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The shape of Bowman's layer in the human cornea
S Patel1, D Z Reinstein, R H Silverman
1Academic Unit of Ophthalmology, Birmingham and Midland Eye Centre, United Kingdom. Dr_SPatel@compuserve.com
Purpose:
The aim of this investigation was to derive a mathematical model for Bowman's layer, the interface between the epithelium and stroma, in the human cornea.
Methods:
The central epithelial thickness distribution within 14 normal human corneas was measured in vivo using high frequency ultrasonic digital signal processing with a measurement precision of 2 microns. The results per eye were averaged and incorporated into existing algorithms for the estimation of the shape of the anterior surface of Bowman's layer using terminology in accordance with Baker's equation.
Results:
The average radius of Bowman's layer was 7.34 mm (SE +/- 0.17 mm). Descriptions of this boundary ranged from a steepening or prolate ellipse to a hyperbola. However, the typical Bowman's layer is hyperbolic with a shape factor, p = -0.22 (SE +/- 1.81).
Conclusion:
The results support previous cadaver studies where Bowman's layer was found to be steeper than the anterior corneal surface but disagree with the concept that the average Bowman's layer is akin to a prolate ellipse. The hyperbolic nature of the average Bowman's layer has the potential to influence the optical performance of the eye.