Checks for shape irregularities in the cornea. LASIK patients with ectasia, a steepness in the lower part of the cornea, or keratoconus, a bulging cornea, can suffer vision loss.PACHYMETER TEST
Measures the thickness of the cornea. If you don't start with enough to leave you with sufficient thickness after surgery, you could suffer vision loss.PATHOLOGY EXAM
Patients with glaucoma, diabetes, AIDS, cataracts, or herpes simplex inflammation are not ideal LASIK candidates. Diabetics and AIDS patients are slow to heal.PUPILOMETER TEST
Measures pupil size--4 to 6 millimeters is normal. At 8 and above, you could experience side effects known as GASH: ghosting, arching, starbursts, and halos.SLIT-LAMP EXAM
Detects epithelial basement membrane dystrophy (EBMD)--irregularities in the cornea's membrane. This condition could lead to painful abrasions after surgery.SCHIRMER TEARING TEST
Detects dry eyes, a condition that can be exacerbated by laser surgery. A tear spot on the test paper that is less than 8 millimeters wide indicates dry eyes.VISUAL ACUITY
Patients who have either severe astigmatism or presbyopia, a rigidity of the lenses that causes focusing problems, are not ideal candidates.