My involvement with accommodating lenses began in 1989, during the time that I was implanting the plate haptic lens by STAAR Surgical (Monrovia, CA) and Chiron Vision (Irvine, CA), as well as the SI18 lens from Allergan, Inc. (Irvine, CA). These lenses have an optic diameter of 6 mm, are made of silicone, and have a refractive index of 1.41. At this time, I realized that patients were very happy if they could see well at distance without correction and only had to wear reading glasses.
A few patients, who had been implanted with plate lenses and had essentially plano refractions, reported that they could read without glasses. This intrigued me, and I decided that this unexpected observation was worth investigating. I refracted these patients and examined them from behind the phoropter in a darkened room and was surprised to find that they could still read J3 or better with their distance refraction. Having the patients read with a distance correction in a darkened room eliminated the pseudoaccommodative factors of a small pupil, cornea steep at 90º, and some degree of myopia. I then subjected these patients to A-scans, first with a cycloplegic and then with pilocarpine. There was an average increase in the vitreous cavity length of approximately 0.7 mm.
I realized that the only possible explanation for the anterior movement of the optic, which explains the ability of these patients to read, was that the ciliary muscle was still functioning and was capable of moving the optic forward in these elderly patients.
In 1989, when selecting lens powers for various eyes, I noticed that an eye implanted with a plate lens needed between 1.0 and 1.5 D more power than one implanted with the SI18 lens. This didn't make sense, because the plate lens is uniplanar and the SI18 lens is vaulted backward. The A-constant of the SI18 lens is 117.2, and that of the plate lens is 119.0, which again did not make sense, because one would expect the most posterior-vaulted lens to have the higher A-constant. It occurred to me that there were powers within the eye during the period of fibrosis that moved the optic of the uniplanar plate lens posteriorly, and the optic of the posterior-vaulted SI18 lens anteriorly. I had noticed during slit lamp examinations that the posterior chamber was much deeper in eyes implanted with the plate lenses than in eyes implanted with loop lenses. Also, by slit lamp examination, there appeared to be a larger range of fixation along the axis of the eye within the capsular bag space with the loop lens as opposed to the plate lens, which appeared to have a constant location in the posterior part of the 5-mm-deep bag space.
After much research, I began to believe that it might be possible to design an IOL that would consistently move anteriorly upon constriction of the ciliary muscle.
I designed my first lens in 1990—a simple plate lens measuring 10.5 mm in length with a groove, the hinge, across the plate adjacent to the optic. The length was comparable to that of the plate lenses implanted at that time, but with a smaller 4.5-mm optic.
I believed this design would offer a greater mechanical advantage in lengthening the plates, thereby allowing increased movement of the optic.
On March 12, 1991, we implanted the first lens in an 85-year-old white female in England. I examined her on July 25, 1991, and, by the fogging technique, the patient was accommodating a little more than 4.0 D. The measurements that I took via A-scans of the anterior chamber depth and the vitreous cavity length indicated that constriction of the ciliary muscle caused a significant 2.5-mm movement of the optic.
TRIAL AND ERROR
During these investigations in 1991, I met Professor Jochen Kammann from Dortmund, Germany, who agreed to implant the lenses in a feasibility study. Over the next 9 years, I designed and manufactured seven lens styles that were sequentially implanted by Professor Kammann. The lenses of the first six designs demonstrated accommodation, but all had a small number of anterior dislocations, which usually occurred during the first 2 to 3 months postoperatively. Discovering an anterior dislocation was disheartening, because it meant having to develop a new lens design; manufacture new molds and lenses of different powers; and sterilize, package, and then implant them in patients. We had to wait several months for the results. In this situation, more than 12 months could pass between evaluating each design.
Professor Kammann implanted 24 eyes with the second design between 1993 and 1994. The centration was perfect, validating the small centration arm that had been added to the lens design. At 12 months, patients showed an average increase in vitreous cavity length of 0.95 mm, and a 1.0-mm decrease in the distance between the anterior surface of the IOL and the cornea. This meant that these patients were still accommodating. Twenty-five months postoperatively, using the fogging technique, we were measuring an average 2.06 D of accommodation in 12 eyes, which was very promising.
Because the accommodating lens project was funded by a private family trust, it was important to try to limit our expenses. In hindsight, it would have been much more efficient to have manufactured and evaluated several designs simultaneously; it would have required a much larger, one-time expense, as opposed to evaluating one design after another. The advantage of evaluating designs one by one, however, was that, as design problems were exposed, additional patents could be filed to cover the new designs. We did not publish any data on our studies during the first several years of research, because, at the time, it was assumed that the ciliary muscle did not function in midlife. We wanted to develop a final design that would accommodate, without the complications of dislocation or decentration, before publication. This allowed the development of a patent portfolio.
CrystaLens BECOMES A REALITY
In 1998, Andy Corley, a longtime friend and former General Manager of Refractive Surgery worldwide at Chiron Vision, suggested we form a partnership to further develop the lens, and, in that year, we developed our final lens design, the CrystaLens. In order to maintain fixation within the capsular bag, polyimide loops were placed across the ends of the plate haptics. The overall length of the lens from loop tip to loop tip was 11.5 mm, and the plate length was 10.5 mm. Grooves or hinges were added adjacent to the 4.5-mm optic, which has a square edge and is manufactured from Biosil (C&C Vision, Aliso Viejo, CA), a third-generation silicone.
Andy and I coordinated the implantation of the seventh lens design in Germany and Mexico to determine its safety. This study included 14 patients who were bilaterally implanted by Arturo Chayet, MD, in Tijuana, Mexico, from January 1999 to February 2000. There were no complications, and the patients are still seeing very well with their distance vision 3 years postoperatively. These promising results prompted us to seek funding in order to continue the project. Fortunately, the lenses showed no dislocations, centration was excellent, and the patients saw well at near and intermediate distances through their distance correction.
THE FORMATION OF C&C VISION
With my assistance, Andy assembled an excellent business plan that we presented, along with the lens' theory of action and results, to several venture capital groups. Brentwood Associates (Los Angeles, CA) provided the initial funding of the company that is now known as C&C Vision. In the early days of the company, we worked from the beachfront patio of the Laguna Beach Hotel, then out of an office in Andy's home, and finally at an office in Aliso Viejo, California. When we needed help in 1998, Tracy Balen, the administrator of my ophthalmology practice, joined the company. With the initial funding, we were able to confirm the lens' safety and efficacy in a small number of patients. We then persuaded Gerardo Lugo, the former head of manufacturing at STAAR Surgical, to join us and establish a modern manufacturing plant. Gerardo developed a highly efficient molding process to produce four lenses in a single compression cycle. During this early period, we also obtained the CE mark for C&C Vision, established early sales in Europe, and began organizing our FDA-approval process.
When we needed a second round of funding, Andy up-dated the business plan so that we could present it, along with the latest clinical data, to several potential venture capital groups. The second round of funding was completed in June 2000, courtesy of Brentwood Associates, Alex Brown (San Francisco, CA), and Pequot Capital (New York, NY).
The company has now grown to a total of 20 employees, and we have opened an office in Rome to handle international marketing. Approximately 2,000 eyes have been implanted worldwide with the CrystaLens with excellent results.
J. Stuart Cumming, MD, FACS, FRCOphth, is Chief Scientific Officer of C&C Vision in Aliso Viejo, California, as well as inventor of the CrystaLens technology. Dr. Cumming may be reached at (949) 916-9352; firstname.lastname@example.org