While most refractive errors can be corrected to some degree with either glasses or contact lenses, many find that this is not a satisfactory or convenient solution. Studies suggest that the majority opt for surgery because they desire more freedom from glasses or contacts. About 25% have become contact lens intolerant, and another 10% are motivated by sports interests or occupational/professional reasons. Below are some suggestions, restrictions, and guidelines to help you determine if you are a good surgical candidate and what to expect after surgery.
Is Refractive Surgery Right for You?
Requirements and Restrictions: Generally, the best candidates for LASIK and other refractive procedures are between 25 and 55 years of age, however those older or younger are not necessarily excluded. A great deal depends on the individual’s health, lifestyle, and degree of motivation with respect to decreasing dependency on glasses or contact lenses.
Limitations as to the degree of myopia, hyperopia, and astigmatism that can be corrected vary by procedure. Presently, LASIK has the highest tolerance of all existing procedures, and has been employed to correct as much as 14 diopters of myopia, about 6 diopters of hyperopia, and 6 diopters of astigmatism. These are upper limits of correction, and may not apply to any one individual. In any case, the patient should not have experienced more than a one diopter change in refractive error during the year prior to surgery. It is important to remember that while our ability to predict outcomes is quite good, nothing is infallible. The degree of correction achieved by any refractive procedure depends entirely upon the severity of the myopia, hyperopia, and/or astigmatism, with less accuracy as upper limits of correction are approached.
Preoperative Testing and Evaluation: Before arriving at a final decision to have surgical vision correction, a thorough evaluation of your candidacy for the proposed procedure by a qualified eye doctor is required. Because there are general health concerns that might preclude any type of procedure, this evaluation will include a full review of your overall medical condition. Additionally, refractive surgery is usually not recommended for people with moderate to advanced glaucoma, macular disease, or corneal diseases such as herpetic keratitis, keratoconus, severe dry eye, corneal dystrophies, or any other significant eye pathology.
If you wear soft contact lenses, they should not be worn for at least two weeks prior to your evaluation. Gas permeable or hard lenses should not be worn for at least one month prior. Contact lens wear distorts the cornea, and these periods of no contact use allow the cornea time to recover fully. Failure to do so could lead to inaccurate measurements and poor surgical results.
A full ocular examination will be performed after a basic screening determines possible procedures to correct your vision. This exam will include:
- Refraction: accurate measurement of the eyes’ refractive state to determine the amount of myopia, hyperopia, or astigmatism present.
- Keratometry: determination of the corneal curvature and power.
- Corneal pachymetry: ultrasound is used to measure the thickness of the corneas, important in determining the safety of certain procedures. Normal thickness is about 540 microns.
- Computerized corneal topography: a sophisticated device creates a computerized elevation map of the cornea, looking for any irregularities that might indicate problems such as keratoconus, which could lead to poor surgical outcomes.
- Tonometry: measurement of the intraocular pressure, looking for signs of glaucoma.
- Slit lamp/ophthalmoscopy: examination of the internal structures of the eye, looking for any other problems such as cataracts or retinal/macular disease.
Results/Expectations: As a result of all the preoperative testing, your surgeon will be able to determine three basic things:
- If you a good candidate for any type of surgical vision correction.
- Which procedure is best suited to your particular situation.
- What kind of visual result you can expect from the surgery.