May 2007
Volume 48, Issue 13
ARVO Annual Meeting Abstract  |   May 2007
Keratocyte Density of Subjects With and Without Keratoconus
Author Affiliations & Notes
  • P. Simard
    School of Optometry, University of Montreal, Montreal, Quebec, Canada
  • C. J. Giasson
    School of Optometry, University of Montreal, Montreal, Quebec, Canada
    LOEX, Université Laval, Quebec, Canada
  • Footnotes
    Commercial Relationships P. Simard, None; C.J. Giasson, None.
  • Footnotes
    Support Canada Foundation for Innovation (CJG) and C.O.E.T.F. (PS)
Investigative Ophthalmology & Visual Science May 2007, Vol.48, 3515. doi:
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      P. Simard, C. J. Giasson; Keratocyte Density of Subjects With and Without Keratoconus. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3515.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose:: Evaluate the density of keratocytes in the cornea of patients with and without keratoconus. Analyze the intra-class correlation coefficient (ICC) between various methods of corneal thickness measurements.

Methods:: In order to fulfill these goals, 15 subjects with early keratoconus and 15 control subjects with normal corneas, paired for age, were recruited. The corneas of both eyes of each subject was examined with biomicroscopy, Orbscan topography, in vivo Confoscan 2 confocal microscopy, and ultrasonic pachometry. Keratocyte density, based on manual count of nuclei on confocal stromal images, was estimated by averaging the density obtained at 5 relative depths of 1) 0%-10%, 2) 11%-33%, 3) 34%-66%, 4) 67%-89% (deep stroma) and 5) 90%-100% (posterior stroma) of stromal thickness. Differences in density were analyzed for statistical significance with an ANOVA for repeated measurements. An ICC was calculated between the 3 methods of corneal thickness measurement.

Results:: A separate analysis of the thinnest (keratoconics: 419 µm; 514 normals: µm) and thickest corneas (keratoconics: 453 µm; normals: 521 µm) revealed that mean keratocyte density between the keratoconics and normals was significantly different only for the thickest cornea in the deep (658 ± 155 and 540 ± 55 cells/mm2, p=0.010) and posterior stroma (748 ± 165 and 614 ± 43 cells/mm2, p=0.005), respectively. The overall intraclass correlation coefficients for mean central corneal thickness obtained with the Orbscan corneal topograph, the confocal microscope and the ultrasonic pachymeter were 0.97 and 0.96 for the right and left eyes, respectively. However, the intraclass correlation coefficient between three measurements of corneal thickness with the confocal microscope were 0.64 for the right eye and 0.51 for the left eye.

Conclusions:: Averaging 3 measurements of corneal thickness with the Confoscan 2 provides a good ICC with pachometry and topography. In the thinnest cornea, there is no significant difference in mean keratocyte density between keratoconic and normal corneas. In the thickest cornea, the stroma from the keratoconic group had a mean keratocyte density higher in the deep and posterior stroma compared to the one observed in control subjects. This last finding might be due to our sample of subjects with early keratoconus.Keywords: Confocal microscopy, pachometry, Orbscan II topography, keratoconus, keratocytes, keratocyte density

Keywords: keratoconus • cornea: stroma and keratocytes • contact lens 

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