Posterior Corneal Astigmatism Changes in Cases with Keratoconus

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...

Posterior corneal astigmatism.

In the optical system of the human eye, total refractive power consists mainly of corneal and lenticular components. Approximately two-thirds of the eye's converging power is at the air–cornea (tear film) interface; one-third is in the lens. Total corneal power is determined by corneal anterior and posterior curvature, corneal thickness, and the corneal refractive indices. Traditionally, anteri...

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...

Total Corneal Astigmatism and Posterior Corneal Surface.