Author Affiliation: Beckman Vision Center, Department of Ophthalmology, University of California, San Francisco.
We appreciate the comments from Dooley and Beatty and acknowledge the supportive findings from the article by Dooley et al entitled “Changes in Intraocular Pressure and Anterior Segment Morphometry After Uneventful Phacoemulsification Cataract Surgery.”1 Both studies support the idea that IOP reduction in subjects undergoing phacoemulsification cataract extraction is related to ACA dimensions. We wish to point out that there are some significant differences between the studies. First, we used the anterior segment optical coherence tomography (ASOCT) device (Visante OCT; Carl Zeiss Meditec) to evaluate the ACA, and the study by Dooley et al used the rotating Scheimpflug camera (Pentacam; Oculus Optikgerate GmbH). The ASOCT device is able to image the angle recess, whereas the Pentacam is unable to do so with sufficient clarity. In addition, metrics such as anterior chamber depth and anterior chamber parameters are determined by automated assessment after identification of the scleral spurs using the Zhongshan Angle Assessment Program. In contrast, equivalent measures on the Pentacam require manual identification of various points, introducing greater potential for variability in the output values. Dooley and Beatty pointed out the difference in angle change between the studies, ours being greater than those found in the study by Dooley et al. However, as he noted, the angle values being measured are not the same (AOD500 for the ASOCT vs ACA for the Pentacam) and the technology for the devices is not the same, so direct comparisons are not adequate.
Lin SC. Discussion of Changes in Intraocular Pressure and Anterior Segment Morphometry Following Phacoemulsification Cataract Surgery—Reply. Arch Ophthalmol. 2012;130(7):949-950. doi:10.1001/archophthalmol.2012.745