Eye Diseases in Hot Climates

John Sandford-Smith

• Publisher: Elsevier
• Year: 2014
• Print ISBN:
  9780723623038
• eBook ISBN:
  9781483103983
• Edition: 2
• Topic: Medicina
• Subtopic: Medicina interna y diagnóstico

Eye Diseases in Hot Climates, Second Edition covers common eye diseases, particularly those that cause blindness and can be treated or prevented. The book starts by describing the basic anatomy and physiology of the eye. The text then discusses clinical methods of eye examination, with focus on prevention; the principles of treatment; disorders of the eyelids and the lacrimal apparatus; and the diseases of the conjunctiva and the psychological causes and diagnosis of conjunctivitis. The symptoms, classification, epidemiology, diagnosis, and treatment and prevention of trachoma are also discussed. The book tackles patterns of corneal disease; the signs, symptoms, epidemiology, and prevention/treatment of vitamin A deficiency in the eye; and diseases of the uvea, lens, retina, optic nerve and visual pathways. The diagnosis and treatment of glaucoma, onchocerciasis and loiasis, leprosy of the eye, squint, orbital diseases, and eye injuries, as well as the diagnosis of common eye conditions are also described. The book will be useful to ophthalmic specialists.

1

Introduction

Publisher Summary

The diseases of hot climates are traditionally called tropical diseases, although some hot countries are not exactly in the tropics. These diseases can be influenced directly by the heat or can be spread by insect or other carriers found in hot climates. The eye is an external organ and so it is particularly affected by the environment. Therefore, poor hygiene, poor nutrition, the climate, and insect vectors all significantly affect both the amount and the type of eye disease in the community. There are some causes of blindness that can be neither prevented nor treated. These are usually degenerative and vascular diseases of the retina in old people and congenital abnormalities in children. These are the main causes of blindness in developed countries and are just as common in developing countries. This chapter describes four ways in which eye diseases in hot, tropical or developing countries differ from those in other countries—(1) eye disease and blindness is very common; (2) most of the blindness is either preventable or treatable; (3) pattern of eye disease can vary considerably from area to another; and (4) medical resources are usually inadequate. It also discusses the basic needs to take care of the eyes in hot countries. It is necessary to train more workers in eye care in developing countries. However, it is not at all obvious who are the right people to train and what are the right skills and knowledge for them to learn.

What is special about eye diseases in hot climates?

The diseases of hot climates have traditionally been called ‘tropical’ diseases, although some hot countries are not exactly in the tropics. These diseases may be influenced directly by the heat or may be spread by insect or other carriers found in hot climates.

A look at a world map will show that most hot countries are also poor countries, often called ‘developing’ countries nowadays. Poverty causes poor hygiene and poor nutrition and these are also important causes of disease.

The eye is an external organ and so it is particularly affected by the environment. Therefore poor hygiene and poor nutrition as well as the climate and insect vectors will all significantly affect both the amount and the type of eye disease in the community. Also poor countries have poor medical services and so diseases are often seen in an advanced or neglected state.

There are therefore several ways in which eye diseases in ‘hot’, ‘tropical’ or ‘developing’ countries differ from those in other countries. These will be described in more detail under the following four headings.

– Eye disease and blindness is very common.

– Most of this blindness is either preventable or treatable.

– The pattern of eye disease may vary considerably from area to another.

– The medical resources are usually inadequate.

1 Eye disease and blindness is very common

It is difficult to agree an exact definition of blindness and also difficult to get accurate statistics of how many people are blind. However according to reports, between 0.1% and 0.2% of the population in most developed countries are blind and, by comparison, in developing countries between 0.5% and 1% are blind. There are good reasons to believe that the difference between the two communities may be much greater than this.

– First, blindness is such a handicap in poor and rural communities that blind people have a much shorter life expectancy.

– Secondly, nearly all blind people in developed countries are old. For example, in England, three-quarters of the people registered as blind each year are over 70. However, developing countries with an expanding population of young people, and a shorter life expectancy, have far fewer old people.

– Thirdly, in most developed countries, there are good reasons for people to register as blind, e.g. Social Security benefits etc. In developing countries, however, there are economic and cultural reasons for people to hide their blindness. I once examined a young man who was totally blind. He asked me to write a note to explain his absence from work, and then said that he was a night watchman!

2 Most of the blindness is either preventable or treatable

There are some causes of blindness which can be neither prevented nor treated. These are usually degenerative and vascular diseases of the retina in old people and congenital abnormalities in children. These are the main causes of blindness in developed countries and are just as common in developing countries. However they are only a small fraction of all cases of blindness (Fig. 1.1).

Fig. 1.1 The typical pattern of blindness in hot climates.

The World Health Organisation (WHO) estimates that about 30 million people in the world are blind, 29 million of these living in developing countries. Most of this blindness is from one of the following five conditions which are all either treatable or preventable.

– Cataract. This is the cause of almost half of the world’s blindness¹ and is treatable.

– Trachoma. At least 5 million people are blind from trachoma and about 80 million children are thought to be in need of treatment.¹

– Malnutrition with xerophthalmia. In Asia alone it is estimated that 250000 children a year go blind from xerophthalmia. Many others are affected less severely.¹

– Onchocerciasis is only a problem in certain tropical areas. However, over 1 million people are thought to be blind from it.¹

– Glaucoma is a widespread and common cause of blindness.

3 The pattern of eye disease may vary considerably from one area to another

The following are 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.

– Xerophthalmia and corneal ulcers in children are caused by dietary deficiencies of vitamin A. However, there are many different factors which determine a child’s diet. In one area, the staple food may be deficient in vitamin A. In another area, it may be the custom to wean children with foods deficient in vitamin A. In other areas, foods rich in vitamin A may be too expensive for poor people to buy.

– Measles is a much more important cause of corneal ulceration in Africa than in Asia.

– Cataract is common all over the world, but it seems to be more common in certain areas, especially the Indian sub-continent.

– Onchocerciasis is very rare on the coast of West Africa. A few hundred miles inland, however, there are areas where almost everyone suffers, and many are blind.

Because eye diseases can vary so much from area to area, any plans for treatment and prevention must be imaginative and flexible. To take the example of 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. In some areas, the pattern of disease does not fit the textbook pattern. This is especially difficult for a non-specialist...

Table of contents

• Cover image
• Title page
• Table of Contents
• Inside Front Cover
• Copyright
• Preface
• Instructions for the Reader
• Acknowledgements
• Chapter 1: Introduction
• Chapter 2: Basic Anatomy and Physiology of the Eye
• Chapter 3: Clinical Methods — History Taking and Eye Examination
• Chapter 4: Principles of Treatment
• Chapter 5: The Eyelids and the Lacrimal Apparatus
• Chapter 6: Diseases of the Conjunctiva
• Chapter 7: Trachoma
• Chapter 8: The Cornea
• Chapter 9: Nutritional Corneal Ulceration and Xerophthalmia
• Chapter 10: Diseases of the Uvea
• Chapter 11: Diseases of the Lens
• Chapter 12: Diseases of the Retina
• Chapter 13: Diseases of the Optic Nerve and Visual Pathways
• Chapter 14: Glaucoma
• Chapter 15: Onchocerciasis and Loiasis
• Chapter 16: Leprosy and the Eye
• Chapter 17: Squint
• Chapter 18: Orbital Diseases
• Chapter 19: Eye Injuries
• Chapter 20: Diagnosis of Common Eye Conditions
• Index