You are probably NOT a good candidate for refractive surgery if:

o You are not a risk taker. Certain complications are unavoidable in a percentage of patients, and there are no long-term data available for current procedures.
o It will jeopardize your career. Some jobs prohibit certain refractive procedures. Be sure to check with your employer/professional society/military service before undergoing any procedure.
o Cost is an issue. Most medical insurance will not pay for refractive surgery. Although the cost is coming down, it is still significant.
o You required a change in your contact lens or glasses prescription in the past year. This is called refractive instability. Patients who are:

o In their early 20s or younger,
o Whose hormones are fluctuating due to disease such as diabetes,
o Who are pregnant or breastfeeding, or
o Who are taking medications that may cause fluctuations in vision,

are more likely to have refractive instability and should discuss the possible additional risks with their doctor.

o You have a disease or are on medications that may affect wound healing. Certain conditions, such as autoimmune diseases (e.g., lupus, rheumatoid arthritis), immunodeficiency states (e.g., HIV) and diabetes, and some medications (e.g., retinoic acid and steroids) may prevent proper healing after a refractive procedure.
o You actively participate in contact sports. You participate in boxing, wrestling, martial arts or other activities in which blows to the face and eyes are a normal occurrence.
o You are not an adult. Currently, no lasers are approved for LASIK on persons under the age of 18.

Precautions
The safety and effectiveness of refractive procedures has not been determined in patients with some diseases. Discuss with your doctor if you have a history of any of the following:

o Herpes simplex or Herpes zoster (shingles) involving the eye area.
o Glaucoma, glaucoma suspect, or ocular hypertension.
o Eye diseases, such as uveitis/iritis (inflammations of the eye)
o Eye injuries or previous eye surgeries.
o Keratoconus

Other Risk Factors
Your doctor should screen you for the following conditions or indicators of risk:

o Blepharitis. Inflammation of the eyelids with crusting of the eyelashes, that may increase the risk of infection or inflammation of the cornea after LASIK.

o Large pupils. Make sure this evaluation is done in a dark room. Younger patients and patients on certain medications may be prone to having large pupils under dim lighting conditions. This can cause symptoms such as glare, halos, starbursts, and ghost images (double vision) after surgery. In some patients these symptoms may be debilitating. For example, a patient may no longer be able to drive a car at night or in certain weather conditions, such as fog.

o Thin Corneas. The cornea is the thin clear covering of the eye that is over the iris, the colored part of the eye. Most refractive procedures change the eye’s focusing power by reshaping the cornea (for example, by removing tissue). Performing a refractive procedure on a cornea that is too thin may result in blinding complications.

o Previous refractive surgery (e.g., RK, PRK, LASIK). Additional refractive surgery may not be recommended. The decision to have additional refractive surgery must be made in consultation with your doctor after careful consideration of your unique situation.

o Dry Eyes. LASIK surgery tends to aggravate this condition.

Source: fda.gov