Dr. Bruce Jackson is the world's leading researcher on multifocal ablations for the treatment of presbyopia. In this month's feature, Dr. Jackson summarizes the history and current status of this exciting new approach to laser vision correction. Also, don't forget to purchase your tickets to the ISRS/AAO Gala Dinner & Dance in Las Vegas. Seating is limited, so it's recommend you purchase tickets online by October 25. Enjoy -- Marguerite McDonald, MD, FACS
- Conventional ablation induces a greater increase of higher order aberrations than customized ablation
- Single inferior segment Intacs may be more appropriate for paracentral and peripheral cones
- Identifying patients at risk of developing post-LASIK corneal ectasia
- Paired opposite clear corneal incisions correct corneal astigmatism better than single clear corneal incisions
- Intraoperative MMC may reduce endothelial cell density after PRK
- FS laser allows for simpler, more accurate corneal wedge resection to correct high astigmatism after penetrating keratoplasty
- ReSTOR IOL provides good uncorrected distance and uncorrected near acuities
- Tickets for the ISRS/AAO Gala Dinner & Dance are now on sale
- ISRS/AAO course in Las Vegas to offer the latest in refractive surgery
- Academy to host an International Centre during the Joint Meeting
- Enhanced Tecnis CL IOL to replace Z9000 and Z9001 Tecnis silicone IOL
- IntraLase’s femtosecond laser approved in Taiwan
- Upcoming meetings
- Multifocal Ablation: Current Status, Future Potential
- Innovative blade box for Carriazo-Pendular
- Specialist in refractive corneal surgery
Conventional ablation induces a greater increase of higher order aberrations than customized ablation
This prospective, randomized study included 27 myopic patients who underwent topography-guided CATz ablation in one eye and conventional ablation in the fellow eye. Visual outcomes were not significantly different between the two groups. However, there was a highly statistically significant increase in higher order aberrations in the conventional ablation group (P<.001). Journal of Refractive Surgery, September 2006
Single inferior segment Intacs may be more appropriate for paracentral and peripheral cones
This case study of a 33-year-old woman who experienced decreased BSCVA two months after Intacs implantation shows that using asymmetrical segments, with the thicker segment above the cone, may increase distortions and result in loss of BSCVA. After the superior Intacs segment was explanted, the inferior segment was exchanged for a thicker one (0.35 mm) and collagen cross-linking with riboflavin treatment was performed. BSCVA returned to 20/20. Journal of Refractive Surgery, online advance release
Identifying patients at risk of developing post-LASIK corneal ectasia
This proposed grading system weights several corneal parameters to come up with a cumulative score to identify which patients are at risk. Applied retrospectively to 37 cases of post-LASIK corneal ectasia, the system helped distinguish between normal and abnormal corneas. Ophthalmology, September 2006
Paired opposite clear corneal incisions correct corneal astigmatism better than single clear corneal incisions
This randomized, prospective clinical study of 40 patients (40 eyes) with astigmatism of more than 1.50 D finds patients with paired incisions experienced a mean astigmatic change of 1.60 D compared to 0.59 in patients with single clear corneal incisions. Journal of Cataract & Refractive Surgery, September 2006
Intraoperative MMC may reduce endothelial cell density after PRK
This randomized, placebo-controlled study of nine patients (18 eyes) finds that a single intraoperative application of MMC 0.02 percent for 30 seconds induced a statistically significant endothelial cell loss: 14.7 at one month and 18.2 at three months. American Journal of Ophthalmology, September 2006
FS laser allows for simpler, more accurate corneal wedge resection to correct high astigmatism after penetrating keratoplasty
The femtosecond laser allowed for an easier, more controlled and more precise excision of tissue in width, length and depth, which may improve the reproducibility of the technique. The risk for corneal perforation may be reduced when using an FS laser. Journal of Cataract & Refractive Surgery, September 2006
ReSTOR IOL provides good uncorrected distance and uncorrected near acuities
Uncorrected near visual acuity was 20/30 or better in 75 percent of patients implanted with the ReSTOR (40 patients, 80 eyes) after cataract surgery, compared to 3.8 percent in the bilateral monofocal IOL group. Spectacle independence (only 2.5 percent required reading glasses compared to 92.5 in the monofocal group) appeared to outweigh the photic symptoms caused by the multifocal IOL. Journal of Cataract & Refractive Surgery, September 2006
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Tickets for the ISRS/AAO Gala Dinner & Dance are now on sale
Join your colleagues for an elegant dinner followed by live music and dancing on Friday, Nov. 10, 7 p.m. to midnight, at the Venetian Hotel. Prestigious awards will also be presented: the Lifetime Achievement Award, Jack T. Holladay, MD, MSEE ; the Founders Award, H. Dunbar Hoskins Jr., MD; the Barraquer Award, Douglas D. Koch, MD; the Kritzinger Memorial Award, Yaron S. Rabinowitz, MD; the Casebeer Award, Michael C. Knorz, MD; the Lans Distinguished Award, Steven E. Wilson, MD; the Troutman Award, Marcelo Netto, MD and the Miradas Award (recipient to be announced). This ISRS/AAO Gala Dinner & Dance is sponsored in part from an unrestricted grant from Alcon. Tickets are $125 each. Seating is limited, so it’s recommend you purchase tickets online by October 25.
ISRS/AAO course in Las Vegas to offer the latest in refractive surgery
Innovation in Refractive Surgery: So New It May Not Be True (course # 692) will feature a panel of leading experts discussing late-breaking topics with vigor and humor.
Academy to host an International Centre during the Joint Meeting
Located in booth #3974 in Hall A at the Sands Expo, the center will include a Spanish and Mandarin-speaking interpreter, light refreshments. It's an ideal place to meet with fellow international attendees, relax and receive assistance with Joint Meeting details and other issues regarding your stay in Las Vegas. And just for stopping by, you will receive a free gift (while supplies last). Admittance is by attendee badge. In addition, the Academy has posted on its Web site travel information specific to international attendees.
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Enhanced Tecnis CL IOL to replace Z9000 and Z9001 Tecnis silicone IOL
Advanced Medical Optics, Inc. announced the new IOL this week at XXIV Congress of the European Society of Cataract and Refractive Surgeons. The lens is currently available in Europe, and is expected to ship to the United States, Canada and Asia Pacific next month, and to Japan by mid-2007.
IntraLase’s femtosecond laser approved in Taiwan
The company plans to immediately commercialize the IntraLase FS laser in Taiwan. As of June 30, 2006, 471 IntraLase lasers were installed around the world and more than 850,000 IntraLase LASIK procedures performed worldwide, according to a company press release.
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|UPCOMING MEETINGS || |
|Oct. 27-28, 2006 |
Venezuelan Symposium of Refractive Surgery
Nov. 10-11, 2006
ISRS/AAO Subspecialty Day Meeting
Sands Expo at the Venetian Hotel
Las Vegas, Nevada, USA
|Nov. 18, 2006 |
10th International Refractive Society of Japan Meeting
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Innovative blade box for Carriazo-Pendular
The Carriazo-Pendular microkeratome enables highest precision and exact predictability of flap thickness. As the first company in the refractive corneal surgery market segment, SCHWIND has developed a blade box that offers even more safety during the performance of the treatment. The blade is guided and protected during insertion and removal without coming into contact with the doctor. Cutting complications and risk of injuries are avoided, the blade remains intact. The innovative safety concept causes no additional effort for the user: the disposable product requires neither sterilization nor cleaning.
Specialist in refractive corneal surgery
For nearly 50 years, the name SCHWIND eye-tech-solutions has stood for innovative solutions in ophthalmology. Today the company is the specialist for refractive corneal surgery. SCHWIND develops, produces and markets a comprehensive product portfolio for the treatment of ametropia: A complete refractive package containing diagnostic systems, software, as well as microkeratome and excimer laser system suitable for a wide range of clinical indications. Established expertise and many years of application experience have made SCHWIND products synonymous with precision, safety and predictability of treatment results
Current and Future Roles of Phakic IOLs
W. Bruce Jackson, MD
Individual surgeons began working on multifocal ablations in the early 1990s. Their work was essentially independent; they were not backed by any of the laser manufacturers. That changed several years ago when VISX (now AMO/VISX) saw the market potential of an ablation design that could give presbyopic eyes acceptable vision at all distances. AMO/VISX made the development of multifocal ablations a company initiative. I became involved in this work in 2001 when I agreed to lead the company's clinical trials of aspheric ablation.
While there are no doubt a number of centers around the world that do a fair volume of aspheric ablations, there is as yet no region where an aspheric ablation is the standard option for most presbyopic patients. AMO/VISX has released their software for wavefront-guided hyperopic aspheric ablations to a number of investigators outside the US and is using their work to gather additional data. There are, for example, four centers in Canada that use the AMO/VISX system to provide aspheric ablations.
I have heard informally that other companies are working on multifocal ablations, but very little if any of their clinical data has been reported at meetings or in journals. Regardless, I would expect that every laser manufacturer is by now paying some attention to presbyopic ablations.
We in Canada were fortunate to have started with bilateral hyperopic aspheric ablations. For regulatory reasons, the United States experience has been very different. Interestingly, although it’s widely employed, the FDA has never approved monovision. Before it would sanction a bilateral aspheric ablation study, the FDA wanted data from single eyes. And so the United States is in the process of doing pilot studies in which one eye will be corrected for distance only and the fellow eye will receive an aspheric ablation. This will allow patients to compare vision in each eye. Data from this study will be necessary before larger, bilateral studies are approved.
Bilateral vs. Unilateral
We began our studies with hyperopes. All of them received bilateral treatments. When we began to work with myopes, however, we simply continued doing bilateral treatments. It quickly became clear that myopes wanted a quality of distance vision that was unobtainable with aspheric ablation in both eyes. We ended up treating one eye for distance only while the fellow eye received an aspheric ablation to get a modicum of near vision as well.
Although there are some surgeons who perform bilateral multifocal myopic ablations, we have been unable to do so. Our myopes wouldn’t accept any compromise of their distance vision; for them occasional use of glasses was preferable to even a small loss of distance acuity.
A Future Standard?
We have found that bilateral aspheric ablation is truly safe and effective for presbyopic low hyperopes. I expect that in this population, monovision will decline in popularity as patients and surgeons become familiar with the new ablation design.
I can’t say the same thing for presbyopic myopes, however. I don’t believe that we have yet hit upon an ideal ablation design for that population. At this point, the best approach appears to be a blended monovision, with one eye monofocal for distance and the fellow eye multifocal. I believe that this is superior to traditional monovision, but I continue to hope that in the future we will be able to treat both eyes and get good distance vision plus the near vision.
Presbyopic myopia will remain a tough nut to crack. With correction, myopes enjoy excellent distance vision and most can read easily without correction. They want great acuity at both distance and near, but to give them good near vision means a degree of compromise in distance vision that is still unacceptable. With time and research that may change; but we’re not yet at that point, and a blended monovision may be our endpoint.
No Visual Symptoms
Our patients with aspheric ablations rarely suffer from the visual symptoms that multifocal intraocular lens patients sometimes complain of, i.e. halos, glare and diminished contrast acuity. There has always been a concern that this would occur with multifocal ablations, but most studies have found this to be a non-issue. Contrast acuity drops initially with aspheric ablations, but it returns over a six to 12-month period.
Part of the reason fewer visual symptoms are associated with aspheric than multifocal IOLs is that the treatment is weaker. If we were to take the effective add power of a multifocal IOL and put that add power on cornea, there would likely be more contrast loss. Typically, the multifocal corneal corrections have had a dioptric range much like traditional monovision, i.e. 1.5 D or less.
Since presbyopic patients who choose aspheric ablations tend to be a bit younger than the average presbyope, effective adds in the 1.5 D range, combined with their remaining accommodation, are enough to provide useful reading vision. In truth, what we are doing with aspheric ablations is boosting or enhancing near vision rather than curing presbyopia. In essence, we are pushing back the clock for these patients; we are not stopping the clock.
Multifocal IOLs, by contrast, aim to give pseudophakic eyes both reading and distance vision, a much tougher goal. If our ablations aimed for 2.25 D or 2.50 D effective adds, we would likely see some loss of low-contrast acuity.
The patients we have treated most successfully have been low hyperopes (+2 D to +2.50 D) in their mid 40s. We tell these patients that a conventional ablation will give them good distance vision, but they will almost certainly need reading glasses for close work. A multifocal ablation will give these hyperopes almost exactly the same distance vision as a conventional ablation, but they will also be able to see up close.
Will they be entirely spectacle free? We don’t promise that, and we let patients know that their hyperopia may increase and their presbyopia will surely progress and diminish the quality of their near vision. While it can be expected to improve near vision for several years, we make sure that patients understand that the aspheric ablation is not a permanent fix.
Absence of ocular surface disease is an important criteria for patient selection. The population that has this procedure is older and more likely to be female; and one of the biggest problems in steepening the cornea with LASIK is dry eye. Since an unstable tear film can produce fluctuating vision, patients must be willing to take artificial tears. Some patients have to be treated with topical cyclosporin (Restasis®; Allergan) and some get punctal plugs to get through that first three to six months.
Key aspects of patient selection:
- Absence of LASIK exclusion factors
- Absence of dry eye disease
- Realistic expectations
- Time limited effect
- May need spectacles for some activities
- Low hyperopia
- If dry eye exists, willingness to pretreat
Patients tolerate the aspheric ablation very well. As noted, glare and halos simply haven't been an issue. The problem we encounter, particularly in myopes, is with the perceived quality of their distance vision. Because of their perceived need for excellent distance vision, some myopes have had to have retreatment to eliminate the multifocal effect and correct their vision to 20/20 or better.
Among hyperopes, the major criticism has been with the quality of their near vision. But these patients have had remarkably little trouble adjusting to the multifocal ablation. In fact, we were initially quite surprised by the rapidity of adaptation. Another surprise was that patients' vision tended to continue to improve with time. For example, vision at 12 months tends to be better than at six months, indicating that some neural adaptation may be taking place.
The Potential of Aspheric Ablation
For the low hyperope who is presbyopic, excimer laser surgery with an aspheric ablation is now excellent option, buying years of good vision at both distance and near. Aspheric ablation for myopes remains a question mark. At this point, we still don't know what the optimal ablation pattern is. Right now both center-distance and center-near options are being investigated and it appears that the center distance ablations have less effect on distance vision than do center-near and are therefore preferred. But significant work remains to be done before we achieve the same level of satisfaction as has been achieved with hyperopes.
The ultimate goal is an aspheric ablation pattern that would become a standard for presbyopes. Although we haven't achieved a fully suitable design for myopes, we continue to work to be able to offer something better than a choice between monovision and monofocal ablation plus readers. If we do gain the ability to reliably provide presbyopic myopes with excellent distance vision and reduced dependence on reading glasses, the market potential is vast.
There is tremendous and growing interest in multifocal ablation. When I first began talking about it at meetings in 2002 and 2003, there were rarely more than a handful of other papers on the subject. Now there are many more, and the numbers are growing.
Part of the excitement is that a number of groups and individuals are working in the field, including surgeons working on their own without significant company support. We are accumulating a great deal of experience, and gradually starting to marry ideas from different investigators. There is a future for multifocal ablation, and right now that future looks bright.
W. Bruce Jackson, MD, FRCSC is professor of ophthalmology at the University of Ottawa, Ottawa, Ontario, Canada. He is a paid consultant to AMO/VISX.
The Ocular Surface is a peer-reviewed journal with review articles on medical and surgical topics related to the anterior eye. Visit the for a free sample copy and special offer for ISRS/AAO members.
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