Home' Trinidad and Tobago Guardian : October 25th 2013 Contents 8
The "eyes are the mirror to the soul"
and the cornea is the window through
which we reach it. Good vision requires a
Age, disease, surgery or trauma may
cause it to lose its clarity. About 5% of the
world's blindness is caused by corneal dis-
ease of which approximately 95% can re-
gain their sight with a corneal transplant.
WHAT IS THE CORNEA?
In observing the normal eye, one first sees the
coloured part or the iris of the eye that contains a
central dark opening, the pupil. The iris is inside
the eye and seen through the crystal-clear watch
glass covering of the front of the eye -- the
cornea. The cornea does not readily come to your
attention because it is transparent. It transmits
light to the interior of the eye allowing us to see
clearly. Corneal injury and diseases can cause dis-
tortion, clouding and scarring. This blocks the
clear passage of light to the back of the eye, re-
ducing sight sometimes even to the point of
WHAT CAN CAUSE CORNEAL
SCARRING AND LOSS OF CLARITY?
Knives, pencils and other sharp objects like
glass from a windshield can cause severe injury to
the cornea. Fireworks, exploding batteries and
toxic chemicals, especially alkalis, can also result
in severe scarring of the cornea.
Most corneal injuries are preventable with pro-
tective glasses, proper precautions when dealing
with hazardous substances and playing sports
e.g. Squash; and wearing seatbelts when travel-
ling in motor vehicles
Infections can cause severe damage, ulceration
Abnormal steepening of the cornea (kerato-
conus), degeneration occasionally following
cataract surgery (corneal oedema or swelling),
and some aging processes can also affect) the
health of the cornea.
Some disorders of the cornea are inherited, and
can lead to corneal clouding and loss of sight.
WHAT IS A CORNEAL
If the cornea becomes cloudy or scarred, sight
may be restored by replacing or transplanting the
cornea. A circular piece of diseased cornea, a little
less than one centimetre in diameter, is removed
and replaced by healthy donor cornea of similar
Although Kidney, heart and liver transplants
are currently the centre of attention, corneal
transplantation (keratoplasty) is the oldest and
most successful of all tissue transplants. The first
Corneal transplant was done in 1905. The success
rate depends on the cause of the clouding of the
cornea, transplants for degeneration following
cataract surgery and those for keratoconus both
have high success rates, whilst corneal transplant
for chemical burns have lower success rates be-
cause of complicating factors involved.
HOW ARE CORNEAL
Corneal tissue for transplant comes from an
eye bank. The process begins at the death of
someone who has been generous enough to be
an eye donor; a most humanitarian act.
Blood tests are carried out by the eye bank to
detect infections such as AIDS, Hepatitis B and C,
and Syphilis. Corneas from patients with infec-
tious diseases are not used for transplantation.
The eye bank also examines the donated cornea
for its suitability for grafting.
The operation lasts about 1 hour and may be
done under local anaesthesia or under general
anaesthesia. It consists of a transfer of the clear
central part of the cornea from the donor's eye to
the patient's eye. The donor cornea is sutured in
place with very fine sutures.
WHAT HAPPENS AFTER
Return of best vision after corneal transplant
surgery may take up to a year after the operation,
depending on the rate of healing and the health of
the rest of the eye.
As in any kind of transplant, rejection of the
donated tissue can take place. Rejection occurs in
about 19% of all cases and is due to your body
recognizing the donor cornea as "foreign". Signs
of rejection may be minor irritation, redness, wa-
tering or worsening of vision. If these occur,
prompt return to your Ophthalmologist is essen-
tial even if it is years after the original operation.
About of rejections if caught early can be
stopped with medication.
Other complications include infection, glau-
coma, astigmatism, cataract and return of the
IN TRINIDAD & TOBAGO
Successful corneal transplant surgery was first
done in Trinidad over forty years ago. We depend
on the availability of corneal tissue from foreign
eye banks abroad. However the demand for this
kind of surgery has increased markedly over the
years and it is often very difficult to acquire
It is estimated that about 36 corneal trans-
plants are done in Trinidad each year. This num-
ber is below the need and will be improved by the
establishment of an eye bank locally.
At Medical Associates:
All modern techniques of Full thickness
and partial thickness corneal transplants are
practiced by our Eye Surgeons.
Normal cornea (right)
Keratoconus (Astigmatic cornea left)
Cataract is a treatable cause of vision im-
pairment and Cataract does not lead to perma-
What are cataracts?
A cataract is present when there is opacifica-
tion, clouding, darkening and hardening of the
The lens is a major part of the focusing mech-
anism of the eye. The normal lens is transparent
and focuses clear, sharp images onto the retina
at the back of the eye so that we can see objects
As the lens becomes increasingly cloudy, vi-
sion gets blurred. This is a slow process and usu-
ally goes unnoticed in the early stages.
Symptoms of Cataracts
Early signs of cataracts include blurred or
cloudy vision, glare sensitivity, distortion and col-
ors appear faded. An Ophthalmologist must de-
termine if these symptoms are caused by a
cataract or by some other eye problem or dis-
Causes of Cataracts:
AGEING: Most cataracts are a result of the
ageing of the lens.
CONGENITAL: Some are congenital being
present at birth or developing in childhood.
Secondary cataracts are caused by inflamma-
tory disease of the eye and some medications
like the use of steroids.
TRAUMA: Direct injury to the eye may result
in the development of a traumatic cataract.
Treatment of Cataracts:
If the disturbance in vision from cataract inter-
feres with your lifestyle or makes it difficult to
continue normally enjoyable activities - the
cataract may need to be removed. Surgery is the
only way to remove a cataract. If surgery is not
done, your vision gradually gets worse.
Generally, there is no such thing as a cataract
being "ripe" or "not ripe" for removal. Surgery is
recommended if the problem interferes with vi-
sion. A rare situation develops if cataracts are
not treated early and they become advanced or
"hyper-mature". They may then cause the eye
pressure to increase or inflammation of the eye.
The cataract must then be removed immediately.
Otherwise, removal of a cataract is at the pa-
It is advisable to avoid undue delays in
cataract surgery when one is diabetic or has
glaucoma. In the presence of diabetic eye dis-
ease, the presence of cataract will interfere with
the Ophthalmologist's ability to monitor and
treat retinopathy. Many patients realize better
control of their glaucoma following removal of
As of now, the only treatment for cataract is
surgery. In a cataract operation, the cloudy lens is
removed and replaced by an artificial
lens (intraocular lens implant or IOL,
also referred to as an implant). Our
surgeons first used artificial lenses in
Cataract surgery is the most fre-
quently performed surgery around
the world -- and the most successful.
Over 95 percent of those who have
cataract surgery regain vision levels
between 20/40 and 20/20.
Before surgery, the surgeon or his
trained technician, will do measure-
ments on the eye (biometry) to de-
termine the lens (IOL) best suited for
the eye on which surgery will be done.
Biometry was first introduced into
cataract surgery at Medical Associ-
ates in 1988.
Most cataract surgery is done under local or
topical anaesthesia with the patient being awake
but lightly sedated.
Cataract surgery will not correct vision loss
due to glaucoma, diabetes, or age-related macu-
lar degeneration. Many people will need to wear
glasses or contact lens after cataract surgery, at
least part of the time, for either near and/or dis-
tance vision and/or to correct astigmatism.
Methods of removing
Generally there are two
approaches to cataract
1. Extra Capsular Cataract
The choice depends on
the surgeon and the hard-
ness of the cataract. Phacoemulsification allows
for surgery using a small incision that does not
require sutures (stitches). PECE was introduced
at Medical Associates (St. Joseph) in 1996 and is
the most modern approach to cataract surgery.
There is no Laser in regular clinical practice for
Dr. Deo-Singh operates on patient.
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