Refractive Surgery Part One:
“Who should do it, and how do we decide”
Jordan Jangula O.D.
Refractive eye surgery–surgery done to correct a person’s nearsightedness or farsightedness such as LASIK (laser-assisted in situ keratomileusis) or PRK (photorefractive keratectomy)–can be a very liberating procedure when done on the right person. Although lens designs and materials for glasses, as well as contact lenses, continue to improve in functionality and convenience, for some patients, refractive surgery is a great option. Many people, due to lifestyle, or some other reason, do not want to wear glasses. For example, some may have a condition called dry eye rendering them unable to wear contact lenses. Others are simply not comfortable with putting anything in their eyes; and still others just simply do not want to be dependent on corrective lenses. Therefore, for many of these patients, refractive surgery can be a very liberating procedure.
The techniques and equipment used for refractive surgery continue to improve and have become very precise, reliable, and safe when patient selection is done correctly; however, it must be stated that these procedures are still surgical and therefore carry some risk. For this reason, additional testing, beyond a routine eye exam, is required before determining whether a patient is truly a good candidate for refractive surgery.
To determine a patient’s candidacy for refractive surgery, a full exam with a cycloplegic refraction is required. A cycloplegic refraction is a refraction done after a patient’s eyes are dilated. These dilating drops are actually stronger than those typically used for dilation in a routine eye exam. The purpose of the stronger drop and dilation are to measure the patient’s prescription when his or her accommodative system (focusing system) is neutralized; or, in other words, the prescription will be more accurate as the eyes are not aided by the brain’s signal to focus the eye. If there is a large difference between the original, routine refraction results and those of the cycloplegic refraction, steps must be taken to further relax the patients focusing system in its natural state. If this step is not done, a refractive surgery correction may be excessive and cause problems in the future.
Another important parameter that doctors take into consideration is corneal thickness. In the refractive surgery procedures LASIK and PRK, corneal tissue is removed to correct the patient’s prescription. High prescriptions require more tissue removal than low prescriptions. Therefore, if there is not enough corneal tissue that can be removed, as the cornea still needs to retain its structure and shape, the patient is not a good candidate for refractive surgery. This thickness is taken into consideration within the context of the pre-surgery shape and structure of the cornea, which is measured with a topographer or tomographer, another additional test used to determine candidacy. The further deviated a patient’s corneal structure and shape is from the norm, the less tissue the surgeon will be willing to remove.
Other factors that need to be considered in order to determine candidacy are lifestyle, patient expectation, age, dry eye, ocular disease, and other health conditions. The eye doctor performing the refractive surgery will review all these things with the patient to both help the patient have an appropriate understanding and expectation, as well as determine whether or not refractive surgery is a good option.