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CRSToday Europe News – April 2009
Conflicting Views About Collagen Crosslinking Therapy
Treating keratoconus with UV-A light and riboflavin to crosslink corneal collagen is a noninvasive and relatively inexpensive procedure. Clinical studies with 3- to 5-year follow-up after corneal collagen crosslinking (CXL) therapy have shown promise for the procedure's ability to halt the progression of keratoconus.1 Although some ophthalmologists have integrated CXL into their refractive practices, others are hesitant because long-term side effects and biomechanical changes in the cornea are generally unknown. For more information, please see this issue's cover focus articles on CXL.
A. John Kanellopoulos, MD, has performed CXL in the laboratory and in his clinical practice in Athens, Greece, since 2002. CXL currently represents 30% of his refractive practice, either as a primary treatment for keratoconus and ectasia or as an adjunctive treatment with PRK and LASIK. "Since 2002, I have applied this technique to more than 800 cases of keratoconus, over 50 cases of post-LASIK ectasia, and several cases of corneal edema and infectious keratitis," Dr. Kanellopoulos explained in an e-mail to Cataract & Refractive Surgery Today Europe. Dr. Kanellopoulos is Director of Laservision Eye Institute, in Athens, Greece; Attending Surgeon for the Department of Ophthalmology at the Manhattan Eye, Ear, & Throat Hospital, in New York; Clinical Associate Professor of Ophthalmology at New York University Medical School; and a member of the CRST Europe Editorial Board.
Looking ahead, Dr. Kanellopoulos believes that once the US Food and Drug Administration (FDA) approves CXL in the United States, it will become a mainstream tool for customizing the biomechanical behavior of the cornea, particularly in refractive surgery. "I think that CXL could become the last step in all future LASIK procedures. We could use this technique to enhance the flap's adherence by crosslinking the central part of the flap to the stromal bed," he said.
CXL is currently the best and only option to stop or minimize the progression of ectatic corneal diseases, according to Thomas Kohnen, MD, Professor of Ophthalmology and Deputy Chairman at the Johann Wolfgang Goethe-University Clinic in Frankfurt, Germany, and Visiting Professor at the Baylor College of Medicine in Houston. Dr. Kohnen is also a member of the CRST Europe Editorial Board. "In most patients, CXL stabilizes ectatic corneal diseases. Patients who experience stabilization after undergoing CXL in one eye often request that I perform the procedure in their second eye to stabilize it as well," Dr. Kohnen said. Additionally, Dr. Kohnen told CRST Europe that he has observed an increase in visual acuity in a few patients following the procedure.
Yet investigators Sally Hayes, PhD, and Keith M. Meek, PhD, of the Structural Biophysics Research Group at Cardiff University in the United Kingdom, claim there are a number of unknown elements about the long-term effects of CXL, and thus further work is necessary. "To the best of our knowledge, there is still no definitive proof that covalent, UV-A—induced crosslinks in the cornea are the basis of enhanced biomechanical strength after CXL treatment,"
Dr. Hayes and Professor Meek said in their article on page 20.
Additionally, Dr. Hayes and Professor Meek contend that two questions still must be answered.1 Are crosslinks confined to collagen, or do they occur nonspecifically? (2) What is the exact rate of connective tissue turnover in the keratoconic corneal stroma? Furthermore, long-term follow-up is needed to measure the durability of the strengthening effect and the potential complications as a result of increasing corneal rigidity, Dr. Hayes and Professor Meek said.
John Marshall, PhD, FRCPath, FRCOphth, the Frost Professor of Ophthalmology and Chairman of the Academic Department of Ophthalmology, Kings College London at Saint Thomas' Hospital, and Nathaniel Knox-Cartwright, MA, MRCOphth, also of St. Thomas' Hospital, contend that CXL excessively increases corneal rigidity. Based on an investigation of the variation in corneal stiffness with age and the effect of CXL, Dr. Marshall and Mr. Knox-Cartwright found that corneal stiffness increased linearly with age, roughly doubling between the ages of 20 and 100 years. They also found that CXL ages the cornea some 600 years.
"Our work shows that CXL increases corneal stiffness more than fourfold. The long-term effects of such a nonphysiological transformation are not yet known," they wrote in their article on page 22. "Clinical studies will hopefully answer this question, but we believe that it is important to develop a method that selectively treats weaker areas within the cornea and ways of modulating the efficacy of the CXL process."
Alcon Received Aspheric Toric IOL Approval, Signed Contract With LCA Vision
The FDA approved the AcrySof IQ Toric IOL (Alcon, Inc., Huenenberg, Switzerland). According to a company news release, the acrylic one-piece lens offers an enhanced aspheric optic that improves image quality and increases contrast sensitivity in cataract patients with astigmatism. Alcon will commercially launch the AcrySof IQ Toric IOL at the 2009 American Society of Cataract and Refractive Surgery (ASCRS) annual meeting in San Francisco.
In other news, under a 5-year contract between Alcon Laboratories, Inc. (Fort Worth, Texas), and LCA Vision, Inc. (Cincinnati), LCA will install Alcon's Allegretto Wave Eye-Q 400 Hz excimer lasers in the company's 75 LasikPlus vision surgery centers by the end of the third quarter, according to a separate news release. Alcon acquired the US rights to the Allegretto laser when it acquired WaveLight AG (Erlangen, Germany) in February 2008.
Bausch & Lomb Signed Two Industry Agreements
Bausch & Lomb (Rochester, New York) and Pfizer Inc. (New York, New York) will copromote both companies' prescription ophthalmic drugs in the United States. Under a 5-year agreement, both company's sales forces will promote Pfizer's Xalatan (latanoprost ophthalmic solution), and Bausch & Lomb's Alrex (loteprednol etabonate ophthalmic suspension 0.2%), Lotemax (loteprednol etabonate ophthalmic suspension 0.5%), Zylet (loteprednol etabonate 0.5% and tobramycin 0.3% ophthalmic suspension), and besifloxacin ophthalmic suspension 0.6%, which the companies said they expect the FDA to approve this year. Pfizer will continue to maintain three midstage development programs in its own pipeline, a joint news release said.
Additionally, Bausch & Lomb has obtained the rights to hydrophobic acrylic polymers made by Santen Pharmaceutical Co., Ltd. (Osaka, Japan), according to a separate news release. Under the terms of the agreement, Bausch & Lomb may commercialize new IOLs made from this material for sale worldwide. Santen reserves the right for the use of these materials in the Japanese market.
AMO Renamed Abbott Medical Optics, Inc.
Abbott (Abbott Park, Illinois) completed its acquisition of Advanced Medical Optics, Inc. (AMO; Santa Ana, California). AMO is now a wholly owned subsidiary of Abbott and has been renamed Abbott Medical Optics, Inc.
In an interview with CRST Europe, Jim Mazzo, president of Abbott Medical Optics (AMO), reiterated that the company will remain an independent entity and continue to provide the full range of refractive, cataract, and corneal products for which AMO has been known. Mr. Mazzo also said that having the size, scope, and global influence of Abbott will allow its strategy to expand. "We will have the financial support to accelerate the development of new technologies," Mr. Mazzo said. "We will continue to grow AMO through our organic pipeline as well as explore other technologies, such as glaucoma implants and retinal devices."
Mr. Mazzo also stressed that AMO will continue to work with the same sales and marketing representatives and customer service team. Thus, the transition should be seamless for AMO's existing clients, he said.
Moreover, Mr. Mazzo believes that the AMO of today will provide ophthalmologists with even greater technologies and resources. "If I was an ophthalmologist, I would be excited about Abbott Medical Optics. Abbott, a powerful and successful company, is entering the ophthalmic space for the first time. Businesses do not invest in spaces by dedicating resources—people, time, and money—unless they know that there will be a positive return," Mr. Mazzo said. "There are many unknown frontiers in our space that we can explore with Abbott. This can only be a positive thing for our doctors."
International Clinical Study to Test Osmolarity Device
OccuLogix, Inc. (dba TearLab Corporation; San Diego), initiated the TearLab Osmolarity System Core Validation Study to demonstrate the efficacy of the system as a practical tool for the diagnosis and assessment of dry eye disease severity, according to a company news release. The TearLab Osmolarity System uses a lab-on-a-chip approach that requires less than 50 nL of tear fluid to measure tear osmolarity.
The clinical study will enroll up to 500 individuals with or without dry eye at 10 sites across the United States, Europe, and Japan. Complete enrollment is expected by the end of the second quarter of 2009, according to a company news release.
Combined Glaucoma, Cataract Surgery Procedure Lowers IOP
The Ex-Press miniature glaucoma shunt (Optonol Inc., Kansas City, Kansas) effectively lowered intraocular pressure (IOP) in patients when the device was implanted under a scleral flap as either a single procedure or combined with cataract surgery, according to a study in the Journal of Glaucoma.1
Elliott M. Kanner, MD, PhD, and colleagues at the University of Tennessee, compared the clinical outcomes of 231 eyes implanted with the Ex-Press miniature glaucoma shunt with 114 eyes that received implantation combined with cataract surgery.
Both groups were treated intraoperatively with mitomycin C.
Patients who received implantation alone were followed for 25.7 ±11.1 months (range, 1–46.2 months). Those who received the combination treatment were followed for 21.9 ±12.5 months (range, 1.9–46.2 months).
At 3 years postoperative, the researchers observed surgical success in 219 eyes (94.8%) implanted with Ex-Press alone and 109 eyes (95.6%) treated with combined procedures (P=.948). Compared with baseline values, the postoperative IOP and number of glaucoma medications were significantly lowered in both groups; however, the change from baseline IOP was significantly greater after Ex-Press implant alone compared with combined surgery (P<.001).
The most common device-related complication was obstruction of the tube (six eyes), which was treated successfully with Nd:YAG laser, the investigators said.
CRST Europe contacted Dr. Kanner to get his perspective on the value of this study for cataract and refractive surgeons. "The Ex-Press implant significantly reduces postoperative complications, specifically hyptonony and complications that can follow from it," he said. "There is also a controlled anterior chamber during the surgery and no iridectomy or sclerostomy, which reduces inflammation and intra- and postoperative bleeding."
Ablation Effective for Myopic Patients With Thin Corneas
Ten-year follow-up data suggests that surface ablation is a safe and effective way to correct myopia in corneas thinner than 500 µm, according to a study in the American Journal of Ophthalmology.1
Laura de Benito-Llopis, MD, of Vissum Madrid in Spain, and colleagues conducted a retrospective study of 75 eyes (49 patients). All patients had a preoperative central corneal thickness (CCT) thinner than 500 µm, had surface ablation to correct myopia, and were followed for at least 10 years. At 3 months and 1, 2, 5, and 10 years after surgery, the investigators evaluated the stability of visual acuity and refraction, predictability, keratometry, safety, efficacy, and postoperative complications.
Before surgery, mean CCT was 481.54 ±15.7 µm (range, 438–499 µm) and mean spherical equivalent was -6.12 ±2.67 D (range, -2.00 to -14.00 D). BCVA significantly improved during the follow-up (P<.01), whereas UCVA showed significant improvement at year 1 and all subsequent visits, the researchers said.
Both sphere and cylinder showed a slight but significant regression (P<.01) between 3 months and 10 years after surgery, according to investigators. Thirty eyes (40%) were within 0.50 D and 43 eyes (57.33%) were within 1.00 D of emmetropia at the 10-year examination.
The safety index improved over the course of the study and was always higher than 0.9. The efficacy index remained stable at around 0.8. Topography did not show signs of corneal ectasia, and keratometry showed no increase in corneal power. Thirty eyes (40%) needed enhancement, the study authors said.
– Compiled by Jennifer Kreatsoulas, PhD, News and Contributing Editor
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