Ophthalmology Update - Cleveland Clinic

i n v e s t i g a t i O n s
Artificial Cornea Provides Hope for Sight in
Patients with No Alternatives
With advances in device design, surgical
technique and postoperative management,
keratoprosthesis implantation has become a
viable approach for attempting to restore
vision in eyes that are at high risk for corneal
transplantation.
Of the several types of keratoprostheses that are
commercially available, the Boston keratoprosthesis
developed by claes dohlman, m.d., ph.d., professor
emeritus of ophthalmology, harvard medical school,
is the most widely used in the United states. cole eye
institute corneal surgeon victor l. perez, m.d., completed
his fellowship training with dr. dohlman and
has been performing implantation of both the type i
and type ii Boston keratoprostheses at cole for 3
years. to date, he has treated six eyes, and the results
have been encouraging with respect to both safety
and visual rehabilitation.
“as my experience with these procedures increases,
so too has my level of comfort for using this approach
in appropriate candidates. now, the keratoprosthesis
has become an important part of my armamentarium
for trying to provide a clear window for vision in
patients with a history of multiple graft failures,”
dr. perez says.
One of the most satisfying cases undertaken so far
involved a russian radiologist who, while living in
that country, suffered corneal burns in both eyes as
a result of having lye thrown at his face. the patient
developed severe corneal melts and was treated
by a russian ophthalmologist with permanent
tarsorrhaphy.
he presented to dr. perez several years later, after
moving to the United states. an ultrasound study
revealed that the eyes were present in the orbit and
that the retinas were attached. therefore, dr. perez
proceeded to open the tarsorrhaphy in the right eye
for further evaluation, but was unable to find the
anterior segment.
“it was clear to me that the only intervention that
might help this man was to implant the type ii
Boston keratoprosthesis and attempt to provide
a tunnel for vision through the lid,” he says.
due to the excessive scar tissue present, the implantation
surgery was lengthy and challenging. however,
dr. perez was successful in implanting the type ii
keratoprosthesis and placed a glaucoma shunt as
well. he reports that the patient has done well postoperatively
and now has vision of 20/100.
“For the first time, this gentleman has been able to
see his grandchildren who were born after his accident,
and he is able to read again. so far so good as
far as safety is concerned as well, but we are proceeding
with very cautious optimism because these are
such complicated cases,” dr. perez says.
most of the Boston keratoprosthesis procedures performed
by dr. perez involved the type i device. in that
series of eyes, he has not encountered any significant
complications, such as corneal melt, device extrusion
or endophthalmitis. visual outcomes have been
limited by macular potential.
“these patients tend to have multiple ocular abnormalities
that limit their visual potential. at least,
however, the keratoprosthetic surgery provides
an opportunity to restore some functional vision,”
dr. perez says.
since retinal conditions are often present in patients
who come for keratoprosthesis surgery, a team
approach with an experienced retinal surgeon is also
important to optimize outcomes.
“We want to try to offer these patients the best
possible vision, and we are fortunate at the cole eye
institute to have talented retinal surgeons who can
collaborate in these procedures,” dr. perez says.
historically, success with keratoprosthetic surgery
has presented a difficult challenge. Biocompatibility
between the prosthetic device and the corneal tissue
and avoidance of device extrusion and corneal
melts have presented a major obstacle. however,
dr. dohlman made a significant contribution to
addressing those problems with his design of the
two-plate keratoprosthetic device that allows nutrients
from the anterior chamber to interface with the
cornea. recognizing that it was also important to
maintain a moist surface, dr. dohlman introduced
the idea of covering the eye with a bandage contact
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