Evidence-based Guidelines for Keratorefractive Lenticule Extraction Surgery.

Topic: Development of evidence-based guidelines for keratorefractive lenticule extraction (KLEx).

Clinical relevance: KLEx refers to various corneal refractive procedures involving removal of refractive lenticules of intrastromal corneal tissue, typically through a small incision, thereby eliminating creation of a corneal flap. This technique has rapidly gained popularity as a possible alternative to flap-based procedures; however, no clinical practice guidelines exist for KLEx.

Methods: These evidence-based guidelines were developed following the WHO guidebook, utilizing the AGREE II tool, and adhering to the RIGHT statement. The body of evidence was drawn from eight literature databases, five clinical guideline databases, and two academic organizations. Recommendations were developed via a Delphi consensus of 44 global experts in refractive surgery, corneal diseases, retinal diseases, glaucoma, and optometry. The certainty of evidence, balance of benefits and harms, patient preferences and values, and economic evaluations were fully considered. The GRADE approach was employed to assess evidence quality and recommendation strengths.

Results: From 385 initial clinical questions, 15 were identified, prompting a review of 250,717 studies, with 609 included for conducting and updating 26 and 2 systematic reviews, respectively. Subsequently, consensus was reached on 38 recommendations for preoperative screening, candidate selection, intraoperative quality control, operating principles, postoperative monitoring, and complication management. For KLEx, an effective and accurate refractive correction is attributed to various factors such as corneal thickness, degree of myopia, treatment nomogram, and optical zone. For KLEx-related complications that could affect vision, comprehensive and effective management strategies were proposed, particularly for wrong-plane dissection and difficult lenticule removal, suction loss, and perioperative infection. Customized surgical planning protocols and operative techniques were analyzed. Among all recommendations, 29 (76%) were labelled as "strong", each externally reviewed. The assessment of corneal biomechanical properties may help improve safety and predictability, though needing further validation. The development process also revealed several research gaps for enhancing KLEx safety.

Conclusions: These guidelines provide evidence-based recommendations for KLEx in clinical practice, such as on preoperative screening for keratoconus, surgical planning, managements and prevention of complications and infection. The guidelines are expected to improve the safe and effective application of KLEx procedures and achieve more satisfactory visual correction.