Posters

Evaluation of posterior and total corneal astigmatism with colour-LED topography

Poster Details

First Author: T.Ferreira PORTUGAL

Co Author(s):    F. Ribeiro                    

Abstract Details

Purpose:

To characterize the posterior and total corneal astigmatism using color point-source light-emitting diodes(LED) topography.

Setting:

Hospital da Luz, Lisbon, Portugal. Universidade de Lisboa, Lisbon, Portugal 

Methods:

In a prospective case series, 755 eyes from 410 patients were evaluated by color-LED topography. Only eyes with normal topographies were considered. The following parameters were studied: magnitude and distribution of anterior and posterior corneal astigmatism, correlation between keratometric and posterior corneal astigmatism, and differences in magnitude and axis between total and anterior corneal astigmatism. 

Results:

Mean anterior corneal astigmatism was 1.16 ± 0.88 D. Mean posterior corneal astigmatism (PCA) was 0.37 ± 0.24 D. PCA was vertically oriented in 70% of eyes. 22% of eyes showed a PCA ≥0.5 D. The correlation coefficients between keratometric and posterior corneal astigmatism were: r2 = 0.23; p<.001 in WTR eyes, r2 = 0.03; p=.005 in ATR eyes and r2 = 0.01;p=.239 in oblique eyes. A difference between anterior and total astigmatism ≥ 0.5 D was found in 8% of eyes.A difference in axis between anterior and total corneal astigmatism ≥ 10° was found in 25% of eyes. 

Conclusions:

The percentage of eyes with posterior corneal astigmatism ≥ 0.5 D and the differences in axis between anterior and total corneal astigmatism were higher than previously reported in the literature. This study supports the consideration of total corneal astigmatism magnitude and axis is mandatory for a precise surgical correction of astigmatism. 

Financial Disclosure:

None