Issue: August
2003
at press
time
When Cornea
Transplants Fail. What Next?
Keratoprosthesis Helps Patients Who Reject Donor
Corneas.
Cornea transplants are highly
successful in many patients, including those with diagnoses of
keratoconus, corneal scars or endothelial dystrophy, all of
which carry a good prognosis. And newer medications are
helping to reduce the incidence of graft rejection. But what
about the small percentage of patients who, because of
immunologic response or other reasons, continue to reject
their transplanted corneas?
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The Dohlman Type 1
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The
Dohlman Type 1 post-op |
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There's hope for these individuals
in the form of a procedure called keratoprosthesis surgery,
which combines man-made materials and a human cornea to
restore vision. In some of the best outcomes, keratoprosthesis
has been able to give patients 20/40 vision.
Michael W. Belin, M.D., professor
of ophthalmology at Albany Medical Center in Albany. N.Y., and
in private practice with Cornea Consultants of Albany,
recently performed his first keratoprosthesis procedure on a
71-year-old woman who had previously rejected several donor
corneas. The woman had multiple vision-related problems,
including diabetes and retinal detachments, that had left her
permanently blind in one eye and capable of only discerning
light in the other.
"I've been following the
development of keratoprosthesis for some time," says Dr.
Belin, who performs a large number of cornea transplants in
his practice, "but it's only been recently that
keratoprosthesis could offer a viable alternative for patients
who've rejected natural corneas."
Dr. Belin used a Dohlman Type 1
rigid two-part, PMMA lens in the procedure he performed. This
keratoprosthesis, developed by Claus Dohlman, M.D., at the
Massachusetts Eye and Ear Infirmary in Boston, has been used
in about 300 patients in the last decade, improving vision for
about half of those individuals. In the 1-hour procedure, the
Dohlman lens is first attached to a "carrier" donor
transplant. The center of the natural cornea is then removed,
and the keratoprosthesis along with the carrier donor cornea
are sutured into place.
The AlphaCor lens, developed in
Perth, Australia, is another type of keratoprosthesis. In a
more time-consuming procedure, the AlphaCor is inserted in the
lamellar bed of a patient's natural cornea. The cornea is then
covered by a conjunctival flap for about 3 months. At the end
of that period, the anterior central 3 mm is excised, exposing
the underlying prosthesis.
"The Dohlman procedure provides an
easier rehabilitation for the patient," says Dr. Belin. "The
AlphaCor many be better for patients who have a lack of
corneal sensation. They may benefit from having the flap.
We're still learning about which procedure may be more
suitable for which patients."
As for the woman who received the
Dohlman keratoprosthesis from Dr. Belin, he reports that she's
still in the healing process, but that her ability to see
light has returned to preoperative levels.
Drug Giants
Partner on New AMD Drug
Novartis Will Help Develop Genentech's
Lucentis.
Novartis Ophthalmics, which is
already a co-partner for Visudyne, the only drug therapy
currently approved for the treatment of the wet form of AMD,
has joined with Genentech to develop and commercialize another
highly promising AMD treatment. The new drug, formerly known
as rhuFab V2, will now be called Lucentis.
The agreement gives Novartis
Ophthalmics an exclusive license to develop and market
Lucentis outside of North America. Genentech will retain the
marketing rights for Lucentis in North America.
Lucentis is one of the emerging
class of anti-VEGF (vascular endothelial growth factor) drugs
that cut off the formation of new blood vessels. In clinical
trials, anti-VEGF drugs have shown effectiveness in stopping
the growth of solid tumors, and also as a treatment for wet
AMD. Lucentis is currently in Phase III clinical trials in the
United States following a highly successful Phase Ib/II trial
in which patients with various forms of wet AMD, on average,
gained 9.0 letters on an ETDRS chart after 98 days. Patients
in the study who were treated with the standard of care lost
an average of 4.9 letters after 98 days.
While some saw the
Novartis/ Genentech partnership as evidence that Visudyne
would soon be surpassed by better therapies, Novartis
Ophthalmics said its goal is to "strengthen our portfolio" of
drugs to treat back-of-the-eye diseases. Paul Hastings, CEO of
Visudyne co-developer QLT Inc., told Ophthalmology
Management that the Novartis/Genentech partnership could
be good news for QLT.
"We have a very upfront, direct and
communicative relationship with Novartis Ophthalmics," said
Hastings. "We are supportive of Novartis' association with
Genentech. Genentech's expertise in anti-VEGF makes them a
wonderful partner."
Hastings said combining Visudyne
and an anti-VEGF drug such as Lucentis makes sense. A Phase
I/II clinical trial using just that combination is currently
under way.
"This combination makes sense
because the anti-VEGF drug is designed to stop the formation
of new blood vessels and Visudyne therapy acts to stop current
leakage by sealing those vessels," said Hastings. "If you look
at the way diseases are treated these days, there's more
emphasis on finding combinations that are more effective than
a single agent."
FDA Approves
Light-Filtering IOL
Alcon's AcrySof Natural Filters Out UV and Blue
Light.
The FDA has approved Alcon's
AcrySof Natural Single-Piece IOL, which will become the newest
addition to the company's AcrySof line of acrylic intraocular
lenses. The AcrySof Natural is the first foldable ultraviolet
(UV) and blue light-filtering IOL to reach the U.S. market and
is specially designed to approximate the light-filtration
properties of a healthy human lens.
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The Acrysof
Natural from Alcon
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The Alcon lens incorporates a
proprietary blue light-absorbing chromophore in addition to a
UV light-absorbing chromophore to safely filter out
ultraviolet and some high energy blue light.
"A growing body of evidence shows
that high frequency blue light may cause retinal damage," says
Robert Cionni, M.D., medical director of the Cincinnati Eye
Institute. "The AcrySof Natural IOL filters out this
potentially dangerous light without negative visual
consequences."
The AcrySof Natural earned the CE
Mark last year and has been well-received
internationally.
"We believe many ophthalmic
surgeons in the United States will also adopt this innovative
technology for their patients," says Cary Rayment, senior vice
president, Alcon U.S.
Alcon won FDA approval for the
AcrySof Natural IOL after conducting a 297-patient clinical
trial to prove the safety and effectiveness of the
lens.
Correction
The listing for the Carl Zeiss
Meditec Stratus OCT was missing from the Retinal Scanners
section of the Diagnostic Instrument Buying Guide, which was
distributed with the July issue of Ophthalmology Management.
Here is the listing as it should've appeared.
Company: Carl Zeiss Meditec
Model: Stratus OCT
Price/Fee: $59,950
Warranty: 1 year
Type of Laser: Super-luminescent
Diode 820nm
Field of View: 26° vertical x 20.5°
horizontal
Area of Retina Analyzed: RNFL,
retinal layers, posterior pole, peripapillary and optic nerve
head
Printout Detail: Objective
measurements of retinal and RNFL thickness; retinal volume;
normative data comparison for RNFL thickness; macular
thickness; optic nerve head printout with disk, cup and rim
measurements and ratios
Additional Features: Gives direct
cross-sectional images of retinal layers with axial resolution
of < 10µm and transverse resolution of 20µm. Anatomical
representation of retinal layer defects. Objectively measures
retinal thickness and volume and RNFL thickness. Includes an
RNFL thickness normative database acquired using an
FDA-approved protocol.
IN THE
NEWS
Diabetes screening technology. The
Doheny Retina Institute, part of the Keck School of Medicine
at the University of Southern California, recently implemented
ComMedica's O-PACS software technology for the early detection
of Type II diabetes and other retinal complications.
The Web-based technology, which
Doheny helped to develop, allows the Institute's doctors to
view, share and make diagnostic decisions from fundus images
sent from anywhere in the United States.
Conference Seeks
to Make Driving Safer
One Priority: Vision Problems of Older
Drivers.
How dangerous are drivers who need
cataract surgery, but refuse to have it? Should individuals
who require low-vision aids be allowed to drive?
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It's legal to
drive wearing a bioptic telescope in 34
states.
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These were two of the issues
tackled recently at the second "The Eye and the Auto"
conference, sponsored by the Detroit Institute of
Ophthalmology. The international symposium brought together
researchers, design engineers, ophthalmologists, optometrists
and representatives of the automotive industry to present
ideas for improving driving performance and making vehicles
easier and safer to operate.
With the number of drivers over the
age of 70 expected to almost triple to about 38 million by
2020, several of the papers delivered at the conference
focused on the vision problems of individuals who continue to
drive into their senior years.
One study, conducted by a team of
researchers led by Cynthia Owsley, Ph.D., professor of
ophthalmology at the School of Medicine, University of Alabama
at Birmingham, compared the accident rates of 103 drivers who
required cataract surgery but declined to have it performed,
against the accident rates of 174 drivers who had their
cataracts removed.
In the follow-up period, the
drivers who declined surgery had almost double the rate of
vehicle accidents as the drivers who had their cataracts
removed.
The researchers said
ophthalmologists should use this information to emphasize the
importance of cataract surgery to patients who want a
lifestyle that heavily depends on driving.
Another study, presented by Eli
Peli, O.D., of the Schepens Eye Institute of the Harvard
Medical School, found that the rules for allowing visually
impaired individuals to drive vary greatly from state to
state. For example, bioptic telescopes are permitted for
driving in 34 states despite the fact that some vision
researchers have found that the ring scotoma caused by the
magnification limits the driver's field of view.
Dr. Peli said new aids that provide
visually impaired drivers with both a wide field of view and
high resolution are needed. He said an in-the-lens bioptic
telescope that his team has designed could provide the
solution that would keep low-vision drivers on the road
safely.
Infants Need Early
Cataract Exams
38%
Are Diagnosed Too Late.
Thirty-eight percent of otherwise
healthy infants with infantile cataracts, a birth defect that
requires surgery before the age of 6 weeks, aren't diagnosed
with the condition early enough, a new study has found.
The study results, reported in the
Archives of Pediatrics and Adolescent Medicine, also
indicate that low-birth-weight infants are six times more
likely to have infantile cataracts than babies whose
birth-weight falls within the normal range.
As you know, infantile cataracts
can cause blindness if untreated, and surgery by 6 weeks of
age is recommended to preserve eyesight. Without visual input,
sight-related areas of the developing brain may be
irreversibly damaged.
The study findings emphasize the
importance of newborn eye exams to detect any eye
abnormalities, including cataracts, the authors say. A study
conducted several years ago found that 14% of youngsters in a
school for the blind had lost their vision due to infantile
cataracts.
In the current study, Tricia R.
Bhatti, M.D., of the Medical College of Georgia School of
Medicine, led a team of researchers who evaluated medical
records from a long-term birth defects surveillance program
called the Metropolitan Atlanta Congenital Defects
Program.
The researchers identified 199
infants born with cataracts between 1968 and 1998 -- a rate of
two cases per every 10,000 births.
Of the cases that occurred as an
isolated defect, 38% were diagnosed after 6 weeks, the
researchers reported. And 15% of otherwise healthy infants
weren't diagnosed until after they reached the age of 5
months.
REFRACTIVE SURGERY UPDATE
Expedited review for ICL.
The FDA has accepted the Pre-Market Approval Application
(PMA) for STAAR Surgical's Implantable Contact Lens (ICL) for
expedited review. The FDA generally grants expedited review
when a device offers the potential for clinically meaningful
benefit as compared to the existing alternatives, or when the
device promises to provide a revolutionary advance over
currently available modalities.
The ICL, a phakic IOL, has been
submitted to the FDA as a treatment for the correction of
myopia in the range of -3D to -20D. STAAR is currently
enrolling candidates in clinical trials for both the hyperopic
ICL and the Toric ICL.
"This acceptance brings us one step
closer to commercialization of the ICL in the United States,"
said David Bailey, president and CEO of STAAR Surgical. "We
continue to believe we will be the first to market this
technology in the United States. We have always asserted that
the ICL would represent the next paradigm shift in refractive
surgery and consider the granting of expedited review status
by the FDA an underscore of this belief."
Epi-LASIK device. CIBA
Vision has submitted a pre-market notification to the FDA for
an epikeratome device to be used in a new refractive surgical
procedure called Epi-LASIK. The device, called the EpiEdge, is
a sub-epithelial separator that produces an epithelial sheet,
thereby eliminating the need for alcohol in refractive laser
procedures such as PRK and LASEK. Because alcohol is toxic to
epithelial cells, CIBA Vision says using the EpiEdge in
Epi-LASIK results in faster healing and less pain for
patients. CIBA Vision anticipates launching the EpiEdge
epikeratome in the United States later this year, pending FDA
approval.
Epi-LASIK was developed by Ioannis
Pallikaris, M.D., a Greek ophthalmologist who also was
instrumental in the introduction of LASIK.
Refractec receives funding.
Refractec Inc., developer of the Conductive Keratoplasty (CK)
treatment for hyperopia, has received an additional $9 million
in venture capital financing to expand the CK procedure
throughout the United States. Since CK was approved last year,
more than 16,000 of the nonlaser vision correction procedures
have been performed. The minimally invasive CK procedure uses
radiofrequency energy to reshape the cornea.