Presbyopic Along with the remarkable evolution of IOL technologies, other efficacious options have emerged for the treatment of presbyopia. With the continued growth of the already substantial presbyopic market, the development of less invasive and possibly more affordable alternatives may be beneficial for patients and surgeons alike. The three technologies featured herein are at various stages of their development, but all are either currently undergoing clinical trials or are expected to be available in the near future.
Presbyopic clinical trials for multifocal ablations performed with the Star S4 excimer laser (Visx, Incorporated, Santa Clara, CA) using the Customvue platform have been conducted, and representatives of Visx, Incorporated, say they are encouraged by the results. The multifocal design employs the company's Variable Spot Scanning technology to alter the shape of the ablation slightly on the patient's wavefront map. Colman R. Kraff, MD, of Chicago and W. Bruce Jackson, MD, FRCSC, of Ottawa, Ontario, presented data from the US FDA and Canadian studies, respectively, at the 2005 annual ASCRS meeting in Washington, DC. They concluded that the efficacy achieved by the wavefront-driven treatments has positioned multifocal ablations as a safe and stable alternative to incisional surgery for the future.
According to 6-month follow-up data from the Canadian trial, in which both eyes received the presbyopic treatment, 72% of the nine patients (18 eyes) achieved 20/25 or distance UCVA and J3 for near (Figure 1).1 At the 6-month postoperative period, none of the patients experienced a significant loss of distance BSCVA. Dr. Jackson reported that 100% of the enrolled patients were pleased with their distance vision, and 86% were satisfied with the sharpness and clarity of their vision.
Dr. Kraff shared 3-month data on three patients enrolled in the single-center, US Investigational Device Exemption study.2 This is the first US trial to utilize Iris Registration (Visx, Incorporated), a critical element of multifocal treatments, according to Dr. Kraff. In the study, the nondominant eye of each patient was treated with Customvue for hyperopia. These eyes also received the investigational shape for presbyopia. Ablating both a central zone, which is steepened to improve near vision, and a peripheral zone for distance vision achieves the multifocal effect. Although only preliminary data are available, all three patients experienced increased near and distance UCVA in their nondominant eye.
According to the company, the Visx system presently has the broadest treatment range for wavefront-guided vision correction, encompassing low-to-moderate myopia, hyperopia, and all forms of astigmatism. The company hopes to extend this range to include high myopia in the third quarter of this year. Visx, Incorporated, has initiated an FDA clinical trial this year on the correction of hyperopic presbyopia and expects to share updated clinical results in the coming months.
Indications of FDA Trials
Intralens Vision, Inc. (Lake Forest, CA), formerly known as Anamed, Inc., has developed a corneal implant that was granted CE Marking in 2001 for the correction of +10.00 to -10.00D of hyperopia and myopia, with and without astigmatism, and for the treatment of presbyopia. The technology is currently undergoing FDA clinical trials to determine its efficacy in the treatment of hyperopia. In addition, the company is conducting initial international clinical trials for the treatment of hyperopic and plano presbyopia. The intracorneal lens is composed of a biocompatible, microporous hydrogel, which is permeable to nutrients, oxygen, water, and lactic acid. Implanted by means of a sutureless, keratophakic surgical procedure, the lens is intended to create a multifocal cornea by recontouring the surface of the eye (Figure 2).
The lens may be removed or exchanged and may undergo future wavefront-guided laser treatments. In contrast to the LASIK procedure, no tissue removal is necessary to correct patients' refractive errors, and Intralens Vision stresses the minimal learning curve and investment involved in adopting the technology. Furthermore, the company claims that this procedure carries a lower perceived risk for patients than LASIK or conductive keratoplasty (CK; Refractec, Inc., Irvine, CA) yet has a multifocal component that can facilitate intermediate and near acuity along with improvement of distance vision.
Study Results and Technological Development
Results from the initial series of international clinical trials assessing the efficacy of the first-generation design of the implant, previously known as the Permavision lens, in correcting hyperopia were not ideal. A total of 11 eyes received lenses, and five implants were removed due to diffuse perilenticular opacity and a resultant loss of BCVA.3 Intralens Vision has since modified the lens design and platform. The lens' edge was reduced from 20µm to less than 10µm, and the implant now measures between 5 and 6mm in diameter. The titanium preloaded delivery system has also contributed to improved performance, according to the company. In addition to the changes in design and the delivery system, the implantation technique involves a different method of irrigation in order to reduce interface debris.
Stephen C. Kaufman, MD, PhD, of Troy, Michigan, is involved in the FDA phase 2 clinical trials for the correction of hyperopia with the intracorneal lens and presented information on its implantation at the annual ASCRS meeting in April 2005.4 He maintained that, because it is removable and its implantation is simple, the lens is an appealing option in refractive surgery. Dr. Kaufman expressed confidence that any minor problems with associated haze, although not progressive or visually impairing, will be solved by continued alterations of the lens' design and improvements in pre- and posttreatment with topical steroids. Intralens Vision also asserts that treating dry eye with punctal plugs will improve patients' visual acuities.
To date, 35 eyes have received the intracorneal lens in international clinical trials for the treatment of presbyopia. The intended target refraction is 20/40 distance and J1 in the nondominant eye versus 20/20 distance and J3 to J4 in the dominant eye. According to the company, the latest patients have achieved J1 with multifocality at 1 week postoperatively.
NEARVISION CK WITH LIGHTTOUCH
H. L. “Rick” Milne, MD, of Columbia, South Carolina, has developed a new technique with the Nearvision CK (Refractec, Inc.) procedure. Dr. Milne discerned the inverse correlation between the amount of pressure applied to the cornea and the subsequent effect the procedure produced. By administering consistently light pressure, the CK with Lighttouch technique allows surgeons to achieve a more robust effect with fewer spots and treat a larger optical zone. Other benefits include decreases in patient discomfort and induced cylinder, higher patient satisfaction, and patients' achieving superior near UCVA in less time postoperatively.
Dr. Milne and Daniel Durrie, MD, of Overland Park, Kansas, conducted a study of Nearvision CK with Lighttouch that produced statistically significant results (Figure 3).5 Of 67 total eyes, 85% were within ±0.50D, and 97% were within ±1.00D of the target refraction after treatment. These results were superior to those of the CK presbyopia clinical trial that utilized the conventional technique, in which 63% of patients were within ±0.50D and 90% were within ±1.00D of the targeted endpoint. During the past 6 months, 28% of
Dr. Milne's procedural volume has been CK with Lighttouch, a significant increase from his previously reported 10% of monthly volume with CK just 1 year ago.
Dr. Milne believes that Nearvision CK with Lighttouch will be a more attractive option for emmetropic and low-hyperopic presbyopes compared with IOL implantation for economic reasons and because it provides patients with a safer, less invasive procedure for their first surgery. Dr. Milne also credits CK as having an edge over LASIK. “CK is rightly seen as a safer procedure than LASIK, and this is essential to these risk-adverse patients,” he said. “The corneal reshaping of CK also gives distinct advantages over LASIK, with improvement in higher-order aberrations, better contrast sensitivity, and less compromise of distance vision compared to LASIK.”
The Nearvision CK procedure received FDA approval in 2002 for treating hyperopia in patients over 40 years of age and in 2004 for the treatment of presbyopia. Refractec, Inc., recently submitted to the FDA for review an Investigational Device Exemption application on the Lighttouch technique.
1. Jackson WB. Development of the optimal multifocal shape for LASIK treatment for hyperopic presbyopia. Paper presented at: The ASCRS/ASOA Symposium on Cataract, IOL and Refractive Surgery; April 18, 2005; Washington, DC.
2. Kraff CR. Report from the US clinical trials: multifocal Customvue LASIK to treat hyperopic presbyopia. Paper presented at: The ASCRS/ASOA Symposium on Cataract, IOL and Refractive Surgery; April 18, 2005; Washington, DC.
3. Alió JL, Mulet ME, Zapata LF, et al. Intracorneal inlay complicated by intrastromal epithelial opacification. Arch Opthalmol. 2004;122:1441-1446.
4. Kaufman S, Doane J. Limited haze associated with the Permavision Intracorneal Lens. Paper presented at: The ASCRS/ASOA Symposium on Cataract, IOL and Refractive Surgery; April 17, 2005; Washington, DC.
5. Milne HL, Durrie D. Lighttouch for conductive keratoplasty. Paper presented at: The ASCRS/ASOA Symposium on Cataract, IOL and Refractive Surgery; April 18, 2005; Washington, DC.