Early multifocal ablation trials show enhanced visual acuity, surgeon says

At the ASCRS Summer Refractive Congress, results to date of U.S. trials of presbyopic laser corrections were outlined.

Colman R. Kraff

SEATTLE — In early results, all participants in an ongoing clinical trial of multifocal ablations have shown visual acuity improvement, according to an investigator.

Follow-up is brief and patients are few to date, but results of the U.S. clinical trial using the Visx Star S4 laser (Advanced Medical Optics) to create multifocal ablations for presbyopia correction are promising, said Colman R. Kraff, MD.

During the ASCRS Summer Refractive Congress in Seattle, Dr. Kraff described the Visx technology’s multifocal treatment design. A variable-spot, scanning, wavefront-guided technology is used to create the subtle ablation pattern to provide near and distance vision.

In the bilateral feasibility study for Food and Drug Administration premarket approval, the dominant eye receives a standard CustomVue treatment, and the nondominant eye receives the CustomVue treatment combined with the investigational presbyopic component, Dr. Kraff explained.

“Early postoperative results show positive outcomes,” he said. “Uncorrected distance vision, intermediate vision and near acuity in the multifocal eye has improved in all subjects. Multifocal eyes achieved 20/40 or better uncorrected near acuity in all five subjects.”

In the presbyopic correction, the central zone is steepened for near vision and the peripheral cornea is targeted for distance vision.

“We do what is called a pupil-size-dependent central zone,” Dr. Kraff said. “The peripheral zone, combined with the LASIK flap, produces an aspheric surface that expands the depth of focus.”

Iris registration is an important component for the presbyopic treatment because the multifocal ablation is pupil-dependent, he said.

“It is critical that we use iris registration to really accurately place the treatment over the pupil centroid,” Dr. Kraff said.

To date, five patients have been evaluated at the 3-month follow-up point.

“If you’re asking why it’s taken so long – almost a year for us to recruit five patients – it is because this is a unique clinical FDA trial with respect to multifocality,” Dr. Kraff said. He said the entry criteria are exacting and the postoperative evaluations are extensive, so recruitment has been a challenge.

“As many of you know, the quality of vision with a multifocal lens, especially patients who have any significant astigmatism, can be quite poor,” he said. “If patients answer in the preoperative questionnaire that they do not like the vision or certain levels of vision with a multifocal contact lens, they are rejected from the study. So the majority of the patients that we screened through this process have been eliminated based on these rigorous FDA criteria.”

Dr. Kraff presented a case study of one patient in the study, a 43-year-old man with preoperative uncorrected distance visual acuity of 20/60 and near visual acuity of 20/100 in the eye that received the multifocal correction. At the 3-month postoperative follow-up visit, he had uncorrected 20/60 distance vision, 20/20 intermediate vision and 20/60 near visual acuity.

Dr. Kraff said the investigation centers are continuing to enroll patients for this trial.

Refractive Corneal Surgery

Surgeons conceive ‘ideal’ laser

Ronald R. Krueger

It may be a little early to start thinking of holiday gift ideas, but several surgeons here were sharing their laser wish lists.

Ronald R. Krueger, MD, Roger F. Steinert, MD, and Karl G. Stonecipher, MD, were each asked to speak about their “ideal excimer laser” in presentations here.

Dr. Krueger said he would optimize the excimer laser spot, eye tracking system, excimer ablation pattern and delivery, and the ergonomics and external efficiency.

“The pulse frequency with some of the lasers are increasing, and I think it would be nice to see most of the lasers coming out to about 400 pulses per second, if possible, in order to decrease the [operative] time,” Dr. Krueger said.

Dr. Krueger cited a study that showed the relationship between spot size and ablation efficiency.

“As we start going with smaller spots, in order to get a very ideal shape being ablated, you are going to have to have a very fast tracker with low latency, and that is still somewhat of a challenge,” he said.

To optimize the eye tracking system, Dr. Krueger said, he would prefer a tracker frequency of greater than 1,000 Hz and a latency of less than 1 ms.

A reproducible and accurate wavefront pattern, corneal wavefront overlap and Q-factor adjustment would also be ideal, he said.

Dr. Krueger said his ideal laser would incorporate a smart software algorithm or nomogram to compensate for biomechanics, wound healing and environmental factors. He would top it off with a moveable laser bed, patient auto-alignment and identification, infrared illumination and foot switch controls in a sequential menu of steps.

Dr. Steinert began his presentation by asking meeting attendees to mentally perform a rank-order evaluation, which is used by marketers to prioritize needs.

“There really is a thing called Disney University in Orlando, and they teach this well-known marketing technique, and in Disney they teach people the magic of how they market,” he said.

Dr. Steinert asked the attendees to think about how Disney employees would rank these elements: waiting times, safety in the park, environment and the shows. He revealed that safety comes first, followed by a clean environment, the shows and the waiting times.

He carried this lesson over and applied rank-order evaluation to refractive lasers.

“Basic attributes include accuracy, reliability, ease of use, versatility and cost,” he said. “I think that is the order, actually.”

Dr. Steinert said ideally he would like to have one machine that can perform both wavefront analysis and the laser treatment.

“Wouldn’t you really like get your wavefront done with all of your patients lying under the same laser instead of measuring in one place and doing it in another?” he asked.

He said he would also like to see an increase in user-friendly items that minimize the potential for error. A femtosecond laser integrated into a refractive laser was also on his wish list.

“Cheap was listed at the bottom of the list, but you can’t do everything I said and make it cheap,” he said. Other wishes included increased patient throughput, decreased enhancements and happier patients.

“The ideal system is never going to be achieved, but it is certainly a worthy goal to pursue,” he said. “The properties that increase accuracy are going to be the most critical. Everything else evolves from that – reliability, ease of use and versatility. Cheap will take care of itself.”

Dr. Stonecipher said that for his ideal laser he would like to see real-time outcome analysis and greater speed.

“It’s easy to have a wireless integration or link on our analyzers or topographers,” he said. “It would be wonderful if you could do that in real time under the laser.”

“Innovation is the key to success,” Dr. Stonecipher said in a presentation handout. “However, technology can be our best ally in some instances or, on the other hand, our worst enemy, creating albatrosses around our neck from which we wish to be detached.”

Following is a review of selected presentations at the meeting. Look for expanded coverage of some of these items in upcoming issues of Ocular Surgery News.

Requests requesting surface ablation

Requests from patients specifically for surface ablation refractive surgical procedures are increasing, according to Douglas D. Koch, MD.

“I have seen more and more patients coming in and asking for surface ablation,” Dr. Koch said. “They don’t want the flap.”

Douglas D. Koch

He spoke about the relative merits of the surface ablation options, including laser epithelial keratomileusis, epi-LASIK and PRK.

Eyes undergoing LASIK return “close to normal” after surgery, Dr. Koch said, but it is possible the eye is not making a full recovery.

“There is some residual nerve fiber loss at 3 years in post-LASIK eyes, but whether that matters or not I can’t say,” he said.

Dr. Koch said the advantages of surface ablation procedures over LASIK include a reduced risk of inducing dry eye and of causing postoperative corneal ectasia. However, he said, data is lacking on whether there is a difference in visual outcomes among the refractive procedures.

“To me the real issue is if [surface ablation] provides better vision, and I don’t have data on that,” he said. “But my sense is it does.”

He said the main differences among LASEK, epi-LASIK and PRK are the ways in which the epithelium is removed; these can include mechanical, alcohol-based or laser techniques. The epithelium is discarded in PRK, chemically modified in LASEK and removed mechanically in epi-LASIK, he said.

“Two clinical studies suggest there might be an advantage to replacing the epithelium to reduce the incidence of late corneal haze,” Dr. Koch said in the materials distributed at his presentation. “However, other literature and our experience suggest that simple epithelial removal without any form of replacement minimizes discomfort and hastens early visual recovery.”

Keratoconus treated with CK

Conductive keratoplasty can be a viable option to treat keratoconus, said Helen Wu, MD.

She presented a case study of a 40-year-old man who had mild to moderate keratoconus and underwent CK to treat it.

The patient had significant surface disease due to rosacea blepharitis that had been treated with multiple modalities by many practitioners, she explained.

The patient was also contact lens intolerant and a high myope with high astigmatism; he did not want to undergo Intacs placement or penetrating keratoplasty.

His uncorrected visual acuity was 20/200 in the right eye and 20/50 in the left eye. His best corrected visual acuity was 20/40 in the right eye and 20/25 in the left eye.

Dr. Wu used CK, placing five spots on the apex of the cone, outside the pupillary border, to flatten the cone based on the elevation map.

“His UCVA improved from 20/200 to 20/50 on the first postoperative day, and he later regressed back to 20/200. He was able to wear a toric soft contact lens with a BCVA of 20/30 in his right eye at 1 month postop,” she said.

“Early results with standard CK technique show regression that is significant after a year, but the LightTouch technique may afford better results and possibly could be used in combination with Intacs,” she said.

Cyclosporine pre-LASIK dry eye

A preoperative regimen of cyclosporine may enhance clinical outcomes for both normal and dry eye patients undergoing LASIK treatment, according to Marguerite B. McDonald, MD.

“Dry eye after LASIK is actually the most common complaint. This has been documented by many authors,” she said. “At this point in time we are treating dry eye in LASIK with unpreserved artificial tears, gels, ointment at night, punctal plugs, nutritional supplements, wraparound goggles and, most recently, we have investigated cyclosporine.”

Dr. McDonald and colleagues in New Orleans conducted a prospective study in which eyes were treated with cyclosporine 0.05% for 1 month before refractive surgery. The study included 42 eyes of 21 patients with moderate to severe dry eyes. They were randomized into two treatment groups before LASIK – those treated with unpreserved artificial tears and those treated with cyclosporine.

“The cyclosporine group was significantly closer to its intended refractive target than the unpreserved tear group at both 3 months and 6 months, and that was highly statistically significant,” she said.

Refractive predictability was also better with cyclosporine than with unpreserved tears at all postop time periods, she said.

“Cyclosporine 0.05% drops appear to be safe and effective in preventing and treating post-LASIK dry eye syndrome,” Dr. McDonald said.

Intracorneal lenses for presbyopia

Richard L. Lindstrom

Intracorneal lenses may present promising treatment options for emmetropic presbyopic patients, according to Richard L. Lindstrom, MD.

Dr. Lindstrom reported early clinical outcomes with small-diameter intracorneal lenses during the conference.

“There are a lot of emmetropic presbyopes,” Dr. Lindstrom said. “A lot of patients can be treated with [conductive keratoplasty] or LASIK monovision, and some of them do well with that, but a lot of patients don’t want to give up that distance to get the near.”

An estimated 44 million people are naturally occurring presbyopes, while 6 million people have post-LASIK presbyopia and 12 million are post-cataract presbyopes, Dr. Lindstrom said.

“All of these patients are potential candidates for refractive surgery to treat their presbyopia,” he said.

Dr. Lindstrom said there are several intracorneal lens options, including one from Acufocus, which is about to begin U.S. clinical trials. Preliminary clinical trials of the device were conducted in Mexico beginning in 2003.

“You might be skeptical about this. I think we all were,” he said. “It is getting some pretty amazing outcomes.”

The Acufocus implant is an ultrathin donut-shaped disc that uses a small-aperture principle. After the correction of ametropia with LASIK, the device is implanted under the LASIK flap while the flap is still lifted, for the purpose of improving near vision.

“I think these small-diameter intracorneal lenses will probably be the future for the emmetropic presbyopes,” Dr. Lindstrom said.

Lens-based Refractive Surgery

Capsule contraction with accommodating IOL

A small number of cases of capsule contraction syndrome has been reported after the first 25,000 implants of the eyeonics crystalens, according to Harvey L. Carter, MD.

In the clinical trial data on 500 eyes submitted to the Food and Drug Administration for premarket approval of the accommodating IOL, no incidence of capsule contraction syndrome was reported, Dr. Carter said.

Harvey L. Carter, MD, described capsule contraction syndrome following accommodating IOL implantation at the ASCRS Summer Refractive Congress. Image: Stiglich JM, OSN

The crystalens, designed to provide a continuous range of vision from distance through intermediate to near, has been approved for marketing in the United States since 2003 for patients undergoing cataract surgery and for the correction of presbyopia.

Dr. Carter said he was the first surgeon to encounter a case of capsule contraction syndrome (CCS) following crystalens implantation. He described the syndrome here at the ASCRS Summer Refractive Congress. Prior to this report of 57 cases in 25,000 implants, eyeonics said it had been made aware of 30 cases of CCS among the first 13,000 implants.

“So we are seeing roughly the same rate of incidence,” Dr. Carter said.

He said the onset of symptoms occurs between 1 and 7 months postoperatively and seems more common in patients less than 60 years old, but CCS has been seen “in virtually all age groups.” He noted that most of the patients in the FDA trial were older than 60 years and had cataract.

Dr. Carter said that although CCS also occurs with standard IOLs, before “the advent of the crystalens technology it really didn’t matter that much.” Because crystalens technology allows the lens to move in the capsule, the occurrence of CCS can be significant, he said.

Symptoms of CCS include an asymmetrical vault of the IOL that can be seen at the slit lamp, striae in the posterior capsule and an oval appearance of the capsulorrhexis over the plate of the crystalens. Also, patients may report a gradual myopic shift, he said.

Dr. Carter described perioperative strategies to reduce the incidence of the syndrome. These include reducing the amount of retained cortex at the time of surgery by meticulous removal of cortex from underneath the crystalens, avoiding creation of a capsulorrhexis of less than 4.5 mm, and educating patients to notify the surgeon if they perceive a gradual but sustained decrease in visual acuity.

“Early treatment is better than late treatment,” he said.

Although surgeons may be tempted to try to correct the syndrome surgically, this does not work, Dr. Carter said. The syndrome is best managed by application of YAG laser directly to areas of obvious retained cortex, he said.

According to Dr. Carter, the eyeonics scientific advisory board released the following recommendations for intraoperative and postoperative care: Create a capsulorrhexis of 5.5 mm to 6 mm, perform meticulous capsule cleanup, rotate the crystalens at least 90° to free hidden cortex and ensure proper haptic location, and treat with an anti-inflammatory for a minimum of 4 weeks.

A more complete report on the diagnosis, treatment and prevention of CCS will appear in the September 15 issue of OSN.

Shallow chamber after ICL

A number of conditions can produce a shallow anterior chamber after implantation of a posterior chamber phakic IOL, and each must be treated differently, said Stephen S. Bylsma, MD.

Dr. Bylsma presented case studies to differentiate the conditions that can cause a shallow chamber after implantation of the STAAR Visian ICL.

“They all can look quite similar to each other,” he said. “We have to stop talking about anterior chamber depth as anterior and posterior chamber, because it’s become critical now that we have this partition that is moveable.”

Among the conditions he discussed were pupillary block glaucoma, oversized ICL vault with angle-closure glaucoma, wound leak, retained viscoelastic syndrome and malignant glaucoma. Correct treatment for these conditions requires accurate diagnosis, he said.

Of some concern for ophthalmologists is how to recognize an ICL vault caused by high pressure.

“It is important to be ready with pupillary block and be able to recognize it as opposed to a high vault,” Dr. Bylsma said. “The diagnostic maneuver is to dilate the pupil. If you dilate the pupil, if it is pupillary block, the vault will go down.”

Phakic anterior chamber IOL

A phakic anterior chamber IOL has shown a low rate of endothelial cell loss in clinical trials to date, said Stephen S. Lane, MD.

Dr. Lane presented the mean outcomes in his implantations of Alcon’s anterior chamber phakic lens, which he said is in an early phase of clinical trials.

“We have to count endothelial cells obviously for clinical trials. To date, I have been able to place 14 of these lenses,” he said. “At a 4-month period of time our average [endothelial cell loss] was 2%.”

The tunnel created for insertion is a little shorter than a typical phaco incision, and the IOL is loaded into a cartridge for insertion, Dr. Lane said.

“The haptics slowly unfold and it is ‘tacoed’ in the upward direction, so as the lens unfolds, it unfolds downward,” he explained.

This anterior chamber phakic IOL has a 6-mm optic, he noted.

Dual-optic accommodating IOL

A dual-optic accommodating IOL was found to be “safe and stable,” according to one investigator’s feasibility study in a small number of eyes.

Ivan L. Ossma-Gomez, MD, MPH, reported that early postoperative data from eyes implanted with Visiogen’s Synchrony IOL showed that uncorrected vision improved in all cases.

Dr. Ossma-Gomez reported on 28 eyes implanted with the accommodative IOL for which he had at least 12 months follow-up.

Early results indicate that 82% of eyes achieved 20/40 or better uncorrected distance visual acuity, and 100% achieved 20/40 or better uncorrected near visual acuity.

“This is a promising technology. It is safe and stable over time in the first 2 years with accommodative amplitudes of over 2.75 D as can be measured at this time,” he said.

Dr. Ossma-Gomez said further results are to be reported at the European Society of Cataract and Refractive Surgeons meeting in September.

A note from the editors:

Look for expanded coverage from this meeting in upcoming issues of Ocular Surgery News.