Pre-operative examination of the patient prior to LASIK is one of the most important steps in having LASIK eye surgery. The data acquired during the examination is what is put into the computer running the Excimer laser machine. The surgical outcome is greatly dependent on the quality of the data put into the laser’s computer.
Chief Complaint or History of Present Illness
The eye doctor needs to take a careful history in order to determine if the patient is a good candidate for LASIK surgery. The eye doctor needs to evaluate the patient’s goals of having surgery. The age of the patient is important. As one nears the age of 40, they will develop presbyopia (inability to focus from distance to near) and may desire monovision with their LASIK procedure.
Past Ocular or Eye History
Any history of past ocular surgery or eye disease is important. These may have an effect on the surgical results. Important diseases are the history of ocular herpes infections, dry eyes, retinal tears, and prior retinal detachment.
Past Medical History
The past medical history needs to be obtained. Diseases such as diabetes, arthritis, lupus, and other autoimmune diseases can have an effect on the surgical outcomes. Many of these diseases are a contraindication for having LASIK surgery.
Family history of certain diseases is important in order to determine the candidacy of a patient for LASIK.
A patient’s job or lifestyle is also important in evaluating whether a patient is a good candidate or the type of laser procedure to be performed.
Medications such as Accutane™, Imitrex™, and other medications may need to be discontinued as they can have an effect on the surgical outcome.
Complete Eye Exam for LASIK or LASEK
Vision Testing and Refraction
The vision is tested uncorrected and with best correction.
The refraction for determining the latest refractive error is performed. The refraction is first performed without cycloplegia (eye drops that paralyze the focusing muscles of the eye) and again after cycloplegia. This is to make sure that both refractions are similar as to not make a mistake on the correct refraction to be used.
Slit Lamp and Fundus Examination
The slit lamp is a microscope used to examine the eye to make sure there are no external ocular diseases present. The intraocular eye pressure is measured.
A dilated fundus examination of the retina is necessary to rule out any retinal or optic nerve disease.
Additional Testing for LASIK or LASEK
Pupil size can be measured with a Pupillometer. Pupil size may have an effect on glare and halos after surgery with recent evidence being that it does not affect glare or halos but this is still being investigated.
Dry Eye Testing
If during the slit lamp exam, it appears that the patient may have dry eyes, dry eye testing should be performed. A Shirmers’ test should be performed. If dry eyes are present, then a treatment program should be started and the patient re-evaluated. Dry eyes can become much worse after LASIK surgery.
Topography and Keratometry
Corneal topography is an essential tool in the pre-op evaluation for LASIK. It produces a 3-D image of the surface of the cornea. It also provides keratometry readings and other measurements of the cornea. Certain eye diseases such as keratoconus, pre-keratoconus, and pellucid marginal degeneration are detected with topography. These diseases are a contra-indication for LASIK procedures.
A separate keratometry can be used to double check the K readings or curvature of the cornea.
Wave Front Analysis
Wave front analysis is done by machines that measure the light wave coming from the eye after a light is shown into the eye. Wave front analysis measures the aberrations found in a patient’s vision. There are low and high order aberrations. The results of the wave front are used to guide the laser treatment to minimize the post-op aberrations and improve the quality of the vision following the procedure.
The work up prior to LASIK or LASEK surgery is one of the most important steps in having refractive surgery. The lasers today are very accurate and the quality of the data going into the computers used to run the laser directly affects the visual outcome.