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A revolutionary new type of glasses know as
‘adaptive glasses’ invented by Professor Joshua Silver, could be the
solution for millions of people suffering from poor vision due to refractive
errors in developing countries. Over 1 billion people suffer from refractive
errors around the world, 10% of them being school children. Most cases occur in
developing countries; the inadequate number of opticians and poor transportation
systems make visiting an optometrist in some countries very difficult. In Ghana
for example, which has a population of almost 20 million, there are only 50
opticians, which means it would take about 200 years on average to visit an
optometrist.
The
glasses differ from conventional ones in that they depend on the regulation of
inflow of silicon oil into each lens; this alters the curvature and hence the
power of the lenses. Two knobs on either side of the frame, which are removed
and discarded after the wearer finds his optimum power, control the inflow of
oil. The process is similar in its optical function to that of the crystalline
lens of the eye. The power of the lenses varies from +6 to -6 Dioptres, and can
be used to correct the vision of over 90% of all people suffering from
refractive errors (long or near sighted). The adjustment of the lens curvature
takes less than one minute for both lenses.
Silver,
an atomic physicist at Oxford University in England, is selling 10 million pairs
of the adaptive glasses to Africa. One pair of spectacles is sold for £6 but
Silver expects the cost to go down with time. Ghana has already planned to buy
400,000 pairs and there is a deal in the works for an additional 9.3 million
pairs to be bought by South Africa.
The
new glasses are expected to have a positive effect on the outcome of Ghana’s
illiteracy eradication programme, which has not had the aspired results, in part
due to the fact that 74% of those in the programme were found to be in need of
glasses. The glasses can be used for an entire lifetime as their focus can be
adjusted as the eyes acuity (image sharpness) changes with age.
The
Right to Sight
Improving
the eyesight of the millions of disadvantaged people in developing countries has
become one of the goals of the World Health Organization (WHO) together with a
large number of international, nongovernmental and private organizations, which
have instigated a new global initiative called "Vision 2020: The right to
sight". The new initiative aims to eliminate avoidable blindness by the
year 2020.
According
to Dr. Gro Harlem Brundtland, the Director-General of WHO, “Blindness
represents a serious public health, social, and economic problem for our Member
States. It either results from the conditions that could have been prevented or
can be successfully treated with the sight restored" (WHO).
It
is estimated that there are around 180 million people who are visually disabled
around the world; 45 million of them are blind. Knowing that over 80% of all
cases of blindness are either preventable or curable and that 9 out of each ten
blind people in the world live in developing countries, gives us an
understanding of the importance of this new global initiative in the developing
world, for both humanitarian and socio-economic reasons.
Five
conditions have been given priority in the elimination of preventable blindness
initiative. These conditions are cataract, trachoma, onchocerciasis, childhood
blindness, and errors of refraction and low vision.
Cataract
(opacity of the lens) is the cause of 50% of cases of blindness around the
world. The number of cataract operations performed each year isn’t nearly
sufficient; this is especially true in developing countries. This can be seen if
we compare the number of cataract operations performed per million population /
year; in the USA the number approximates 5000 operations whilst in Africa the
number is closer to 200. According to the Journal of Community Eye Health, this
insufficiency has led to a backlog of around 20 million unoperated cases around
the world. In order to prevent the ensuing increase in the backlog in the
upcoming years, a major increase in the number of cataract operations performed
each year is essential.
Trachoma
is the major cause of blindness in the world. The disease is transmitted from
person to person through flies, dirty hands or towels. If left untreated, the
eyelids curve inward causing the eyelashes to scrape against the cornea, which
thus loses its transparency resulting in blindness. The disease is being
combated in endemic countries by a strategy known as ‘SAFE’ (Surgery,
Antibiotics, Facial Cleanliness and Environmental Hygiene). The goal of the
global initiative is to eliminate trachoma by the year 2020. 5 million
trichiasis operations (operation to correct the in-turned eyelid) are to be
performed between the years 2000 and 2010. 60 million cases of active
disease are to be treated during the same time period.
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Every
5 seconds one person in our world goes blind and a child goes blind
every minute. |
Onchocerciasis
is caused by an infection with the parasitic worm Onchocerca volvulus. The adult
female worms live in the subcutaneous tissues for up to 14 years. The females
lay millions of microfilaria (microscopic larvae), which migrate throughout the
body and may reach the eye causing a type of blindness known as ‘river
blindness’. The disease is endemic in 30 African and 6 Latin American
countries. There are around 270,000 cases of blindness caused by this disease
and 99% of them occur in Africa. 120 million people are at risk of contracting
the disease in endemic countries. A single annual dose of the drug
‘ivermectin’ is being used to bring this disease under control in affected
countries.
Childhood
blindness is caused mainly by vitamin A deficiency (xerophthalmia),
measles, conjunctivitis in the newborn, congenital cataract and retinopathy of
prematurity (Journal of Community Eye Health). Xerophthalmia affects around
350,000 children each year. The adequate supplementation, dietary changes or
fortification of foods with vitamin A has lead to swift progress in the
elimination of this disease. Most of the other causes of childhood blindness
require early detection and management that will require much effort.
Refractive
errors and low vision will be dealt with by promoting the manufacture of locally
produced low cost glasses and optical devices, and by the implementation of
refractive services in primary health care and school services.
The
global initiative to eliminate preventable blindness by 2020 is an important
step towards the improvement of both the socio-economic and developmental
situations in the developing world. The benefits to be gained will certainly
balance out the costs and effort needed to implement such a programme. Professor
Silver’s invention is a step in the right direction in the combat against poor
vision in developing countries.
Sources:
Aisha
El-Awady has a bachelor’s degree in medicine from Cairo University
and is currently working as instructor of Parasitology in the Faculty of
Medicine.
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