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Refractive Surgery | Oct 2010

Accommodating Lens Technologies Continue to Improve

Several models are already commercially available in Europe, with others now in development and clinical testing.

AAs recently as 20 years ago, the prospect of presbyopia correction via IOL implantation alone was no more than a notion. Busacca1 had established that the ciliary muscle changed shape during accommodation, and Coleman2 had demonstrated that vitreous cavity pressure increased upon constriction of the ciliary muscle, but no lenses were available to take advantage of these steps of the accommodative process. Patients typically received a monofocal IOL that left them with adequate vision at a single distance. They relied on spectacles or contact lenses to achieve vision at the other distances.

In 1986, Thornton described what is thought to be the first evidence of an IOL moving along the axis of the eye with accommodation.3 He was able to measure a significant reduction in anterior chamber depth during ciliary muscle constriction in 20% of eyes he implanted with a loop lens. Three years later, J. Stuart Cumming, MD, FACS, FRCOphth, the designer of the Crystalens and co-founder of Eyeonics (since acquired by Bausch + Lomb, Rochester, New York), observed apparent accommodation in patients who received plate-haptic silicone IOLs.4 Some of these elderly patients who were close to emmetropia said they could read without glasses postoperatively, and testing revealed that many could read J3 or better in dim light.

On slit-lamp exams, the plate-haptic lens appeared to vault farther posteriorly in the capsular bag than a threepiece silicone posterior-vaulted loop lens (SI 18; Allergan, Inc.; now Abbott Medical Optics Inc., Santa Ana, California). From these findings and further ultrasound examinations, Dr. Cumming reasoned that the forces within the eye could move the optic of the plate-haptic lens anteriorly with accommodation. He concluded that a functioning ciliary muscle was responsible for the movement of the optic, and in 1990, designed an accommodating lens that would move along the axis of the eye.

Accommodating Lens Designs

Using a plate-haptic design to create a prototype of the first accommodating IOL, Dr. Cumming reduced the diameter of the optic; enlarged the length of the haptics, increasing the optic's ability to move; and placed a hinge adjacent to the optic, across the plate haptics. The overall length and optic diameter of the IOL were 10.5 mm and 4.5 mm, respectively. Dr. Cumming implanted the world's first accommodating IOL on March 12, 1991. Although the 85-year-old patient achieved significant accommodation, she also experienced fogging, and the lens dislocated 6 months postoperatively.5 Dr. Cumming redesigned the lens, this time teaming with Joachen Kammann, MD, of Dortmund, Germany. Over the next 9 years, the pair tweaked the lens' design, implanting six models that demonstrated some accommodation (up to 1 mm of anterior movement) but still resulted in dislocation in some cases. The seventh design became the first Crystalens model.

Accommodating IOLs have since come a long way. Although the technology is not perfect, some models have been shown to achieve pseudoaccommodation. The cover focus in this issue is designed to explore the accommodating IOLs of today—those that are currently available as well as those in development and clinical testing. We have invited a panel of key opinion leaders to take part in a survey of these lenses, exploring the effectiveness or potential effectiveness of each lens design. The designs discussed include the Akkommodative 1CU (HumanOptics AG, Erlangen, Germany), the Crystalens AO (Bausch + Lomb), the FluidVision (PowerVision, Inc., Belmont, California), the NuLens DynaCurve (NuLens, Ltd., Herzliya Pituach, Israel), the SmartIOL (Medennium, Inc., Irvine, California), the Synchrony (Abbott Medical Optics Inc.), the Tek-Clear (Tekia, Inc., Irvine, California), and the Tetraflex (Lenstec, St. Petersburg, Florida). Vision Solutions Technologies (Rockville, Maryland) asked that its LiquiLens not be featured in this survey. (See Accommodating IOL Designs on page 49 for a description of each IOL.)

Two Camps

When it comes to the use of accommodating IOLs, there seem to be two camps of anterior segment surgeons—surgeons who are proponents for their use and surgeons who believe that current designs do not provide enough accommodation (see Criticisms). However, there appears to be at least some potential behind this technology, as another company hopes to enter the market. Recently, Hoya Surgical Optics, Inc. (Chino Hills, California), announced a partnership with IOL developer Adoptics (Biel, Switzerland) to develop a shape-changing accommodating IOL. Other companies may soon be jumping on board.

CRST Europe has secured a panel of anterior segment surgeons to participate in this survey of accommodating technologies. In the following pages, Victor Bohórquez, MD; Sheraz M. Daya, MD, FACP, FACS, FRCS(Ed), FRCOphth; Robert K. Maloney, MD; Samuel Masket, MD; Mark Packer, MD, FACS; Magda Rau, MD; and Sunil Shah, FRCOphth, FRCS(Ed), FBCLA, answer the following five questions with regard to IOLs they either have used or are familiar with:

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
3. What are the advantages of the lens design? The disadvantages?
4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
5. What is your opinion on the future of this lens technology?

This survey is meant to provide readers with background information on accommodating lens designs and offer a sneak peak into what key opinion leaders in lensbased surgery think of these technologies. This cover series is not intended to provide clinical information or study results. We hope you enjoy the forward-looking thoughts of our panelists.