Posters

Agreement of pachymetric measurements in normal and keratoconus eyes using spectral-domain optical coherence tomography and Scheimpflug-Placido topographer

Poster Details

First Author: H.Bayhan TURKEY

Co Author(s):    S. Aslan Bayhan   C. Gurdal           

Abstract Details

Purpose:

To compare spectral-domain optical coherence tomography (SD-OCT; RTVue, Optovue) and Scheimpflug-Placido topographer (Sirius, CSO, Italy) in terms of their agreement of pachymetric measuruments in healthy and keratoconic eyes.

Setting:

Bozok University Faculty of Medicine, Ophthalmology Department, Yozgat, Turkey.

Methods:

In this prospective study, 30 eyes of 30 keratoconus patients and 30 eyes of 30 control subjects were included. Corneal thickness (CT) at different locations (center; 2.0 mm and 5.0 mm nasal, temporal, superior, and inferior) and minimum CT were determined with the Scheimpflug-Placido topographer and SD-OCT. Bland-Altman plots were used to assess agreement among the instruments, and 95% limits of agreement (LoA) for comparison of each location were calculated.

Results:

All pachymetric measurements correlated with each other, with Pearson correlation coefficients ranging from 0.794 to 0.970 in control eyes and from 0.725 to 0.971 in keratoconic eyes (all p<0.05). There were no significant differences in the mean central and mimimum CT measurements between instruments in the control group (both, p>0.05), but the difference in the mean central CT measurement was significant in the keratoconus group (p<0.05). The central CT measurements displayed the smallest range of LoA (31.7 µm) in control eyes, whereas minimum CT measurements had the smallest range of LoA (49.1 µm) in keratoconic eyes. The measurements corresponding to the 2.0 mm and 5.0 mm locations obtained by the Scheimpflug-Placido topographer were consistently higher than those provided by SD-OCT, with ranges of agreement larger than 59.4 µm in control eyes and 102.4 µm in keratoconic eyes.

Conclusions:

Although correlated, CT measurement differences between the Scheimpflug-Placido topographer and SD-OCT can be clinically significant in normal and keratoconic eyes. FINANCIAL INTEREST: NONE