For 40 years, diseases and surgery
of the cornea and ocular surface have been a major interest
of Eye Health's corneal specialist, Kenneth R. Kenyon, MD.
Beginning with a cornea transplant, the first operation
he ever witnessed as a medical student, Kenyon has remained
devoted to the development of this increasingly important
sub-specialty. As Director of the Cornea Service of the
Mass. Eye & Ear Infirmary and Associate Professor of
Ophthalmology at Harvard Medical School for 12 years prior
to joining Eye Health in 1990, he devised, taught and published
many of the surgical techniques in this area that are practiced
today world-wide. The cornea is the transparent "window"
of the eye that permits light to enter the pupil and to focus
on the retina to produce clear vision. Normally crystal clear
and dome-shaped (like a contact lens), it can become cloudy
or misshapen as a consequence of injury, disease or surgical
complications, thereby greatly reducing vision.
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| Following severe
ocular injury, the cornea is scarred by extensive
corneal laceration (note sutures), there is extensive
iris tissue loss, and the ruptured lens has a milky
white cataract. |
Following corneal
transplant plus extensive reconstruction of the iris
and cataract removal by Dr. Kenyon, the same eye attains
nearly full restoration of vision and appearance. |
The good news is that cornea transplantation (termed
keratoplasty) using human donor corneas are the most successful
of organ transplants, enjoying a 95% favorable prognosis
in most cases. Thanks to the world's best network of eye
banks, in the USA approximately 40,000 cornea transplants
are performed annually on an elective (i.e. scheduled)
basis.
Only the central portion of the cornea is involved in transplantation.
The surgeon removes a circular disc of the patient's cornea
and replaces it with a similarly sized disc of donor cornea,
which is then secured with microscopically fine sutures
that are 1/10th the diameter of a human hair. Despite the
precision involved, this surgery is performed on an ambulatory
outpatient basis and in straightforward cases requires only
30 minutes to complete. In eyes with more substantial abnormalities
of the iris and lens, Dr. Kenyon has devised techniques
to combine cornea transplants with cataract removal, intraocular
lens implantation or exchange, and repair of damage to the
iris and pupil. Sutures are removed or adjusted to reduce
astigmatism on an individual basis. Thus glasses or contact
lens will generally not be prescribed until the transplant
has become stable and healed, usually after 3 months.
Apart from the cornea, the other tissues comprising the
ocular surface, specifically the conjunctiva (a transparent
membrane covering the white of the eye or sclera) and the
limbus (immediately adjacent to the cornea and the source
of vital stem cells) are also subject to disease or injury.
Starting in 1978, Dr. Kenyon devised the surgical technique
of conjunctival autograft for treatment of localized conjunctival
diseases such as the pterygium (an inflammation of the conjunctiva
extending on to the cornea which commonly affects fisherman,
construction workers and others exposed to sun & wind),
thereby improving the prognosis for cure from 50% to 95%.
This surgery has become the technique used universally for
treating such disorders. Beginning in 1984, Kenyon then
developed the limbus autograft predominantly for eyes that
had sustained diffuse ocular surface damage such as by chemical
burn. This technique of stem cell transplantation (Figure
2) has also been widely adopted during the past two decades
and has improved the success of subsequent corneal transplant
in such eyes from 50% to 90%. More recently, operating at
the Greater New Bedford Surgicenter, Dr. Kenyon has adapted
the technique of amnion membrane transplantation for use
in conjunction with corneal transplants to treat eyes with
loss of corneal sensation following infection or injury,
and has also greatly improved the prognosis for these so-called
high-risk keratoplasties. Kenyon's pioneering efforts have
been recently recognized in The New York Times and The New
England Journal of Medicine, as well as by noted North Dartmouth
author, Ann Parson in her recent book about stem cells, "The
Proteus Effect" (Joseph Henry Press, 2004).
At Eye Health's Center for Cornea & Ocular Surface
Disease, patients are referred both regionally and internationally
for evaluation and management. Hundreds of cornea transplants
and other ocular surface surgeries have been performed routinely
by Dr. Kenyon at the Greater New Bedford Surgicenter with
excellent outcomes. As a result, such patients no longer
have to be referred to Boston for performance of these sight-restoring
procedures. |