Boulder Eye Surgeons
Donald J. Keller, MD & Brian E. Nichols, MD PhD

Crystalens™ Accommodating Lens

CATARACT SURGERY TAKES AN ENORMOUS STEP FORWARD

NEW DEVELOPMENT!

At the beginning of 2010, Bausch & Lomb released the latest evolution in their series of accommodating intraocular lenses. The Crystalens AO is the first aberration-free accommodating lens (IOL) with aspheric optics. The Crystalens AO has prolate aspheric surfaces and is designed to be free of spherical aberration. It is designed to improve retinal image quality without compromising depth of field and therefore provides greater quality of distance and intermediate vision.

crystalens
The latest design of the Crystalens includes an enlarged optic (5.0mm) and better optical performance with an aspheric design. This results in the best performing Crystalens to date.

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.

crystalens distancecrystalens intermediatecrystalens near
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.

crystalens movement
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.

Additional information can be found at the Crystalens website.