Norm Evaluation of the Horizontal Corneal Diameter (White-to-White) with the Orbscan II System
Rüfer F., Schröder A., Meyer M., Gockeln R., Erb C.
Department of ophthalmology, Hannover School of Medicine (Hannover)
Purpose: The horizontal diameter (white-to-white) of the cornea gives important clinical information about structural abnormalities, corneal dystrophies and affects surgical procedures. As mentioned norm values are described imprecisely in literature, purpose of this study was to re-evaluate the normal corneal diameter as a diagnostic parameter.
Method: The horizontal corneal diameter was evaluated by the Orbscan II system in 370 right eyes and 373 left eyes of 390 healthy volunteers aged from 10 80 years. 148 subjects were female, 242 were male. Each measurement was performed twice. Differences in gender as well as differences between right and left eyes were analyzed statistically in parametric tests.
Results: The average corneal diameter was 11.71 ± 0.42 mm. For men normal values were 11.77 ± 0.37 mm, for women 11.64 ± 0.47 mm. Thus the resulting normal ranges were 11.04 to 12.50 mm for men and 10.70 to 12.58 mm for woman. Differences in gender proved to be not significant in t-test for independent samples (p=0.071). There were no differences between right and left eyes.
Conclusions: The horizontal corneal diameter shows no differences in gender. With the norm values mentioned above, a more precise diagnostic is possible in future.
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