Elsevier

Ophthalmology

Volume 106, Issue 11, 1 November 1999, Pages 2216-2220
Ophthalmology

Central corneal pachymetry in patients undergoing laser in situ keratomileusis1Historical image

https://doi.org/10.1016/S0161-6420(99)90508-0Get rights and content

Abstract

Objective

To report the preoperative ultrasonic central pachymetric measurements on a large group of eyes undergoing laser-assisted in situ keratomileusis (LASIK) surgery for myopia and myopic astigmatism, to determine whether central corneal thickness is correlated with other geometric features of the eye or is correlated with age or gender, and to discuss the resulting limitations on possible ablation depths.

Design

Prospective, multisite, cross-sectional study.

Participants

Eight hundred ninety-six eyes in 450 patients from 21 to 66 years of age.

Main outcome measures

Central corneal thickness and its correlation to intraocular pressure, corneal curvature, axial length, horizontal corneal diameter, refraction, age, and gender.

Results

The mean central corneal thickness was 550 μm with a standard deviation of 33 and a range of 472 to 651 μm. The lower 25th quantile was 528 μm. The central corneal pachymetry correlated with the mean manual keratometric measurement (P = 0.0001), simulated keratometry (Sim K) (P = 0.0001), and intraocular pressure (P = 0.0001). Central corneal thickness did not correlate with axial length, age, gender, horizontal corneal diameter, and refraction.

Conclusion

This clinical study shows there is a substantial range of central corneal thickness in normal myopic eyes. With LASIK, there is a general concern that one should not thin the cornea further than a given amount. Because this study shows wide variability in central corneal thickness, it is prudent to measure pachymetry before surgery and gear treatment plans accordingly. Possible treatment limits relative to corneal thickness are discussed.

Section snippets

Patients and methods

The data for this report were compiled from a prospective, randomized, physician-sponsored investigation devise exemption study on 450 LASIK patients evaluating the bilateral simultaneous treatment of both eyes versus the treatment of the eyes 2 or more weeks apart. All data in this report are limited to the preoperative examinations, with the exception of the horizontal corneal diameter measurement, which was taken at the time of surgery with calipers by one of four operating surgeons from the

Results

Demographic data of the patients in this study were as follows: 53% were female, mean age was 40 years, age range was 21 to 66 years. Figure 1 shows the distribution of central pachymetric readings. The mean thickness was 550 μm, with a standard deviation of 33 and a range of 472 to 651 μm. The 75th quantile was 572 μm and the 25th quantile was 528 μm. Central pachymetry was negatively correlated with mean keratometric measurement (P < 0.0001) as measured by manual keratometry and the Sim K as

Discussion

To our knowledge, this study reports the largest series of eyes for central corneal pachymetric measurements. These measurements are important because they document the central corneal thickness in a large group of eyes undergoing myopic lamellar refractive surgery. We believe it is essential to measure central corneal thickness in myopic eyes before scheduling LASIK surgery to ensure the central thickness is sufficient to prevent leaving the corneal bed too thin after treatment. The residual

Acknowledgements

The authors thank the Cornea Research Foundation of America for data retrieval and analysis.

References (12)

  • G. von Bahr

    Corneal thicknessits measurement and changes

    Am J Ophthalmol

    (1956)
  • L.E. Probst et al.

    Mathematics of laser in situ keratomileusis for high myopia

    J Cataract Refract Surg

    (1998)
  • F.K. Hansen

    A clinical study of the normal human central corneal thickness

    Acta Ophthalmol (Copenh)

    (1971)
  • E.L. Mortola et al.

    Central and peripheral corneal thickness. A clinical study

    Arch Ophthalmol

    (1968)
  • Checklist of information usually submitted in an Investigational Device Exemptions (IDE) application for refractive...
  • S. Esquenazi

    Comparison of laser in situ keratomileusis and automated lamellar keratoplasty for the treatment of myopia

    J Refract Surg

    (1997)
There are more references available in the full text version of this article.

Cited by (0)

1

The authors have no proprietary or financial interest in any product mentioned in this article.

View full text