Posters

Using biometry and topography based measurements to predict refractive astigmatism after cataract surgery

Poster Details

First Author: S.Pantanelli USA

Co Author(s):    D. Cui   N. Kansara   A. Luo   I. Scott           

Abstract Details

Purpose:

Historically, corneal astigmatism has been estimated using simulated keratometry (SimK). This method relies on data from a central three-millimeter diameter and does not take into account posterior corneal astigmatism (PCA). Using combined dual-Scheimpflug Placido disc corneal topography enables measurements that include PCA, like Total Corneal Power (TCP2). Alpins defined the corT method, which uses all available Placido based information from the anterior cornea, as well as corT(total), which incorporates PCA. The purpose of this study was to evaluate the relative correlation of topography and optical biometry based keratometry with post-operative refractive astigmatism (RA).

Setting:

This study included eyes that underwent cataract surgery with implantation of a B&L enVista MX60 lens at Penn State Eye Center between January 2016 and June 2018.

Methods:

Eyes included in the analysis underwent pre-operative swept-source optical coherence tomography based biometry (IOLMaster 700) and topography/tomography using a dual-Scheimpflug Placido disc-based device (Galilei G4). RA was compared to measured astigmatism using the following methods: 1) SimK, 2) SimK + measured PCA, 3) TCP2, 4) corT, 5) corT(total), and 6) IOLMaster. A difference vector (DV) was calculated between the manifest RA and each of the above measurement methods. Primary endpoints include mean DV, proportion of eyes with a DV magnitude < 0.5 diopters (D), and proportion of eyes in which the RA class was predicted correctly.

Results:

Comparison of measured methods was based on data from 230 eyes. Mean DVs were 0.41 x 003 D, 0.15 x 007 D, 0.25 x 037 D, 0.32 x 003 D, 0.15 x 001, and 0.28 x 004 D for the six afore-mentioned methods, respectively. The proportion of eyes with a DV magnitude ≤0.5 D were 31.7%, 39.1%, 37.8%, 38.5%, 37.0%, and 38.7%, respectively. The proportion of eyes in which the measured and RA orientation matched were 47.4%, 57.4%, 57.8%, 50%, 54.8%, and 50.4% respectively.

Conclusions:

Measurement methods that incorporate PCA are more accurate in predicting post-operative RA. All of the studied methodologies performed more poorly on WTR than ATR eyes.

Financial Disclosure:

research is funded, fully or partially, by a company producing, developing or supplying the product or procedure presented