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M. Fujioka, Y. Tatsumi, A. Kusuhara, K. Taguchi, H. Maeda, M. Nakamura, A. Negi; Agreement of Three Types of Instruments in Measuring Central Corneal Thickness and the Association With the Anterior Depth . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1349.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the agreement of central corneal thickness (CCT) measurements taken with noncontact specular microscopy (NSM), ultrasonic pachymetry (US) and Scheimpflug system and the association of anterior chamber depth (ACD) with the CCT inter–method differences.
Right eyes of 136 persons without anti–glaucoma drugs (101 females,35 males),which included 32 patients with primary open angle glaucoma (POAG group) , 15 with ocular hypertension (OH group), 45 with primary angle closure glaucoma (PACG group), and 44 controls (normal group). Mean age was 61.3±17.9years. CCT was measured once with each method in a random order. ACD was simultaneously measured with the Scheimpflug system. CCT inter–method difference was assessed by the Bland–Altman method. The association of the ACD with the CCT inter–method differences was analyzed by linear regression.
The mean CCT taken with US, Scheimpflug, and NSM was 553.4±39.6µm, 565.7±37.6µm,552.5±43.3µm, respectively. There was no significant difference in CCT measurements of 4 groups (One–factor ANOVA: NSM,p=0.15 ;US, p=0.47; Scheimpflug, p=0.2). ACD of PACG group was significantly shallower compared with other 3 groups (Bonferroni/Dunn correction : p<0.01). The 95% limits of agreement were 4.61±42.99µm between US and NSM, –12.14±42.57µm between US and Scheimpflug, and –16.74±54.88µm between NSM and Scheimpflug. Significant correlations between the US to Scheimpflug CCT difference and ACD and between the NSM to Scheimpflug CCT difference and ACD were observed (Simple regression analysis: R2=0.031,p<0.01 and R2=0.019,p<0.01,respectively). Scheimpflug significantly overestimated the US and NSM CCT measurements in eyes with shallower anterior chamber.
There were fair agreement in measuring CCT taken with the three instruments. However, the significant association of ACD with the CCT difference between the Scheimpflug and other two methods may reflect the distinct analytical methodology or algorithm of the Scheimpflug system.
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