Measurement centration and zone diameter in anterior, posterior and total corneal astigmatism in keratoconus

Total Corneal Astigmatism and Posterior Corneal Surface.

Total Corneal Astigmatism Measurement.

We read with interest the article by Tonn et al. on corneal astigmatism. At the beginning of the article, the authors indicated that: ‘‘Scheimpflug tomographers provide a map of the anterior chamber and therefore a more accurate model of the cornea, its thickness, and posterior surface.’’ Since the anterior chamber is really a space, and not a structure, it is probably clearer to say that Schei...

Contribution of posterior corneal astigmatism to total corneal astigmatism.

PURPOSE To determine the contribution of posterior corneal astigmatism to total corneal astigmatism and the error in estimating total corneal astigmatism from anterior corneal measurements only using a dual-Scheimpflug analyzer. SETTING Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. DESIGN Case series. METHODS Total corneal astigmatism was calculated using ray trac...

Importance of Posterior Corneal Astigmatism in Eyes with Keratoconus

Characteristics of Posterior Corneal Astigmatism in Different Stages of Keratoconus

Purpose To evaluate the magnitudes and axis orientation of anterior corneal astigmatism (ACA) and posterior corneal astigmatism (PCA), the ratio of ACA to PCA, and the correlation between ACA and PCA in the different stages of keratoconus (KCN). Methods This retrospective case series comprised 161 eyes of 161 patients with KCN (104 men, 57 women; mean age, 22.35 ± 6.10 years). The participant...