EyeWorld Asia-Pacific September 2012 Issue

September 2012 9 EWAP FEAturE Views from Asia-Pacific aberration reduction if you can get a good wavefront reading and manage defocus and astigmatism.” His successes in this area have included a patient who was visually disabled and contact lens intolerant; after surgery, the patient had 6/7.5 (20/25) visual acuity, and Dr. Lindstrom had corrected 11 D of astigmatism. In addition to PRK, LASIK is another option, Dr. Berdahl said. “LASIK flaps have the benefit of less likelihood of re-epithelialization difficulties and haze formation,” he said. Toric IOLs under a PK are also an option, Dr. Berdahl explained. “The downside is that if the patient needs a PK in the future, he will have lenticular astigmatism in the IOL,” he said. Dr. Kanellopoulos will use an IOL if the patient has significant anisometropia. He has Kyu-Yeon HWANG, MD, and Choun-Ki JOO, MD Department of Ophthalmology & Visual Sciences College of Medicine, The Catholic University of Korea #222 Banpo-daero, Seocho-Ku, Seoul, 137-040, Korea Tel. no. +82-2-2258-7620, 7621 Fax no. +82-2-533-3801 yeoh424@hanmail.net, ckjoo@catholic.ac.kr E ven a successful corneal transplantation frequently results in many visual disorders, including astigmatism, myopia, anisometropia, and hyperopia. Among these complications, a high degree of astigmatism is the major problem. Surgical intervention is considered if optical methods such as spectacles or contact lenses fail to provide adequate visual rehabilitation. There are some refractive options for the surgical interventions, for example, PRK with MMC and LASIK using microkeratome or femtosecond laser. Photorefractive keratectomy (PRK) has been performed to reduce astigmatism after penetrating keratoplsty (PK), but regression and stromal haze were found to occur over time. Such problems led to the consideration of LASIK as a preferred treatment for refractive errors after KP. The advantages of LASIK compared with PRK include faster visual recovery and a low risk of anterior stromal haze and regression. Therefore, the authors prefer LASIK to manage post-keratoplasty astigmatism. Recent studies show that LASIK with femtosecond lasers have high efficiency in correcting ametropia in post-keratoplasty patients, enabling the treatment of high degrees of astigmatism in astigmatic keratotomy (AK). They claimed that a thinner lamellar cut with femtosecond laser can cause lesser complications such as dehiscence at the graft–host junction. Yet, the femtosecond laser has the limitation for creating a flap in LASIK in the infrared range, which makes the laser unable to pass through a cornea with opacification, resulting in an unsuccessful flap. The phakic IOL or toric phakic IOL is another option. It enables the correction of ametropia without altering the graft. However, longer follow-up is necessary to evaluate the rate of endothelial cell loss and the stability of the refractive result. Deciding a favorable time to perform refractive surgery after keratoplasty is also crucial. Crossliking is helpful to stabilize unstable corneas before refractive surgery. Yet, more research needs to be done to apply this technique in humans As keratoplasty is becoming a routine procedure with higher quality and minimal invasion, refractive surgery is gaining more importance. More studies should be done to make this surgery more predictable and efficient with fewer limitations. Editors’ note: Dr. Hwang and Prof. Joo have no financial interests related to their comments. used the Artisan phakic IOL, the Artiflex toric phakic IOL (both from Ophtec, Groningen, the Netherlands) placed on the iris, the Visian ICL (STAAR Surgical, Monrovia, Calif., USA), and the Cache (Cache AcrySof, Alcon, Fort Worth, Texas, USA/Hünenberg, Switzerland). Dr. Kanellopoulos also commonly uses astigmatic keratotomy (AK) in these patients. In its traditional form, AK is limited in terms of reproducibility and long-term efficacy, he said. “Femtosecond laser-assisted astigmatic keratotomy appears to offer a significant advantage in this technique, and we have been recently using the LenSx femtosecond laser [Alcon] in performing femtosecond laser- assisted and OCT-guided astigmatic keratotomies with excellent success,” Dr. Kanellopoulos said. Before the laser was available for this use, he had used a diamond blade set at 110% of the depth at the 6-mm optical zone. One limitation with the femto- assisted AK approach is that the maximum cylinder that can be corrected is 5 or 6 D. In situations that require higher correction, he recommended using AK along with PRK or LASIK. Dr. Kanellopoulos prefers to perform the AK within the graft, including an optical zone of under 8 mm. Other options include performing the AK on the graft-host interface and on the host tissue. “My personal preference is performing AK within the graft because I find the graft tissue more reliable as far as the refractive outcome,” he said. He added that post-keratoplasty patients require careful monitoring for their refractive stability and the longevity of the graft. This includes discussing with patients the possibility of future enhancements. “The goal here is to achieve not necessarily emmetropia but to reduce anisometropia and reduce significant cylinder to be able to at least bring these patients to a comfortable solution with soft contact lenses or spectacles in order to better function in their everyday lives,” he said. Future possibilities Greater use of the excimer laser for refractive surgery in post- keratoplasty patients intrigues a number of surgeons. “Topography- guided ablations have the potential to revolutionize treatment of all irregular astigmatism, including from PKs. Better ablation profiles and faster treatment times have made me more comfortable with excimer ablations over PKs,” Dr. Berdahl said. The use of the laser for more reproducible incisions helps treat astigmatism, but the challenge is how to afford the technology when there is not reimbursement for it, Dr. Lindstrom said. Use of the excimer laser may help revive the older technique of wedge resection, Dr. Kanellopoulos said. “This was performed in the flat meridian of the very significant astigmatism. It has variable results when done by hand and a diamond blade,” he said. “Femtosecond and OCT-assisted wedge resections would be a much more predictable procedure.” Further evolution of phakic IOLs and greater availability of toric phakic IOLs would also aid in post- keratoplasty refractive surgery, Dr. Kanellopoulos said. Corneal crosslinking may also help in the future to stabilize unstable corneas before refractive treatment, Dr. Berdahl said. EWAP Editors’ note: Dr. Kanellopoulos has financial interests with Alcon. Dr. Lindstrom has financial interests with Abbott Medical Optics (Santa Ana, Calif., USA), Alcon, Bausch + Lomb (Rochester, NY, USA), and other ophthalmic companies. Dr. Berdahl has no financial interests related to this article. Cont act info rmation Berdahl: +1-605-328-3937, johnberdahl@gmail.com Kanellopoulos: +1-917-770-0586, ajkmd@mac.com Lindstrom: +1-952-567-6051, rllindstrom@mneye.com