Refractive Decision-Making

CRST: How do you choose among LASIK, PRK, and lenticule extraction in routine practice?

Y. Ralph Chu, MD: When my colleagues and I evaluate patients for laser vision correction (LVC), the selection criteria are the same regardless of procedure: a healthy ocular surface, normal corneal topography and tomography, and overall ocular health, including lens and retinal evaluation. Although the US FDA provides approved ranges for each procedure, there is no strict cutoff—overlap is common. We use manifest refraction and patient-specific factors to guide the decision.

In general, for patients in the -1.00 to -2.00 D range, LASIK or PRK is typically preferred. Laser-assisted lenticule extraction (LALEX) is possible in this range, but many patients choose LASIK. Between -2.00 and -6.00 D, all three procedures—LASIK, PRK, and LALEX—are excellent options. LALEX is especially appealing for patients who wish to avoid a corneal flap, those with dry eye disease (DED) or allergies, and individuals in professions with an increased risk of ocular trauma. PRK is often selected for thinner corneas, ocular surface concerns, or peripheral corneal scars that might interfere with femtosecond laser energy transmission.

For patients with refractive errors above -6.00 D, the EVO ICL (STAAR Surgical) is increasingly popular, though LASIK and LALEX may still be considered in select cases. My absolute contraindication for any form of LVC is evidence of corneal ectatic disease or irregular corneal topography—these patients are not candidates.

CRST: For a patient with high myopia, how do you choose among corneal laser surgery, phakic IOLs, and refractive lens exchange?

Zaina Al-Mohtaseb, MD: The literature supports excellent outcomes in low to moderate myopia (up to -6.00 D) with both LASIK and the EVO ICL. For higher myopia, multiple comparative reviews have shown that implantable collamer lenses often yield superior optical quality—lower amounts of induced higher-order aberrations, strong uncorrected distance visual acuity, and excellent accuracy—whereas LASIK remains effective but may be limited by corneal biomechanics and thickness at very high corrections.

In general, I choose LASIK for less than -6.00 D of myopia and for hyperopic patients with normal corneas when the ectasia risk is low and there is no significant ocular surface disease or DED. I consider PRK in this group if corneal tomography and topography are normal but the cornea is on the thin side. For greater than -6.00 D of myopia, for suspicious corneas, or when the DED risk is high, I favor an ICL—provided candidacy criteria are met (eg, anterior chamber depth ≥ 3 mm and adequate endothelial cell density). For adults 40 years of age or older and those who value reversibility, I also lean toward an ICL. For presbyopic or hyperopic patients older than 50 years of age, I consider refractive lens exchange (RLE).

Dr. Chu: When counseling patients with high myopia, three factors drive the decision: their age, refractive error, and corneal health (ocular surface, keratometry, and corneal thickness).

For patients younger than 45 years, we prioritize less invasive options such as phakic IOLs or LVC because they are typically prepresbyopic and still benefit from the crystalline lens. For patients with low myopia, normal pachymetry, and a healthy cornea, LVC remains an excellent choice. That said, more patients now proactively choose an EVO ICL—even in low ranges—because of the high-quality vision it provides, its reversibility, and a reduced risk of postoperative ocular surface issues.

For patients 45 years of age or older and those with early presbyopia, RLE is an important part of the discussion. (Editor’s note: See the sidebar for Dr. Chu’s thoughts on nonsurgical options for emerging presbyopia.) For patients with high myopia—sometimes beyond the treatable range of an ICL—RLE may be the only option to achieve full correction.

Every evaluation includes counseling on the lifelong increased risk of retinal detachment in highly myopic eyes—something surgery does not eliminate and that patients must understand.

Blake K. Williamson, MD, MPH: I favor a phakic IOL whenever patients are candidates, particularly those with high myopia. Phakic IOLs avoid large corneal ablations, are reversible, and preserve the cornea for potential laser refinement later. In my practice, qualifying patients who have a refractive error of -3.00 D or greater are typically offered an EVO ICL, with LASIK reserved for touch-ups.

When LASIK candidacy is questionable (eg, thin cornea or significant DED), I favor a phakic IOL. I avoid RLE in patients with high myopia because of the retinal detachment risk. When patients primarily wish to eliminate reading glasses, I consider RLE only after a posterior vitreous detachment and a complete evaluation by a retina specialist.

CRST: What are the key metrics you use to assess ectasia risk?

Dr. Al-Mohtaseb: I evaluate the following factors for ectasia risk before LASIK:

• No. 1: Corneal topography patterns suggesting irregular astigmatism (eg, inferior steepening, skewed radial axis, asymmetric bow-tie);
• No. 2: Thin pachymetry (≤ 500 μm);
• No. 3: Abnormal tomography (Belin/Ambrosio Enhanced Ectasia Display on the Pentacam [Oculus Optikgeräte]) combining elevation and pachymetry analyses (eg, elevation peaks vs best-fit sphere);
• No. 4: Anterior segment OCT with epithelial thinning and patterns consistent with ectasia risk; and
• No. 5: Percent tissue altered greater than 40% and a residual stromal bed thickness less than 300 μm.

CRST: Enhancements after LVC or presbyopia-correcting IOL implantation: What does your decision tree look like, and what is your threshold for treatment?

Dr. Chu: Our enhancement decision tree starts before the original surgery. During the preoperative evaluation, we assess whether a patient would be a good candidate for LVC after a lens-based procedure. If the cornea is not favorable, we ensure patients understand that future enhancement options may be limited—and that they may still need glasses or contact lenses despite investing in a procedure intended to reduce that dependence. Some patients accept the trade-off, particularly when lens-based surgery remains their best chance at improved vision. For them, technologies such as the Light Adjustable Lens (LAL; RxSight) or the IC-8 Apthera IOL (Bausch + Lomb) can be especially valuable.

When considering an enhancement after surgery, our evaluation mirrors a primary LVC workup; the patient’s corneal health and visual goals are critical. We do not simply treat the residual refractive error; we treat toward the outcome the patient wants. For example, some patients with a history of refractive surgery may have a subtly multifocal cornea that provides a blend of distance and near vision. Correcting the residual error may sharpen one focal point but reduce overall range, so an informed discussion is essential.

Since the advent of the LAL, we prefer this option whenever possible. Its precision in fine-tuning vision—and its low risk of inducing new corneal aberrations—makes it our go-to enhancement strategy in patients with a history of LVC.

Luke Rebenitsch, MD: With presbyopia-correcting IOLs, adjustability matters. Patients expect optimization, and the LAL is the latest way to achieve it. We have used multifocal IOLs for more than a decade. Early designs were highly sensitive to defocus. The latest presbyopia-correcting IOLs—especially extended depth of focus lenses—are more forgiving. Still, the ability to offer an enhancement remains essential.

Our enhancement pathway begins 3 to 4 months following surgery to allow neural adaptation and stabilization of the effective lens position. If patients are satisfied, we avoid additional surgery. If not, we start with a refraction and correct ametropia—typically with LVC. If symptoms persist or a refraction does not explain them, we evaluate the patient for ocular surface disease, posterior capsular opacification, floaters, and less common macular pathology. We prefer to perform LVC before an Nd:YAG laser capsulotomy to keep an IOL exchange feasible. If LVC and management of media issues do not meet our goals, we discuss an IOL exchange. Only about 1% to 2% of our patients require an exchange. We usually begin with the dominant eye and often select a monofocal lens such as the LI61AO (SofPort AO, Bausch + Lomb) to improve their night vision and reduce halos/dysphotopsias. If necessary, we also treat the fellow eye.

For primary LVC, expectations are similarly high. We evaluate patients at 1 month (myopic treatment) or 3 months (hyperopic treatment). If they are satisfied, they are asked to return annually. We are quick to offer an enhancement when clinically meaningful (eg, symptomatic plano intolerance or 0.25–0.50 D of anisometropia) even if the patient’s visual acuity is 20/20. Our overall LVC enhancement rate is about 3% to 5% (higher with LASIK and lower with LALEX). In select cases, we expand the optical zone with topography-guided LVC; therapeutic/refractive combinations are rare.

Dr. Williamson: If a patient is unhappy and a manifest refraction reveals a residual refractive error that improves vision meaningfully at the phoropter or with a contact lens trial, I proceed with a laser enhancement, even for small corrections (eg, 0.50 or 0.75 D).

If vision does not improve with a manifest refraction, I evaluate other potential causes such as posterior capsular opacification and consider performing an Nd:YAG laser capsulotomy. (Capsulotomy timing must be thoughtfully planned because an early procedure can complicate a potential IOL explantation.) If symptoms persist, I consider vitreous causes; in certain situations, a vitrectomy performed by a retina specialist can help.

My goal is plano. Achieving it usually resolves concerns. If, despite achieving a plano result and allowing a reasonable period for neural adaptation (about 3 months), a patient remains truly unhappy with a multifocal IOL, I do not hesitate to proceed with explantation.