Advanced surface ablation (ASA) and laser-assisted in situ keratomileusis (LASIK) are two of the most commonly performed refractive surgery procedures designed to reduce or eliminate the need for eyeglasses or contact lenses. Both procedures utilize laser technology to reshape the cornea and change its focusing power, correcting vision problems like nearsightedness (myopia), farsightedness (hyperopia), and astigmatism. However, the techniques used in ASA and LASIK differ.
LASIK: A Popular Choice for Fast Visual Recovery
LASIK is currently the more widely performed procedure in the United States and worldwide. According to the American Refractive Surgery Council, over 40 million LASIK procedures have been done globally since the technique was introduced in the 1990s. The popularity of LASIK stems from it being a quick outpatient procedure with relatively fast visual recovery. Most patients experience improved uncorrected vision within 24 hours following their LASIK treatment. Additional advantages are that it provides predictable results for many patients and minimally impacts the structural integrity of the eye.
The LASIK procedure begins with creating a thin flap in the cornea using a femtosecond laser. This flap is folded back to expose the corneal stroma underneath. The surgeon then reshapes the stroma with a cool excimer laser to change the corneal curvature and refractive power. Once the desired change is achieved, the flap is laid back into place and allowed to heal. The flap typically adheres within several minutes but takes up to six months to fully bond with the underlying cornea. The lack of pain associated with the LASIK procedure itself also adds to its appeal for many patients.
However, LASIK does come with risks, the most common being dry eyes, which can persist for several weeks or months after surgery. Creating the corneal flap also weakens the cornea and makes it more prone to trauma. Rare but serious vision-threatening complications like corneal ectasia can occur if too much tissue is removed from the cornea. Other risks include temporary glare, halos, and fluctuation in vision, especially in the first few months after LASIK. Patients with very high degrees of myopia, extreme corneal dryness, or thin corneas may not be good candidates for LASIK.
ASA: A Flap-Free Option for Specific Cases
ASA takes a different approach by reshaping the cornea’s surface layer without creating a flap. The excimer laser energy is applied directly to the corneal epithelium to vaporize tissue and alter the corneal contour. This surface ablation technique avoids complications associated with the LASIK flap. However, it provides less correction of extreme nearsightedness compared to LASIK. Studies show ASA only safely treats up to 6 or 7 diopters of myopia versus LASIK which can correct 12 diopters when performed by an experienced LASIK surgeon.
Because no flap is created, ASA results in more post-operative pain and slower visual recovery compared to LASIK. It may take a week or longer for vision to fully stabilize. The risk of traumatic flap dislocation down the road is eliminated, although this is a low risk following LASIK as well.
For these reasons, ASA may be preferred for patients with borderline corneal thickness, high degrees of myopia, or occupations with high risk of ocular trauma like construction workers or athletes. It also poses less risk of developing corneal ectasia in these higher-risk populations. However, enhancement rates are often higher with ASA since the limited ablation depth makes overcorrection more difficult. Most surgeons reserve ASA for specialized cases where LASIK is not optimal.
Choosing Between LASIK and ASA: A Personalized Decision
When performed properly by an experienced refractive surgeon, both ASA and LASIK are proven options for correcting nearsightedness, farsightedness, and astigmatism. Over 95% of patients achieve 20/40 vision or better with either procedure. The American Academy of Ophthalmology reports patient satisfaction rates of over 90% for both ASA and LASIK as well.
For most candidates, LASIK provides faster recovery with less pain and better visual outcomes, especially for higher degrees of correction. However, patients with borderline corneal thickness or high-risk occupations may benefit more from ASA’s safety profile.
The decision of whether to have ASA or LASIK depends on an individual patient’s ocular characteristics, lifestyle, and surgical goals. A detailed preoperative exam and measurement of corneal topography and thickness help determine which procedure is optimal. Patients are encouraged to thoroughly discuss the comparative risks and benefits of ASA versus LASIK with their refractive surgeon.
