LASIK and PRK clinical results are hot topics at the RSIG and ISRS meetings

Longer-term clinical results for myopic corrections and short-term results on hyperopia were emphasized.

ByIrving J. Arons

Both the Refractive Surgery Interest Group (RSIG) and the International Society of Refractive Surgery (ISRS) meetings, held prior to the American Academy of Ophthalmology (AAO) meeting in New Orleans, were primarily devoted to laser in situ keratomileusis (LASIK), and to a lesser degree photorefractive keratectomy (PRK). The emphasis at both meetings was on longer-term clinical results for myopic correction and, because of the shorter time in clinical trials, short-term results on hyperopia. The RSIG meeting had about 1,400 attendees — up significantly from the previous 2 years — while the ISRS had a little over 1,000 attendees — about equal with previous years (with many crossovers from the other meeting).

Three of the sessions I attended were devoted to a broad-based review of the current crop of microkeratomes for LASIK; alternative methods for the treatment of high myopia and hyperopia; and an update on methods for the treatment of presbyopia.

LASIK and microkeratomes

The microkeratomes of choice among high-volume refractive surgeons include the "gold standard" Bausch & Lomb Surgical (Claremont, U.S.A.) Automated Corneal Shaper (ACS), and their newer pivoting head device, the Hansatome. The Carriazo-Barraquer microkeratome from Moria, another pivoting head instrument, is also popular.

One survey of the 1,000 members of the ISRS (with a nearly 30% response) indicated that about 70% of ISRS surgeons still use the ACS, while 18% and 12%, respectively, prefer the Hansatome and the Carriazo-Barraquer.

The other microkeratomes with good reviews included the Moria One LSK; the Innovatome from Innovative Optics (Albuquerque, U.S.A.); the LaserSight ADK; and the Flapmaker from Solan (Jacksonville, U.S.A.). One noted LASIK high-volume surgeon told me to take a look at the Nidek (Tokyo, Japan) MK-2000 microkeratome. It has a simple design and can be applied to the eye and used with one hand. Other devices of note included the Krumeich-Barraquer, just acquired by Summit Technology (Waltham, U.S.A.), with its wide range of adjustability, and the Insight Technologies Instruments (Milford, U.S.A.) family of devices.

More surgeons prefer the automated designs to the manual, as they believe that the automated designs give fewer problems of incomplete flaps. But a few surgeons still like the manual designs because they provide more control over the creation of the flap. The debate over reusable versus disposable continues, although Jeffrey Robin, MD, at the ISRS meeting made a good case for switching over to disposables — provided the manufacturers can make them reproducible and reliable. Even though they cost more on a per case basis, Dr. Robin (who helped develop the Flapmaker) predicts that in the future they will gain wider acceptance because of their ease of use.

One good review of most of the micro keratomes on the market was given by Michael Belin, MD, and Robert Schultze, MD, at the RSIG. Their presentation included a table of 23 systems similar to, but not as complete as, the guide published by Ocular Surgery News. (See page 13.)

There are at least 28 different types of microkeratomes, including two water jets and two lasers, on the market or in clinical trials, most of which were shown at the meeting.

Treatments for high myopia, hyperopia

The debate continues on when to perform LASIK, now estimated to have an 80% share of all refractive procedures performed in the United States and close to that elsewhere in the world. Some surgeons perform LASIK on almost all of their patients, while others choose to use it only on higher myopes.

Hyperopia can be corrected by either PRK or LASIK. Officials at Sunrise (Fremont, U.S.A.) hope their LTK system will receive favorable U.S. Food and Drug Administration (FDA) review for hyperopia by next summer or fall. This 3-second procedure’s results look excellent on the over 40 age group, with little regression reported, and as I have previously reported, has a good shot at providing presbyopic correction as well, by means of a monovision route. Visx (Santa Clara, U.S.A.) received FDA approval in early November for the use of its Star S2 Excimer Laser System for hyperopia.

Other options

In addition to LASIK or multi-zone/multi-pass PRK, some of the potential future alternatives discussed for high myopia included phakic IOLs; using two types of anterior chamber lenses — the Artisan lens from Ophtec (Groningen, Netherlands) and the two models of the Nuvita lens from B&L Surgical/Chiron; the use of the STAAR (Monrovia, U.S.A.) Implantable Contact Lens (ICL); and the use of clear lens extraction followed by the insertion of a standard posterior chamber IOL. The problem with the latter is the loss of accommodation until an injectable lens is brought to market.

George Waring, MD’s, excellent presentation at the RSIG meeting on phakic anterior chamber IOLs traced their development from the early 1950s to the present, indicating the history of some of the current designs, including some of the posterior chamber lenses, as well.

Presbyopia

The session on presbyopia — which affects 100% of those over age 45 to 50 — can be corrected by spectacles (bifocals, trifocals or no-line multifocals), contact lenses or even multifocal IOLs for those who have had cataract surgery. Now the options include refractive surgery by means of monovision PRK or LASIK, with the possibility of "sculpting" a multifocal cornea at some time in the future. (Ron Schachar, MD’s, scleral band surgical procedure also was discussed, but dismissed by many in the audience as based on dubious theoretical considerations.)

To my great surprise, a majority of the audience at the RSIG meeting attending the presbyopia session are already providing monovision correction (both PRK and LASIK) as an option to their presbyopic patients. Peter McDonnell, MD, gave an excellent talk on monovision, discussing the options, but warning the audience that only about 80% of patients can tolerate the disparity between their eyes, and that approximately 20% of the population cannot. He suggested that everyone being considered for monovision should be tested using soft contact lenses before attempting surgery.

Other techniques for myopic correction

In addition to PRK and LASIK, the Intrastromal Corneal Ring (ICR) from KeraVision (Fremont, U.S.A.) is inching closer to the end of trials for low myopia, while the STAAR ICL is in the final phases of investigation. The latest on gel injected adjustable keratoplasty (GIAK) was presented, but this technique has lost its sponsor, Storz (now part of B&L Surgical), and the inventors are looking for someone else to pick up the development costs. The other laser technique, intrastromal ablation, with the formation of and removal of an in-place lenticule was discussed. Intralase (Ann Arbor, U.S.A.), the company formed by the University of Michigan based on the acquisition of the Intelligent Surgical Laser picosecond laser patents, but now focused on a femtosecond laser, is about to begin clinical trials and bears watching.

Custom cornea

In one of the more impressive presentations, Marguerite McDonald, MD, medical director for Autonomous Technologies (Orlando, Fla.), gave an excellent talk on the prospects of producing custom corneal corrections. Using wavefront analysis that takes into account the total visual signals being presented to the retina, including aberrations produced by the cornea and lens, Autonomous believes it can accomplish surface corrections with its combined tracking and small spot scanning laser system to overcome these aberrations and to provide improved visual acuity rather than just adequate vision. In other words, the company believes that its "custom cornea" program can provide 20/15 vision, rather than just 20/20 or 20/40 corrections for most people. Others, including Bausch & Lomb Surgical, are hoping to do the same. In a presentation to the press, Dr. Waring announced that B&L Surgical hoped to be able to achieve "20/12 corrections by the year 2012."

Another trend apparent both from the presentations and from news picked up on the exhibit floor was that many of the refractive laser companies are beginning to form collaborations with the topography instrument suppliers that, hopefully, will lead to topographically-directed ablations. What Autonomous is attempting to do, however, appears once again to be ahead of the pack.

For Your Information:

Irving J. Arons is managing director of Spectrum Consulting with offices at 4 Harvard St., Peabody, MA 01960; phone and fax: +(001) 978-531-0939; e-mail: iarons@erols.com. Mr. Arons has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any companies mentioned.

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