A recent study published in MedComm—Future Medicine investigated corneal epithelial ingrowth following SMILE (Small Incision Lenticule Extraction) surgery to understand the mechanisms behind the condition and devise potential preventive strategies for improving refractive surgery outcomes.
The investigators identified four primary causes of epithelial ingrowth (EI) following SMILE procedures:
- Disruptions to the cells during surgery can lead to their migration from the limbus to the subflap.
- Cell or tissue fragments left under the corneal flap during surgery can form clusters of lesions.
- Some patients may be genetically predisposed to develop EI. (In these cases, EI often presents in both eyes.)
- Isolated areas of EI unrelated to the flap edges or incision can occur in the center of the flap.
Compared to LASIK which has a post-operative EI incidence of 6.1% to 1.4%, the incidence of EI post-SMILE is relatively low at around 0.02%. However, the small incision used in SMILE can present further challenges in addressing complications, and the researchers noted understanding the mechanisms of corneal EI is essential for proper treatment.
The study analyzed four cases of corneal EI post-SMILE. Each patient presented with blurred vision and a mild foreign body sensation post-SMILE surgery. Upon examination, slit-lamp microscopy revealed epithelial ingrowth at the edge of the lenticule interface, and opaque bubble layers (OBL) were identified as a key contributor to microchannel formation in the corneal stroma that facilitated epithelial cell migration.
The investigators separated and removed the ingrown epithelial cells through a small incision using a corneal dissector. The patients responded well to surgical interventions, with no recurrence of epithelial ingrowth after 12 months of follow-up. They also described additional treatment methods that could lower the risk of EI recurrence, especially when more invasive procedures increase the risk of infection. These included Nd:YAG laser, photorefractive keratectomy, and adjunctive therapies.
“We take preventative measures before surgery, starting with the condition of the corneal epithelial layer,” the researchers wrote. “By ensuring proper application of topical anesthesia and preoperative communication with patients, we avoid unwanted eyeball movement during operation, thus reducing the risk of epithelial injury. Additionally, optimal positioning of the suction cone and timing of suction initiation is crucial for minimizing risk of developing complications, such as OBL and microtunnels in the subflap area. Postoperatively, we apply topical corticosteroids and use bandage contact lens to promote healing and prevent recurrence of EI.”
They suggested further studies should determine the efficacy of treatment methods, including tissue sealants, in larger populations.
A full list of author disclosures can be found in the published research.
