Identifying Ideal Candidates for Refractive Surgery

We are often the first-line eyecare providers in discussing refractive surgery with patients. Therefore, it is important that we are knowledgeable when it comes to patient selection. This article discusses the ideal candidates for each refractive surgery option, organized by the two main categories of procedures: laser procedures and lens-based refractive surgery.

LASER PROCEDURES

LASIK, PRK, and SMILE all fall under this category. The decision to recommend one over the other depends on various ocular measurements, such as refractive error and corneal thickness and topography, as well as the patient’s occupation, lifestyle, and surgical expectations.

Laser surgery candidates are generally 18 years of age or older, as this is the age at which we reach a stable refraction, presbyopia is still several years away, and both the anterior segment and posterior segment are mature. The latter is important in increasing the reliability of presurgical measurements and the predictability of visual outcomes. 

Regarding required ocular characteristics, these patients should have a healthy anterior segment (eg, no cataract or dry eye disease, etc.) and posterior segment (eg, no diabetic macular edema, etc.). All refractive surgery patients should understand that these procedures do not guarantee optimal vision and are not permanent and should be aware of potential risks, such as infection, undercorrection, etc. Per FDA standards, LASIK and PRK can treat up to roughly 12 D of myopia, 6 D of astigmatism, and 6 D of hyperopia.

• Ideal LASIK Candidates. These patients should have an adequate corneal thickness (the normal range is typically 500 μm to 600 μm), a residual stromal bed thickness of 250 μm to 300 µm, and normal corneal topography and tomography. Also, their pupils cannot be too large for the planned optical zone (Figure). Because flap complications, such as flap dislocation, are a risk with LASIK, ideal patients should not be involved in high-contact sports or occupations. These patients can expect blurred vision, burning, foreign-body sensation, photophobia, and tearing immediately postoperatively. Finally, they should realize that ocular dryness, glare, halos, starbursts, and reduced contrast sensitivity can occur, oftentimes early in the postoperative period.

• Ideal PRK Candidates. These patients often have thin corneas (480 µm to 500 µm). Of note: In patients needing 6 D or more of refractive correction, there is an increased risk of corneal stromal haze.¹ Patients should be counseled to expect burning, discomfort, foreign-body sensation, glare, halos, ocular dryness, photophobia, reduced contrast sensitivity, and starbursts immediately postoperatively. Most importantly, these patients should be aware and accept that full visual recovery can take up to 6 months.

• Ideal SMILE Candidates. SMILE is approved for myopia and myopic astigmatism but cannot be used to treat hyperopia in the United States. The smaller incision area and absence of a flap make SMILE a good option for patients who have preexisting dry eye disease or if there is a concern for flap complications.² Patients should expect about a week for visual recovery and symptoms of foreign-body sensation, dryness, blurry vision, and photophobia during the recovery process. They should also be counseled that enhancements, if needed in the future, may be more difficult compared with other laser surgeries because no flap is involved.

LENS-BASED REFRACTIVE SURGERY PROCEDURES

Implantable collamer lenses (ICL) and refractive lens exchange (RLE) fall under this refractive procedure umbrella. 

The former is placed behind the iris in a phakic eye, allowing the patient to still fully use their accommodative system. The latter allows for a large range of visual outcomes using different types of IOLs, though it’s important to set realistic patient expectations regarding the vision provided by each (see “Educating Patients on IOL Options”). These patients must understand that these procedures do not guarantee optimal vision or prevent the normal aging of the eye, and they must accept the risks (eg, infection, subcapsular cataract formation, etc.). Also, these patients should expect mild blurred vision, foreign-body sensation, glare, halos, photophobia, and a pressure or awareness of the eye immediately after surgery.

• Ideal ICL Candidates. These patients are between 21 and 45 years of age and have a stable pre-presbyopic refraction (ie, a spherical equivalent of between 4 D and 20 D of myopia and 2.50 D of astigmatism, depending on the specific ICL brand), a clear crystalline lens, an adequate endothelial cell count (ie, 2,500 to 3,500 cells/mm²), and healthy anterior (eg, no uveitis or dry eye disease, etc.) and posterior (eg, no glaucoma, etc.) segments. Further, they should have a > 3 mm anterior chamber depth, healthy iridocorneal angles, adequate sulcus-to-sulcus dimensions (300 μm to 600 μm) for proper sizing, and the right vaulting potential (250 μm to 750 μm) between the ICL and the crystalline lens.³ Patients should be made aware that full visual recovery can take up to a month. STAAR Surgical currently offers FDA-approved options. Currently, no FDA-approved hyperopic ICLs are available in the United States.

• Ideal RLE Candidates. These patients are typically older than 50 years of age with moderate to high hyperopia (ie, 2 D to 6 D) and are not ideal candidates for laser surgeries due to their presbyopic status. RLE can offer a wide range of vision for presbyopic patients with the various options of advanced technology IOLs. These patients should expect blurry, fluctuating, and hazy vision immediately after surgery and acknowledge that full visual recovery typically occurs in 4 weeks to 6 weeks.

PREPARATION IS KEY

Because we are oftentimes the first to hear about a patient’s desire for refractive surgery options, we should be prepared to walk them through the decision-making process to help them choose the option that fits their lifestyle and visual goals and ensures an expected outcome. These conversations build trust, strengthen patient relationships, and help maintain continuity of care.