|Drug dispensing contact lens developed
|Patients may be able to use glaucoma medications without experiencing the usual side effects associated with them, thanks to a new contact lens that deliver precise amounts of medication, according to reports in the Review of Optometry.
Scientists at the Institute of Bioengineering and Nanotechnology (IBN), Singapore, who developed the lenses, said the material used can be tailored to dispense different drugs and remain effective for extended periods of time.
The inventors also hope the lens could be used to dispense lubricants into the eyes of those that suffer dry eye.
The debate is growing
Satisfied users of Alcon Inc.’s LADARVision excimer laser abound, but other surgeons are convinced retreatments were too frequent after they used the system.
with one laser squarely
in the center.
LADARVision detractors cite a study published in the April 2003 edition of Ophthalmology as evidence that they’re right. The study, authored by Peter Hersh, M.D., an Alcon (Forth Worth, Texas) consultant concluded that “patients treated on the LADARVision laser had almost twice the rate of retreatment (18.2%) compared with the Summit Apex Plus laser (9.7%),” which is no longer manufactured.
Still, Dr. Hersh and others said that retreatment rates alone are so variable and so surgeon- and patient-dependent that it is unwise to lay blame on the LADARVision.
“There are hundreds of doctors around the world who use the LADARVision system and the vast majority of them are extremely satisfied with its performance,” said Doug MacHatton, Alcon's vice president of investor relations and strategic corporate communications. “Numerous peer-reviewed articles, as well as independent surveys of refractive lasers confirm that the LADARVision delivers excellent patient outcomes and that its enhancement rate is similar to other laser systems.”
Mr. MacHatton noted that retreatment rates reported out of LADARVision's Food and Drug Administration (FDA) clinical trials range from 3% to 10%.
Alcon headquarters in Fort Worth,
Texas. Source: Alcon
As for the 18.2% LADARVision retreatment rate that was published in Ophthalmology, Mr. MacHatton said, “Dr. Hersh’s analysis of the causes of enhancements are clearly supportive of Alcon’s position that retreatment rates or secondary procedures are primarily the result of variable patient healing, initial refractive error and complexity, practice of medicine decisions, and the many variables in any laser refractive procedure.” He also said the laser used in Dr. Hersh’s study was an earlier version of LADARVision before the upgrade to the company’s current LADARVision 4000.
Some surgeons—Mr. MacHatton and others note—retreat 20/20 eyes for higher patient satisfaction. Steven C. Schallhorn, M.D., director of cornea services, Naval Medical Center, San Diego, who has analyzed LADARVision surgery for numerous studies, and Richard J. Mackool, M.D., Astoria, N.Y., an Alcon consultant who uses LADARVision extensively, noticed no problems with retreatments after using the excimer laser.
Others note that because LADARVision has the widest range of any laser, it is used for more extreme, difficult patient populations.
“Our retreatment rates are extremely low, and almost nonexistent, since we’ve gone to CustomCornea,” said Dr. Mackool, director, Mackool Eye Institute.
CustomCornea is Alcon’s wavefront-guided laser procedure using LADARVision.
While Dr. Mackool said his retreatment rates are actually less than the normal 8% to 10% range, “there may be a lot of people out there who have higher retreatment rates because they tackle more extreme refractive errors,” he said.
However, not everyone agrees.
Surgeons voice concerns
Sam Omar, M.D., medical director, Advanced Vision Institute, Longwood, Fla., said after he did about 40 cases with LADARVision between 2000 and 2001, he stopped using the machine due to both a high retreatment rate and poor outcomes. He estimated that he enhanced about 20% of his LADARVision patients.
Excimer laser ablation of an eye
In order to fix the problem, Dr. Omar said he modified his nomogram three times and worked with Alcon staff, but the problem remained unresolved.
Source: Mackool Eye Institute
“LADARVision at times would be spectacular,” Dr. Omar said. “Other times, the result would be a failure. You'll program in a +4 treatment on a patient who was +3 because you're making your nomogram adjustment, and after a month or two the patient would be +2.”
Other ophthalmologists also voiced serious concerns about LADARVision.
“While none of the multiple laser platforms I have used since 1996 is perfect, my experience with LADARVision was particularly troubling,” said Roy S. Rubinfeld, M.D., of Washington Eye Physicians & Surgeons, Chevy Chase, M.D. “I had several occasions where the thing would just stop working,” said Rubinfeld, who claimed his retreatment rate was at least 25% for two LADARVision machines used to perform a total of more than 1,000 cases from 2000 to 2002.
“I had one time where I had to put the flap back with a flashlight because the illumination light went off so I couldn’t figure out where the flap was,” Dr. Rubinfeld said.
Undercorrections, overcorrections, astigmatism, and regression after LADARVision often prompted his retreatments, Dr. Rubinfeld said.
Study author defends LADARVision
While the retreatment rate associated with LADARVision was almost double that of the Summit Apex Plus in the study, Dr. Hersh concluded that “the difficulty of the initial procedures performed on the LADARVision laser, for example, higher degrees of astigmatism correction or mixed astigmatic corrections, compared with the Apex Plus laser, where more spherical myopic corrections were treated, may partially account for these findings.”
Furthermore, Dr. Hersh concluded that because the LADARVision was the newer machine in his practice, patient expectations could have been greater with the platform, causing more desire for enhancement. Later, during an e-mail exchange, Dr. Hersh said: “We did not at all concentrate on or design our methodology based on the difference between lasers. Thus, this is the wrong study from which to draw any conclusions regarding differences in retreatment rates between different systems.”
But other data—while not precise—suggest that retreatments after LADARVision can occur with abnormal frequency.
Data show high retreatment numbers
According to data presented under oath in a deposition, 27 U.S. surgical sites enhanced 20% or more primary LADARVision treatments from 2000 to 2002. That percentage is based on the ratio of all retreatments to all primary treatments recorded during that time frame. In 2002 alone, the data indicate that 55 sites had enhancement rates of 20% or greater, although sources familiar with the data noted that the enhancement rates could be somewhat off (either larger or smaller) depending upon whether some retreatments occurred at sites other than the original, occurred after primary treatments in previous years, or for other reasons.
In particular, AAPECS Eye Care (Virginia Beach, Va.) had retreatment rates of 17.8% in 2000, 18.1% in 2001, and 32.6% in 2002, according to the data.
“Before they came out with CustomCornea, I had significant retreatment rates,” said Ronald B. Frenkel, M.D., owner of AAPECS Eye Care. “But I’m a little bit different than most other people in that I would retreat a 20/20 eye. If someone came to me and they were unhappy with their vision and I could make it better, I did. But I still think my results were not as good as they should have been.”
He also questioned the 2002 retreatment rate listed for his clinic, noting that he has done many retreatments on patients whose primary treatments occurred in previous years.
“I still do probably two retreatments every two weeks, but none of them are on patients that I’ve done within the past year,” Dr. Frenkel said.
In fact, with CustomCornea, Dr. Frenkel said he has only retreated one patient.
Nine TLC Laser Eye Centers had LADARVision enhancement rates of 20% or greater in 2002, the data showed. A spokeswoman for TLC Laser Eye Centers, which she said has 70 clinics nationwide and uses LADARVision, said the company is not aware of any problems with the system's retreatment rates.
Alcon officials acknowledged that the data appear to be based on a document their company prepared in 2002 to summarize the number of primary and secondary procedures billed to customers. The officials contend that the document cannot be used to assess a laser's performance.
“In order to properly determine enhancement ratios for any laser or practice, it is necessary to know when the primary procedure was done, whether it was done on a different laser or by another doctor,” Mr. MacHatton wrote to EyeWorld. “In addition, comprehensive clinical data is needed on the pre- and post-operative assessment of patient populations. This would include the composition of high myopes, hyperopes, and patients with high levels of astigmatism or mixed astigmatism, the post-operative surgical results compared to the targeted ablation, and the enhancement philosophy of each physician.”
“The referenced data….does not contain or rely on any of this information, so using it to analyze enhancements is completely invalid,” Mr. MacHatton wrote to EyeWorld.
A surgeon operating using
Source: Mackool Eye Institute
Excimer laser ablation of an eye
Source: Mackool Eye Institute
Access to retreatment data
Alcon receives primary and secondary procedure data from all LADARVision 4000 machines for billing purposes, but surgeons contend it is not something they can readily retrieve from Alcon.
“Alcon refused to supply their billing information showing retreatment rates on our LADARVision laser after I requested that they do so,” said R. Doyle Stulting, M.D., Ph.D., professor of ophthalmology, Emory University, Atlanta.
Officials at Alcon said the information is readily available to individual surgeons.
Alcon officials told EyeWorld that the information could not be used for clinical analysis because it is incomplete without surgical site data. They said they do send clinical teams to surgical sites if ophthalmologists suspect a problem with LADARVision.
A lawsuit, filed on behalf of EBW Laser Inc. (Greensboro, N.C.) against Alcon in North Carolina, contends that underlying problems with LADARVision were intentionally concealed by Alcon. That lawsuit alleges that two LADARVision machines “suffered from unpredictable and erratic problems apparently caused by poor maintenance and repairs but aggravated by a design flaw in the machines that rendered the doctors using the machines unable to test their accuracy other than relying upon the machine’s own reports.” One system caused a retreatment rate of more than 50%, the lawsuit contends.
In an August letter to physicians, Bill Barton, vice president and general manager of Alcon’s surgical division, referred to the lawsuit allegations as “invalid contentions of parties who are attempting to avoid payment of multi-million dollar debts owed to Alcon.”
Meanwhile, the FDA has contacted at least one surgeon to request information about the performance of the LADARVision.
Everette Beers, Ph.D., the FDA’s chief of the diagnostic and surgical devices branch in the division of ophthalmic and ENT devices, declined to comment whether there is an investigation into LADARVision. While medical equipment manufacturers must report to the FDA any adverse effects that happen with unexpected severity or frequency, Dr. Beers said as long as patients don’t lose best corrected visual acuity, the FDA doesn’t necessarily consider retreatments adverse events.
Alcon officials said the company has not reported a high incidence of retreatments with any LADARVision system to the FDA because it hasn’t needed to do so.
“We haven’t identified any systemic issues that exist with the LADARVision 4000,” Mr. MacHatton said.
LADARVision was recalled twice in 2000 and 2001, and in many instances the same machines were recalled, according to two FDA enforcement reports. The reason for the 2000 recall, which applied to 136 units, was that patients had an “unsatisfactory vision correction due to error in ablation mask function.” The explanation for the 2001 recall, which affected 85 units, was that “unanticipated laser pulses reaching the cornea will cause ablation of the corneal surface, which could result in a central corneal defect of about 1 mm in diameter.”
Alcon officials note that no patients were injured on machines affected by the recalls.
Mixed views on retreatment
Whether or not higher retreatment rates have occurred because of an inherent LADARVision glitch, Alcon officials maintain retreatments generally are minor occurrences.
Similarly, Dr. Schallhorn doesn’t think retreatments are serious problems.
“Any time you have to lift the flap there’s a slight risk,” Dr. Schallhorn said. “I wouldn’t put it into a high-risk category.”
In his Ophthalmology study, Dr. Hersh mentioned that retreatments often do or don’t occur depending on patient’s subjective interpretation of what is visually satisfactory, reminding readers that “patient satisfaction, not emmetropia per se, is the essential goal of any refractive surgery procedure.”
Further confounding the issue of retreatment, Dr. Hersh said, is its definition. Some scientific literature even considers treating diffuse lamellar keratitis after LASIK a retreatment, he said.
Dr. Rubinfeld said he doesn’t consider retreatments just “touch-ups.”
“Additional risks occur with every surgical treatment and patients don’t want to be enhanced,” he said. “Whatever you can do to make your enhancement rate lower is good. You owe it to your patients.” h
Editors’ note: Drs. Omar, Schallhorn, Frenkel, Stulting and Rubinfeld have no financial interests related to their comments. Drs. Mackool and Hersh are consultants for Alcon.
Beers: 301-594-2018 ext 136, fax 301-827-4601, email@example.com
Frenkel: 757-552-0800, fax 757-497-5900, firstname.lastname@example.org
Hersh: 917-225-8965, 201-692-9646, email@example.com
MacHatton: 817-551-8974, Doug.MacHatton@AlconLabs.com
Mackool: 718-728-3400, fax 718-728-4882, firstname.lastname@example.org
Omar: 407-389-0800, fax 407-650-3400, email@example.com
Rubinfeld: 301-654-5114, 301-654-9132, Rubinkr1@aol.com
Schallhorn: 619-532-6702, fax 619-532-7272, firstname.lastname@example.org
Stulting: 404-778-6166, email@example.com