The correction of presbyopia with excimer laser surgery

Transcription

1 5(3):92 96, 2007 R E F R A C T I V E S U R G E R Y Excimer Laser Correction of Presbyopia: The Final Frontier Gustavo E. Tamayo, MD Bogotá Laser Refractive Institute Bogotá, Colombia Ó 2007 by Lippincott Williams & Wilkins, Philadelphia The correction of presbyopia with excimer laser surgery on the cornea is the ultimate goal for this type of surgery, since all other treatments for refractive defects have been successfully developed and implemented. Surgery with excimer laser is safe and extremely effective with today s standards; therefore, most manufacturer companies are working and devoting great research funds and efforts in the development of a technique to treat this aging defect located inside the eye, in the ciliary muscle, and the lens not in the cornea. Several attempts for correcting presbyopia in the cornea with laser surgery have been made. Most of them have not been successful and in fact can be blamed for the bad reputation of surgery on the cornea for the correction of this refractive problem. However, being excimer laser surgery a widely accepted surgery due to its simplicity and safety, this type of surgery has a definitive role in the future treatment of presbyopia. The treatment of presbyopia with excimer laser until a few years ago was based in a technique called monovision. This technique corrects the dominant eye for distant vision and leaves the nondominant eye for near vision with some degree of myopia. Today, however, most laser manufacturers are studying and developing laser ablations to produce multifocality in the cornea. That is the subject of this article. Address correspondence and reprint requests to Gustavo E. Tamayo, MD, Bogotá Laser Refractive Institute, Calle 114, no Torre B Suite 906, Bogotá, Colombia ( gtvotmy@telecorp.net). The author is paid consultant of AMO VISX Inc. G.E.T. owns the patent for peripheral treatment of presbyopia and is a consultant for Cooper-Vision Inc for special project. HOW THE TREATMENT WORKS Two different changes in the shape of the cornea must be created by the excimer laser to be able to correct or at least to improve the presbyopia defect. As they are changes in shape, they are measured by topography only. 1 Those changes are multifocality and prolateness. The definition of both indicates clearly that they are different topographic concepts and in fact complementary when it comes to improve depth of field (Fig. 1), which is the ultimate consequence of the multifocal and prolate cornea. Anyoblatecornea(flatterinthecenterthaninthe periphery) does not help with near vision. Aging changes the normal negative spherical aberration of the crystalline lens to a less negative and finally to a positive one. The excimer laser treatment of the cornea must produce the change to a negative spherical aberration again to increase the depth of focus. This is traduced in the wave front map for the presence of a negative Z40 and a negative Z60 high-order aberration. TYPES OF TREATMENT FOR PRESBYOPIA Two types of excimer laser treatments have been developed and implemented by different companies. 1. Central treatment: near vision is produced by the center of the cornea and the distant vision is produced by the periphery. 2. Peripheral treatment: near vision is produced by the periphery, and the center is left for distant vision. These 2 types of ablations are the only ones applied by all excimer laser companies, and they are the result of several studies that finally demonstrate that any treatment that produces multifocal and prolate shape of the cornea will work only if it is related to the center of the pupil. Decentered ablations, although may induce the same topography changes, at the same time induce irregular astigmatism that deteriorates the quality of vision to the point to make the vision so bad that patients become intolerant to the correction even in the presence of better near visual acuity. The multifocality and the prolateness of the cornea explain by themselves the reason why 2 completely different and even opposite treatments can work well to correct presbyopia in the cornea. DIFFERENT FACTORIES AND DOCTORS APPROACHES 1. AMO VISX STAR S4. This is the company that has advanced farther in the treatment of presbyopia with 92

2 Excimer Laser Correction of Presbyopia FIGURE 1. Volumetric simulation of a normal depth of field (left side) and increased depth of field after multifocal corneal treatment (right side). excimer laser to the point to have studies in phase 1 of Food and Drug Administration (FDA) approval. In the next section, techniques and results from this company will be presented and discussed H Eye Tech Technovision Excimer Laser Platform. This is a central multifocal laser-assisted in situ keratomileusis (LASIK; PresbyLASIK). It creates a central hyperpositive zone of 1.5 mm, followed by another circumferential zone of 1.5 mm that connects the central area for near vision with the peripheral zone of more than 3.0 mm for distance Central corneal power for near vision creating a Bsmall central island.^ This is a patented ablation profile for Luis A. Ruiz, MD, in Bogotá, Colombia. Its intention is to produce near vision in the center of the cornea and leave the periphery for distant vision. 4. Schwind Eye-Tech Solutions with ESIRIS laser. This software is called PRESBY CAM (Custom Ablation Manager). It uses the principle of balanced multifocal monovision. One eye is treated for distance at the center and near vision from the periphery. The other eye is treated on the center for near and at the periphery for distance The PARM technique, patented by Rozakis and Avalos, has a hyperopic procedure of 6-mm optical FIGURE 2. Postoperative wave front map of an eye treated with the AMO VISX S4 for hyperopia with presbyopia. Small central myopic zone for near; periphery for distant vision. Volume 5, Issue 3 93

3 Tamayo zone and a central myopic ablation of 4.0 mm to reverse the hyperopic treatment. It is called by them a true bifocal ablation Other different approaches from different doctors: Dr Anschutz in Germany: central island and sectorial zones; Dr Oliveros in Bogotá, Colombia 6 : large myopic ablation followed by hyperopic ablation; Dr Telandro in Cannes, France, with a NIDEK laser 7 : ablation profile with central zone for distance and concentric zones for intermediate and near; Dr Alaa El Danasoury with a NIDEK: central zone used to treat the present refractive defect and addition of hyperopic treatment of 7 to 10 mm and to reverse this effect, addition of myopic treatment from 3.5 to 5.0 mm; Dr Cantu in Puebla, using the NIDEK 5000 with different concentric zones; Dr Schelonka in Denver, Colo, creates different zones of different powers as the AMO array multifocal lens; Dr Pinelli in Milan, Italy, patented the PML technique: ablation of concentric zones. THE AMO VISX STAR S4 APPROACH AMO VISX Hyperopia-Presbyopia Multifocal Approach This approach utilizes a proprietary-patented profile from the company to steepen a central zone for near vision and leaves the periphery for distance (Fig. 2). It is intended for hyperopic patients up to who at the same time have presbyopia. It is actually under an FDA clinical trial under the direction of Colman Kraff, MD. An international study was conducted in Ottawa, Canada, by Bruce Jackson with more than a year s follow-up. Seventy-five eyes of 43 hyperopic presbyopic patients were treated with the multifocal approach with LASIK. Mean preop refraction was T 0.58 and FIGURE 3. Wave front map of a hyperopic presbyopic eye. Note the lack of multifocality and the absence of the specific aberrations always linked to a multifocal cornea. 94

4 Excimer Laser Correction of Presbyopia FIGURE 4. Postoperative wave front map of the same eye in Figure 3. The treatment consisted of correction of the hyperopic astigmatism defect plus the addition of the peripheral treatment for presbyopia. The center of the cornea is left for distance vision and the periphery for near. Special mention of the aberration Z40, typical of a multifocal cornea. cylinder of T Mean age of the subjects was 56 years. At 12 months, 96% of the subjects achieved bilaterally 20/25 distance vision and J3 at near vision. Contrast sensitivity returns to normal levels at 6 months, and 83% are within T0.5 diopter of emmetropia. Patient satisfaction is good, and spectacle independence is achieved and maintained. Because of encouraging results from the Canadian studies, this software is already available internationally for any AMO VISX S4 IR and in a clinical trial in the United States for FDA approval. 8 AMO VISX Myopia-Presbyopia Approach In 2001, Gustavo Tamayo, MD, and M. Serrano from Bogotá, Colombia, patented the peripheral approach to leave the center for distant vision and the periphery for near vision (Figs. 3 and 4) The ablation profile creates a high dioptric power peripheral cornea, and it is the periphery of the surface that takes the divergent rays from near and converges them into the fovea, due to its higher power. 9 This patent was licensed to the company. It is the method being tested in Canada for myopia when accompanied by presbyopia, and the results have been very encouraging. In European Society of Cataract and Refractive Surgeons 2006, the author presented the results of the peripheral approach to treat myopia with presbyopia in 54 eyes with a mean follow-up of 35.8 months. The average age was 55.9 years. Although 6 retreatments for near and 7 retreatments for distant vision were included in the presentation, the final result is excellent: 70% of the eyes were J1 or better and 20/ 25 or better monocular, and 100% were J3 or better monocular and 20/40 or better. No severe complications were reported and of particular importance is the fact that no loss of best corrected visual acuity (BCVA) was found. Small myopic shift in 70% of the eyes was reported, and contrast sensitivity visual acuity returned to normal at 3 months. Volume 5, Issue 3 95

5 Tamayo CONCLUSIONS Excimer laser correction of presbyopia can be achieved successfully with today s technology. A lot of research in the area is currently being carried out by all laser manufacturers to the point that this modality of treatment of presbyopia has a place in the armamentarium to fight this aging condition. REFERENCES 1. Wilson SE, Klyce SD. Screening for corneal topographic abnormalities prior to refractive surgery. Ophthalmology. 1994;101:147Y Jackson WB. Development of the corneal multifocal shape for LASIK treatment for hyperopic presbyopia. Paper presented at: ASCRS/ASOA Symposium on Cataract, IOL and Refractive Surgery, Washington, DC, April 18, Alio J. Presbylasik. Paper presented at: The 8th ESCRS Refractive Surgery Meeting, Barcelona, Spain, March Schwind Eye-Tech Solutions. Press release at the ESCRS Refractive Surgery Meeting, Lisbon, Portugal, September 10, Avalos G, Silva A. Presbyopic LASIK: the PARM technique. Chapter 16. In: Presbyopia: A Surgical Textbook. Thorofare, NJ: Slack Inc; 2002:139Y Oliveros G. Multifocal technique for presbyopia. Paper presented at: The 8th ESCRS Refractive Surgery Meeting, Barcelona, Spain, March Telandro A. Presbylasik. Paper presented at: The ISRS/AAO Meeting, Chicago, IL, October 14, Kraff CR. Report from the US clinical trials: multifocal CustomVue LASIK to treat hyperopic presbyopia. Paper presented at: ASCRS/ASOA Symposium on Cataract, IOL and Refractive Surgery, Washington, DC, April 18, Tamayo G, Serrano M. VSS presbyopia treatment. Poster presented at the AAO Meeting, Chicago, IL, October 14,