Effect of Gender and Race on Ocular Biometry

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Many publications have referred to the eye’s “average” or “normal” axial length (AL) or corneal power (K). The former has been customarily accepted as being 23.50 mm, the latter as 43.50 D. In 1980, our first reported publication1 of a large series of 7500 cataractous eyes, using immersion A-scan ultrasound, reported a mean AL of 23.65 (±1.35) mm, a mean K of 43.81 (±1.60) D and a mean anterior chamber depth (ACD) (corneal epithelium to anterior lens surface) of 3.24 (±0.44) mm. Our later study2 of 600 cataractous eyes (age 19 to 97 y), again using immersion A-scan ultrasound, reported a mean lens thickness (LT) of 4.63 (±0.68) mm but in the 503 of these eyes over age 60 the mean LT was 4.68 (±0.64) mm. Such average values have been used for various purposes, including schematic eyes used in optics and the development of intraocular lens (IOL) power formulas such as the Holladay 2 formula.
However, these studies did not differentiate between gender or racial groups. Previous studies have shown that taller and heavier individuals have longer ALs. Tan et al3 in a study of 1845 Asian eyes, reported that for every 10 cm (3.94 inches) increase in height, AL increases by 0.30 mm. It could therefore be conjectured that as males are usually taller, this is the major cause of longer AL. However, Lim et al4 showed in 2788 Asian eyes, when corrected for height, males still had a statistically longer eye than females. Females have also been shown to have significantly smaller corneal diameters than males in a large 23,239 eye study by Hoffmann and Hütz5 but we found no other studies to support this fact.
The goal of this study was to collect large series of ocular biometry published reports to determine whether there are differences in biometric values based on gender and race that might be useful in developing more accurate IOL power formulas.

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