EyeWorld Asia-Pacific September 2011 Issue

41 EW CORNEA September 2011 AT A GLANCE • Monovision LASIK is a better option, and ultimately a lens-based option is the best as it gets at the root of the problem—the natural lens’s loss of accommodation and overall stiffening. On the other hand, a multifocal cornea with presbyLASIK can provide enhanced near vision as well as good distance vision correcting myopia, hyperopia, and astigmatism • There are also some downsides to presbyLASIK, the biggest of which, as with monovision LASIK, is the temporal nature of the treatment approach • With the INTRACOR procedure, surgeons change the shape of the cornea, making the central part of the cornea a little steeper, essentially creating a magnifying glass in front of the eye. Without cutting open the corneal surface as would be done for a flap procedure, the surface remains untouched and there is no risk for infection because there’s no way bacteria can get into the cornea • Patients need to know that with current presbyopia treatment procedures, good light conditions are important. Patients always have a near point at a specific distance from the eye, and they need to adapt to this new situation Tae-im KIM, MD Associate Professor, Yonsei University, Severance Hospital 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752, Korea Tel. no. +82-2-2228-3570 Fax no. +82-2-312-0541 tikim@yuhs.ac M ore than just prolonging life span, slowing down or reversing the aging process has become one of our primary concerns. Many people do not want to face the situation where they have to struggle just to read the menu in a restaurant any more. Moreover, even though they do not currently have problems with presbyopia, if they undergo refractive surgery near the age of 40, one may be hit with the immediate need for reading glasses and this presents great obstacles for middle-aged adults undergoing refractive surgery. In general, there are two ways to correct a presbyopic eye; one is by exchanging the crystalline lens with an IOL which is designed to separate light into two or more focal points and the other is by reshaping the cornea. However, when compared with the fast and fascinating progression of rejuvenation medicine, overcoming presbyopia remains a challenge. To create corneal multifocality by excimer laser surgery, there have been many attempts for decades by several excimer laser companies, but most of their endeavors have been unfruitful due to their short term effect and limited accuracy. Herein, this topic introduces recently released techniques that promise to create central corneal multifocality with excimer or femtosecond laser ablation. Even though the new techniques provided quite successful surgical outcomes in the immediate postoperative period, continuing natural lens changes and optically uneven corneas should be properly considered. Also, modifying the corneal shape may induce unexpected problems in subsequent ocular surgery or age-related changes of the macula or optic nerve. Instead of a multifocal cornea, inducing small amounts of myopia in the non-dominant eye is the concept of monovision LASIK. This procedure is relatively safe, avoiding optical irregularity. As with many good things, people with monovision may have some degree of decreased depth perception. Especially in my country, many patients find it hard to adapt to a binocular unpaired refractive condition. Therefore, glasses or contact lens simulation should be tried prior to surgery to determine if monovision is suitable for an individual’s needs and ability to adapt. Lens-based hyperopic correction is the best approach to avoiding the disadvantage of near glasses. However, in cases without any changes in the crystalline lens, reshaping the cornea may be the only solution to overcome the ocular aging process. Because of the limitations of each procedure, for successful management of a patient’s expectations, proper patient education and adequate control of their expectations are critical. Editors’ note: Prof. Kim has no financial interests related to her comments. PresbyLASIK vs. monovision LASIK Even with the positive results the procedure has produced, however, some surgeons have fairly strong feelings against it. “I think there are better ways to treat presbyopia than presbyLASIK,” said D. Rex Hamilton, MD, associate clinical professor of ophthalmology, and director, Laser Refractive Center, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Calif., USA. By creating a multifocal cornea, function is traded for quality of vision, and by performing LASIK or PRK, tissue is permanently removed from the cornea, he explained. Dr. Hamilton said he thinks monovision LASIK is a better option, and ultimately a lens-based option is the best as it gets at the root of the problem—the natural lens’s loss of accommodation and overall stiffening. On the other hand, if a multifocal cornea is created, once a cataract develops later in life requiring lens surgery, the surgeon then has to deal with a cornea that’s somewhat compromised optically. There are also some downsides to presbyLASIK, the biggest of which, as with monovision LASIK, is the temporal nature of the treatment approach. As presbyopia progresses over time, the surgical effect becomes less optimal. Still, according to Dr. Jackson, as North America tends to be a bit more conservative than Europe, presbyLASIK, if FDA-approved, would be embraced as part of a two-stage approach. “I think a lot of surgeons would do [presbyLASIK] first and then, when the patient really does have a cataract, move to cataract surgery,” he said. If presbyLASIK receives FDA approval, Dr. Jackson said it will be very popular because some surgeons are convinced of its value and are already performing it off- label. Shaping without dissecting A different treatment approach from presbyLASIK, INTRACOR makes use of the femtosecond laser to create multifocality in the cornea. Surgeons focus the laser beam at a specific depth without dissecting the corneal surface, said Mike P. Holzer, MD , associate professor and director, refractive surgery, University of Heidelberg, Germany. The procedure changes the shape of the cornea, making the central part of the cornea a bit steeper, essentially creating a magnifying glass in front of the eye, he said. Without cutting open the corneal surface, as would be done for a flap procedure, the surface remains untouched and there is no risk for infection because there’s no way bacteria can get into the cornea, Dr. Holzer explained. This results in an extremely quick recovery time and no risk of continued on page 42