A 37-year-old woman presented to the Bochner Eye Institute with blurred vision in her left eye following a LASIK enhancement performed one year ago in Mexico City.
She had undergone her primary LASIK procedure five years earlier. Her primary complaint was blurred vision in the left eye, both during the day and at night, without any associated irritation or foreign body sensation.
EXAMINATION FINDINGS:
- Right eye: Clear and well-centered flap; uncorrected visual acuity (UCVA) was 20/20.
- Left eye: Evidence of extensive epithelial ingrowth involving both the peripheral and central cornea;
- UCVA was 20/80, with best-corrected visual acuity (BCVA) of 20/70 (-0.75 -2.50 x 75).
DIAGNOSIS:
Epithelial ingrowth in the left eye.
MANAGEMENT PLAN:
A flap lift was planned with removal of epithelial cells and placement of temporary sutures at the flap periphery to reduce the risk of recurrence.
SURGICAL OUTCOME:
The procedure was uneventful. Early post-operative assessment revealed a clear interface and improved UCVA of 20/50. Sutures were gradually removed over the subsequent 4–6 weeks. At two months post-op, the patient achieved a UCVA of 20/25.
KEY LEARNING POINTS:
1. Etiology:
The exact cause of epithelial ingrowth remains unclear. Possible contributing factors include:
- Flap Adhesion Issues: Poor adhesion or apposition may allow surface epithelium to migrate into the space.
- Corneal Epithelium Disruption: Intraoperative or postoperative disturbance of the corneal epithelium has been implicated.
- Flap Melt Mechanism: Hypoxic epithelial cells within the flap release collagenase, leading to keratolysis of the flap tissue.
2. Risk Factors:
- Technique-Dependent Risk: More common with microkeratome flap creation using a metal blade compared to a femtosecond laser.
- Timing of Enhancements: Higher incidence in LASIK enhancement procedures performed over a year after the primary surgery.
- Preferred Enhancement Methods: Beyond One Year: PRK is often favoured. Within One Year: Flap lift with excimer correction is typically preferred.
Preoperative Factors:
- Epithelial basement membrane dystrophy.
- History of recurrent corneal erosions.
- Advanced age.
- Diabetes mellitus.
- Epithelial ingrowth in the contralateral eye.
Intraoperative Factors:
- Intraoperative epithelial defects.
- Postoperative inflammation (e.g., lamellar keratitis).
- Flap relift or enhancement procedures.
- Flap edema, misalignment, or shifting.
- Ablation extending beyond the flap diameter.
- Irregular flaps, buttonholes, or free caps.
- LASIK performed on eyes with prior corneal transplantation or radial keratotomy.
- SMILE procedures.
3. Clinical Diagnosis:
Epithelial ingrowth is classified into three grades based on severity:
Grade 1:
- Characteristics: Thin, 1–2 cells thick; confined to within 2 mm of the flap edge; transparent and difficult to detect.
- Flap Changes: None. Nonprogressive.
- Treatment: No intervention required.
Grade 2:
- Characteristics: Thicker ingrowth; discrete, translucent nests of cells at least 2 mm from the flap edge; visible on slit lamp; no demarcation line.
- Flap Changes: Rolled or greyish corneal flap edge, but no melting or erosion. Progression is common.
- Treatment: Non-urgent treatment recommended within 2–3 weeks.
Grade 3:
- Characteristics: Pronounced ingrowth; several cells thick, extending beyond 2 mm from the flap edge; opaque areas with white necrotic epithelial cells lacking a demarcation line.
- Flap Changes: Rolled, thickened white-grey flap margins with significant melting due to collagenase release. Confluent haze and stromal bed exposure occur as the flap retracts.
- Treatment: Urgent intervention required, with close monitoring due to frequent recurrences.
4. Treatment Approach:
- Intervention: Flap lift with epithelial debridement, with or without temporary sutures.Other techniques have also been described including the use of the YAG laser, and fibrin glue instead of sutures to seal the flap edge.
- Prognosis: The use of sutures significantly reduces the likelihood of recurrence and improves outcomes.
FINAL THOUGHTS
Timely identification and appropriate management of epithelial ingrowth are crucial to prevent complications and optimize surgical outcomes.
