Professor Joseph Colin is one of the world's most eminent refractive surgeons, with years of hands-on experience with various phakic IOLs. In this month’s feature, Joseph beautifully summarizes the pros and cons as well as the history and future of phakic IOLs. Enjoy -- Marguerite McDonald, MD, FACS
- Persistent decrease in keratocyte density in the anterior stroma following MMC treatment may warn of future complications
- LASIK may be appropriate in patients with well-controlled or inactive autoimmune disease
- Promising new approach to LASIK combines surface and lamellar procedures
- Double-K clinical history method may be the most reliable way to calculate IOL power after refractive surgery
- Protein on the corneal epithelium suppresses corneal blood vessel growth
- Autologous serum may promote faster corneal wound healing in diabetic patients
- Good functional results with the Centerflex IOL, but PCO development was common
- AcrySof Natural IOL doesn’t affect the diagnostic ability of blue–yellow perimetry
- Tickets for the ISRS/AAO Gala Dinner & Dance are now on sale
- Academy to host an International Centre during the Joint Meeting
- Academy introduces exciting new opportunity for international members – The International Ophthalmologist Education Award
- FDA approves WaveLight’s wavefront-guided procedure
Current and Future Roles of Phakic IOLs
Persistent decrease in keratocyte density in the anterior stroma following MMC treatment may warn of future complications
An evaluation of PRK with mitomycin C in rabbits finds that the decreased cellularity noted at one month postop persisted at six months followup. Researchers also find treatment with 0.002 percent MMC for 12 seconds to one minute appears just as effective as higher concentrations for longer duration in the rabbit model. Journal or Refractive Surgery, June 2006
LASIK may be appropriate in patients with well-controlled or inactive autoimmune disease
This retrospective review included 26 patients (49 eyes) with inactive or stable disease who had LASIK. No eye developed corneal thinning, melting, persistent epithelial defect, persistent keratitis, scleral thinning, scleritis or scleromalacia at follow-up (mean 19 months). Journal of Cataract & Refractive Surgery, August 2006
Promising new approach to LASIK combines surface and lamellar procedures
This retrospective study included 25 patients (33 eyes) who had LASIK after an unintentional ultra-thin flap, less than 80 µm. At one day postop, UCVA was 20/25 or better and remained stable at final followup (mean 14.58 months). Patients were satisfied, and there were no complications. Journal of Cataract & Refractive Surgery, August 2006
Double-K clinical history method may be the most reliable way to calculate IOL power after refractive surgery
Researchers theoretically compared 11 methods of predicting postoperative refraction in 98 eyes that had undergone myopic laser surgery. They found that 96.9 percent of these eyes would have received an IOL that was within ±0.5 D of achieving theoretical emmetropia. Ophthalmology, August 2006
Protein on the corneal epithelium suppresses corneal blood vessel growth
A series of studies with mice show that adding VEFGR-3 (vascular endothelial growth factor receptor-3) to corneas stripped of their epithelial layers prevented blood vessel growth, while corneas exposed to a VEGFR-3-blocking agent induced blood vessel growth. Results hold promise for treating eye disease and cancer. Proceedings of the National Academy of Sciences, July 25
Autologous serum may promote faster corneal wound healing in diabetic patients
This randomized study included 23 patients undergoing pars plana vitrectomy who received corneal abrasion for better intraoperative visualization. Autologous serum lead to a much faster closure of corneal epithelial wounds after abrasion, compared with hyaluronic acid. American Journal of Ophthalmology, August 2006
Good functional results with the Centerflex IOL, but PCO development was common
A three-year evaluation of the foldable hydrophilic single piece IOL finds low values for endothelial cell loss and inflammatory signs and no anterior capsule shrinkage. PCO formation was higher compared to other IOLs, resulting in a Nd:YAG rate of 29.41 percent after three years. British Journal of Ophthalmology, August 2006
AcrySof Natural IOL doesn’t affect the diagnostic ability of blue–yellow perimetry
There was no difference in short-wavelength automated perimetry values between eyes with the yellow-filtering AcrySof Natural IOL and those with the conventional AcrySof IOL or between this series of pseudophakic eyes and a normal population. Journal of Cataract & Refractive Surgery, August 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 and the Troutman Award, Marcelo Netto, MD. 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.
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 and Internet access
Academy introduces exciting new opportunity for international members – The International Ophthalmologist Education Award
Award recipients will receive a certificate and be recognized on the Academy's Web site and in EyeNet Magazine. Applicants must complete 90 continuing medical education (CME) credits over a three-year period, half of which must be Academy-sponsored CME.
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FDA approves WaveLight's wavefront-guided procedure
According to a company press release, the approved treatment approach combines the Allegro Analyzer with the 200 hertz Allegretto Wave excimer laser, offering physicians the choice of wavefront optimized and wavefront-guided LASIK treatment options.
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|Upcoming Meetings || |
Sept. 19-23, 2006
XXXII National Meeting of Ophthalmology
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
Sept. 9 – 13, 2006
XXIV Congress of the ESCRS
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Current and Future Roles of Phakic IOLs
Joseph Colin, MD
Phakic intraocular lenses (IOLs) have been used in Europe since 1987. They were developed to correct high myopia at a time when the available corneal refractive procedures (eg, non-freeze keratomileusis and epikeratophakia) were unable to produce safe, accurate, predictable refractive corrections for these patients.
Three types of phakic IOL appeared in Europe at this time: angle-supported anterior chamber IOLs pioneered by Georges Baikoff in France; iris-fixated IOLs initiated by Jan Worst in the Netherlands; and posterior chamber IOLs developed by Svyatoslav Fyodorov in Russia. Although phakic IOLs have been in development far longer than LASIK, they have achieved nothing like its acceptance among patients and surgeons. Reasons for the slow development of phakic IOLs include:
- The high rate of complications and resulting bad reputation gained in early phakic IOL trials,
- Worries about patients'; ability to tolerate subsequent versions, and
- The need for intraocular surgery with a large incisions for nonfoldable lenses.
Although there were significant complications, all three of the early lens designs produced good refractive results. The early angle-supported and the posterior chamber IOLs produced unacceptably high rates of complications. (In the case of angle-supported lenses, the problem was injury to the corneal endothelium; the posterior chamber lenses produced a high incidence of cataract.) In an effort to reduce these problems, angle-supported and posterior chamber lenses have undergone a series of progressive incremental design changes. At this point, follow-up for the latest iterations of these designs has been relatively brief.
Iris-fixated lenses induced far fewer unwanted anatomical side-effects. The problem with this design was that, until very recently, the PMMA material from which the lenses were made required a large limbal incision. This was at a time when cataract surgery incisions were getting smaller and smaller. Moreover, a patient implanted with an iris-supported PMMA lenses will require a second large-incision surgeon later in life when it becomes necessary to remove the lens for cataract surgery.
Phakic IOL vs. Refractive Lens Exchange
In patients over 40, it is logical to consider clear lens extraction and implantation of a multifocal IOL. Hyperopic patients tend to be pleased with this solution; myopes, however, are used to superb near vision and may be much less appreciative of a solution that leaves their near vision slightly compromised.
In young high myopes with deep anterior chambers phakic IOLs have numerous advantages, including preservation of accommodation and the fact that the procedure is additive and, thus, potentially reversible. Retinal detachment is a worry in any intraocular surgery on highly myopic eyes. However, this has not been an issue with phakic IOLs. It is possible that keeping the natural lens in place in young myopic eyes represents a major safety advantage versus clear lens extraction.
An interesting option is also the development of a multifocal phakic IOL. This could provide near and distance vision for older patients while preserving the anatomical integrity of the anterior segment. Angle-supported multifocal IOLs have been implanted, but the results have been less than desired due to difficulty centering the lens. (Decentered multifocal lenses can produce unwanted visual side effects.)
The major advantage of phakic IOLs is that they are an additive procedure and allow for a degree of reversibility if the patient is dissatisfied with the result. If at some point in the future better accommodating IOLs than we have today are developed, the value of reversibility in phakic IOLs will have to be weighed against the quality vision, safety, and lack of reversibility of the improved accommodating IOLs.
The best candidates for phakic IOL implantation are:
- Myopes between 20 and 45 years old with corrections between –8 D and –20 D and anterior chamber depths greater than 3.0 mm.
- Hyperopes between 20 and 40 years old with corrections between + 6 D and + 10 D.
A second group of candidates includes patients with thin corneas and/or asymmetric corneal topographies. In these eyes, preserving the structure of the cornea will decrease the risk of postoperative ectasia. Other potential candidates include eyes with high astigmatism or keratoconus (which can be corrected with toric phakic IOLs ) and eyes with high ametropia following penetrating keratoplasty.
The potential value of intraocular solutions for patients with asymmetric topographies is underscored by a recent report of a low myope with form fruste keratoconus who developed ectasia following PRK.¹ In addition, there will always be patients who are attracted to a procedure that can, if necessary, be reversed, an option this is not available with laser ablation or refractive lens exchange.
The currently available phakic IOLs have achieved a very small market share compared with laser procedures; however it is important to remember that the main indications for phakic IOLs are eyes with high ametropias, and these are far less common than mild and moderate ametropias.
New generations of phakic IOLs , including foldable anterior chamber and iris-fixated IOLs, new designs for posterior chamber IOLs, and the introduction of spherical, spherico-toric, and multifocal optics to these platforms, will increase the commercial development of this interesting refractive surgical option.
1. Malecaze F, Coullet J, Calvas P, et al: Corneal ectasia after photorefractive keratectomy for low myopia. Ophthalmology. 2006 May;113(5):742-6.
Joseph Colin, MD, is professor of ophthalmology at the University of Bordeaux and Chief of Service at the Centre Clinique Ophtalmologique CHU de Bordeaux, France.
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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