Cataract Surgery After LASIK

There are many names for laser vision correction (LVC) in use today. The most common is LASIK, which stands for laser in-situkeratomileusis or laser-assisted in-situ keratomileusis. Others include photorefractive keratectomy (PRK), advanced surface ablation (ASA), sub-Bowman’s keratomileusis (SBK) and laser-assisted sub-epithelial keratomileusis (LASEK). They all use an eximer laser to achieve the same result: correction of a pre-existing refractive error to reduce or eliminate dependence on glasses or contact lenses.

LVC is an excellent procedure if you are an appropriate candidate. However, if you have undergone or plan to undergo LVC, you should know how it relates to cataract surgery. IOL calculations are based on a number of individual eye measurements and several estimates that determine what power of IOL to place in your eye after cataract removal. One of these measurements is the power of your cornea. This is important, because after LVC, the power of the cornea is changed. This is how the refractive error of your eye is altered to improve your uncorrected vision. By selectively molding the shape of your cornea, the refractive power is adjusted to better focus light on the retina thereby decreasing your dependence on glasses.

The technology used to measure the power of your cornea has difficulty getting exact measurements after LVC, because of the altered architecture of the cornea. There is nothing wrong with your cornea, just with the way in which it is measured. Fortunately, there is now new technology available and under development that significantly reduces this error. But for now, it is important that you retain your original eye measurements prior to LVC, and your postoperative measurements once your eye has stabilized after surgery. This includes your refractions and your corneal power measurements. With this information, your cataract surgeon can make adjustments to the measured corneal power, which can then be used to calculate your IOL power. In most cases, this is effective, but is still slightly more unpredictable than in patients who have not undergone LVC. Therefore, there is a greater risk of an unexpected refractive outcome (a glasses prescription that is stronger than what was anticipated) in patients who have undergone LVC. This can be remedied either with an IOL exchange, a laser enhancement on the cornea (a “touch up” in the refraction), a “piggyback IOL” (a second IOL placed in front of the first), or glasses and contact lenses. These are all acceptable ways to address an unexpected refractive outcome after cataract surgery in the setting of prior LVC, but keep in mind that if you have previously had LVC, you may not be a candidate for an enhancement, so this may not be an option for your eye.

© Vision Information Services, LLC, Mooresville, NC 2012