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What is laser vision correction?
Laser vision correction is a collective term used for refractive surgical techniques called PRK (photorefractive keratectomy), LASIK (laser in-situ keratomileusis), as well as modern variations on PRK called Epi-LASIK, LASEK and others. All procedures use the same excimer laser and can treat myopia, astigmatism, and hyperopia.
Why laser vision correction?
Millions of people have improved their quality of life with laser vision correction by reducing or eliminating dependence on glasses or contact lenses. They no longer have to settle for daily blurry vision upon wakening, or while swimming or bathing. Patients enjoy freedom to participate in sports and a cosmetic improvement without the hassles of contact lenses and spectacles. Many of our patients can no longer tolerate contact lenses or have had contact lens-related complications, such as corneal infections or damage from overwear. Some seek laser vision correction for safety during emergencies, such as during an accident or other instance when broken or lost glasses or contact lenses can be a handicap.
How does the laser work?
Both PRK and LASIK use the same excimer laser, which was developed by IBM in the 1980’s for etching microcircuitry on computer chips. Since then, the computer-controlled excimer laser has undergone numerous medical trials to prove its efficacy and safety in sculpting the cornea to treat focusing problems of the eye. The excimer laser is a special “cold” invisible laser that removes precise amounts of corneal tissue without causing heat damage and without penetrating into deeper tissues of the eye.
Are there special concerns if I wear contact lenses?
Contact lenses change the shape of your cornea and can cause imprecise measurements, treatment, and recovery. Therefore, it is important to discontinue contact lens wear before your refractive evaluation AND before your laser vision correction procedure as follows:
- Soft contact lenses for 2 weeks
- Extended wear contact lenses (that you sleep in) for 3 weeks
- Rigid gas permeable lenses for two weeks, plus a week for every decade of contact lens wear
If you find it difficult to discontinue your contact lenses, speak to us about possible solutions. For example, rigid contact lens wearers can be temporarily fit in soft contact lenses to decrease the time in glasses before surgery. We may have glasses that you may borrow if you do not have any.
What about reading glasses? What is monovision? What is stereovision?
Refractive surgery will not change your need for reading glasses that occurs naturally between 40 and 50 years of age. People in this age group can still be excellent candidates--but they may require reading glasses after surgery, especially if they previously wore bifocals, wore reading glasses, or took off their glasses to read. One alternative is to correct one eye for distance and the other for near, which is called monovision. Not everyone can adapt to this type of vision, and there is some loss of depth perception, but monovision is the only way to rid the need for reading glasses. We sometimes recommend a trial with contact lenses, which can be fit by our contact lens specialists, to see whether monovision works for you.
Stereovision is a popular compromise. The dominant eye is treated for distance, and the non-dominant eye is treated for an intermediate range. This allows for depth perception and "on-the-go reading vision," such as for price tags, cell phones, and menus. However, reading glasses will be required for prolonged reading.
Sometimes, we may recommend cataract surgery or clear lens extraction. This surgery is more involved, but makes more sense in some patients with high corrections or over the age of 53. Some of these patients enjoy both near and distance vision without glasses with intraocular lens implants such as Restor® and crystalens®. Dr. Mandava performs these procedures at Greenwich Hospital.
Are there any side effects with laser vision correction?
The most common side effect is mild dry eye which can be treated with lubricants. This leads to gentle fluctuations in vision, but usually minimal to no discomfort. Occasionally, the dry eye is more severe, especially in those with pre-existing dryness, and requires further attention. Dry eye is almost always temporary but may take months to resolve. This side effect is less pronounced in PRK and Epi-LASIK. Another side effect is glare or haloes around lights, especially at night. Most glasses or contact lens wearers already have glare that is unnoticed or not bothersome. After LASIK, mild glare is common in the first weeks, though rarely a problem, and fades over the first few months. This side effect is more pronounced in Epi-LASIK and PRK. One study showed about 10-15% of people to have more noticeable glare, about 10-15% to have improved glare, and the rest to have the same amount of glare as before LASIK. Significant glare that affects lifestyle is very uncommon (<1%). Glare issued have decreased significantly over the years with advancements such as larger optical zone sizes and CustomVue™ treatments.
What are the risks?
Refractive surgery has been available for decades. The main reason that doctors and patients have embraced laser vision correction is a decrease in risks to a reasonable level.
- Overcorrection, undercorrection, or regression (return of some refractive error) are possible and may require an enhancement procedure to fine tune vision about 5% of the time (see below).
- Corneal Haze is a risk with PRK and Epi-LASIK for high amounts of treatment. A medicine called Mitomycin-C is sometimes used to decrease corneal haze. This risk is very rare after LASIK, which is the main reason that LASIK is more commonly recommended for high treatments.
- An irregular flap occurs less than 0.2% of the time after LASIK. In such a case, the flap is replaced without completing the laser. After a few months or more, LASIK is usually successfully completed. This complication never occurs with Epi-LASIK or PRK.
- A rare complication is called ectasia, where the cornea has increased elasticity and does not hold it’s shape. We screen carefully with advanced tools (Pentacam) to find those who already have or are prone to this. For some borderline cases, we recommend Epi-LASIK or PRK, which disrupts few corneal fibers (since there is no flap), and is less prone to cause ectasia. Ectasia causes visual disturbances and blurriness that can usually be treated with a hard contact lens.
- A significant decrease in best-corrected spectacle visual acuity occurs in less than 1% of treated eyes from scarring, infection, a flap complication, or other causes. Typically, eyes that fit into this category have much improved unaided vision, despite the complication. However, glasses cannot improve vision to the level possible before the procedure. Of these patients, the vast majority has vision correctable to 20/40 or better and is able to function normally.
There are other, less common risks. I am frequently asked, "What is the worst that can happen?" The answer is an unusually severe infection that requires a cornea transplant. I have never seen this occur, but as a corneal specialist, I have successfully performed numerous cornea transplants for similar infections caused by contact lens wear or trauma. I am not aware of any reports of complete blindness after laser vision correction.
How long is the recovery time?
For LASIK, the initial healing period is 12 to 24 hours. Typically, there is a minimal foreign body sensation over this period, but some patients have no discomfort at all. About 90% of patients have functional vision and are comfortable after one day. A good estimate of final vision occurs in about 2 weeks, but vision may continue to stabilize over a 3-month period. Most people require eyedrops for less than a week. After LASIK, most people can return to work after a day or two.
For PRK and Epi-LASIK there is an initial healing time of 3 to 5 days when there is usually some discomfort, such as foreign body sensation, soreness, and sensitivity to light. Vision is usually foggy these first days. After 3 to 5 days, vision usually clears to a functional level and the bandage contact lens is removed. Maximum visual improvement may take 2 to 3 months, and sometimes more. During this time, eyedrops are used at tapering doses. After Epi-LASIK, most people can return to work in 3 to 4 days, but their vision is not yet optimal.
Will the procedure ever need to be repeated?
About 5% of the time, there is a residual refractive error or regression which requires an enhancement procedure for fine tuning vision. This occurs due to human variability in response to the laser and healing patterns. The need for an enhancement is determined at about the 4-6 month visit. Because the degree of treatment is usually small, the chances of 20/20 vision are even better than after the first procedure, and enhancements are usually very successful.
Can I have both eyes treated at once?
Most patients choose to treat both eyes at once with LASIK or Epi-LASIK. Advantages of bilateral LASIK include decreased total recovery time and balanced vision during the recovery. However, there are slightly increased risks, and it is more difficult to predict when functional vision will return. I recommend one eye at a time in cases where I expect a longer visual recovery. We will discuss your options and decide together what is best for you.
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