LASIK can be performed on virtually any eye; however, sometimes it is not advisable or even permitted. The reasons for exclusion are legal, medical, psychological, and ocular. It is important that each person considering the surgery be fully informed as to the nature and expected outcome of the surgery. Additionally, it is essential that each perspective patient communicate his/her relevant health information and expectations to the refractive surgeon.

AGE : It is required by the FDA that a person undergoing LASIK must be at least eighteen years old. It is assumed that the refractive error (prescription) of the patient will be fairly stable at this time. Also, since this procedure is essentially cosmetic surgery, attainment of legal age is appropriate in order to provide fully informed consent. There is no upper age limit to LASIK eligibility; neither does it affect the nature or outcome of the surgery.

ENDOCRINE : Hormone fluctuations can affect the refractive error of a person's eye. Surgery during a period of such instability would probably produce changes which would not be correct once the endocrine system returns to normal. Therefore, LASIK is not recommended for women who may be pregnant, nursing, or undergoing changes in oral contraceptive therapy.

HEALTH : The cornea is composed of a matrix of collagen fibers, the same material which comprises tendons and other connective tissue. Therefore, persons who have autoimmune disorders, e.g., rheumatoid arthritis, Sjogren's Syndrome, Systemic Lupus Erythematosis, etc., may be at risk for unpredicted changes following surgery. Other medical problems, such as diabetes mellitus, high blood pressure, heart problems, etc. do not affect the outcome of LASIK surgery.

PSYCHOLOGICAL : Awareness and acceptance of less than a 'perfect' result is essential prior to undergoing LASIK. The results of surgery are usually excellent but there is no guarantee that the surgery will meet or exceed a patient's expectations. The proper mental attitude for the prospective patient is to expect that LASIK will substantially improve the uncorrected visual acuity but glasses may be necessary for some activities.

HERPESVIRUS INFECTION : A history of herpes simplex infection of the eye may be a contraindication to LASIK surgery. It is believed that the virus may permanently reside in nerve cells outside the eye and that any trauma (such as LASIK) might reactivate an infection. However, this area is undergoing change. Studies are being done to see if treatment with antiviral medication prior and after the operation might prevent such a recurrence.Herpes infections of other parts of the body do not pertain to qualifying for LASIK surgery.

PUPIL SIZE : The excimer lasers in the United States currently treat an area of the cornea that measures 7 - 8 mm in diameter. Therefore, it is important that the pupil size be less than the area of treatment. Measurement of the pupil size should be performed with distance fixation in dim illumination. Most of the reported difficulties with glare experienced by LASIK patients come from those with pupillary size irregularities.

REFRACTIVE ERROR : Most persons are either nearsighted or farsighted with some degree of astigmatism. After the age of 42, people also experienced difficulties with focusing at near — this is known as presbyopia. LASIK does not correct presbyopia; reading glasses are a must for older patients following surgery. The range of refractive errors which can be treated are:

Myopia (nearsightedness) : -0.75 diopters to 10.0 diopters

Hyperopia (farsightedness) : +0.75 diopters to +5.0 diopters

Astigmatism (associated with myopia) : 0 to 4.0 diopters

Presbyopia : no treatment (clinical trials now taking place)

It is important not to confuse 'eligibility' with 'desirability'. LASIK is a cosmetic procedure which is expensive and may have side effects and complications. One should carefully weight the plusses and minuses on a percentage basis, mix in the $$$, discuss the idea with loved ones, and only gradually make a decision for surgery.