Epithelial ingrowth after laser in situ keratomileusis: clinical features and possible mechanisms

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Abstract

PURPOSE: To analyze the incidence, clinical course, and possible mechanisms of epithelial ingrowth after laser in situ keratomileusis (LASIK).

DESIGN: Interventional case series.

METHODS: Retrospective evaluation of 4,867 eyes of 2,502 patients who had LASIK. The type of microkeratome (LSK-One or MK-2000), corneal flap thickness, and clinical course were analyzed. We also compared the cutting characteristics of both microkeratomes in pig cadaver eyes by scanning electron microscopy.

RESULTS: The frequency of epithelial ingrowth was significantly greater in the MK-2000 (34 of 1,680 eyes; 2.0%) than the LSK-One group (30 of 3,187 eyes; 0.94%; P = .001). In 24 eyes (37.5%), blood, cell infiltration, ointment under the corneal flaps, or epithelial defect were detected at the area of epithelial ingrowth postoperatively. The incidence of epithelial ingrowth was correlated with the incidence of epithelial defect during surgery (P < .001) and with incidence of diffuse lamellar keratitis after surgery (P = .003). Flap thickness was thinner in eyes with epithelial ingrowth (126.0 ± 29.1 μm) compared with flap thickness in eyes without epithelial ingrowth (133.8 ± 27.3 μm; P < .001). Scanning electron microscopy showed clear differences in the appearance of flap edges created by the two types of microkeratomes. Epithelial ingrowth disappeared or remained unchanged in 54 eyes (90%) and progressed in six cases (10%).

CONCLUSIONS: Poor adhesion caused by excessive hydration due to epithelial defect as well as by foreign bodies between the flap stromal bed and thickness and morphologic characters of the corneal flap, depending on the type of microkeratomes, are related factors for development of epithelial ingrowth.

Section snippets

Design

This study was an interventional case series of patients with epthelial ingrowth occurring after LASIK.

Patients

Four thousand eight hundred sixty-seven eyes of 2,502 patients (1,452 male and 1,050 female; average age 34.5 ± 9.0 [SEM] years), who underwent myopic LASIK from May 1998 to March 2001 at Minamiaoyama Eye Clinic, were included in this study. The mean attempted correction was −6.08 ± 2.58 diopters. Sixty-four eyes (1.3%) of 54 patients (33 male and 21 female, average age 38.6 ± 9.0 [SEM] years) developed epithelial ingrowth. The slit-lamp examination findings, type of microkeratome used, and

Microkeratomes and flap thickness

Epithelial ingrowth was diagnosed in 30 eyes (0.94%) of the LSK-One group (3,187 eyes) and 34 eyes (2.0%) in the MK-2000 group (1,680 eyes). The frequency of epithelial ingrowth in the MK-2000 group was significantly higher than that in the LSK-One group (P = .001). When the incidence of epithelial ingrowth was compared among different types of heads, it was found that heads with lower estimated thicknesses were more likely to develop epithelial ingrowth (Table 1).

The corneal flap was

Discussion

The incidence of epithelial ingrowth after LASIK in the present study was 1.31%. Epithelial ingrowth was diagnosed within 1 month in 79% of eyes. These results are consistent with previous reports.2, 3, 4, 5, 6 Epithelial ingrowth mainly developed near the corneal flap margin, most often at the temporal edge.

Many findings were observed before the epithelial ingrowth. A loose epithelial layer or epithelial defect was detected significantly more often in cases with epithelial ingrowth than in

Acknowledgements

The authors thank Mrs. Chikako Sakai, Minamiaoyama Eye Clinic, for her help with statistical data analysis, and Yoshihisa Oguchi, MD, Department of Ophthalmology, Keio University School of Medicine, for supervising the electron microscopic observation.

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