The history of contemporary laser in situ keratomileusis
(LASIK) returns to 1985 when Peyman first presented the idea
of performing laser ablation in a corneal flap. In 1990, Pallikaris
completed the first LASIK procedure in a rabbit model. To date,
LASIK remains the most widely performed laser refractive surgery
worldwide, with over 1.2 million LASIK surgeries being performed
annually in the USA and Europe. Since its introduction, the role
of LASIK has extended from the preliminary improvement of
simple refractive errors to additional indications, containing
the management of postkeratoplasty astigmatism/ametropia,
postcataract surgery refractive error and presbyopia.
The long-standing efficiency, expectedness and security of
LASIK have been well-known in the literature. A recent systematic
review of LASIK in 67 893 eyes described admirable clinical
outcomes after new LASIK surgical procedure; 99.5% of cases
completed uncorrected distance visual acuity of 6/12 or better
and 98.6% of them did spherical equivalent refraction within
±1.0 dioptre (D) of target refraction[1,2].
However, the establishment of a line among the flap and the
basic corneal stroma may cause flap-related and flap-stromal
interface difficulties like displacement of flap, infectious keratitis,
diffuse lamellar keratitis and epithelial ingrowth (EI). Post-
LASIK epithelial ingrowth (PLEI) is an infrequent problem that is
considered by the ingrowth of corneal epithelium at the border
among the flap and stromal bed after LASIK, resulting in a variety
of clinical manifestations [3,4].
The prevalence of post primary LASIK EI is not high, probably
from 0.9% to 3.9%. Though, the risk of EI is meaningfully raised
in numerous clinical conditions, particularly when the flap is
elevated for retreatment. EI has been infrequently reported after
trauma and further types of intervention such as sharp trauma,
keratoplasty, cataract operation and pterygium surgery. These
clinical expressions are due to the accidental progression of corneal
epithelial cells within the intraocular space, leading to creation
of epithelial cells on the exterior of intraocular constructions
like ciliary body, iris, lens capsule, posterior cornea and anterior
chamber angle .
A comprehensive knowledge of these risk factors allows
enhanced preoperative patient advising and risk evaluation.
Modifiable and non-modifiable risk factors of epithelial
ingrowth following LASIK include:
a. Modifiable risk factors such as surgical instrumentation,
surgical technique during retreatment, conformation of LASIK
flap edge, corneal epithelial injury and LASIK flap dislocation
b. Non-modifiable risk factors like increased age (weak
evidence), type 1 diabetes mellitus, corneal epithelial basement
membrane dystrophy or recurrent corneal erosion syndrome,
Hyperopic LASIK > myopic LASIK and flap lift for retreatment.