Purchase this article with an account.
Eric Joseph Kim, Ildamaris Montes de Oca, Li Wang, Mitchell Weikert, Sumitra Khandelwal, Zaina Al-Mohtaseb, Douglas D Koch; Corneal radius of curvature measurements in normal and post-refractive surgery eyes using point-source color LED and dual-Scheimpflug Placido topographer. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1626.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To report anterior and posterior corneal radius of curvature (ROC) measurements with point-source color LED and dual-Scheimpflug Placido topographers in normal and post-refractive surgery eyes.
In this prospective comparative study, a single observer performed three consecutive measurements in one eye of each subject using the Cassini point-source color LED topographer (i-Optics) and the Galilei dual-Scheimpflug Placido tomographer (Ziemer). The anterior and posterior corneal ROC was measured in the following groups: (1) normal, (2) myopic post-refractive surgery, and (3) post-radial keratotomy (RK) eyes. For each group, the minimum and maximum anterior/posterior ROC ratios were used to calculate the theoretical minimum and maximum posterior corneal power given a measured anterior corneal ROC. The variability in the theoretical posterior corneal power was calculated as the difference between the theoretical minimum and maximum values.
In patients analyzed to date, the anterior/posterior ROC ratio as measured by the Galilei was 1.20 ± 0.02, 1.28 ± 0.06, and 1.13 ± 0.11 in normal (n=34), post-refractive (n=21), and post-RK (n=6) eyes, respectively. The ratio as measured by the Cassini was 1.19 ± 0.03, 1.25 ± 0.05, and 1.27 ± 0.05 in normal, post-refractive, and post-RK eyes, respectively. The variability of the theoretical posterior corneal power as measured by the Galilei was 0.49 ± 0.02 D, 1.16 ± 0.06 D, and 1.29 ± 0.06 D in normal, post-refractive, and post-RK eyes, respectively. The variability as measured by the Cassini was 0.52 ± 0.02 D, 0.89 ± 0.06 D, and 0.49 ± 0.04 D in normal, post-refractive, and post-RK eyes, respectively. These results are presented in Tables 1 and 2.
Preliminary results suggest that the variability in the anterior/posterior ROC ratio may help explain part of the error in intraocular lens calculations when a fixed ratio is assumed. Final results and conclusions will be presented.
This PDF is available to Subscribers Only