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Risks of LASIK

November 2014 by Dr Nita Shah

It is important to understand the risks of LASIK Eye Surgery as you or loved ones consider elective eye surgery. Most patients have a great LASIK experience and spectacular results. That is why LASIK is so popular and why it has the highest percentage of happy patients of any elective procedure ever studied. That is the good news.

The bad news is that some patients do experience problems from their LASIK. Most of these are transient and part of the healing process or not a big deal compared to the freedom from glasses. Some of the risks of LASIK are a big deal and are not transient. That is why you want to have a really good LASIK surgeon.

Those that choose LASIK take comfort in the fact that the problems and risks of LASIK that matter are rare. I have performed hundreds of LASIK procedures. As such, I have a very good understanding of the risks of LASIK.

As you contemplate your LASIK surgery you will either take comfort in the millions that have had outstanding results or hold back because of those that have had troubles.

Sub Conjunctival Hemorrhages

Sub Conjunctival Hemorrhages

The suction rings used to make the flap can cause red blotches to appear on the white part of the eye at the time of surgery. These are resorbed by the body over the course of several weeks and resolve completely.

Risks of LASIK

Target Error Risks of LASIK

The most commonly encountered risk is a slight target miss where LASIK greatly improves your vision without glasses but it is not perfect. In this scenario your vision is good but a thin, part time, pair of glasses would make it even better. This great improvement could be considered a victory or a disappointment depending on your desire for perfection.

Fortunately, if the target error impacts your life, you can usually choose to have the LASIK enhanced by having a small amount of additional laser applied. We offer these touchups at no or low cost for some extended period. The odds of needing an enhancement are affected by the magnitude of your prescription, your desire for perfection, and the quality and kindness of the laser center you choose.

Your laser center should be able to give you the exact percentage of patients they touchup. Be advised that there are two ways to obtain a low enhancement rate:

  • Do meticulous, accurate surgery using the best technology, nomograms, and techniques so it is right the first time, or
  • Make it difficult for patients that need an enhancement to obtain one by discouraging or refusing care. Quality laser centers focus on accuracy and while making medically prudent enhancements readily available to their patients.
Stability of LASIK

Stability of LASIK

One of the risks of LASIK is that your eyes change after your procedure and you need glasses again or an enhancement to your LASIK.

Myopia occurs and progresses as your eye grows longer than ideal. There are two basic types of myopia. Myopia that progresses during puberty and myopia that progresses in the college age years. When your eye stops growing, myopia stops progressing. If LASIK is performed after your eye has stopped growing then the results usually last until cataracts develop in your senior citizen years. The formation of cataract can cause some myopia to return, but this can be corrected at the time of cataract surgery.

A very small percentage of patients have eyes that never stop growing so their myopia progress every year they are alive. LASIK does not stop this process. If these patients do have LASIK, their vision would be excellentat first, but the myopia would slowing begin to return over time.

A small percentage of women have an increase in their myopia with pregnancy. Changes in myopia with previous pregnancies are not predictive of whether you will or will not change in future pregnancies.

Gas permeable contact lenses can squeeze the cornea and create temporary changes in prescription needs. Patients go without their contact lenses for a series of weeks prior to LASIK to allow their corneas to return to their natural shape before surgery. The corneas of most patients stabilize at around one month without contacts. Occasionally, the corneas appear to stabilize, LASIK is performed, and then a year or so later the corneas change again. These changes in prescription could create the need for an enhancement. When I see late changes in prescription it is almost always in a previous gas perm contact wearer or in a patient that is starting to develop cataracts.

Eye Infection

Eye Infection

LASIK patients tend to be healthy with good immune systems so infection is rare. Antibiotic drops are used post operatively to further decrease the chances for infection. About one out of every 5,ooo patients still develop an infection. Usually these are easily treated with topical antibiotics, but can result in corneal scarring if discovered late or if the microbes are resistant, underscoring the need for good hygiene and for keeping all post operative appointments.

LASIK Flap Complications

LASIK Flap Complications

LASIK requires the creation of a thin flap in the cornea. This flap is lifted, the eye is treated, and the flap is repositioned. Within seconds, the eye secures the flap by hydrostatic pressure. The flap becomes more secure over time as collagen fibers tie down the edges of the flap. Complications can arise in creating the flap or with trauma postoperatively.

The initial flap can be too thin, too thick, damaged, or irregular. If the flap created is not acceptable, the surgery can usually be postponed and the vision corrected with a different technique on a separate day.

If you inadvertently bump your eye on the day of surgery, the flap can become wrinkled. If this is affecting your vision, your doctor will smooth it back out as uncorrected flap irregularity of any cause can permanently decrease the quality of your vision. For this reason, the first postoperative visit is particularly important, as it is easiest to correct flap irregularities early rather than latter.

Loose Epithelium

Loose Epithelium

The advantage of LASIK over PRK is that the epithelium (the clear covering on the cornea) is not removed. This allows a faster return of vision and less discomfort. In rare instances, the epithelium will loosen as the flap is created.

Ectasia

Ectasia

The cornea receives its strength from small collagen fibers that crisscross the cornea. Some individuals are born with abnormal collagen patterns that create weak corneas. These weak corneas can progressively lose their normal round shape causing blurry vision. This process is called ectasia and in rare cases may even require a cornea transplant to improve vision. Researchers have discovered that it is relatively easy to strengthen these weak corneas through a process called crosslinking.

It is not safe to create a flap in a cornea that is already weak as this would accelerate ectasia. Modern pretesting machines help surgeons better identify these weak corneas before surgery.

Older machines measured the outer shape of the cornea to test for irregularity. Newer machines, like the Pentacam topographer, also test the inner shape of the cornea. Since irregularity often starts first on the inner surface of the cornea, this technique allows surgeons to better predict who is and who is not a safe candidate for LASIK.

Much of the safety gains in LASIK have come from our better ability to predict who is and who is not a great LASIK candidate. Having said that, the testing equipment is not perfect and some patients still develop ectasia as one of the risks of LASIK.

If you are a vigorous eye rubber, discuss this with your LASIK eye surgeon as this can cause ectasia.

Dry Eye

Dry Eye

Most patients experience dry eye symptoms after LASIK for the first three to six months. During that time, many need to take artificial tears to maintain comfort and visual quality. Almost all patients return to their baseline after that healing process. In rare circumstances, the dryness may persist for longer and impact the consistency of visual quality and the way your eyes feel. Significant dry eye can be life altering.

If you have significant dry eye problems even before LASIK, then you should discuss these symptoms carefully with your eye surgeon prior to LASIK as LASIK may not be right for you.

The good news is that there are a number of different treatments available for those with dry eye.

Quality of Vision

Quality of Vision

Many patients see better after LASIK without glasses than they did before with glasses. This is also true for night driving. However, there are some that technically see 20/20 but feel that the quality of their vision is not as crisp as before surgery or that they have some starbursting with night driving. Usually this is becuase there is a small amount of uncorrected nearsightedness or astigmatism. If the symptoms are mild and more of an observatoin than a problem, then doing nothing is usually the best course of action. If the problems are impacting your lifestlye then glasses, contact lenses, or a LASIK enhancement can be considered.

Nearsightedness or astimgatims are considered lower order causes of defocus. There are other more complex causes of defocus. These are called higher order aberrations. If these are causing a decrease in the quality of your vision, and we can measure the aberrations with an aberrometer, we could consider a wavefront guided enancement to try to improve visual quality.

Residual astigmatims, higher order aberrations, or epithelial irregularity can casue double vision in an eye. Glasses, contact lenses, or an enhancement can ususally correct this problem.

Dry eye can also cause a decrease in the quality of vision

Risks and Benefits of LASIK Eye Surgery

Risks and Benefits of LASIK Eye Surgery

This list is not exhaustive, but it is representative of the most common risks of LASIK. The fact that complications are rare is comforting, but it is important to consider that it doesnt matter if a problem is one in a million if YOU are the one.

As a very experienced LASIK surgeon, you will need to make an assessment of your desire compared to the risks of LASIK to make the right decision for you.

Please contact me if you have further questions or schedule a time to meet if you want to find out your specific risk profile.

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