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Advances in refractive surgery for presbyopia reflect new choices, future possibilities
 Michael C. Knorz |
Presbyopia affects all of us, and the gradually increasing disability to read reminds us that we are getting older. With the often-cited baby boomers approaching the age of presbyopia, there will be a huge demand for corrective surgery in the coming years. What is there to offer?
Laser treatment options include CK, monovision LASIK, and aspheric or multizonal ablations, sometimes called presbyLASIK. CK is typically used in one eye of emmetropic patients to create monovision, but its effect is not lasting, and it is therefore rarely used today.
Monovision LASIK is now the most frequently used procedure to correct presbyopia because of a high success rate, its lasting effect and the lack of any visual side effects such as glare or halos or reduced contrast sensitivity. Monovision LASIK cannot, however, correct the full range of presbyopia, being limited to about 1.5 D.
PresbyLASIK describes a variety of aspheric or multizonal ablation profiles designed to provide an additional 1 D to 2 D of depth of field by creating a multifocal cornea. Clinical results are reported to be good using various laser systems.
IntraCor (Technolas Perfect Vision), an intrastromal femtosecond laser procedure, also creates a multifocal cornea by inducing negative spherical aberration.
As a note of caution, it must be kept in mind that any multifocal corneal shape causes visual side effects such as halos and ghosting and that it is sometimes difficult to reverse the procedure in case the patient is unhappy about these side effects. Therefore, patient selection is important, and a multifocal laser treatment is not indicated for every patient.
Another surgical option is the implantation of an intracorneal inlay. There are currently three different inlays available. Inlays are placed under a flap or inside a pocket in the nondominant eye. Inlays are attractive because of the minimally invasive technique and potential reversibility, but they also present a compromise with some side effects.
Presbyopia-correcting IOLs include multifocal and so-called accommodating IOLs. Multifocal IOLs offer the largest depth of field, providing both excellent distance and near vision, but there are some side effects, such as halos, which limit their use in certain patients. On the safety side, a multifocal IOL can be exchanged for a monofocal IOL if visual side effects are disabling, which is an advantage over a multifocal laser treatment. Accommodating IOLs show no halos but offer much less depth of field and are therefore usually combined with a mini-monovision approach.
In my refractive practice, monovision LASIK is still the most frequently used procedure to correct presbyopia. It is closely followed by multifocal IOLs, because they provide full reading ability. I also use accommodating IOLs such as the Synchrony (Abbott Medical Optics) with increasing frequency. The Kamra inlay (AcuFocus), combined with LASIK to create some mini-monovision, is used in hyperopes up to 2 D, and IntraCor as well as multifocal ablations are performed in selected patients.
What else is on the horizon? Intralenticular femtosecond laser treatment to soften the aging crystalline lens is now entering clinical studies and may enable us to address the cause of presbyopia, but it will take a few more years to become available. There is also a lot of research going on in the field of presbyopia-correcting IOLs, and many new IOLs are expected to be introduced in the near future.
- Michael C. Knorz, MD, can be reached at FreeVis LASIK Center, University Medical Center, Mannheim, Germany; +49-621-3833410; fax: +49-621-3831984; e-mail: knorz@eyes.de.
- Disclosure: Dr. Knorz is a consultant for Technolas Perfect Vision and Abbott Medical Optics.