Purchase this article with an account.
J. Xu, J. Bao, F. Lu, J. He; Comparison of Reference Points in a Scheimpflug Imaging System (Pentacam) and a Placido-Ring System (ATLAS). Invest. Ophthalmol. Vis. Sci. 2009;50(13):5088.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
A Scheimpflug imaging system (Pentacam) is claimed to have reference point at the corneal apex for its measurement maps of the ocular surfaces while the Placido-ring corneal topography system is usually referred at corneal vertex. Purpose of this study is to compare the reference points of the two systems.
Thirty three subjects were examined with both Pentacam (Oculus Inc., Dutenhofen, Germany) and ATLAS (Carl Zeiss Meditec Inc., Jena, Germany) systems. Offset of pupil center from the reference point in the result map was used to infer location of the reference point. Mean offsets of the pupil center in both x- and y-axes was calculated and the correlation of the pupil center offsets between the two systems was examined.
Mean offsets of pupil center from reference point in the Pentacam system were -0.06 (OD) and 0.07 (OS) in x-axis direction, and -0.01 (OD) and 0.004(OS) in y-axis direction. The mean offsets were not significantly different from those in the ATLAS system (t=-0.458, p>0.1, OD; t=0.064, p=0.05, OS in x-axis; and t=0.550, p>0.1, OD; t=0.034, p>0.05 OS in y-axis). Significant correlations of the pupil center offsets were found between the two systems with r=0.938, p=0.000 (OD) and r=0.827, p=0.000 (OS) for x-axis, and r=0.891, p=0.000 (OD) and r=0.628, p=0.000 (OS) for y-axis.
The results suggest that like the ATLAS system, the Pentacam system might be referred at the corneal vertex also.
This PDF is available to Subscribers Only