The axial length and corneal radius of curvature ratio in Sudanese adult myopes
Purpose: Evaluating association of axial length and corneal radius of curvature ratio (AL/CR) with myopia among Sudanese adults.
Methods: The Observational, cross sectional study was conducted at Makka Eye complex Omdurman and University Eye complex clinic from March to July 2015. Corneal radius of curvature, axial length and the degree of myopia of 200 myopic eyes and 60 emmetropic eyes were measured and the axial length/ corneal curvature radius AL/CR ratios calculated.
Results: The mean AL/CR ratio for myopic subjects was 3.14 ± 0.164 ranging from 2.86 to 3.71. There was a positive correlation between AL/CR and age in myopes (r = 0.31, p < 0.0001). The mean CR and AL of myopic subjects were 7.57 ± 0.32 mm, and 26.18 ± 0.96 mm, respectively. Myopic eyes had a shorter CR (t= 18.5, p< 0.0001), a longer AL (t= 11.00, p< 0.0001) and thus, a higher AL/CR ratio (t= -8.19, p< 0.0001) than the emmetropic eyes. Linear regression indicated a 11.9D shiti in myopia with each 1 unit change in AL/CR ratio (r2 = 58%, p < 0.0001), a 1.6 D shiti in myopia with each 1mm change in AL (r2 = 37%, p < 0.0001), and a 3.3 D shiti in myopia with each 1 mm change in CR (r2 = 22%, p < 0.0001).
Conclusion: The study shows that myopic adults had shorter CR, longer AL and higher AL/CR ratio when compared with emmetropic subjects.
Keywords: Axial length/corneal radius of curvature ratio AL/CR; axial length AL; corneal radius of curvature CR; refractive state in SE.