Cataract Surgery after LASIK
LASIK reduces nearsightedness by lifting a flap of cornea, reshaping the corneal tissue beneath the flap with an excimer laser, then replacing the flap. The anterior curvature of the cornea is lessened, making the eye less nearsighted. If you have had LASIK, there are important issues that can come up before and after surgery.
1. Prior LASIK makes it harder to determine the degree to which cataract surgery will improve your vision
Cataracts cause glare, reduced contrast, and a change in your refraction. All of these things can also occur after LASIK. It can be difficult on clinical exam to determine how much each of these symptoms is due to the cataract, and how much is due to prior LASIK. This makes it more difficult to determine the need for surgery and the prognosis for improvement. If you had LASIK years ago, and have only noticed symptoms recently, then it is more likely that your symptoms are due to cataracts. Symptoms of glare and reduced contrast, if due to LASIK, will not get better with cataract surgery.
2. Prior LASIK makes it harder to determine the correct power of lens to put in the eye
By flattening the central cornea, LASIK introduces a change in the simple, natural parabolic shape of the anterior cornea. This makes it harder to determine the exact refractive power of the lens that will be placed in your eye during surgery. Surgeons miss their refractive targets more often in patients who have had LASIK. As a result, you may come out more nearsighted or farsighted than expected.
3. LASIK causes dry eye, and cataract surgery can make this worse
LASIK causes dry eye in some people. There are several reasons for this. Normal tearing requires good corneal sensation, and LASIK cuts some of the nerves necessary for corneal sensation. Also, LASIK flattens the central cornea, which destabilizes the tear film. Cataract surgery can also make dry eye worse in some cases. Your risk is affected by how much nearsightedness was treated. If the first number of your pre-LASIK glasses prescription had a number greater than -6.00, you are at higher risk for dry eye. Risk is also higher for postmenopausal women.
4. Focus takes longer to stabilize after LASIK
The refractive result from your cataract surgery typically stabilizes within a week or two if you have not had LASIK. In patients who have had LASIK, the refractive result may fluxuate over a month or two. This might delay decision making for the second eye.
5. A history of LASIK may reduce your options for presbyopia correction
Refractive precision is essential to the success of presbyopia correcting lens technology- and is more difficult to achieve after LASIK. Also, glare and halos may be present after LASIK, and these symptoms can be made more obvious with presbyopia correcting lenses.
LASIK makes it more difficult to assess the need for surgery, because the side effects of LASIK and the symptoms of cataract are similar. After cataract surgery, the refractive outcome takes longer to stabilize, and is less predictable. Dry eye, which can be caused by LASIK, can get worse. Any glare and reduced contrast that is due to to LASIK will persist after cataract surgery. Satisfaction with multifocal lenses and extended depth of focus lenses is often less.
None of these issues are necessarily deal breakers when it comes to presbyopia correcting lenses. Next we will look at how to approach presbyopia correcting technology if you have had LASIK.
What you can do
Ask your surgeon to discuss their plan for managing the special issues encountered by post-LASIK patients. Specifically:
1. Do you have state-of-the-art equipment for measuring the cornea and length of the eye? State-of-the-art assessment tools such as the Zeiss IOLMaster 700 or Lenstar LS900 provide more detailed corneal information than their predecessors. These systems are not the only ones on the market, but are the ones you are most likely to encounter in the United States.
2. Is your operating room set up to measure the length of the eye during surgery with intraoperative aberrometry? Intraoperative aberrometry systems measure the eye during cataract surgery, after the natural lens has been removed. This has been shown to improve the refractive accuracy of cataract surgery, which is a particularly difficult problem if you have had LASIK. Please note that most surgeons, including many of the best, do not have access this technology.
3. How do you measure my dry eye preoperatively and how do you manage dry eye postoperatively? Dry eye can be an issue for all patients after cataract surgery, but is particularly pronounced in post LASIK patients- and managing it is particularly important to the success of presbyopia correcting lenses.
4. If the postoperative focus is not what we had agreed upon, what is your plan for fixing it? Even the very best surgeons experience some variability in their results. If your vision does not come out like you expected, you and your surgeon may need to work together to refine the result. Options might include repeat LASIK, intraocular lens exchange, and nonsurgical methods such as contact lenses or glasses.