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Evaluating Patients for LASIK Surgery

By: Phillip J. Calenda, MD – Ophthalmology


Almost every American from eighteen to eighty years of age has heard enough about LASIK to understand on a basic level what it is and how it works. On average approximately 1,000,000 LASIK procedures are performed annually in the United States. The vast majority of these procedures are successful, but unwanted side effects and/or suboptimal results can occur in a small percentage of patients. Below is a discussion of the essential elements in the pre-operative evaluation of a patient being considered for LASIK.

Patients are typically at least eighteen years old and suffer from nearsightedness (myopia), farsightedness (hyperopia), and/or astigmatism. Their eyeglass prescription must be stable prior to surgery. The generally accepted guideline for stability is a change of 0.75 or less in any component of the prescription over the last year.  So, if one year ago a patient wore –2.00 glasses and today they are using –2.75 or less their prescription is considered stable. Conversely, a prescription that changed from –4.00 twelve months ago to –5.00 today is not considered stable. A patient with such a prescription should be rechecked in the future for stability of their prescription.

Surgical Requirements, Contra-Indications and Process

A patient’s eyes need to be healthy to undergo LASIK surgery.  What exactly does this mean?  That recent case of conjunctivitis from wearing contact lenses overnight will need to clear up before surgery.  More serious issues such as the degenerative corneal disease keratoconus, which affects about 1 in 2,000 people, make patients ineligible for surgery.  Lesser conditions, such as the presence of dry eyes, pinguecula (excessive growth of tissue on the white part of the eye), or pterygiums (growth of the white part of the eye onto the cornea) do not necessarily make patients ineligible for LASIK surgery.  Some patients with retinal conditions; mild, well-controlled glaucoma; and other ocular abnormalities may need to be evaluated by another ophthalmologist and cleared for surgery.  In any case, the general ocular health and specifically the health of the patient’s cornea, the part of the eye contact lenses rest on and LASIK surgery is performed on, will be thoroughly tested prior to surgery.

Measurements of the size, curvature, and thickness of the cornea, the pupil size in dim lighting, the intraocular pressure, and the ideal eyeglass prescription will be taken.  A dilated examination will be performed to check for the presence of cataracts, retinal and other disorders, and to confirm the patient’s optimal eyeglass prescription.  Scans are often done to assess if a patient would benefit from so called “custom” treatment.  Such treatments evaluate the patient’s prescription in a way that goes beyond an eyeglass or contact lens prescription.  In some cases custom treatment can offer patients better quantitative and qualitative vision than so called traditional LASIK.  Patients should be aware that a period of abstinence from soft contact lenses is required prior to surgery to insure the most accurate measurements are obtained.

A listing of any medical problems, medications, and allergies a patient has is obtained.  Some medical conditions, such as diabetes, can affect how a person responds to LASIK, how quickly they heal, and how likely the patient is to suffer prolonged side effects from the procedure.  The same holds true for certain medications, including anti-depressive and antihistamine medicines.  Any unusual healing tendencies are noted, such as a history of keloids, that is, exuberant scar formation after injury or surgery.  Finally, a thorough discussion of the patient’s expectations and their understanding of the risks and benefits of the procedure is undertaken.

Improvements in diagnostic equipment, such as more advanced corneal topography systems, and safer and more sophisticated lasers have greatly reduced the incidence of poor outcomes in patients.  Permanent, bothersome glare and halos is much less likely to occur after LASIK treatment today compared to such treatments ten years ago.  Femtosecond lasers to create the flaps in LASIK surgery offer an added level of safety and predictability compared to earlier generations of mechanical devices (microkeratomes) that were used in flap creation.  Finally, newer medications, such as Restasis, have aided in controlling dry eyes and inflammation post-operatively in patients, improving patient comfort and outcomes.

A thorough pre-operative assessment, meticulous surgical technique, and careful monitoring of patients post-operatively go a long way towards maximizing patient outcomes and satisfaction.

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