Crystalens™ Accommodating Lens
CATARACT SURGERY TAKES AN ENORMOUS STEP FORWARDNEW DEVELOPMENT!
At the end of 2006, Eyeonics released a new version of the Crystalens. The new lens includes a design change with a larger 5.0mm optic.
New design of the Crystalens with an enlarged optic (5.0mm)
on the right compared with the previous design on the left.
On average, near vision with the new design is as good or
better than the previous design.
Read the article below for
introductory information on the future of cataract surgery!
An article by Donald J. Keller, MD & Brian E.
Nichols, MD PhD as published in Physicians Practice
magazine, January 2005. Boulder Eye Surgeons was the first
practice in the Denver metro area to use this revolutionary
technology.
Cataracts are a leading cause of reversible vision loss in
this country. As the eye ages, the lens inside the eye
becomes less clear, much like the yellowing of an old
photograph. This cloudiness of the natural lens inside the
eye is called a cataract.
Over the past 50 years, surgery to remove a cataract and
implant an artificial lens has significantly improved. The
first intraocular lens was implanted by Howard Ridley, MD,
in 1949 through a large incision. Today, traditional
cataract surgery utilizes foldable lenses implanted through
sutureless incisions less than 3mm. However, until now, we
have been unable to reestablish accommodation, or the
ability of the eye to focus from distance to near vision.
In November of 2003, the FDA approved the first intraocular
lens, the Crystalens™, which was finally able to restore
accommodation.
The Crystalens accommodating IOL is a revolutionary
breakthrough in vision enhancement. It is an IOL
replacement that accommodates like the eye's natural lens,
allowing for focusing at distance, intermediate and near.
The ability to provide patients with clear vision at all
distances is a significant breakthrough in IOL technology.
The Crystalens changes position in response to changes in
the ciliary muscle. On the left, the lens is flexed
backwards, resulting in good distance vision. In the middle
pane, the lens shifts forward, resulting in a focus on
intermediate objects. And on the right, there is maximal
forward displacement of the lens, resulting in focus on
near objects.
The Crystalens is the result of
more than 14 years of research and development by J. Stuart
Cumming, MD, FACS. Early in his research, Cumming noted
that the ciliary muscle of the eye did not stop functioning
in older patients. (The ciliary muscle is responsible for
focusing the eye.) He created a replacement lens that moves
in a backwards and fowards motion along the axis of the eye
in response to pressure changes that result from relaxation
and contraction of the ciliary muscle. As a result,
patients are able to experience the vision they had when
they were younger - for a vast majority, without the need
for glasses or contact lenses.
The Crystalens is attached to the ciliary muscle, a
circular muscle that surrounds the lens in the eye. When
the ciliary muscle contracts it bulges backwards and
increases pressure behind the lens, thus forcing the optic
forward. Relaxation of the muscle increases the pressure in
front of the lens to move the optic backwards, thus
enabling the lens to focus naturally at all distances.
The Crystalens is a biconvex
lens with a 4.5 mm optic. It's made from a material called
Biosil, a biocompatible third-generation silicone. The
Crystalens has flexible hinged plate haptics with two
polyamide flexible loop extensions at the ends of each
plate. The hinged haptics are designed to allow the optic
to move forward during accommodative effort.
The U.S. clinical trial of the Crystalens Model AT-45 was
conducted in 324 patients. The range of axial lengths
studied in the clinical trial was 21.0 to 26.6 mm and the
dioptric power rane was 16.5 to 27.5 D. The clinical
results were obtained using an 'A' Constant of 119.0, the
SRK/T formula, immersion biometry or interferometry and
manual keratometry.
The one-year results achieved for 304 patients provided the
data to support the conclusion that, postoperatively, the
majority of patients implanted with this lens achieve
excellent near, intermediate, and distance vision without
spectacles. Visual acuity with or without correction at all
distances improves when both eyes are implanted with a
Crystalens.
In 124 bilaterally-implanted patients, the proportion of
patients achieving uncorrected visual acuities of 20/32
(J2) or better at one year was:
| Distance | 97.6% |
| Intermediate | 100% at 80 cM |
| Near | 93.5% at 40 cM |
In the 74 bilaterally-implanted patients who were within ±0.5 D of the intended target in each eye, the proportion of patients achieving uncorrected visual acuities of 20/32 (J2) or better at one year was:
| Distance | 100% |
| Intermediate | 100% at 80 cM |
| Near | 97.3% at 40 cM |
As with any surgical procedure, risk is involved. However, the incidence of adverse events experienced during the clinical trial was comparable to or lower than the incidence reported in the historic control population for normal cataract surgery.