Ординатура / Офтальмология / Английские материалы / Comprehensive Ophthalmology_Khurana_2007

Telecanthus

Narrowed interpupillary distance

Esotropia (35% cases)

High refractive errors

Cataract

Iris hypoplasia

Keratoconus

Ocular abnormalities in chromosomal deletion syndromes

Cri-du-Chat syndrome (5p.)

Hypertelorism

Epicanthus

Antimongoloid slant

Strabisums

Cri-du-Chat syndrome (11 p.)

Aniridia

Glaucoma

Foveal hypoplasia

Nystagmus

Ptosis

Cri-du-Chat syndrome (13 q.)

Retinoblastoma

Hypertelorism

Microphthalmos

Epicanthus

Ptosis

Coloboma

Cataract

De Grouchy syndrome (18q.)

Hypertelorism

Epicanthus

Ptosis

Strabismus

Myopia

Glaucoma

Microphthalmos (with or without cyst)

Coloboma

Optic atrophy

Corneal opacity

Turner syndrome (XO)

Antimongoloid slant

Epicanthus

Ptosis

Strabismus

Blue sclera

Eccentric pupils

Cataract

Colour blindness

Pigmentary disturbances of fundus

ADVERSE OCULAR EFFECTS OF

COMMON SYSTEMIC DRUGS

C.V.S. drugs

Digitalis: Disturbance of colour vision, scotomas

Quinidine: Optic neuritis (rare)

Thiazides: Xanthopsia (yellow vision), Myopia

Carbonic anhydrase inhibitors: Ocular hypotony, Transient myopia

Amiodarone: Corneal deposits

Oxprenolol: Photophobia, Ocular irritation

G.I.T. drugs

Anticholinergic agents: Risk of angle-closure glaucoma due to mydriasis, Blurring of vision due to cycloplegia (Occasional).

C.N.S. drugs

Barbiturates: Extraocular muscle palsies with diplopia, Ptosis, Cortical blindness

Chloral hydrate: Diplopia, Ptosis, Miosis

Phenothiazines: Deposits of pigment in conjunctiva, cornea, lens and retina, Oculogyric crisis

Amphetamines: Widening of palpebral fissure, Dilatation of pupil, Paralysis of ciliary muscle with loss of accommodation

Monoamine oxidase inhibitors: Nystagmus, Extraocular muscle palsies, Optic atrophy

Tricyclic agents: Pupillary dilatation (glaucoma risk), Cycloplegia

Phenytoin: Nystagmus, Diplopia, Ptosis, Slightblurring of vision (rare)

Neostigmine: Nystagmus, Miosis

Morphine: Miosis

Haloperidol: Capsular cataract

Lithium carbonate: Exophthalmos, Oculogyric crisis

Diazepam: Nystagmus.

Hormones

Female sex hormones

Retinal artery thrombosis

Retinal vein thrombosis

Papilloedema

Ocular palsies with diplopia

Nystagmus

Optic neuritis and atrophy

Retinal vasculitis

Scotomas

Migraine

Mydriasis

Cyloplegia

Macular oedema

Corticosteroids

Cataract (posterior subcapsular)

Local immune suppression causing susceptibility to viral (herpes simplex), bacterial and fungal infections

Steroid-induced glaucoma

Antibiotics

Chloramphenicol: Optic neuritis and optic atrophy

Streptomycin: Optic neuritis

Tetracycline: Pseudotumour cerebri, Transient myopia

Antimalarial

Chloroquine

Macular changes (Bull’s eye maculopathy)

Central scotomas

Pigmentary degeneration of the retina

Chloroquine keratopathy

Ocular palsies

Ptosis

Electroretinographic depression

Amoebicides

Diiodohydroxy quinoline: Subacute myelo optic neuropathy (SMON), optic atrophy

Chemotherapeutic agents

Sulfonamides: Stevens-Johnson syndrome

Ethambutol: Optic neuritis and atrophy

Isoniazid: Optic neuritis and optic atrophy

Heavy metals

Gold salts: Deposits in the cornea and conjunctiva

Lead: Optic atrophy, Papilloedema, Ocular palsies

Chelating agents

Penicillamine: Ocular pemphigoid, Ocular neuritis, Ocular myasthenia

Oral hypoglycemic agents

Chloropropamide: Transient change in refractive error, Diplopia, Stevens-Johnson syndrome

Vitamins

Vitamin A

Papilloedema

Retinal haemorrhages

Loss of eyebrows and eyelashes

Nystagmus

Diplopia and blurring of vision

Vitamin D

Band-shaped keratopathy

Antirheumatic agents

Salicylates: Nystagmus, Retinal haemorrhages, Cortical blindness (rare)

Indomethacin: Corneal deposits

Phenylbutazone: Retinal haemorrhages

INTRODUCTION

BLINDNESS AND ITS CAUSES

Definition of blindness

Magnitute of blindness

Global blindness

Blindness in India

Causes of blindness

Global blindness

Blindness in India

Developing versus developed countries

GLOBAL INITIATIVES FOR PREVENTION OF BLINDNESS

Global programme for prevention of blindness

Vision 2020: Right to Sight

Vision for the future (VFTF)

NATIONAL PROGRAMME FOR CONTROL OF BLINDNESS IN INDIA

Objectives

Plan of action and activities

Basic programme components

Programme organization

Strategic plan for Vision 2020: Right to Sight in India

Role of eye camps in prevention of blindness

Eye banking

Rehabilitation of the blind

In recent years, community ophthalmology has developed as an important branch of community medicine. Its activities emphasize the prevention of ocular diseases and visual impairment; reduction of ocular disability; and promotion of ocular health, quality of life and efficiency of a group of people at the community level. Thus, it can be defined as a system (rather than a branch of community medicine) which utilises the full scope of ophthalmic knowledge and skill, methodology of public health and services of other medical and non-medical agencies to promote ocular health and prevent blindness at the community level with an active, recognised and crucial role of community participation.

The concept of community ophthalmology has become more relevant and essential to achieve the goal of ‘Vision 2020: The Right to Sight’ and to, accomplish the theme behind ‘Vision for the Future (VFTF)’.

DEFINITION OF BLINDNESS

Different definitions and terms for blindness such as total blindness, economic blindness, legal blindness and social blindness are in vogue in different countries so much so that 65 definitions of blindness are listed in a WHO publication (1966).1 In ophthalmology, the term blindness strictly refers to the inability to perceive light (PL absent).

WHO definition of blindness. In order to have comparable national and international statistics, the WHO in 1972 proposed a uniform criterion and defined blindness as, “Visual acuity of less than 3/60 (Snellen) or its equivalent”.2 In order to facilitate the screening of visual acuity by non-specialised persons, in the absence of appropriate vision charts, the WHO in 1979 added the “Inability to count fingers in day-light at a distance of 3 metres” to indicate vision less than 3/60 or its equivalent.3

Visual filed less than 10º, irrespective of the level of visual acuity in also labelled as blindness (WHO,

19774).

Other definitions of blindness in vogue are:

Economic blindness: vision in better eye <6/60 to 3/60

Social blindness: Vision in better eye <3/60 to 1/ 60

Legal blindness: Vision in better eye <1/60 to perception light

Total blindness: No light perception (PL -ve).

Categories of visual impairment. In the Ninth Revision (1977) of the International Classification of Diseases (ICD), the visual impairment (maximum vision less than 6/18 Snellen) has been divided into 5 categories. Categories 1 and 2 constitute “low vision” and categories 3, 4 and 5 constitute “blindness” (Table 20.1). Patients with the visual fields between 5° and 10° are placed in category 3 and those with less than 5° in category 4.

Table 20.1. Categories of visual impairment

(WHO, 1977)4

Avoidable blindness. The concept of avoidable blindness includes both preventable blindness and curable blindness.

Preventable blindness is that which can be easily prevented by attacking the causative factor at an appropriate time. For example, corneal blindness due to vitamin A deficiency and trachoma can be prevented by timely measures.

Curable blindness is that in which vision can be restored by timely intervention. For example, cataract blindness can be cured by surgical treatment.

MAGNITUDE OF BLINDNESS

Magnitude of global blindness

The number of blinds across the globe is not within the exact realms of counts. However, from time to time, the World Health Organization (WHO) provides the estimates. At present, WHO estimated:

180 million people worldwide are visually disabled of whom nearly 45 million are blind.

About 80% of blindness is avoidable, i.e., either curable or potentially preventable.

About 32% of the world’s blind people are in the age bracket of 45-59 years but a big majority i.e.,

about 58% are over 60 years of age.5

Geographial distribution of global blindness. About 90% of the world’s blinds live in developing countries and around 60% of them reside in sub-SaharanAfrica, China and India. There is a significant difference in the level of blindness in the developing as compared to the developed countries of the world, as there are:

3 blind people/1000 population in developed countries of Europe, America and Japan,

9 blind people /1000 population in Asia, and

12 blind people /1000 population in Africa.

Regional burden of blindness. For having an easy means of comparison among different regions of the world, a ratio referred to as the Regional Burden of Blindness (RBB) was evolved. This means the ratio of the proportion of the number of blind in a particular region to the global number of blind and the proportion of the regional population to the world population. The sub-Saharan Africa, India and other Asia and Islands have RBB ratio greater than unity 6. This indicates that in these regions, the burden of blindness is to be taken into special consideration in terms of fixing priorities on a global scale.

Magnitude of blindness in India

While the problem of blindness is global, its magnitude is much higher in India. Of the estimated 45 million, India alone has 8.9 million blind people, (2001-2002 survey, NPCB), which comes to about onefifth of the total in the world. The prevalence of blindness in India, as determined by the three major surveys conducted in the last 3 decades is as below:

Factors for higher prevalence of blindness in India are:

1.Gross inadequacy of ophthalmic personnel.

2.Lack of availability of services near the homes of the people and the problem of communication.

3.Under-utilisation of available manpower.

4.Rural/urban imbalance in availability of services.

5.Lack of knowledge and concern, malnutrition, lack of eyecare, superstitions and ignorance.

6.Prevalence of infections.

7.Man-made blindness due to quack practice and home remedies.

CAUSES OF BLINDNESS

Causes of global blindness

Major causes of blindness and the estimated number of blinds due to them are as under5:

Causes of blindness in India

The problem of blindness in India is not only of its gigantic size, but also of its causes, which are largely preventable or curable with the present available knowledge and skill. Three major population based surveys have been carried out in India to estimate the magnitude and causes of blindness. These surveys have shown that trends in blindness

continue to change, though the major causes of blindness still continue to be the same (Table 20.2).7,8,9

Developed countries versus developing countries

The main causes of blindness in developed countries are different from those of developing countries.

In developed countries, 50 percent of all blindness is because of age related macular degeneration (ARMD), while another 10-20 percent each is because of glaucoma, diabetic retinopathy and cataract.

In developing countries the frequent causes are cataract, infectious diseases, xerophthalmia, injuries, glaucoma, and onchocerciasis.

GLOBAL INITIATIVES FOR

PREVENTION OF BLINDNESS

The concept of avoidable blindness (i.e., preventable or curable) has gained increasing recognition during the last three decades. Inter-national Agency for the Prevention of Blindness (IAPB) formed in 1974, is an inter-national non-governmental agency which has a close and complementary relationship with WHO (an international inter-governmental agency in the field of prevention of blindness).

The major global initiatives taken for prevention of blindness are:

Global programme for prevention of blindness.

Vision 2020: The Right to Sight, and

Vision for the future (VFTF).

GLOBAL PROGRAMME FOR CONTROL OF BLINDNESS

The WHO launched a global programme for prevention of blindness in 1978. In accordence with which many countries have already come up with a ‘National Blindness Control Programme’.

Control strategies suggested by WHO include:

1.Assessment of common blinding disorders at local, regional and national levels.

2.Establishment of national level programmes for control of blindness suited to the national and local needs.

3.Training of eye care providers.

4.Operational research to improve and apply appropriate technology.

VISION 2020: THE RIGHT TO SIGHT

‘Vision 2020: The Right to Sight’,10 is a global initiative launched by WHO in Geneva on Feb. 18,1999 in a broad coalition with a ‘Task Force of International Non-Governmental Organisations (NGOs)’ to combat the gigantic problem of blindness in the world.

Partners of Vision 2020: Right to Sight include:

I.World Health Organisation (WHO),

II.Task Force of International NGOs, which has following members:

International Agency for Prevention of Blindness (IAPB)

Christopher Blindness Mission (CBM)

Helen Keller International

ORBIS International

Sight Savers International

Al Noor Foundation

International Federation of Ophthalmological Societies

Lions Clubs International Foundation

Operation Eye Sight Universal

The Carter Centre

Objective of vision 2020. Objective of this new global initiative is to eliminate avoidable blindness by the year 2020 and to reduce the global burden of blindness which currently affects an estimated 45 million people worldwide.

Implementation of vision 2020. Vision 2020 will be implemented through four phases of five year plans, the first one started in 2000 and second in 2005. The two subsequent phases of implementation will commence from 2010 and 2015, respectively.

STRATEGIC APPROACHES: GLOBAL PROSPECTIVE

Strategic approaches of Vision 2020: Right to Sight (Global prospective) are:

Disease prevention and control,

Training of eye health personnel,

Strengthening of existing eye care infrastructure,

Use of appropriate and affordable technology, and

Mobilization of resources.

Disease prevention and control

Globally, WHO has identified five major blinding eye conditions, for immediate attention to achieve the goals of Vision 2020, which are:

Cataract

Childhood blindness,

Trachoma,

Refractive errors and low vision, and

Onchocerciasis.

These conditions have been chosen on the basis

of their contribution to the burden of blindness, feasibility and affordability of interventions to control them. Each country will decide on its priorities based on the magnitude of specific blinding conditions in that country.

Cataract

Cataract remains the single largest cause of blindness. There is an estimated figure of 19 million people worldwide who are blind because of curable cataract. Aim under ‘Vision 2020’ is to eliminate avoidable blindness due to cataract, i.e., to decrease the number of cataract blinds in the world from 19 million to zero by the year 2020.

Strategy to achieve the aim is to increase the cataract surgery rate (CSR), i.e., number of cataract surgeries per million population per year as below:

Emphasis is to be placed on achieving:

High success rates in terms of restored vision and quality-of-life outcome.

Affordable and accessible services

Measures to overcome barriers and increased use of services.

Childhood blindness

Childhood blindness is considered a priority area due to the number of years of blindness that ensues. Prevalence is 0.5-1 per 1000 children aged 0-15 years. There are 1.5 million blind children estimated in the world of whom 1 million live in Asia and 3 lakhs in Africa. There are 5 lakh children going blind each year (one per minute) also.

Causes of childhood blindness vary from place to place and change over time. The main causes include: Vitamin A deficiency, measles, conjunctivitis, ophthalmia neonatorum, congenital cataract and retinopathy of prematurity (ROP).

Aim is to eliminate avoidable causes of childhood blindness by the year 2020.

Strategies and activitis under the global initiative vision 2020 include:

I.Elimination of preventable blindness by:

Measles immunisation,

Vitamin A supplementation (see page 436),

Monitoring use of oxygen in the premature new born,

Avoidance of harmful traditional practices,

Promoting school screening programmes for diagnosis and management of common conditions like refractive errors and trachoma in endemic areas, and

Promoting eye health education in schools. II. Management of surgically avoidable causes of

childhood blindness such as cataract, glaucoma, and retinopathy of prematurity (ROP).

Trachoma blindness

Trachoma is a leading cause of preventable blindness worldwide with an estimated 5.9 million persons blind or at immediate risk because of trichiasis.10 The disease accounts for nearly one-sixth of the global burden of blindness. In India, blindness due to trachoma (0.39%, WHO-NPCB 1986-89) is on the decline when compared with previous figures (20%, ICMR 1975).

Effective interventions have been demonstrated in developing nations using the SAFE strategy:

Surgery to correct lid deformity and prevent blindness,

Antibiotics for acute infections and community control,

Facial hygiene, and

Environmental change including improved access to water and sanitation and health

education.

Elimination of blindness due to trachoma is considered feasible, eradication of trachoma is not. Trachoma has disappeared from North America and Europe because of improved socio-economic conditions and hygiene. Research needs include validation of rapid community assessment techniques, identification of barriers to the acceptance of preventive surgical procedure, studying effectiveness of annual treatment cycles and costeffective studies. W.H.O. has organized an Alliance for Global Elimination of Trachoma by the year 2020 (GET2020).

Refractive errors and low vision

Aim is to eliminate visual impairment (visual acuity less than 6/18) and blindness due to refractive errors or other causes of low vision. It is estimated that there are 35 million people in the world who require low vision care.

Strategies recomended under ‘Vision 2020’initiative include:

Screening to identify individuals with poor vision which can be improved by spectacles or other optical devices.

Refraction services to be made available to individuals identified with significant refractive errors.

Ensure optical services to provide affordable spectacles for individuals with significant refractive errors.

Low vision services and low vision aids to be provided for all those in need.

Onchocerciasis

Onchocerciasis (river blindness) is known to be endemic in 37 countries.An estimated 17 million people are infected with onchocerciasis. Approximately 0.3- 0.6 million people are blind from the disease. About 95% of infected persons reside in Africa, where the disease is most severe along the major rivers in 30 countries. Outside Africa, the disease occurs in Mexico, Guatemala, Ecuador, Columbia, Venezuela and Brazil in the America, and in Yemen in Asia.

Aim is to eliminate blindness due to onchocerciasis by the year 2020.

Target is to develop ‘National Onchocerciasis Control Programme’ with satisfactory coverage in all the 37 countries where disease is endemic.

Strategy is to introduce community directed treatment with annual doses of Mectizan (ivermectin). The disease in expected to be brought under control by the year 2010, if present efforts in endemic countries are successfully implemented.

STRATEGIC PLAN FOR ‘VISION 2020’: THE RIGHT TO SIGHT IN INDIA

It is described under National Programme for Control of Blindness in India (page 451).

VISION FOR THE FUTURE (VFTF)

Vision for the future (VFTF): International Ophthalmology Strategic Plan to Preserve and Restore Vision11, launched in Feb 2001, is another global initiative (in addition to Vision 2020) for prevention of blindness.

Implementation of this program is being done by International Council of Ophthalmology (ICO) by working closely with other international, supranational and national organizations. It is parallel to and complementary of ‘Vision 2020’. Care is being taken to avoid duplication.

Top priorties for action of this programme are:

Enhancement of ophthalmology residency training around the world, particularly through definition of principles, guidelines and curricula.

Development of model guidelines and recommendations for ophthalmic clinical care in critical disease areas.

Dissemination of sample curricula for training of medical students and allied health personnel.

Advocacy and support for ‘Vision 2020: Right to Sight’, particularly by encouraging national ophthalmologic societies to support the initiative and become involved.

Helping national ophthalmologic societies develop more effective organizations.

NATIONAL PROGRAMME FOR CONTROL OF BLINDNESS (NPCB) IN INDIA

India was the first country in the world to launch the ‘National Programme for Control of Blindness (NPCB)’ in the year 1976 as 100 percent centrally sponsored programme which incorporated the earlier trachoma control programme started in the year 1963 and vitamin A prophylaxis programme launched in 1970.

OBJECTIVES

In 1976, the NPCB was launched with following goals:

To provide comprehensive eye care facilities for primary, secondary and tertiary levels of eye health care.

To reduce the prevalence of blindness in population from 1.38% (ICMR 971-74) to 0.31 by

2000 AD.

The programme got a major flip drug 1994-2001 when World Bank assisted “Cataract Blindness Control Project” was launched to reduce the cataract back-log in 7 States which were identified to have the highest prevalence of cataract blindness by WHONPCB survey (1986-89). These, in descending order, are: Uttar Pradesh, Tamil Nadu, Madhya Pradesh, Maharashtra, Andhra Pradesh, Rajasthan and Orissa.

However, the latest survey conducted between 2001 and 2002 has estimated a prevalence of 1.1% in the general population, indicating just a marginal reduction in the prevalence of blindness.

Recently, government of India has adopted ‘Vision 2020: Right to Sight’ under National Programme for Control of Blindness. The initiative ‘Vision 2020’has been launched with the objective to eliminate avoidable blindness by the year 2020.

PLAN OF ACTION AND ACTIVITIES

The plan of action and activities of ‘National Programme for Control of Blindness (NPCB) in India can be described under three headings:

Basic programme components,

Programme organization, and

Strategic plan for ‘Vision 2020: Right to Sight’ in India.

BASIC PROGRAMME COMPONENTS

The basic components of NPCB since its inception includes the following 12:

Extension of eye care services.

Establishment of permanent infrastructure.

Intensification of eye health education.

A. Extension of eye care services

It is being done through the state and district mobile units by adopting an ‘eye camp approach’ and by enlisting the participation of voluntary organisations. The following facilities are being provided in remote areas:

1.Medical and surgical treatment for the prevention and control of common eye diseases. Eye camp approach is of great help in reducing the backlog of cataract by mass surgeries. Recent emphasis is on reach-in-approach.

2.Detection and correction of refractive errors.

3.Thorough ocular examination including vision of school children for early detection of eye diseases and promoting ocular health.

4.Rehabilitation training of visually handicapped.

5.General survey for prevalence of various eye diseases.

B. Establishment of permanent infrastructure

The ultimate goal of NPCB is to establish permanent infrastructure to provide eye care services. It is being done in three-tier system i.e., peripheral, intermediate and central level.

1. Establishment of peripheral sector for primary eye care. The concept of primary eye care is one of

the most significant developments in the field of eye health care over the last few years. A wide range of eye conditions can be treated/prevented at the grassroot level by locally-trained primary health workers who are the first to make contact with the community.

Peripheral sector for primary eye care at PHC and subcentre levels is being strengthened by:

Providing necessary equipment,

Posting a paramedical ophthalmic assistant, and

Organising refresher courses for doctors and other staff of PHC on prevention of blindness. By the year 2002, 5033 PHCs had been

strengthened.

Community ophthalmic practice at primary care level is summarized in Table 20.3.

2.Establishment of intermediate sector for ‘secondary eye care’. Secondary eye care involves definitive management of common blinding conditions such as cataract, glaucoma, trichiasis, entropion and ocular trauma.

The intermediate sector for secondary eye care is being strengthened by development of diagnostic and treatment facilities at district and subdivisional levels under the charge of an eye specialist.

3.Establishment of central level for ‘tertiary eye care’. Tertiary eye care services include the sophisticated eye care such as retinal detachment surgery, laser treatment for various retinal and other ocular disorders, corneal grafting and other complex forms of management not available in secondary eye care centres.

The central level for tertiary eye care services and development of manpower is being strengthened by