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Emilie Costantini, Olivier Touzeau, Cecile Allouch, Thomas Gaujoux, Vincent Borderie, Laurent Laroche; Characteristics Of The Corneal Thinnest Point In Normal Subjects Analyzed By Orbscan. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4176.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize the corneal thinnest point (thickness, location, relations with fellow eye) and to investigate the influence of the clinical factors on the thinnest point.
500 healthy eyes (including ametropia) of 250 normal subjects aged 7 to 97 years were prospectively analyzed using Orbscan. Mirror-image symmetry (enantiomorphism) of the thinnest point of fellow eyes was quantified by the distance between the point of the right eye (XR,YR) and the point corresponding to a perfect enantiomorphism of the left eye (-XL,YL).
Thickness of the thinnest point is 538.4 µm +39.8 (97.5% of central measure) and is correlated with central and controlateral measurements (r≥0.96 p<0.001). The difference with the fellow eye is 9.0µm +7.5 (1.68%). The mean "thickness difference" and "distance" between the central and thinnest points are 13.5 µm +9.9 and 0.87 mm +0.53, respectively. The average location of the thinnest point is in inferotemporal quadrant, 13° (right) and 20° (left) under the horizontal. The distributions of right eyes and left eyes are no different (inferotemporal: 61.6%, superotemporal: 26.2%, inferonasal: 8.2%, and superonasal: 4.0%; p=0.11). Sex, refraction and corneal parameters (including toricity, radii of curvature, diameter, irregularity and asphericity) have no significant influence on thickness and location of the thinnest point and its relations with the fellow eye (r≤0.06 p≥0.08). Correlations between thinnest point characteristics and age are poor but significant: increasing of the thickness (r=0.12 p=0.02 +3.6µm by decade), the distance (r=0.09 p=0.025), the difference between fellow eyes (r=0.15 p<0.001), and diminution of the enantiomorphism (r=0.17 p<0.001).
Corneal thinnest point is usually located in inferotemporal and is characterized by a high degree of enantiomorphism. With the exception of the age, the others clinical factors have no significant influence on corneal thinnest point which the characteristics seem to have an embryologic origin.
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