The relationship between keratoconus and axial myopia

Purpose: To study the relationship between keratoconus and axial myopia. Methods: We prospectively studied refraction and ocular biometry in 100 consecutive keratoconus eyes, and 100 emmetropic eyes. Biometric data (including posterior segment length) were obtained by A-scan ultrasound, Orbscan, and ultrasonic pachymetry. Biometric measurements were compared in both groups. Results: Anterior chamber depth, posterior segment length and axial length were significantly different between the two groups (p<0.001). Axial length was significantly greater in the keratoconus group than in the emmetropic group (23.97 mm versus 23.21 mm, p<0.001). Posterior segment length was significantly greater in the keratoconus group than in the emmetropic group (16.54 mm versus 15.99 mm, p<0.001). In the keratoconus group, the posterior segment length and the subjective spherical equivalent were significantly correlated (r(s)=-0.45, p<0.001). Conclusion: The increase in posterior segment length in the keratoconus group and the correlation between posterior segment length and spherical equivalent in the keratoconus group suggest a statistical relationship between keratoconus and axial myopia.