realistically at the whole situation.
  • Traditional and alternative medical practice is carried out throughout the world including in rich countries, where there are many alternative types of healers. Many patients throughout the world therefore have great faith in traditional healers. For some traditional healers, their main motive may be to extract money from their patients. However, there are many more who have a genuine concern to help, and may feel a sense of vocation in their work. Remember, there are also quite a lot of orthodox medical practitioners whose main motive is also to extract money from their patients.
  • The methods and principles used by different traditional healers are very varied. They range from barbaric and unsafe procedures, to innocuous but harmless procedures, to safe, sensible practices that may be better than anything that is locally available, particularly in places with no or very poor ‘Western’ medical services.
  • Some traditional healers also dispense conventional ‘Western’ medicine. For example, there are many healers who sensibly use chloramphenicol ointment for conjunctivitis. Develop a good relationship with the local healer as early as possible and do not to ignore or oppose them. One example was when a doctor befriended some traditional healers, and gained their interest by showing them a cataract operation. He then tactfully explained to them what damage could happen to the eyes of young children, and then supplied them with unlabelled bottles of chloramphenicol drops to use instead of toxic herbs in sick children with bad eyes.
  • There is often religious and spiritual significance to disease, particularly in Africa. Although some people may disapprove of this, it is very important to patients in many cultures.
  • Most traditional medical practitioners are much closer to the community than the orthodox medical professionals, and they are much more readily available. For example, in India there are many homeopathic and Ayurveda practitioners in the villages and small towns, but doctors are usually only to be found in larger towns and cities. In Africa, the traditional healer is often the only source of any ‘treatment’ for many people. Furthermore they are usually very well respected in their communities, probably more so than visiting Western practitioners or those working a long way away. It is therefore very important to work with traditional healers and not against them or in competition with them.
  • 26The only way of definitively overcoming the bad practices of the traditional healer is to provide an alternative service. It is therefore important to focus energy on providing a good, safe and available service in poor countries and not on fighting the traditional healers.
  • Currently orthodox medicine has many failings and complications, and it must be acknowledged it too is far from perfect.
Increasingly, health workers have tried to encourage communication and co-operation with traditional healers rather than condemnation. One way has been to invite traditional healers into hospitals or clinics or even into operating theatres. The foundation for co-operation is mutual respect. Where this has occurred there have been opportunities to learn from traditional healers how local people think of disease and how they react to it. There have also been opportunities to teach traditional healers some of the ideas of modern medicine. Where there has been good co-operation, some traditional healers are happy to refer patients when the problem is beyond them, for instance a blind patient with cataract.
The ‘traditional’ treatment for cataract, couching, must be discouraged because the results are usually so bad and ‘Western’ cataract surgery has such successful outcomes. However, couching only persists in areas where modern medicine has been unable to deliver cataract surgery.
This chapter is all about generalisations and ideas. It is important to finish by considering the individual blind person and his personal needs. The late founder of the International Agency for the Prevention of Blindness, Sir John Wilson, who was himself blind, said of blindness, ‘Only in statistics do people go blind by the millions. Each person goes blind by himself.’ Each unnecessarily blind person brings suffering and deprivation to himself or herself and their family. In addition, there is the frustration of being useless and totally dependent on others. It is harder being blind in those parts of the world where there is no education, rehabilitation or social welfare for blind people.
Those of us who care for blind people need to know what it is like to feel their limitations. One eye doctor who runs a training course for ophthalmic medical assistants in Africa makes half the students spend a day wearing blindfolds so as to experience being blind, and the other half to learn how to look after these ‘blind’ people. The next day, the roles are reversed. Several years ago, patients with certain diseases were treated with eye-pads applied to both eyes and strict bed-rest. Most doctors who tried it for themselves stopped recommending it for their patients, when they realised how unpleasant it was. To go blind may involve more than just loss of quality of life. It often involves loss of actual life itself. Most children who go blind from xerophthalmia do not live long, and it is probable that elderly people who go blind die sooner than those who can see. Occasionally, such patients can have their sight restored with surgery. A patient who has been blind for a year or so is delighted to receive their sight back, but interestingly those who have been blind most 27of their life often struggle more, often becoming confused and disturbed by the busy world of visual stimuli and some wish they had never had their sight back.
People who have been blind for many years usually adapt to it, and strengthen their other senses. They usually do so with great aptitude and dignity and it is our responsibility as health practitioners to treat them as people and not just as patients.28