Posters

Comparison between keratometry measurements by high-resolution Scheimpflug imaging and conventional topography in normal and keratoconic eyes

Poster Details

First Author: S.Mahmoud EGYPT

Co Author(s):                        

Abstract Details

Purpose:

To evaluate the difference between the keratometry (K) obtained with the Pentacam high resolution (HR), and corneal topography in both normal and keratoconus

Setting:

This is a retrospective study. All the investigations were done at a private eye center in Alexandria, Egypt.

Methods:

57 eyes of healthy subjects and 37 with keratoconus, diagnosed either clinically or by corneal topography, were examined retrospectively. Keratometry measurements in the flat (Kf) and steep (Ks) meridians were taken with the ALLEGRO Topolyzer VARIO System (Alcon Surgical) and the Pentacam HR(Oculus, Wetzlar,Germany). The Test-retest variability (TVR), coefficient of variation (CoV) were calculated to evaluate the difference between the two instruments.

Results:

By topography,the mean kf was43.33±1.35 in normal and 45.41±3.40 in keratoconus.By pentacam,the mean kf was42.86 ±1.32 in normal and45.28±3.70 in keratoconus.There was a statistically significant difference between the two instruments in the normal group only(p<0.001).By topography,the mean ks was 44.62±1.78 in normal and 48.01±4.81 in keratoconus.By pentacam, was 44.3 ±1.70 in normal and 48.87±5.10 in keratoconus.There was a statistically significant difference between the two instruments in both groups(p<0.001).In normal corneas the CoV for kf and ks were(0.65,0.48%),while in keratoconus were(0.80,1.13%).In normal corneas the TVR for kf and ks were (0.68,0.46),in keratoconus were(1.05,1.51).

Conclusions:

The keratometry measurement by the pentacam HR tend to be higher than those obtained by corneal topography and the difference between the measurements is higher in keratoconus than normal corneas. This difference should be considered if we are using the pentacam data for procedures like IOL power calculation. Also based on the results, for patient follow-up, one keratometry device is recommended

Financial Disclosure:

None