As IOL technology moves forward, the focus of lens replacement surgery is shifting away from cataract patients toward presbyopic ones.
Are the new lenses up to the task?
Last November, the FDA approved the first accommodating IOL in the United States. Unfortunately, this new technology may not be available to many seniors with cataracts.
At $800 per lens, the Crystalens AT-45 (Eyeonics) is priced too high for Medicare patients.
So who will use it? The new lens will most likely find its niche in a younger crowd—those with presbyopia who can pay out-of-pocket for the procedure known as refractive lens exchange.
The question is, will a substantial number of younger patients opt to replace their presbyopic human lenses with accommodating IOLs, long before cataracts develop? If so, this would shift the focus of lens replacement surgery away from older patients with cataractous lenses.
An even bigger question: Is the technology suited to the task?
A Look at the Lenses
Two similar accommodating lenses are currently in use. The Crystalens is the only accommodating IOL approved by the FDA for use in the United States. The 1CU IOL (HumanOptics) is approved for use in Europe.
Theory in motion. These lenses have a single, small round optic attached to hinged haptics. With accommodative effort, the haptic hinges flex, moving the optic forward and thereby increasing positive power. With relaxation of accommodation, the lens moves back, said I. Howard Fine, MD.
The forward and backward motion simulates natural lens accommodation, giving the pseudophakic patient both distance and close vision, said Monica L. Monica, MD, PhD, MHA. However, she pointed out, “Just how well the accommodating IOLs actually accommodate has been questioned.”
Dr. Fine concurred. “We don’t have objective measures of accommodative amplitude. We do not have objective measurements of movement of the lens to document that the hypothetical mechanism for how they work is accurate. That has been a problem [for some critics].”
Visual results. The Crystalens produces good visual results, Dr. Monica noted, with a high percentage of people able to see 20/20 at distance and J3 for reading. “However, some recent studies have not been able to show anterior and posterior movement adequate enough to produce that focusing effect,” she said. “Therefore, the mechanism of the focusing ability of the lens may be in question.”
Evaluation of the 1CU IOL performance using ultrasound biomicroscopy and dynamic change of accommodative amplitudes measured by wavefront analysis showed amplitudes of 0.75 to 1.5 D in patients younger than 50 years of age, and 0.5 to 1 D in patients aged 50 and older, said Gerd U. Auffarth, MD, PhD.
“Accommodation is difficult to measure, and there is no standard method,” said Jack A. Singer, MD. “The bottom line is how well patients can function without correction.”
The Crystalens has shown good visual acuity results for several years. “The FDA approved the Crystalens because the visual acuities at distance, near and intermediate were so wonderful,” Dr. Fine said. He added that “The [visual acuity] data are better for the Crystalens than for the HumanOptics lens.”
In the FDA-monitored clinical trials of the Crystalens, Dr. Fine’s group implanted 100 lenses, or 25 percent of the entire FDA study. Twenty-four of Dr. Fine’s patients received the lens in both eyes.
A year and a half after surgery, 100 percent of the patients in the study had distance vision of at least 20/30, and J3 for near and intermediate vision, Dr. Fine reported. In 71 percent of the patients, the result was 20/20 or better for distance vision and J1 or better for near and intermediate vision.
He stated that his patients are happy with the lens. “Many of them use glasses at near for prolonged reading,” he reported, “but a huge percentage of them are spectacle independent. All of them had a dramatic decrease in spectacle dependence.”
The ability to produce near vision must be significantly better than that of a nonaccommodating IOL for the lens to receive FDA approval, Dr. Monica commented, adding that the lens “probably gives good intermediate vision in the majority of patients, but a good number of patients may still require reading glasses for small print or very close work.”
The accommodative effect is independent of the postoperative refractive error. “So theoretically, a patient who needs glasses for distance vision postoperatively would only need single vision glasses or a very weak bifocal,” said Daniel A. Long, MD.
Ideally, the use of the accommodating IOL combined with good implant calculation and astigmatism correction during surgery will result in a patient who does not need glasses postoperatively, Dr. Monica said. “We have not, however, consistently conquered the problem of correcting postoperative astigmatism.”
Implanting an accommodative lens requires excellent surgical skills and attention to detail during the procedure, the experts agreed.
The Crystalens has a 4.5-millimeter diameter optic. “This is relatively small and could cause glare with a dilated pupil at night,” Dr. Monica said. “Due to the small optic size, centration is extremely important.”
When implanting the 1CU lens, A. John Kanellopoulos, MD, encountered some clinical difficulties. “It requires a central small capsulorhexis (about 4 mm) and a near-perfect phaco procedure,” he reported. Dr. Auffarth has found that a 5- to 5.5-mm capsulorhexis results in better near acuities than a 4- to 4.5-mm capsulorhexis with this lens.1
Dr. Kanellopoulos added that getting accurate preoperative biometry and IOL power calculation was difficult with the 1CU lens. “We assume this problem derives from the variable IOL position within the bag following implantation,” he said. “The position may not be stable in the bag, thereby altering the A constant. As a result, refractive surprises were common and disappointing.”
Accommodative lenses are relatively new, and long-term results are not yet available, but Dr. Kanellopoulos found that the accommodative effect did not last in his patients. Early in 2001, he implanted the 1CU IOL in about 20 cases. He found that the lens initially had significant clinical accommodation, but that this accommodative action regressed three to six months after the procedure.
“These were clinical measurements and do not provide solid evidence of true accommodation due to lens movement with accommodation. Only a few patients still have accommodation” at present, he said.
On the other hand, Dr. Auffarth, who has experience with more than 100 implants of the 1CU IOL, saw no change in performance during 12 to 18 months of follow-up.
What might cause loss of accommodation? “Fibrosis of the capsular bag may make the capsular bag so firm and nonmobile that the focusing effect may be lost,” Dr. Long commented. He speculated that “over the years, the flexing of the lens forward and backward may cause the haptics to weaken and break.”
Dr. Fine noted, however, that current lenses have been tested for stability and durability and “should theoretically work indefinitely.”
Positioning for Presbyopes
The experts agreed that the Crystalens is apparently being positioned as a presbyopic product—that is, as a prosthetic lens to be used during clear lens exchange refractive surgery in presbyopic patients rather than to be implanted during cataract surgery.
To illustrate this point, Dr. Monica noted that Medicare reimburses $50 for a lens implant and approximately $150 for a new technology implant. “We don’t think that Medicare allows the surgeon or surgery center to charge the Medicare patients the difference in the price,” she said. “The lens is expensive, costing $800, and has limited availability in most managed care plans.” (In contrast, AMO’s multifocal Array IOL is about $200.)
Dr. Fine agreed. “It is not covered by Medicare for cataracts. You can use it for cataracts, but Medicare reimburses you only $150 and you can’t balance-bill the patient,” he said.
Patients who have a cataract and who have Medicare as their primary insurance will not have access to the Crystalens until the CMS policy is changed to unbundle the IOL and allow Medicare beneficiaries to pay for the Crystalens upgrade out-of-pocket, Dr. Singer explained. “Several of my Medicare patients have already contacted the CMS and their federal legislators regarding this. There is precedent here: Medicare allows their beneficiaries to pay out-of-pocket to upgrade to a deluxe hearing aid and for designer spectacle frames after cataract surgery,” he said.
Patients who do not have a cataract and have Medicare as their primary insurance also can pay out-of-pocket for a clear lens exchange with Crystalens, Dr. Singer said.
Dr. Fine agreed. “Medicare patients who are having refractive lens exchange, not cataract surgery, can pay for it. We would consider this lens for anybody who wants a refractive lens exchange.” He offers his presbyopic patients a choice between the Crystalens and the multifocal Array IOL because of the price differential.
Dr. Fine believes that refractive lens exchange will become the primary refractive procedure. “We are increasingly improving the technology for lens extraction,” he explained. “It is safer and more efficacious [than other procedures]. Methods for lens power calculation and IOL technology are improving. That is why refractive lens exchange will dominate refractive surgery.”
He has already used the Crystalens for refractive lens exchange in four of his patients, but he noted that the follow-up period is too short to assess the results adequately. His first patient had 20/30 and J3 at two months after surgery in one eye, and was about to have her second eye done at press time. “We have a lot of confidence in the lens because of our experience in the FDA-monitored clinical trial,” Dr. Fine said.
Other surgeons are still waiting for the chance to try the lens. Eyeonics “is selecting surgeons carefully, with an approval process and a questionnaire regarding volume of surgery, technique and workup of patients,” Drs. Monica and Long reported. “So far, we have not been approved to use the lens. Availability is limited, and this is a drawback.”
Next Step: Dual Optics
Current accommodative IOLs have pushed IOL technology one step closer to replicating the human crystalline lens, in all of its complexity, but they are only a beginning.
Several dual-optic accommodative lenses also are in the works. Researchers hope that these lenses will increase accommodation amplitude and reduce the risk of opacification of both the anterior and posterior capsules.
Synchrony IOL. Visiogen’s Synchrony IOL contains two optics that are linked by a bridge of curved silicone haptics. With accommodation, the +30 D-powered anterior optic moves forward. The negatively powered lens stays up against the posterior capsule.
“It works like a Galilean telescope,” Dr. Fine explained. “As you separate the distance between the plus-powered lens in the front and the negative-powered lens in the back, you get increasing magnification.”
The Synchrony IOL has been implanted overseas. As part of the multicenter trial, Dr. Auffarth has six months of follow-up data on seven patients so far. He noted that IOL power calculation is crucial for dual-optic accommodative IOLs. Interlenticular opacification has not appeared so far, he said. Visiogen hopes to begin U. S. clinical trials of this lens later this year.
Sarfarazi silicone IOL. In 2003, Bausch & Lomb licensed another single-piece molded silicone lens with a dual optic from inventor Faezeh Mona Sarfarazi, MD, according to a company news release. Bausch & Lomb will fund research and development of this technology.
Gas-filled IOL. This lens, currently on the drawing board, involves two fused lenses with gas in the space between them. The gas remains in the periphery outside the diameter of the lenses, until accommodation forces the gas centrally. This separates the two lenses and changes the shape of the anterior lens to make it more plus-powered, Dr. Fine said.
Speaking about accommodative IOLs in general, Dr. Kanellopoulos noted, “This work is pioneering for the resolution of postcataract presbyopia, the treatment of presbyopia in general and refractive errors.” Further studies should be done to improve design and to validate data, he said.
Drs. Monica and Long summed it up this way: “We are excited about the potential of focusing lens implants; hopefully, the technology will improve.”
1 Vargas, L. G. et al. In press, J Cataract Refract Surg.
Crystalens Patient Survey: Activities Without Spectacles (U.S. Bilateral Subjects)
|Activity||Yes N/N (%)||No N/N (%)|
|Perform most visual functions||120/128 (93.7%)||8/128 (6.3%)|
|Read most things||100/129 (77.5%)||29/129 (22.5%)|
|Go shopping||116/124 (93.5%)||8/124 (6.5%)|
|Participate in sports||84/87 (96.6%)||3/87 (3.4%)|
|Attend social gatherings||120/126 (95.2%)||6/126 (4.8%)|
|Drive||111/121 (91.7%)||10/121 (8.3%)|
|Read a newspaper||73/128 (57.0%)||55/128 (43.0%)|
|Sew or do needlework||35/91 (38.5%)||56/91 (61.5%)|
|Work on a computer||75/93 (80.6%)||18/93 (19.4%)|
|Do handy work around the house||119/126 (94.4%)||7/126 (5.6%)|
|Walk||117/128 (97.7%)||11/128 (8.6%)|
|Shop||117/128 (91.4%)||11/128 (8.6%)|
|Watch television||120/130 (92.3%)||10/130 (7.7%)|
Accommodation is a complicated process, and exactly how it actually works is still a matter of debate, Dr. Monica noted.
The Helmholtz theory of accommodation, which dates to 1854, states that accommodative action is achieved through contraction of the circular ciliary muscle. This action relaxes the tension on the lens zonules that pull the lens around its equator and flatten it, Dr. Kanellopoulos explained. As a result, the lens becomes rounder, thicker, and moves forward, and focusing power increases.
Although the Helmholtz theory has been challenged through the decades, it remains the leading theory of accommodation, and the current accommodative lenses are based on this premise.
Meet the Experts
Gerd U. Auffarth, MD, PhD Vice-chairman of the department of ophthalmology at the Heidelberg University Eye Clinic, Heidelberg, Germany, and head of the Heidelberg IOL and refractive surgery research group. Financial interests: Is a paid investigator for Visiogen.
I. Howard Fine, MD Clinical professor of ophthalmology at Oregon Health & Science University in Portland, and in private practice in Eugene. Financial interests: Is a paid consultant for AMO, Bausch & Lomb, Pfizer and iscience, and has had travel and research support from Alcon, Eyeonics and Staar Surgical.
A. John Kanellopoulos, MD Clinical associate professor of ophthalmology at NYU Medical School and director
of Laservision Eye Institute, Athens, Greece. Financial interests: Clinical investigator of the 1CU IOL, but has no financial interest in any of the products described in this article.
Daniel A. Long, MD In private practice in New Orleans. Financial interests: None.
Monica L. Monica, MD, PhD, MHA In private practice in New Orleans. Financial interests: None.
Jack A. Singer, MD President of Singer Eye Center, Randolph, Vt. Financial interests: None.