ASCRS 1999 maps new frontiers in refractive surgery

Issue: June 1999

SEATTLE — It was apropos that the 25th anniversary meeting of the American Society of Cataract and Refractive Surgery (ASCRS) was highlighted by presentations on a new generation of lens implants and refractive corneal and lens surgery.

Cataract surgical topics certainly had a large presence on the program, but the greatest excitement seemed to be generated by avant garde techniques of refractive surgery.

Phacorefractive surgery

Although surgeons have been reluctant to remove a clear lens for strictly refractive purposes, the advantages for high myopes and contact lens intolerant patients warrant the procedure, said Dennis L. Williams, MD, of Tarpon Springs, Fla.

Several reasons have deterred surgeons from performing lens extraction for refractive correction, including fear of retinal detachment, a lack of supply of high powered IOLs, problems with lens power calculations and the likelihood of iatrogenic astigmatism inducement. However, today’s cataract surgical techniques have reduced complication rates, lens power calculations are very accurate and high-power IOLs are readily available, Dr. Williams said.

Reducing PCO

David Apple, MD, a cataract specialist at the Medical University of South Carolina, presented a report on his database of 15,000 explanted IOLs and autopsy globes. In the course of his ongoing investigation, Dr. Apple has identified six ways to reduce the incidence of posterior capsule opacification (PCO). The elimination of PCO would have a major impact on health care costs in the United States, as Nd:YAG capsulotomy is the second most commonly performed Medicare-reimbursed surgical procedure.

Dr. Apple said enhanced hydrodissection and cortical clean-up, in-the-bag IOL fixation, a small capsulorrhexis overlapping the IOL optic, biocompatible IOL material, a “shrink-wrap”-like adhesion between the posterior IOL surface and the posterior capsule and the use of IOLs with square-edged optics are the six essential ingredients in the prevention of PCO. Overall, he reported that rates of PCO are decreasing nationally. Within a few years, he expects the incidence of PCO to fall below 10%.

The prevention of PCO also was the subject of a presentation by Jochen Kammen, MD, of Dortmund, Germany. Dr. Kammen unveiled a bipolar cautery spatula he is using to remove lens epithelium debris from the capsular bag following phacoemulsification. The system sends an electric current of about 1.5 W through a spatula tip that eradicates debris as the instrument is swept across the capsule. Dr. Kammen reported that capsules rarely are damaged with the new procedure, but he said that a highly viscous viscoelastic is recommended and that the procedure is contraindicated in patients with small pupils.

Presbyopia correction

Accommodation can be restored after the onset of presbyopia, according to several surgeons who spoke here. Spencer Thornton, MD, Hideharu Fukasaku, MD, and Robert H. Marmer, MD, presented two surgical methods to alleviate presbyopia.

Dr. Thornton, of Nashville, Tenn., presented his results with the anterior ciliary sclerotomy (ACS) technique to overcome presbyopia. In this technique, the conjunctiva is incised in four quadrants and paired radial incisions are made in the sclera, starting at the limbus and extended outward. Each incision is 3 mm long and 600 µm deep. The incisions are manually spread apart and checked for depth. The conjunctiva is closed over the incisions to prevent infection.

Dr. Fukasaku, of Yokohama, Japan, presented results of a 12-patient study of ACS. Pre- and postoperative accommodative amplitude were measured, and anterior movement of the lens was verified postoperatively by ultrasound biomicroscopy. Patients increased their accommodative ability by an average of 1.9 D postoperatively, which enabled them to perform most daily tasks.

Dr. Marmer, of Atlanta, presented another technique based on an alternative theory of the cause of presbyopia. Instead of the hypothesis that the lens loses accommodation through hardening, this theory postulates that although the eye finishes growing in puberty, the lens continues to grow throughout life. This expansion crowds the ciliary muscles and prevents them from providing accommodation.

Dr. Marmer presented the results of a technique in which four PMMA segments are inserted into partial thickness scleral pockets placed in the four quadrants of the globe, each about 2.5 mm away from the limbus. This allows the sclera to expand outwardly and thus re-establishes zonular tension.

LTK results promising

Douglas Koch, MD, of Houston, medical director of Sunrise Technologies, presented results of the Food and Drug Administration (FDA) phase 3 study of the Sunrise LTK system to treat hyperopia. He presented data on 345 eyes followed for 6 months. All participants in the study were ages 40 years or older, with a range of hyperopia of 0.75 D to 2.5 D.

The Sunrise laser creates two concentric circles of eight laser spots at 6 mm and 7 mm optical zones. Efficacy and safety data met all FDA target values, Dr. Koch said. No adverse reactions were found.

Uncorrected postoperative visual acuity was 20/40 or better in 85% of eyes and 20/25 or better in 58%. In the study, 65% of patients fell within 0.5 D of their target refraction and 89% fell within 1 D of their target refraction. In the study, two cases had induced cylinder more than 2 D.

Accommodating IOL?

In a presentation on what might prove to be the first truly accommodating IOL, Stephen Slade, MD, of Houston reported on early clinical experience with the AT45 in Mexico. The AT45 is the latest design modification of the IOL designed by J. Stuart Cumming, MD.

The AT45 is designed with a hinged optic-haptic junction designed to flex in response to the ciliary muscle’s restored ability to contract after crystalline lens extraction. The IOL obtains its add power as it shifts forward with the vitreous face under ciliary muscle contraction.

Studies of the AT45 found that 1 mm of forward motion provides about 2 D of accommodation. Safety evaluations of the lens found that it was not associated with any increase in intraocular pressure, corneal edema or decentration. Most patients who received the lens achieved 20/40 or better best-corrected visual acuity and none lost any best-corrected acuity.

Phakic IOLs

David Brown, MD, a cataract specialist in St. Paul, Minn., presented phase 1 and 2 FDA study results of the STAAR Surgical ICL for myopia. In what he described as “remarkable” visual results, 41% of 102 patients achieved 20/20 or better and 80% were 20/40 or better best-corrected acuity.

Most patients were within 0.5 D of emmetropia, and 87 of eyes were within one line of their preoperative level. Dr. Brown reported no visual loss as a result of ICL implantation.

ASCRS practice profile study

David Leaming, MD, of Palm Springs, Calif., presented his annual practice profile report on ASCRS members. About 5,000 surveys were mailed; 30% of members responded. Dr. Leaming said that laser in situ keratomileusis is by far the most common refractive procedure in the United States. Volume in 1998 was up 168% over 1997, an increase that by all accounts was expected.

What was unexpected, however, was data from the Health Care Finance Administration included in Dr. Leaming’s report, which indicated that the annual number of cataract procedures decreased in the United States last year. In 1998, there were 1.818 million cataract procedures, compared with 1.934 million in 1997. PMMA, the survey found, was the most common IOL material implanted.

Business news

In addition to the clinical data being presented, several companies also announced developments that will affect refractive vision correction. Two of the excimer laser manufacturers seemed ready to capture a large piece of the laser vision correction market, as both Summit Technology and Visx Inc. announced future marketing plans.

Summit chief executive officer Robert J. Palmisano reported that Summit is poised to regain market share in the refractive laser field.

Now that Summit has completed its purchase of Autonomous, the company intends to bring Autonomous systems to market as soon as possible. Autonomous will retain most of its own corporate structure, while coordinating with Summit only on manufacturing, sales and customer service.

Direct-to-consumer ads

Visx announced at a press conference that it is embarking on a $10 million direct-to-consumer advertising campaign for laser refractive surgery. Liz Davila, president and chief executive officer of Visx, said the company is projecting that 800,000 refractive procedures will be performed using Visx lasers this year, doubling the number of procedures performed in 1998.