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LASIK Candidacy

LASIK Candidacy


Generally speaking, candidates for LASIK (laser-assisted in situ keratomileusis) surgery are those who:

  • Are nearsighted, farsighted, or have astigmatism
  • Wish to reduce or eliminate the need for corrective eyewear
  • Are at least 18 years of age
  • Are in good overall health
  • Have adequate corneal thickness
  • Have a stable corrective eyewear prescription
  • Are not pregnant or breastfeeding
  • Do not have glaucoma, or have highly controlled glaucoma
  • Are taking aggressive measures to control dry eye syndrome, or have been rehabilitated following a diagnosis of dry eye syndrome. 

However, as with any medical procedure, there are no absolutes, and the only way to accurately determine whether a patient is an appropriate candidate for LASIK is to undergo an in-depth evaluation by an eye care professional. Today, we are all well aware of the life-changing benefits that many have experienced as a result of this sophisticated refractive surgery. As anyone who has worn glasses or contacts can tell you, the idea of being able to depend on your own eyes is appealing, to say the least.

For the right patient, LASIK can make freedom from corrective eyewear a reality. During initial consultations, my staff will spend at least 90 minutes or more asking and answering questions, and getting an idea of their expectations to make certain that they are candidates for the procedure.

Of course, a LASIK candidate also must feel confident undergoing the procedure. My colleague Jon Peet, M.D. says advancements in LASIK technology have been the single greatest factor in helping to make more patients comfortable with undergoing refractive surgery.

"Wavefront measurements (digital mapping of the cornea) and eye tracking (a safety measure that immediately deactivates the excimer laser if the eye moves to the slightest degree) have contributed to more predictable outcomes, which improves patient confidence and therefore encourages more people to seek treatment," Dr. Peet said. "Meanwhile, this potentially drives down cost to some extent, further broadening access."

Patient education plays a crucial role in the success of LASIK eye surgery. If you are considering taking steps toward permanently correcting refractive errors, it pays to become as familiar as possible with the principles of LASIK, as well as the distinguishing characteristics of a suitable candidate. This knowledge will allow you to ask informed questions and play a more active role in determining if LASIK or another procedure is the appropriate way for you to achieve improved vision.

The LASIK Procedure

The cornea is the dome-shaped front surface of your eye. It is the point at which light enters the eye and becomes refracted. Tiny irregularities in the corneal surface can have a profound effect on how light is refracted, which can result in nearsightedness (having difficulties focusing on far objects), farsightedness (having difficulties focusing on close objects), or astigmatism (vision at every distance is distorted). Your glasses or contact lenses have specific contours, or correction, that are intended to compensate for corneal irregularities, resulting in clearer vision.

LASIK surgery is a process of using an excimer laser to vaporize small portions of the cornea in order to refine its shape. This requires using a special laser to create a small hinged flap in the outermost layer of the cornea (epithelium) to expose the stroma. After reshaping the cornea, the flap is replaced.

Because LASIK involves refining the stroma, and depends on the corneal flap to facilitate healing, having especially thin corneas can preclude some patients from undergoing the procedure.

Corneal Thickness

In the evolution of laser refractive eye surgery, LASIK is preceded by photorefractive keratectomy, or PRK. PRK involves the removal of the epithelium, rather than the creation of a flap, to access the underlying tissue. As such, it requires a longer and less comfortable recovery period, which prompted doctors to begin researching and developing modern LASIK surgery. However, PRK is still commonly used to treat some patients whose corneas are too thin to accommodate a flap.

Fortunately, technology is continuing to evolve, making it possible for some patients with borderline corneal thickness to undergo LASIK. Many practices, such as mine, have adopted the femtosecond laser, a precise tool that replaces the keratome blade in creating the corneal flap. This increased precision makes creating the corneal flap much less invasive, so those who are not candidates for traditional LASIK may be candidates for all-laser LASIK (sometimes called iLASIK). However, in addition to thickness, several other characteristics of the cornea are crucial distinguishing characteristics of a LASIK surgery candidate.

Prescription Stability

If you have had to change your corrective eyewear prescription in the last two years, you probably should not undergo LASIK surgery at this time. Any changes could indicate that your corneas are in a state of flux, and that the results of LASIK surgery could potentially be short lived. I require that patients have a stable prescription for at least two years before moving ahead with refractive surgery.

We find that patients are most likely to have achieved stable vision by around age 22

Although vision can fluctuate at any age, we find that patients are most likely to have achieved stable vision by around age 22. While many 18-year-old patients are anxious to achieve freedom from glasses and contact lenses, it is often recommended that they wait until their mid-20s, increasing their chances of experiencing the greatest long-term benefits of LASIK.

Pregnancy can also cause vision to fluctuate because of the dramatic hormonal changes that take place. This is true even among patients who have 20/20 vision. That is why I always recommend that any patient who is pregnant, or planning to become pregnant, wait until a year after pregnancy to undergo LASIK. By that time, the hormones have usually returned to a normal balance that will no longer affect vision. Meanwhile, I recommend that women who undergo LASIK avoid becoming pregnant for at least 6 months following surgery.

While prescription stability is a major issue among younger patients considering LASIK, patients beyond age 40 have their own unique risks and characteristics that must be considered before moving ahead with laser refractive surgery.


The crystalline lens lies behind the cornea, the colored ring of tissue that surrounds the pupil. It focuses light upon the retina, which generates nerve impulses that the brain eventually perceives as visual images. The lens is composed of water and protein. For reasons that are not entirely understood, the protein within the lens can begin to clump, obstructing vision.

This chronic and progressive condition is called cataracts, and it eventually requires the surgical replacement of the lens with a synthetic intraocular lens (IOL). Your risk of developing cataracts increases dramatically past age 40. Patients diagnosed with cataracts are not necessarily precluded from undergoing LASIK. After a thorough evaluation, the doctor can determine your options.

The advent of all-laser LASIK surgery has made it possible for those who have undergone cataract surgery in the past to undergo LASIK surgery. IOLs contain correction, and can help those who are nearsighted, farsighted, or have astigmatism to see more clearly.

However, some patients with IOLs still require glasses. In these cases, if a patient wishes to achieve 20/20 vision, LASIK can help them achieve their goals.

Conversely, if a patient who has undergone LASIK eventually begins to develop cataracts, modern cataract surgery makes it possible to replace the crystalline lens without affecting the corneal refinements created during LASIK.

Monovision LASIK

Monovision LASIK is a treatment that was developed to help patients with presbyopia, a condition that usually presents after age 40, in which the crystalline lens begins losing its ability to focus on close objects.

I often receive inquiries from professionals age 40 or older who must spend considerable time at work reading, including educators, attorneys, and clergy. LASIK is most effective for correcting distance vision, but there are ways to use this treatment to help those who want better close-up vision.

True monovision involves correcting the dominant eye for distance vision, and correcting the other for close vision. Patients can gain an understanding of the effects of monovision by wearing two different prescriptions of contact lenses during a trial period. If a patient does not find this imbalance agreeable, I may recommend modified monovision. In this instance, I will back off a little and just preserve some reading power in one eye, which usually satisfies the patient's desire to reduce their need for reading glasses, but with a less pronounced difference in focusing ability from one eye to the other.

Dry Eye Syndrome

If you do not produce enough tears to keep the eye adequately lubricated, or if one of the layers of your tears - water, mucus, or oil - is out of balance, it can result in constant irritation, redness, excessive tear production, and other symptoms. Dry eye syndrome is fairly common - in fact, more than half of the patients who approach my practice about LASIK are unaware that they have dry eye syndrome. They just know that wearing contact lenses is very uncomfortable.

All patients will experience some degree of dry eye following LASIK surgery

This condition must be controlled before a patient can safely undergo LASIK, because dry eyes can seriously impede the healing process. I pursue dry eye diagnosis very aggressively during pre-LASIK consultations to make certain dry eye is not missed. In some cases, the eye can be rehabilitated through procedures that close the tear ducts. Meanwhile, if a patient is aggressively taking care of dry eyes with treatments like prescription eye drops, artificial tears or punctual plugs, they may be able to safely undergo LASIK.

It should be noted that all patients will experience some degree of dry eye following LASIK surgery. It usually corrects after a couple of months.


Aqueous humor is a fluid that maintains pressure within the anterior chamber, the space between the lens and the cornea, which is also occupied by the iris. Glaucoma occurs when this fluid cannot properly drain, causing pressure to build within the eye. This pressure can damage the optic nerve, leading to compromised vision or blindness.

Patients with controlled glaucoma may be able to safely undergo LASIK.


Virtually anyone who wears glasses or contact lenses would probably choose to have 20/20 vision using their own eyes. However, those in certain professional occupations can be especially suited for LASIK eye surgery because their jobs are easier to perform when unencumbered by corrective eyewear. This can include technicians of all stripes, as well as physicians and other medical professionals. LASIK can also offer tremendous benefits for those who love to take part in outdoor activities such as skiing and diving.

In Her Own Words: Julia's LASIK Pre-screening

Julia is a patient of mine who recently underwent LASIK surgery. She wasn't very familiar with the details of the procedure, so we had a lot to review during her consultation.

"I knew nothing about LASIK prior to my consultation, so I guess you could say I went in blind, no pun intended," she said. "All I was sure of was that I was tired of not being able to see well, and feeling like I was missing out on life. The consultation was informative and exciting."

As always, we conducted a battery of tests to make certain that she was a candidate for surgery.

Prior to meeting with Dr. Clark, I had not considered conditions like glaucoma or dry eye to be a factor in candidacy

"Prior to meeting with Dr. Clark, I had not considered conditions like glaucoma or dry eye to be a factor in candidacy," Julia said. "The consultation was helpful in fully explaining every aspect of LASIK, from general procedure information to specific details regarding both of my eyes."

Julia was fortunate to have no issues with glaucoma or dry eye that would preclude her from undergoing surgery.

"Preparation was easy," she said. "There were some appointments prior to surgery in order to get proper measurements and readings. The staff was so knowledgeable, and that made me feel comfortable. You are given eye drops and specific instructions for their use before and after the procedure. Dr. Clark and his staff are very clear on the entire process, so you know exactly what to expect every step of the way."

Make Sure LASIK is Right for You

LASIK has helped millions to experience a better quality of life, but it is not suitable for everybody. If you suffer with nearsightedness, farsightedness, or astigmatism, and would like to reduce or eliminate your dependency on glasses or contact lenses, consult with an eye professional. Your refractive surgeon and his staff should spend ample time examining your medical history, asking plenty of questions about your health and goals, and, of course, listening to your concerns and answering all of your questions.

Advancements in medical technology have made it possible for more men and women than ever before to safely undergo LASIK surgery. However, if your surgeon determines that you are not a candidate, there are alternatives that can help you reduce your need for corrective eye wear. There is no better way to determine your candidacy for LASIK than to select a reputable, credentialed ophthalmologist. Listen to friends' recommendations, conduct extensive online research, and don't be afraid to consult with more than one surgeon to determine if LASIK is the right way to reach your goals.

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