What Is Epithelial Ingrowth?
Epithelial ingrowth is a complication that occurs after eye surgeries. Epithelial ingrowth happens when epithelium cells abnormally grow below the new corneal wound. The epithelium cells replicate underneath where the cornea was incised open.
Epithelial ingrowth usually occurs after LASIK (Laser-assisted in-situ keratomileusis) refractive surgery. In LASIK, an incision is made to open the outer layer of the cornea. The cornea is the clear layer that covers the front of the eye, and it is incised during LASIK in order to correct the refractive error. During the LASIK surgery procedure, epithelial cells may migrate under the incision flap and grow. Epithelial ingrowth can cause blurry vision and light sensitivity. Epithelial ingrowth is treated by removing the offending epithelium cells, by lifting up the area of the incision and scraping underneath it to remove the epithelial cells.
Epithelial ingrowth is rare and only happens to approximately 3-5% of people who have LASIK surgery.
- Epithelial ingrowth occurs when epithelial cells migrate and grow under a new corneal wound.
- Epithelial ingrowth can occur after Laser-Assisted In-Situ Keratomileusis (LASIK) refractive eye surgery.
- Symptoms of epithelial ingrowth include blurry vision and light sensitivity after LASIK surgery.
The corneal epithelium is the outermost, top layer of the cornea. The epithelium layer protects the cornea, and is made up of corneal epithelial cells. During epithelial ingrowth, these epithelial cells migrate into the inner layers of the cornea. Hence, the condition is termed ‘epithelial ingrowth’ because the outer epithelium grows into the inner layers.
Epithelial ingrowth happens after the cornea is incised, usually after eye surgery. During eye surgery such as LASIK, the outer layer of the cornea is incised in order to reshape it and correct the refractive error. After the cornea is incised and a wound is created with a blade, epithelial cells may slough off the blade and go underneath the corneal flap, where they can proliferate.
Epithelial Ingrowth Risk Factors
Again epithelial ingrowth is a rare complication. Only 3-5% of patients develop epithelial ingrowth after LASIK surgery.
Other risk factors besides LASIK for developing epithelial ingrowth include:
- Recurrent corneal erosion
- Epithelial basement membrane dystrophy
- Microkeratome surgery procedures
- Epithelial damage prior to surgery, such as corneal abrasion or dry eye
- Diabetes mellitus, causing poor wound healing
Understanding Epithelial Ingrowth
Epithelial ingrowth is usually of two forms:
Benign epithelial ingrowth does not affect the vision much and it happens in the peripheral areas of the cornea. Specifically, ophthalmologists categorize benign epithelial ingrowth as within 2 millimeters of the corneal wound. It usually disappears on its own without treatment within a few months.
The aggressive form of epithelial ingrowth is defined as involving 30% or more of the flap surface, or epithelial ingrowth that reoccurs after removal. The middle layer of the cornea (stroma) can melt if there is aggressive epithelial ingrowth. It is more likely to affect the vision, and requires treatment.
The Probst/Machat classification can also be used to grade epithelial ingrowth from Grade I to III.
Symptoms of Epithelial ingrowth Include:
- Light sensitivity (photophobia)
- Blurry vision
- Foreign body sensation
- Dry eyes
- Appearance of small gray-white spots on the cornea (areas of epithelial ingrowth)
Benign epithelial ingrowth may be observed (Grade I), but aggressive epithelial ingrowth (Grade II and III) need to be treated. Aggressive epithelial ingrowths typically need repeat surgery where the initial LASIK corneal flap is lifted, and the epithelial ingrowth is scrapped off. Patient’s need to be carefully followed thereafter because recurrence rates can be as high as 40%.