Small Incision Lenticule Extraction (SMILE) is a type of laser refractive surgery used as an alternative to LASIK and PRK that involves the creation of an intrastromal lenticule within the cornea, which when removed, reshapes the cornea to give the desired refractive outcome. However, complications can occur, particularly when the surgeon fails to completely remove the lenticule, which can cause irregular astigmatism that can dramatically reduce patients’ quality of vision. With more than five million SMILE procedures conducted worldwide, correcting these issues is a challenge due to the intrastromal location. Professor Farhad Hafezi, Medical Director of the ELZA Institute, published an article in Ophta reviewing the complications of SMILE procedures and strategies for their repair.
One of the possible approaches for repair is called corneal wavefront-guided transepithelial photorefractive keratotomy (transPRK), which involves using aberrometric data and corneal epithelial maps to plan a laser ablation that reduces the aberrations caused by the incomplete lenticule removal.
Other SMILE repair methods include re-SMILE, which involves cutting a second lenticule from the bottom of the original SMILE cut, and the “Cap to flap” ablation, which involves turning the SMILE cap into a LASIK flap and performing another excimer laser ablation. However, both of these approaches weaken the cornea more than the transPRK approach, and all of these methods have their own challenges, and it is important to choose the best approach for each patient’s needs.
Prof. Hafezi highlighted that corneal cross-linking (CXL) can also be used to improve corneal biomechanics of these corneas – something that is important when multiple refractive procedures cumulatively remove significant amounts of corneal stromal tissue. CXL involves the application of riboflavin (vitamin B2) to the cornea to saturate the stroma, which is followed by a period of UV illumination. This causes a photochemical reaction that cross-links molecules in the stroma together (mostly collagen and proteoglycans), increasing corneal biomechanical strength. The technique has been shown to be effective in halting the progression of corneal ectasias like keratoconus.
The success of SMILE procedures depends not only on the expertise of the surgeon but also on the ability to correct any complications that may arise. Prof. Hafezi’s article provides insight into the various approaches available for repairing failed SMILE procedures. Corneal wavefront-guided transPRK stands out as a method that offers significant advantages over the other options, including preserving more corneal biomechanical strength, which helps to avoid the development of postoperative ectasia. With millions of SMILE procedures performed worldwide, it is important to have access to the most effective techniques for repairing any complications that may arise.
