Yes. Cataract surgery is possible after LASIK surgery. However, in cataract surgery, calculations are needed to determine the ideal power of the lens used to replace the cataract. These calculations depend on assumptions that are no longer valid after LASISK and other refractive surgeries. As a result, targeting a certain vision outcome (such as not needing glasses to see far away) is harder.
Many formulas can be used to help with the changes due to refractive surgery. Although they are helpful, they are generally not very accurate. To improve the calculations, some formulas use the clinical information from the refractive surgery. However, most of the time, this information is not even available. The latest generation of formulas take advantage of the most accurate methods of measuring the power of the cornea, the front shell of the eye.
Some instruments can only measure the front surface of the cornea. Since this is changed in refractive surgery, it is difficult to determine the cornea’s true power. More advanced instruments can now also measure the back surface. The latest formulas utilize the information from both surfaces for the most accurate calculations.
Another way to improve the outcome of the calculations is to use the ORA intraoperative aberrometer. The eye can be thought of as needing a certain refractive power to see clearly. If the eye has too much or too little refractive power, images are blurry and the eye needs some sort of refractive correction, such as glasses, to bring images back in focus.
During cataract surgery, after the cloudy cataract has been removed, ORA can be used to measure the true refractive power of the eye. In essence, ORA determines the strength of the glasses needed to allow the eye to see clearly. With this measurement, ORA can then calculate the actual power of the intraocular lens needed for the desired refractive outcome. The only variable that ORA cannot control is the actual location where the new intraocular lens will settle inside the eye. Each eye will heal differently, and that variation will lead to slight variations in the final refractive outcome.
Lastly, the selection of the intraocular lens can play a critical role in determining how happy a patient is after cataract surgery. Some intraocular lenses are more forgiving with vision even if the refractive outcome is not completely perfect. Other intraocular lenses may allow for more aggressive targeting of a specific desired refractive outcome. For example, the power of the Light Adjustable Lens can be modified with ultraviolet light weeks after it has been implanted, allowing a more custom match for the refractive patient.
Choosing the intraocular lens power can be challenging at times, and refractive surgery adds another layer of difficulty. At the San Jose Eye Institute, we believe that in choosing lens powers, more information is always better — from gathering redundant data points with different machines, to calculating lens powers with multiple formulas, to using the ORA intraoperative aberrometer. Even with the Light Adjustable Lens, we want to get as close to our ideal target as possible. With good clinical judgement, appropriate intraocular lens selection, and active patient participation, many times, the optimal refractive outcome can be achieved successfully, even following refractive surgery.