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...

PURPOSE To evaluate with the use of corneal topographic data the differences between total corneal power calculated using ray tracing (TCP) and the Gaussian formula (GEP) in normal eyes, eyes that previously underwent laser in situ keratomileusis/photorefractive keratectomy (LASIK/PRK), and theoretical models. METHODS TCP and GEP using mean instantaneous curvature were calculated over the cen...

BACKGROUND Posterior keratoconus is a rare cause of a corneal opacity in an infant. It is characterized by thinning of the posterior cornea without ectasia of the anterior cornea. Imaging of this condition with anterior segment optical coherence tomography (AS-OCT) has not been reported in the literature. CASE PRESENTATION A six week old African-American male presented with a congenital corne...

Purpose. To assess the amount and the axis orientation of anterior and posterior corneal astigmatism after refractive lenticule extraction (ReLEx) for myopic astigmatism. Methods. We retrospectively examined 53 eyes of 53 consecutive patients (mean age ± standard deviation, 33.2 ± 6.5 years) undergoing ReLEx to correct myopic astigmatism (manifest cylinder = 0.5 diopters (D)). Power vector anal...

PURPOSE To compare geometrical shape factors of keratoconus corneas after cross-linking (CXL) by means of Scheimpflug imaging with those of untreated fellow eyes. SETTING Institut für Refraktive und Ophthalmo-Chirurgie, Zürich, Switzerland. METHODS Scheimpflug imaging of the anterior segments was performed with the Pentacam (Oculus, Wetzlar, Germany) in 21 patients with progressive keratect...

In 25 eyes, age range 60-80 years, in purpose of preoperative treatment prior to cataract surgery, measurements of the radius of curvature as well as main meridians of the anterior and posterior corneal surfaces were performed. Average value of the curvature of the anterior corneal surface (R1) was R1 = 7.84 mm, while posterior radius (R2) was 6.4 mm. Main meridian of the anterior corneal surfa...

PURPOSE To assess the relationship between the thinnest corneal location and the steepest and maximum elevation corneal locations in subjects with keratoconus and the effect of gas permeable contact lens wear on the location of these points. METHODS Sixty-one consecutive subjects (98 eyes) with keratoconus. Thirty-one (49 eyes) and 30 (49 eyes) subjects were gas permeable contact lens (CL-W) ...

PURPOSE We demonstrated a novel automated algorithm for segmentation of intraoperative optical coherence tomography (iOCT) imaging of fluid interface gap in Descemet stripping automated endothelial keratoplasty (DSAEK) and evaluated the effect of intraoperative maneuvers to promote graft apposition on interface dimensions. METHODS A total of 30 eyes of 29 patients from the anterior segment ar...