Donna Qahwash, DO
This aggravating LASIK flap complication has always been one that gives our co-managing partners concern, as it can be benign or a threat to vision. Because the decisions about when and how to treat it are multifactorial and there are several modalities utilized, I have written this brief article to offer insight on our approach to this condition.
Ninety-five percent of cases we are confronted with Epithelial Ingrowth, EI, are related to the mechanical keratome (bladed) created flap. Bladed flaps were created with an angle of 26 degrees as opposed to the superior architecture of the laser created flap of 75-110 degrees allowing an easier access to the interface in the bladed flap. Purchasing the femtosecond laser in 2005 drastically reduced the occurrence of this condition in our practice, but there continues to be a multitude of LASIK patients operated upon prior to that date (bladed flaps) that continue to require handling of EI. The other risk factors for its development include Radial Keratometry cases, Epithelial Defect occurring at the time of the procedure, retreatment in older patients, and flap lift 2 or more years after primary LASIK.
We especially discuss the pros and cons of enhancement with (high rate of ingrowth) and without flap lift/PRK (healing issues with occasional poor visual results) in all our patients requiring enhancement who have bladed flaps created in the initial procedure.
EI will typically be noted at the slit lamp between one week and one month. In benign Grade 1 ingrowth, one identifies cells within 1 to 2 mm of the flap edge. Persistent fluorescein staining of the flap gutter, followed by negative fluorescein staining inside the flap edge, are signs of possible EI occurrence. As long as there is a demarcation line, an area of scarring at the anterior edge of the epithelium, there is no progression to vision loss and hence no required treatment. If in doubt, photograph it and simply schedule a follow-up exam days later for determination of severity. The majority of these mild, clinically insignificant cases are managed with observation.
Initial surgical treatment for EI is performed with flap lift, removal of epithelial cells from the posterior surface of the flap and the stromal bed with a 64 Beaver blade or similar instrument, and replacement of the flap without sutures or tissue glue. When performing a surgical removal, often the invasive wall of cells that moves in can literally pull the flap edge underneath it, so anatomical restoration of this “rolled edge” is crucial in the surgical treatment. A bandage lens may be placed for comfort, but there is no clinical evidence that it can halt recurrent ingrowth from occurring.
With recurrent episodes of EI, additional measures are typically taken, with our greatest success being with interrupted sutures removed after two weeks. We have had better results with sutures than with tissue glue.
Occasionally, with recurrent EI, Nd YAG Laser photodisruption as described by Alio (Spain) has been advantageous for successful eradication, but may require a few treatments.
As long as flap melt does not occur, patients typically retain both uncorrected and corrected distance acuity following appropriate management with low rates of recurrence.