PURPOSE To describe topographic changes in a case of limbal conjunctival carcinoma. METHODS Corneal topography was performed before and 3 months after excision. RESULTS Preoperative topography revealed a localized flattening (37.1 diopters [D]) adjacent to the tumor and extending to the corneal apex, causing a 3-diopter asymmetric with-the-rule astigmatism. Preoperative corneal curvature wa...

The purpose of this study was to evaluate posterior corneal surface variation after femtosecond laser-assisted keratomileusis in patients with myopia and myopic astigmatism. Patients were evaluated by corneal tomography preoperatively and at 1, 6, and 12 months. We analyzed changes in the posterior corneal curvature, posterior corneal elevation, and anterior chamber depth. Moreover, we explored...

PURPOSE Understanding corneal biomechanics is important to refractive or therapeutic corneal treatments. The authors studied the corneal response to variable intraocular pressure (IOP) in porcines eyes after UV collagen cross-linking (CXL), in comparison with untreated eyes. METHODS Twenty-three enucleated eyes were treated with standard CXL conditions (365 nm, 3 mW, 30 minutes), and 15 contr...

BACKGROUND To compare the changes in anterior and posterior corneal elevations after combined transepithelial photorefractive keratectomy (PRK) and accelerated corneal collagen cross-linking (CXL) and after PRK. METHODS Medical records of 82 eyes of 44 patients undergoing either combined transepithelial PRK and CXL (PRK-CXL group) or transepithelial PRK (PRK group) were examined retrospective...

PURPOSE To investigate the distribution of posterior corneal astigmatism in eyes with with-the-rule (WTR) and against-the-rule (ATR) anterior corneal astigmatism. METHODS We retrospectively examined six hundred eight eyes of 608 healthy subjects (275 men and 333 women; mean age ± standard deviation, 55.3 ± 20.2 years). The magnitude and axis orientation of anterior and posterior corneal astig...

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...

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...

PURPOSE To report the long-term clinical outcome in a patient diagnosed as having bilateral progressive keratoconus who received a single corneal collagen cross-linking (CXL) treatment in the right eye and repeated CXL in the left eye. METHODS Observational case report. Topographical changes were assessed by high-resolution Scheimpflug imaging. The right eye underwent a standard epithelium-of...

PURPOSE To evaluate changes in anterior corneal topography and higher-order aberrations (HOA) after 14-days of rigid gas-permeable (RGP) contact lens (CL) wear in keratoconus subjects comparing two different fitting approaches. METHODS Thirty-one keratoconus subjects (50 eyes) without previous history of CL wear were recruited for the study. Subjects were randomly fitted to either an apical-t...