Your eye surgeon should do a thorough eye examination before you undergo LASIK.  Besides taking your detailed eye and other disease history,  your eye surgeon should perform at least the following checks. Don’t trivialize the LASIK procedure, and don’t allow your eye surgeon to trivialize it either. Good doctors, who have experience with LASIK and who care about their doctors, will do the following tests.

  • Determination of uncorrected vision and vision as corrected by your own glasses/ contact lenses. This will give the eye surgeon of how much you will benefit by LASIK, and what your expectactions are likely to be.
  • Determination of the magnitude of refractive error in each eye
  • Measurement of the surface of the cornea by “mapping” its topography (corneal curvature or shape) to check whether there are any abnormalities within the cornea, and especially to check whether there are any corneal thinning disorders (like keratoconus) present.
  • Measurement of pupil size in dim and room light. Your pupil size will determine whether you are eligible for LASIK, how much correction you can safely undergo, and whether you will suffer from night vision difficulties after LASIK.
  • Assessment of whether there is presence of squint, and whether the squint is because of an imbalance in the refractive errors between your eyes, or a muscle imbalance in the two eyes.
  • Examination of the eyelids to see whether there are any prominent structures likely to scratch the cornea after LASIK, and what effect the eyelids have on tear flow.
  • Examination of the conjunctiva, a transparent membrane which covers the white of the eyes, to see if there is anything there which may make LASIK surgery more difficult, or whether the eyes are suffering from any allergy, infection or irritation.
  • Examination of the cornea to determine if there are any abnormalities (for e.g. corneal scars or fine blood vessels near the edge of the cornea)  that could affect the outcome of surgery.

Some of the following examinations may require dilatation of the eye  (i.e putting special eye drops to artificially widen the pupil of the eye, so that the surgeon can see inside the eye better).  Dilatation causes poor vision (especially in bright light) and difficulty in reading for a few hours. Don’t get unnecessarily alarmed.

  • Examination of the  lens inside the eye to determine if clouding of the lens (cataract) or other abnormalities are present.
  • Measurement of corneal thickness (pachymetry). Since LASIK reshapes the cornea by removing microscopic amounts of corneal tissue, very thin corneas (i.e. < 475 microns) should not undergo LASIK. Corneal thickness may limit the amount of correction that is possible in your eye.
  • Measurement of intraocular pressure to detect glaucoma or pre-glaucomatous conditions. Glaucoma is a disease of the eye which damages the nerve cells which carry signals from the eye to the brain. This damage can result from high intra-ocular pressure.
  • Assessment of the back of the eye, areas which are not ordinarily to an casual observer of the eye: Areas in the back of the eye, like the retina, could also be affected by systemic disease (like diabetes or blood pressure) or eye diseases (like glaucoma or retinal breaks or glaucoma). It is important to rule out such problems or treat them before undergoing LASIK.