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THE CORNEA
 | What Is The Cornea?
The cornea is the clear front window of the eye. It transmits light to the
interior of the eye allowing us to see clearly. Corneal injury, disease, or
hereditary conditions can cause clouding, distortion, and scarring. Corneal
clouding, much like frost on a glass windowpane, blocks the clear passage of
light to the back of the eye, reducing sight sometimes even to the point of
blindness. In addition, corneal injury and disease can be painful, sometimes
the most intense pain we can experience.
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| What Can Cause Corneal Injury?
Knives, pencils, and other sharp objects can cause severe injury to the
cornea. Fireworks, exploding batteries, and toxic chemicals, especially
alkalis, can also result in severe scarring of the cornea. In fact,
protection of the cornea is the reason emergency washing of the eye is
absolutely necessary when the eye is exposed to toxic chemicals. Most
corneal injuries are preventable with protective glasses and proper
precautions when dealing with hazardous substances.
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| What Causes Corneal Disease And Degeneration?
Infections, whether bacterial, fungal, or viral are frequent causes of
severe corneal damage and ulceration. Abnormal steepening of the cornea (
keratoconus ), degeneration occasionally following cataract surgery (corneal
edema or swelling), and some aging processes can also affect the clarity and
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 Transplant?
If the cornea becomes cloudy, the only way to restore sight is to
replace or transplant the cornea. Corneal transplantation (keratoplasty) is
the most successful of all tissue transplants. An estimated 15-20,000
corneal transplants are done each year in the United States. The success
rate depends on the cause of the clouding. For example, corneal transplants
for degeneration following cataract surgery and those for keratoconus both
have high success rates, while corneal transplants for chemical burns have
lower success rates. |
| How Are Corneal Transplants Done?
Corneal tissue for transplant comes from an eye bank. The process begins
at the death of someone who has been generous enough to be a donor. Names of
patients needing corneal transplants are placed on a waiting list until
tissue is available. The operation consists of a transfer of the clear
central part of the cornea from the donor's eye to the patient's eye. Soon
after the operation, the patient can walk about and resume activity. |
| What is a Corneal Abrasion?
A scratch on the front portion of the eye is called a corneal abrasion.
Most corneal abrasion injuries are due to a fingernail, paper, or foreign
body. Due to the extreme sensitivity of the cornea, a corneal abrasion can
be very painful, even when it is a minor
scratch. |
| How is a Corneal Abrasion Treated?
If something becomes lodged in the eye, it is imperative to seek medical
care immediately. With the use of fast-acting anesthetic drops, most small
foreign objects can be removed quickly and painlessly. Antibiotic drops are
usually applied to ward off infection. Other anti-inflammatory drops may be
used to keep you comfortable while the cornea heals. To protect the eye and
promote healing, the eye is usually patched. Patching takes the form of
either a eye pad or a bandage soft contact lens. Although patching may be
inconvenient, it helps to minimize movement of the eyelids, which would
interfere with the healing process. Corneal tissue heals rapidly.
Improvement is usually noticed within 24 hours. Patients must consult with
an ophthalmologist who can provide the appropriate level of care necessary.
If you wish to inquire about cataract services, please calfor a medical referral or to receive additional
information |
| EXTERNAL DISEASE AND CORNEA
External disease and cornea is a subspecialty which encompasses
congenital, inflammatory, allergic, degenerative, and neoplastic conditions
affecting the anterior aspect of the eye (including eyelids, conjunctiva,
cornea, iris, and lens). The clinic is equipped with the latest diagnostic
technology including computerized endothelial cell analysis, corneal
topographic mapping, ultrasonic pachymetry, a dedicated on-site
ophthalmicmicrobiology laboratory, and a wide range of photographic
equipment including computer enhanced analysis. It acts as a referral centre
for patients with complex medical problems, as well as those requiring
corneal surgery. Corneal transplantation can restore vision to patients
affected with corneal degenerations, dystrophies, trauma and following
corneal infections such as herpes which may leave a dense scar.
Keratorefractive surgery is currently one of the most controversial but
exciting topics in ophthalmology. The ability to correct myopia, hyperopia
and astigmatism with the Excimer laser has caught the enthusiasm of the
public and over five hundred thousand patients world-wide have already been
treated using these procedures. The Eye Institute was the first academic
centre in Canada to acquire an Excimer laser which is used for the
correction of refractive errors, removal of corneal scars and opacities and
research related to wound healing. Over 1000 patients have been treated and
are being followed. Although cataract surgery with insertion of a plastic (intraocular)
lens is one of the most common and successful surgical procedures performed
by ophthalmologists, subspecialists in cornea are frequently asked to handle
more complex cases requiring cataract extraction,corneal transplantation,
and reconstruction of the front of the eye. Research in external disease and
cornea is focused on the management and clinical outcome of refractive
errors treated with the Excimer laser, as well as laboratory studies of
basic wound healing following laser therapy. In addition, a number of
clinical trials are in progress to evaluate new antibiotics and
anti-inflammatory drugs. |
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