Background In this retrospective randomized case series, we compared bilateral symmetry between OD and OS eyes, intercorneal differences and Functional Optical Zone (FOZ) of the corneal aberrations. Methods Sixty-seven normal subjects (with no ocular pathology) who never had any ocular surgery were bilaterally evaluated at Augenzentrum Recklinghausen (Germany). In all cases, standard examinat...

PURPOSE To determine the efficacy of the KeraSoft(®) IC (KIC) (Ultravision International Limited, Bedfordshire, UK), a silicone hydrogel contact lens, for the optical management of non-surgical corneal ectasias and to compare it with the Rose-K 2 RGP contact lens. METHODS In a retrospective study ninety-four eyes fitted with KIC (group A) were compared with seventy-seven eyes fitted with Rose...

Capable of three-dimensional imaging of the cornea with micrometer-scale resolution, spectral domain-optical coherence tomography (SDOCT) offers potential advantages over Placido ring and Scheimpflug photography based systems for accurate extraction of quantitative keratometric parameters. In this work, an SDOCT scanning protocol and motion correction algorithm were implemented to minimize the ...

PURPOSE To evaluate the optical aberrations induced by LASIK refractive surgery for myopia on the anterior surface of the cornea and the entire optical system of the eye. METHODS Total and corneal aberrations were measured in a group of 14 eyes (preoperative myopia ranging from -2.5 to -13 D) before and after LASIK surgery. Total aberrations were measured using a laser ray-tracing technique. ...

PURPOSE To measure the lower tear meniscus dynamics with Fourier domain-optical coherence tomography (FD-OCT) in keratoconus patients without dry eye findings to evaluate the effects of the corneal ectasia on lower tear meniscus parameters, and to determine the most affected meniscus variable from the corneal ectasia in keratoconus. METHODS Prospective, clinical study. Forty-one eyes of 25 ke...

A knowledge of the shape of the cornea is of major importance for the planning and monitoring of surgery, and for the correct diagnosis of corneal diseases. Many authors have studied the geometry of the second corneal surface in the central region and it has been stated that there is a high correlation between the central radii of curvature and asphericities of the two corneal surfaces. In this...

the porcine eye is often used as an ex vivo animal model in ophthalmological research. it is well-suited for investigations concerning refractive surgery; however, corneal topography data are scarce. this study investigated the corneal topography and pachymetry of the porcine eye to provide further reproducible data. we evaluated freshly enucleated porcine eyes (n = 16) by performing computeriz...

PURPOSE When keratorefractive surgery is used to treat a central corneal diameter smaller than the resting pupil, visual symptoms of polyopia, ghosting, blur, haloes, and glare can be experienced. Progress has been made to enlarge the area of surgical treatment to extend beyond the photopic pupil; however, geometric limitations can pose restrictions to extend the treatment beyond the mesopic pu...

PURPOSE Intrastromal corneal-ring segments (ICRSs) are applied to improve highly distorted vision in keratoconic, myopic, and astigmatic patients. Selections of ICRS geometry and position are primarily based on empirical nomograms. We developed a finite-element model (FEM) predicting the corneal response to different ICRS geometries in normal and keratoconic corneas. METHODS A two-dimensional...