J Korean Med Sci.  2007 Feb;22(1):142-145. 10.3346/jkms.2007.22.1.142.

The Safety of 250 micrometer Residual Stromal Bed in Preventing Keratectasia after Laser in situ Keratomileusis (LASIK)

• Kim TH
• Lee D
• Lee HI

• KMID: 1713254
• DOI: http://doi.org/10.3346/jkms.2007.22.1.142

Abstract

To determine if the residual corneal stromal bed of 250 micrometer is enough to prevent iatrogenic keratectasia in laser in situ keratomileusis (LASIK), we studied 958 patients who underwent LASIK from April 2000 to October 2003 retrospectively. The estimated probabilities of the residual stromal bed, that was less than 250 micrometer, were calculated using the published flap thickness data of Moria C&B microkeratome. Then we calculated the ratio of the real incidence of keratectasia to the expected the percentage of the patients with less than 250 micrometer residual stromal bed in our study. Using the LASIK flap thickness data of Miranda, Kezirian and Nagy, the expected probabilities that the residual stroma would be less than 250 micrometer were 8.8%, 4.3% and 1.5% of the 1,916 eyes respectively, while keratectasia developed in both eyes (0.1%) of 1 patient in our study. The estimated ratio of the keratectatic eyes to eyes with less than 250 micrometer stromal bed were 1.2-6.9%. Compared to the number of eyes with residual stromal thickness less than 250 micrometer, the incidence of keratectasia was relatively low. The residual stromal bed thickness of more than 250 micrometer may possibly be safe, but further observations for long period are necessary.

Keyword

Corneal Stroma; Ectasia; Dilatation, Pathologic; Keratomileusis, Laser In Situ

MeSH Terms

Postoperative Complications/*prevention & control
Middle Aged
Keratomileusis, Laser In Situ/*adverse effects
Iatrogenic Disease/*prevention & control
Humans
Dilatation, Pathologic
Corneal Stroma/*pathology
Corneal Diseases/etiology/*prevention & control
Adult

Figure

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  Fig. 1 Topographical changes in a patient who developed keratectasia 2 yr after LASIK. Preoperative corneal topography image. (A. Right, B. Left) Corneal topography taken 1 week after LASIK (C. Right, D. Left). Corneal topography taken 2 yr after LASIK in the right eye (E) and in the left eye (F) in the same patient. Clinically evident iatrogenic keratectasia was found 2 yr postoperatively.

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