Novel tomographic parameters for determination of ectasia progression

Session Details

Session Title: Cross-Linking

Session Date/Time: Sunday 11/09/2016 | 08:00-09:30

Paper Time: 08:32

Venue: Auditorium A

First Author: : M.Belin USA

Co Author(s): :    J. Meyer   J. Duncan   M. Borgstrom              

Abstract Details

Purpose:

To investigate whether the parameters utilized in the ABCD Keratoconus Grading System (anterior and posterior radius of curvature taken from a 3.0 mm zone centered on the thinnest point (ARC, PRC) , and the minimal pachymetry reading (Min PACH)) can be utilized to document and diagnose ectatic progression.

Setting:

University of Arizona Department of Ophthalmology & Vision Science and Information Technology Services, Tucson, Arizona and the University of Auckland Ocular Imaging Unit at Greenlane Hospital, Auckland, New Zealand.

Methods:

– 84 patients with keratoconus were imaged with the Pentacam HR. Each patient was imaged three times, removed from device after each image. A total of 252 exams were analyzed. An additional 135 normal exams were similarly analyzed. A pooled variance estimate and a one-sided confidence intervals were computed using both SPSS version 23 and STATA 13. A one-sided interval was chosen as progression is indicated by thinning and/or steepening of the anterior and/or posterior corneal surfaces. A decrease in radius of curvature or decrease in pachymetry would be suggestive of progression. Both 80% and 95% confidence intervals were determined.

Results:

In the keratoconic group the standard deviation, 80% and 95% one-sided confidence interval for change for the ARC was 0.062, 0.052 & 0.102 mm. For the PRC 0.062, 0.052, & 0.102 mm, and for the Min PACH 6.03, 5.07, & 9.92 microns respectively. In the normal population standard deviation, 80% and 95% one-sided confidence intervals were; ARC 0.015, 0.012, 0.024 mm, PRC 0.050, 0.042, 0.024 mm, and PACH 4.79, 4.03, & 7.88 microns.

Conclusions:

The ABCD Keratoconus Grading System is a new keratoconus classification recently released on the Oculus Pentacam. The grading system uses the ARC, PRC, Min PACH and DCVA as 4 independently measured parameters to describe both the anatomic changes and visual function in keratoconus. The same parameters can be utilized to determine disease progression when the changes over time exceed the normal measurement noise. Both normal and keratoconic confidence intervals were determined so that the practitioner can select the most appropriate values based on the degree of disease severity. The above data will be incorporated into a future keratoconus progression display.

Financial Disclosure:

... travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented