Abstract
Purpose::
The traditional method for sizing the Anterior Chamber (AC) and Posterior Chamber (PC) phakic have been use of White-to-White (WW) diameter. Our aim was to determine the statistical relationship between accurate measured values of Angle Diameter (AD) and Sulcus Diameter (SD) and the WW estimation.
Methods::
Artemis-2 scans were acquired on the anterior segments of 99 eyes in 80 subjects. All eyes were phakic and without known anterior segment pathology. Scans were acquired in the horizontal meridian and measurements performed of WW, AD, SD and the Anterior Chamber Depth (ACD, endothelium to anterior lens surface). Bivariate correlations between factors were determined. In addition, linear regression models for estimation of AD and SD based on ACD and WW were produced.
Results::
Correlation coefficients of 0.683, 0.618 and 0.356 were found between WW and AD, SD and ACD, respectively. All correlations were statistically significant (p<.001).In multivariate models, R values of 0.743 and 0.674 were found for prediction of AD and SD based on ACD and WW. The standard deviations between predicted and measured values for AD and SD were 0.40 mm and 0.47 mm, respectively.
Conclusions::
Our findings show that while ACD and WW both correlate with AD and SD, their practical value in predicting AD and SD is limited. Multivariate models show standard deviations of over 0.4 mm, implying that in 5% of cases, predictive errors of 0.8 mm will occur. Direct measurement of AD and SD are necessary for proper sizing of AC and PC phakic implants.
Clinical Trial::
www.clinicaltrials.gov NCT00279695
Keywords: anterior chamber • anatomy • refractive surgery: phakic IOL