Abstract
Abstract: :
Purpose: To compare, using child subjects, axial length measurements made with non-contact optical coherence methods and with ultrasound methods. Methods: Subjects were 178 Chinese children taking part in the Singapore Cohort study of the Risk factors for Myopia (SCORM), 85 F, 93 M, mean age 10.58+/-0.77 years. Spherical equivalent refractive error (cyclopleged) ranged from +2.2D to -7.9 D (average -1.7 +/-2.0D). Axial length was measured on the subjects' right eyes using an IOLMaster biometer which uses optical coherence principles followed by an Nidek Echoscan US 800 biometer which operates using ultrasound. 37 subjects underwent repeat testing on both instruments to asses test-retest reliability. Results from right eyes are reported. Results: On average, IOLMaster measurements of axial length were 24.15 (S.D.1.07) mm, significantly different (p=0.001) from Echoscan measurements averaging 24.00 (S.D.1.05) mm, with measurements from each method being strongly correlated (r=0.958). 95% confidence limits for retest-test differences were +0.65 mm and -0.83 for Echoscan and +0.038mm and -0.050 mm for IOLMaster, as shown in the Bland-Altman plots. Test and retest values were highly correlated for IOLMaster measurements (r=1.000) and for Echoscan (r=0.950). Conclusions: Ocular coherence biometry is a suitable method for measuring axial length in children.
Keywords: myopia • optical properties