<p>Posterior corneal astigmatism: a review article</p>

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...

Corneal topographic astigmatism (CorT) to quantify total corneal astigmatism.

PURPOSE To evaluate the performance of corneal topographic astigmatism (CorT) based on total corneal power measurements. METHODS Anterior, posterior, and total corneal power measurements of 526 virgin eyes obtained using the CSO Sirius tomographer (Costuzione Strumenti Oftalmici, Scandicci, Florence, Italy) were analyzed. Individual CorTs were created from each set of data. These CorTs were a...

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...

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...

Total Corneal Astigmatism and Posterior Corneal Surface.