Inlays, Onlays, Rings & Things – Part 2
ASCRS 2000 Roundup
Irving J. Arons
The annual ASCRS symposium on cataract, IOL, and refractive surgery was held at the Hynes Auditorium in Boston, May 20-24, 2000. More than 10,500 attendees, including about 7000 physicians and other medical personnel, along with about 3500 exhibitors, heard presentations covering a range of ophthalmic topics from the latest in IOLs and phacoemulsification for cataract surgery (including laser phaco), to the newest techniques for performing refractive surgery. There were also presentations on treatments for glaucoma and retinal disease, including the newly approved Visudyne therapy for halting "classic" age-related macular degeneration.
As usual, I concentrated on two areas: the latest developments in laser refractive surgery; and on new technologies that may impact ophthalmology in the years ahead. In refractive surgery, the emphasis at the meeting was on how all of the laser companies are now including some form of diagnostics (wavefront or other) for evaluating the eye and using that information, i.e., a better refraction, for performing LASIK. I conducted a survey of all the major U.S. and international laser companies to determine the specifics of their lasers, trackers -- where available, and the diagnostic device(s) they intend to use to perform customized ablations. The survey results will be available next month.
This month, I would like to inform you about some of the interesting new technologies presented, some of which are in clinical trial, while others are just beginning to be developed. I believe that many or all may have an impact on ophthalmology in the future.
Inlays, Onlays, Rings & Things
Ten years ago, in 1990, following that year' ASCRS meeting, I wrote a column for the May 1990 Ophthalmology Management with the above title. I described some of the interesting approaches to correcting vision, from the mild renewed interest in RK, probably brought on by the then intense interest in PRK, and the inability of a large number of physicians to get involved in the ongoing clinical trials, to a renewed interest in other means for shaping the cornea. Some of the advances underway included various forms of epikeratophakia using inlays and rings, made of both hard and soft plastics; onlays made of both human tissue and synthetic lenticle materials; and the advances being made in both standard and multifocal IOLs for use in phakic eyes. At the time, there were also presentations about the possibility of injecting either a hydrogel or silicone material into a cleaned out capsule via a small injection hole, to provide an injectable, accommodating lens for treating presbyopia.
Some of the epi-inlays, both collagen and hydrogels, in addition to cryolathed human tissue, included lyophilized donor corneal tissue (the Kerato-Lens and Kerato-Patch) from Allergan Medical Optics, a hydrogel called Kerato-Gel from the same company, and a hydrogel from Alcon Surgical. The IOL company, Surgidev, was sponsoring trials on a microperforated nutrient and gas permeable polysulfone material, while Optical Radiation had developed a fresnel hydrogel intracorneal lens, and the KeraVision intracorneal ring trials were still in pre-clinical trials.
As for onlays, Chiron Ophthalmics and GE Medical Systems were sponsoring programs to place either hydrogel or collagen onlays on de-epithelized cornea and have the epithelium grow back over the onlay to hold it in place. (Don't forget that there were no meaningful microkeratomes available at that time.) GE's program was underway at Emory University and involved an excimer laser, in a program called LASE (Laser Adjustable Synthetic Epikeratoplasty) with a collagen onlay supplied by Domilens. The theory was that the onlay would be placed on the cornea and reshaped as needed by the excimer laser prior to re-epithelization.
And then there was the injectable lens. Innovative Surgical Products, under the sponsorship of Allergan Medical Optics, was working on a method to inject an enzyme into the capsule to dissolve the cataractous lens, followed by injection of a liquid polymerizable silicone polymer, that would fill the capsule and provide accommodation. (Low level efforts at developing an injectable lens remain ongoing, but not by ISP or Allergan.)
Of all of these interesting technologies, only the KeraVision rings ever made it into commercialization, and that, only within the past few years. However, similar devices/programs as described ten years ago, are still being worked on today.
As I wrote back then, in the field of surgical vision correction, lasers may have had the spotlight, but a lot was going on in both the footlights and backstage, which leads me into what I discovered this year. Again, the spotlight is on laser vision correction, especially with the future potential of customized ablations, but innovative technologies are still being developed that could have an impact on vision correction over the next decade.
Inlays, Onlays, Rings & Things: Part Two
Although not an intra-stromal inlay, today's implants include the collomar ICL (implantable contact lens -- that is inserted in front of the natural lens) from Staar Surgical, for correcting high myopia, in Phase III clinical trials, and a new attempt at a microporous intracorneal lens inlay called the PermaVision Intracorneal Lens. It is made from a proprietary, patent allowed, 78% water content biocompatible hydrogel called Nutrapore. Produced by Anamed Inc., the 4.5 to 6 mm diameter micro-precision meniscus-shaped lenticle has an edge thickness of 10 microns, and a center thickness of 30 to 50 microns, for correcting hyperopia, by steepening the cornea. According to the company, the hydrogel mimics the stroma, having an identical refractive index to avoid optical aberrations or glare, and because of its microporosity and high water content, allows fluids, gases, and nutrients to flow freely through it, to nourish the front of the cornea. The lenticle is put in place by forming a flap with any microkeratome, placing the lens carefully, without decentration, over the pupillary axis, and closing the flap. Obviously, if needed, the lens can be repositioned, replaced, or removed simply by lifting the flap, making the procedure adjustable and reversible (similar to the KeraVision Intacs). To date, 11 animal eyes with up to 12 months followup, and 8 human eyes with 5 months followup, have been implanted at 3 sites in 3 countries, with corrections varying from +2.25 to +6.75. Clinical trials will be expanding over the next several months, to new sites in Europe, the Middle East, South America and Canada signed on for the study.
In addition to treating hyperopia, the company has plans for treating myopia, hyperopic astigmatism, and for presbyopia, the latter with a bifocal lens design. According to company officials, TLC Laser Eye Centers was an early investor.
On the onlay front, a newly formed company, MedRx Technologies, founded in 1999, has entered into contracts to acquire Imperial Medical, a manufacturer and distributor of IOLs; C-Scan, the corneal topography system from Technomed, and Inpro Laser, a German excimer laser company. In refractive surgery, the company intends to provide the means for custom optical profiling, incorporating ReFrax, a collagen corneal masking gel (from Imperial Medical), that will be used in conjunction with any excimer laser (including the company's) to reshape the corneal surface. In use, the gel is applied to the cornea's surface, an applinator (a sophisticated collagen mold customized for each patient -- similar to a hard contact lens) is placed on top of the gel, which hardens in about 15 seconds, attaining the shape of the mold. The surgeon than uses an excimer laser to photoablate layers of the hardened gel, to attain the desired new corneal shape. The company hopes to begin distributing the product internationally during the third quarter of this year, and to begin U.S. clinical tests in mid- to late-2000. Training of European and South American surgeons is scheduled for this summer. The ReFrax system will sell for approximately $700 to replace corneal transplants, and for about $250 for standard refractive surgery.
In terms of rings, I learned that KeraVision has designs not only on low to moderate myopia correction, but also for astigmatic correction with partial or shorter ring segments, and also for hyperopic correction with the placement of 4, 6, or 8 radial segments aligned similar to RK cuts.
Other "things" picked up by walking around the exhibit hall and attending the Technology Forum sponsored by Medical Laser Insight, included both a new laser method for treating hyperopia, the 1.9 micron diode laser from Rodenstock, that is owned by ProLaser Medical Systems, and a non-laser technique from Refractec; new advances made by IntraLase with its femtosecond laser, both for use as a microkeratome and for ablating tissue within the stroma; some insight (but only a little) into what JT Lin and Surgilight is planning to do in treating presbyopia with his infrared laser system; and a little about how C&C Vision plans to overcome the problems involved with its accommodating IOL.
In addition to the PermaVision ICL mentioned above, Refractec (with its RF [radio frequency] energized tiny probes) and ProLaser with its diode laser, along with Sunrise Technology and its holmium laser system, are all seeking to take over the treatment of hyperopia from excimer lasers. Refractec's ViewPoint CK (conductive keratoplasty) system uses tiny probes that are inserted 80% into the cornea's thickness to cause a thermal column of collagen shrinkage to provide corneal steepening for hyperopia (and, via monovision, for presbyopia). According to Marguerite McDonald, the treatment time totals about three minutes, with either 8 or 16 spots are treated, each taking about 0.6 seconds, once the hand-held probe is positioned and inserted into the cornea. Some 400 patients have been treated to date, ranging from +1 to +4 diopters. The device is expected to sell for about $40,000, plus a $100 per procedure charge.
The Rodenstock DTK system (diode laser thermal keratoplasty), produced by ProLaser Medical Systems, also uses a handheld contact probe (without penetrating the cornea) that focuses the laser's energy into the stroma, supposedly providing a more controlled, deeper release of the thermal energy to gain more predictable results with less regression as compared to the non-contact system from Sunrise. This small, compact diode laser will sell for about $50,000, much less than the anticipated $250,000 system from Sunrise. U.S. clinical trials are expected to begin shortly. There are more than twenty Rodenstock diode DTK lasers in use in Europe, with more than 600 patients successfully treated. ProLaser Medical Systems was established earlier this year, with the purchase of the assets of Rodenstock Instrumente GmbH, including the DTK laser program. The company has decided to retain the Rodenstock name because of its reputation.
An interesting innovation on the new Sunrise Hyperion laser is internet connectivity. This allows the company to perform per procedure billing, but also allows collection of patient treatment and outcomes data. If the laser user adds in the pre-op and postop data from each patient, the compiled data base becomes accessible by new doctors, or previous users each time a new patient is treated, providing an updated algorithm for treatment of a patient fitting the same or a similar profile. This appears to be a innovative way of compressing the learning curve.
IntraLase has made considerable progress in developing its femtosecond laser, now called the Pulsion FS, with its recent 510(k) FDA approval for use as a laser microkeratome. A planar cut takes about one minute to accomplish, with plans to do it faster in the works. The only problem, at least as seen in the demonstration video, is that the flap (or lenticle, when used to create a lenticle within the stroma for intrastromal ablation) appears to "stick" to the stromal tissue, and is difficult to remove. Perhaps a lubricant to separate the tissue is needed. An additional application, expected before commercial introduction at this year's Academy of Ophthalmology meeting, is clearance for creating the channel(s) for Intacs insertion. Currently, the creation of a removable intrastromal lenticle takes between 2-2½ minutes, compared to 20 to 40 seconds for excimer laser ablation (after flap formation). The laser will be sold on a per procedure basis when it becomes available.
In a not easy to understand presentation, JT Lin of SurgiLight attempted to describe what his company was doing in attempting to correct presbyopia. All that could be determined was that the company was conducting trials in Venezuela using its IR 3000 infrared laser to either ablate or coagulate tissue in the sclera to create more space for the natural lens to accommodate, similarly to what Presby Corporation does with its plastic scleral bands. However, since the Venezuelan physicians were apparently not following any type of protocol, the results obtained were not very meaningful. We will just have to wait and see if anything comes from this laser approach.
Last, but not least, Bill Link, formerly the head of Chiron Vision before it was sold to Bausch & Lomb, and now running a venture fund (Versant Ventures) funding ophthalmic innovation, spoke about C&C Vision, and its accommodating lens for treating presbyopia. The lens is a bi-hinged IOL positioned in the back of the lens capsule that, during reading, the ciliary muscles can "push" the central optics forward to provide accommodation. More than 80 lenses have been implanted to date, with good results. The major problem to be overcome is the need for keeping the lens stationary during the healing/seating period following insertion. This is now done by applying atropine drops for several days to immobilize the ciliary muscles, and thus not push the whole lens out of position. More clinical testing remains to be done to see how long the immobilization period must be for this lens to work properly.
In summary, in addition to all of the excitement about "customized ablation" refractive surgery, there were other interesting developments taking place at ASCRS. I hope I was able to capture some of the highlights for you.