Man reports experiencing blurry vision for 2 months after LASIK

The patient also had a foreign body sensation in his left eye since the procedure.

Issue: August 1, 2006

ByHelen K. Wu, MD

ByStefanie Schuman, MD

A 47-year-old man who had LASIK in both eyes 2 months prior presented complaining of blurry vision in both eyes since the procedure. He also reported a foreign body sensation in the left eye since then. His ocular history was significant for LASIK in both eyes 2 months before presentation in another country and replacement of a dislodged flap in the left eye on postoperative day 1. Medical history includes hypertension for which he takes medication. Ocular medications include artificial tears in the left eye three times a day.

Examination

On examination, best corrected visual acuity was 20/40+ in the right eye and 20/50+ in the left eye. Pupils were equal, round and reactive to light with no afferent papillary defect. Extraocular muscle movements were full in both eyes. IOP by applanation was 10 mm Hg in both eyes. Slit lamp exam revealed a well-healed corneal flap in the right eye and a corneal cap with three areas of haze in the left eye (Figures 1 and 2). Otherwise, there was no anterior chamber inflammation, corneal infiltrate or areas of corneal thinning in either eye. Corneal topography revealed central irregular astigmatism in both eyes (Figure 3).

Slit lamp photographs of the left eye show patchy areas of corneal haze. Images: Schuman S, Wu HK
Corneal topography reveals central irregular astigmatism in both eyes.

What is your diagnosis?

Blurry vision

Differential diagnosis in this case includes epithelial ingrowth, diffuse lamellar keratitis and infection (most commonly nontuberculous mycobacteria, gram-positive organisms and fungi).

This patient was diagnosed with epithelial ingrowth. After LASIK, epithelial ingrowth has been reported to occur in 1% to 20% of cases, with a cumulative mean of 4.3% in a review of LASIK publications. Most cases are self-limited, occurring at the edge of the flap and extending inward less than 0.5 mm, and cause no adverse effect on the results of surgery.

Jane
Loman

Zinaria Williams

However, when epithelial ingrowth becomes clinically significant, surgical removal is required. Epithelial ingrowth can extend into the pupil and cause decreased vision or induce nighttime glare as it approaches the edge of the pupil. It can also induce astigmatism by raising an area of the flap. Epithelial ingrowth can cause epithelial irregularity with fluorescein staining at the edge of the flap creating a foreign body sensation. If progressive, epithelial ingrowth can lead to keratolysis or induce melting of the overlying flap.

The clinical signs of epithelial ingrowth include epithelial pearls in the flap interface, which can sometimes appear as a sheet of confluent opacity. Fluorescein pooling at the edge of the flap, a white fibrotic demarcation line, and keratolysis or melting of the edge of the flap can also be seen.

Risk factors of epithelial ingrowth include trauma, LASIK enhancements, lacerated flaps, buttonholed flaps, thin or irregular flaps, and free flaps. Two hypotheses exist on the pathogenesis of epithelial ingrowth after LASIK. One states that epithelial cells are implanted in the lamellar interface by the microkeratome blade or during irrigation of the stromal bed. The second hypothesis postulates that epithelial cells grow under the edge of the flap and progress into the interface.

The continuity of the epithelial ingrowth with the surface epithelium makes the second hypothesis more likely. It has therefore been suggested that epithelial ingrowth consists of an epithelial fistula underneath the flap with a tract extending to the edge of the flap. A fistula may form owing to poor flap adhesion, which allows for surface epithelial cells to enter into the lamellar interface. Epithelial defects, basement membrane dystrophy or excessive hydration of the flap intraoperatively may cause poor flap adhesion and predispose to fistula formation.

Epithelial ingrowth develops with basal cells of the corneal epithelium first extending along the flap-stroma interface. The invading epithelial cells proliferate and differentiate with polarity. Differentiated cells cannot exfoliate but accumulate as an epithelial pearl within the flap-stroma interface. The degenerated cell debris accumulates as an epithelial pearl.

Treatment

Reported techniques for removing epithelial ingrowth include lifting the flap and scraping the epithelial ingrowth (with or without adjunctive treatments such as ethanol and mitomycin), phototherapeutic keratectomy or suturing of the flap. The recurrence rate after scraping alone has been reported to be 44%. Suturing the flap followed by placement of a bandage contact lens to create a tight apposition between the flap and the stromal bed has been proposed to be effective at preventing the recurrence of ingrowth without the complications of other adjunctive treatments.

For more information:

Stefanie Schuman, MD, and Helen K. Wu, MD, can be reached at New England Eye Center, Tufts University School of Medicine, 750 Washington St., Box 450, Boston, MA 02111; 617-636-4219; fax: 617-636-4866; Web site: www.neec.com.

Edited by Jane Loman, MD, and Zinaria Williams, MD. Drs. Loman and Williams can be reached at New England Eye Center, Tufts University School of Medicine, 750 Washington St., Box 450, Boston, MA 02111; 617-636-4219; fax: 617-636-4866; Web site: www.neec.com. Drs. Loman and Williams have no direct financial interest in the products mentioned in this article, nor are they paid consultants for any companies mentioned.

References:

Asano-Kato N, Toda I, et al. Epithelial ingrowth after laser in situ keratomileusis: clinical features and possible mechanisms. Am J Ophthalmol. 2002;134(6):801-807.

Asano-Kato N, Toda I, et al. Histopathological findings of epithelial ingrowth after laser in situ keratomileusis. Cornea. 2005;24(2):130-134.

Domniz Y, Comaish IF, et al. Epithelial ingrowth: causes, prevention, and treatment in 5 cases. J Cataract Refract Surg. 2001;27(11):1803-1811.

Melki SA, Azar DT. LASIK complications: etiology, management, and prevention. Surv Ophthalmol. 2001;46(2):95-116.

Rojas MC, Lumba JD, Manche EE. Treatment of epithelial ingrowth after laser in situ keratomileusis with mechanical debridement and flap suturing. Arch Ophthalmol. 2004;122(7):997-1001.