How Prevalent Are Adverse Effects in LASIK and PRK?

Photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) were greeted as clinical breakthroughs when made available in the 1990s, but this did not stop researchers from trying to improve upon them further.

The intervening years have been marked by a series of refinements, such as using smaller laser spot sizes and faster repetition rates, anticentral island corrections, wavefront-optimized and -guided ablations, eye trackers, and cyclotorsion correction. PRK techniques incorporated the use of intraoperative mitomycin C and postoperative bandage soft contact lenses and topical nonsteroidal anti-inflammatory drops. LASIK flaps, originally prepared with a mechanical microkeratome blade, are now routinely made using a femtosecond laser. However, the impact these innovations have had on the safety and efficacy of PRK and LASIK has remained somewhat unclear.

In a recent publication, Schallhorn and colleagues sought to clarify this issue by analyzing data from a huge refractive surgery database from the United Kingdom. Drawing on data from 36,937 consecutive patients (71,300 eyes) undergoing PRK or LASIK between 2014 and 2016, they reviewed adverse events and change in postoperative visual acuity.

The authors found an extremely low incidence of intraoperative and early postoperative adverse events for both PRK (2.3%) and LASIK (1.3%), corroborating most refractive surgeons' experience. I believe this is due at least in part to improved corneal mapping technology, which allows us to better recognize patients who are poor candidates for refractive surgery.

These safety findings are made more persuasive by the study's design. Although all postoperative care was provided at no additional cost, patients treated thereafter by another provider were instructed to submit the bill to their surgeon for reimbursement. Consequently, the authors are confident that the majority of adverse events in the patients were identified. They do acknowledge that only fairly short-term postoperative complications were captured because patient follow-up declined from 89% at 1 month to 20% at 1 year.

Even more impressive, the authors found that the majority of patients with adverse events still retained excellent corrected distance visual acuity (CDVA). Less than 0.5% of patients with an adverse event lost two or more lines of CDVA. In the few patients who had CDVA reduced to less than 20/40, the loss was always unilateral. No patients had less than 20/40 CDVA in both eyes.

One of this study's more interesting findings was that approximately two thirds of patients who lost two or more lines of CDVA had ocular surface issues. This finding reinforces the importance of carefully evaluating patients for ocular surface conditions preoperatively, maximizing the health of the ocular surface before proceeding with refractive surgery, and aggressively managing ocular surface disease postoperatively.

Although this study confirms the safety of PRK and LASIK, it also reminds us that even state-of-the-art corneal refractive surgery has potential complications.

Christopher J. Rapuano, MD, is a nationally and internationally recognized expert in corneal diseases, Chief of the Wills Eye Hospital Cornea Service, and Professor of Ophthalmology at Sidney Kimmel Medical College at Thomas Jefferson University.

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Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.

Cite this: Christopher J. Rapuano. How Prevalent Are Adverse Effects in LASIK and PRK? - Medscape - Aug 25, 2020.

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