Presby-LASIK was introduced as a treatment for presbyopia about 1 decade ago. These procedures use the same surgical approach as standard LASIK but, instead of a monofocal result, a multifocal surface is created on the cornea in an effort to increase depth of focus and reduce spectacle dependence, in this case for near vision. Presby-LASIK ablation profiles are generally designed to steepen the central cornea for near vision and target the peripheral cornea for distance vision.1 Patients with hyperopia or myopia typically respond best to presby- LASIK; however, it can be used in most eyes with success, whatever their preoperative refractive status.
Because presby-LASIK is a relatively new treatment, not many of my patients have reached the age typical of cataract surgery. Having said that, these patients will eventually require cataract surgery, and developing a strategy now for these cases can be beneficial. Below are my preliminary thoughts on how best to approach cataract surgery in presby-LASIK patients.
APPROACH TO CATARACT SURGERY
Select a monofocal or accommodating lens. First and foremost, I would never implant a multifocal IOL in an eye after presby-LASIK. With the induction of aberrations and decrease in contrast sensitivity resulting from this combination of lenticular and corneal multifocality, chances are high that the patient would be unhappy after surgery.
The ideal strategy would be to customize the asphericity of the IOL to match the patient's corneal asphericity; however, that is impossible at this time. The second-best strategy is to aim for an end result of neutral asphericity of the IOL. One way to do this is to select a monofocal IOL with an aspheric profile that best balances out the preexisting asphericity. For instance, our presby-LASIK technique induces either no aberrations or negative asphericity. If no aberrations are induced, I would select a monofocal IOL with negative asphericity, such as the AcrySof IQ (Alcon Laboratories, Inc.), but if negative asphericity is induced I would select a monofocal IOL with neutral asphericity, such as the Akreos MI60 MICS IOL (Bausch + Lomb).
I would also consider implanting an accommodating IOL, as these patients typically do not want to give up their ability to read at near. Additionally, they do not want to wear glasses after surgery, which is evident from their election of presby-LASIK to begin with.
Target refraction. A target refraction of -1.00 to -1.25 D in the nondominant eye and -0.50 D in the dominant is advisable to create a mini-monovision.
IOL power calculation. I typically use the SRK/T formula for IOL power calculation. Although corneal changes after presby-LASIK occur in the central cornea, most corneal topographers do not image the central cornea, and therefore there is no reason to use a different IOL power calculation in eyes with low ametropia. However, for eyes that previously required a correction of more than 2.00 D, I would suggest following the recommendations of the ASCRS online calculator and/or measuring the central 2 mm K values, selecting the flatter for previously myopic patients or the steeper for previously hyperopic patients.
Pay attention to corneal topography. Presby-LASIK produces a multifocal corneal profile, but several years after the procedure, epithelial proliferation can regularize the corneal profile. Therefore, in some cases, it is not surprising to find that corneal topography no longer reveals the surgically induced multifocality. In these cases, it might be possible to use a multifocal IOL, but I still would not suggest it.
Identify and treat dry eye. Studying the ocular surface before cataract surgery is crucial, especially in eyes that have previously undergone refractive surgery. I aim to take good care of the ocular surface, which includes avoiding the use of topical medication as much as possible (I prefer to use intraocular mydriatic solution) and limiting the use of topical anesthetics.
In eyes with ocular surface disease, I would choose to delay cataract surgery until the deficiency is properly treated. Again, in these cases, I would never implant a multifocal IOL.
Avoid inducing astigmatism. Residual astigmatism is usually not a problem after presby-LASIK if the refractive surgery targeted astigmatic correction. Therefore, we are especially careful not to induce astigmatism during cataract surgery in these eyes. Using a microincision cataract surgery (MICS) technique can minimize induced astigmatism and provide patients with quicker visual recovery after surgery.
Much evolution in refractive surgery has occurred in the past 10 years, and so the patients we operated on 10 and even 5 years ago are different from the patients we operate on today. Paying special attention to corneal topography will help us define the changes created by multifocality, and we can then tailor the cataract surgery procedure to the patient's specific conditions.
My particular advice for cataract surgery in presby-LASIK eyes is to check for corneal ocular surface aberrations and to rely on corneal aberrometry and corneal topography to characterize corneal multifocality before surgery. I currently do not recommend implanting multifocal IOLs in these eyes, but I would consider an accommodating IOL if the situation permitted. Lastly, the rule for IOL power calculations following presby-LASIK is to use SRK/T in eyes with low ametropia and the ASCRS online calculator if the preoperative refraction was greater than 2.00 D.
Jorge L. Alió, MD, PhD, is a Professor and the Chairman of Ophthalmology at the Miguel Hernandez University, Alicante, Spain, and Medical Director of Vissum Corp., Spain. Professor Alió did not provide financial disclosure information. He may be reached at tel: +34 96 515 00 25; e-mail: email@example.com.
- Ortiz D, Illueca C, Alió JL. PresbyLASIK versus multifocal refractive IOLs. Ophthalmology Times Europe. http:// tinyurl.com/c7j5gou. Accessed August 2, 2012.