Risk Assessment for Ectasia after Corneal Refractive Surgery

doi:10.1016/j.ophtha.2007.03.073

Ophthalmology

Volume 115, Issue 1, January 2008, Pages 37-50.e4

https://doi.org/10.1016/j.ophtha.2007.03.073 Get rights and content

Purpose

To analyze the epidemiologic features of ectasia after excimer laser corneal refractive surgery, to identify risk factors for its development, and to devise a screening strategy to minimize its occurrence.

Design

Retrospective comparative and case–control study.

Participants

All cases of ectasia after excimer laser corneal refractive surgery published in the English language with adequate information available through December 2005, unpublished cases seeking treatment at the authors’ institution from 1998 through 2005, and a contemporaneous control group who underwent uneventful LASIK and experienced a normal postoperative course.

Methods

Evaluation of preoperative characteristics, including patient age, gender, spherical equivalent refraction, pachymetry, and topographic patterns; perioperative characteristics, including type of surgery performed, flap thickness, ablation depth, and residual stromal bed (RSB) thickness; and postoperative characteristics including time to onset of ectasia.

Main Outcome Measures

Development of postoperative corneal ectasia.

Results

There were 171 ectasia cases, including 158 published cases and 13 unpublished cases evaluated at the authors’ institution. Ectasia occurred after LASIK in 164 cases (95.9%) and after photorefractive keratectomy (PRK) in 7 cases (4.1%). Compared with controls, more ectasia cases had abnormal preoperative topographies (35.7% vs. 0%; P<1.0×10⁻¹⁵), were significantly younger (34.4 vs. 40.0 years; P<1.0×10⁻⁷), were more myopic (−8.53 vs. −5.09 diopters; P<1.0×10⁻⁷), had thinner corneas before surgery (521.0 vs. 546.5 μm; P<1.0×10⁻⁷), and had less RSB thickness (256.3 vs. 317.3 μm; P<1.0×10⁻¹⁰). Based on subgroup logistic regression analysis, abnormal topography was the most significant factor that discriminated cases from controls, followed by RSB thickness, age, and preoperative corneal thickness, in that order. A risk factor stratification scale was created, taking all recognized risk factors into account in a weighted fashion. This model had a specificity of 91% and a sensitivity of 96% in this series.

Conclusions

A quantitative method can be used to identify eyes at risk for developing ectasia after LASIK that, if validated, represents a significant improvement over current screening strategies.

Section snippets

Materials and Methods

A literature search was performed in January 2006 on the PubMed database (www.pubmed.gov) for all relevant articles published from 1997 through December 2005. Search terms included corneal ectasia, keratectasia, keratoectasia, iatrogenic ectasia, and keratoconus AND LASIK. The search was limited to English language articles only. This search yielded 221 articles that were reviewed and selected for direct relevance to the topic of ectasia developing after excimer laser corneal refractive surgery

Results

One hundred seventy-one cases met inclusion criteria for this study, including 158 published cases of ectasia after excimer refractive surgery6, 51, 52, 53 and 13 unpublished cases from the authors’ institution (Figure 1, Figure 2, Figure 3, Figure 4 [available at http://aaojournal.org], Figure 5, Figure 6, Figure 7, Figure 8). Of these 171 cases, 164 (95.9%) occurred after LASIK and 7 (4.1%) occurred after PRK. There were 186 control cases.

An additional 36 unpublished cases from the authors’

Discussion

This aggregate analysis of published ectasia cases, combined with experience at the authors’ institution, provides insight into the risk factors for ectasia after excimer laser corneal refractive surgery. Although less common now, ectasia still occurs at an unacceptably high frequency. Further, the onset of ectasia may be delayed for years after surgery, so some individuals who seem to have undergone successful refractive surgery may experience ectasia in the future.

Rather than representing a

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The purpose of this study is to describe a case of unilateral keratoconus associated with ipsilateral craniofacial fibrous dysplasia and its subsequent management with corneal collagen cross-linking.
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: Manuscript no. 2006-1191.

: The authors have no financial interests in any of the products or topics mentioned in the article.

: Supported in part by Research to Prevent Blindness, Inc., New York, New York, and the National Institutes of Health, Bethesda, Maryland (grant no. P30 EY06360).

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Original articleRisk Assessment for Ectasia after Corneal Refractive Surgery

Purpose

Design

Participants

Methods

Main Outcome Measures

Results

Conclusions

Section snippets

Materials and Methods

Results

Discussion

J Cataract Refract Surg

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Ophthalmology

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Ophthalmology

Ophthalmology

Ophthalmology

J Cataract Refract Surg

J Cataract Refract Surg

Ophthalmology

Original article
Risk Assessment for Ectasia after Corneal Refractive Surgery