OBJECTIVES To evaluate success rates in the correction of astigmatism with toric and spherical soft contact lens fitting. METHODS 30 patients with soft toric lenses having more than 1.25 D of corneal astigmatism (25 eyes; Group A) or having 0.75-1.25 D of corneal astigmatism (22 eyes; Group B) and 30 patients with soft spheric lenses having 0.75-1.25 D of corneal astigmatism (28 eyes; Group C...

A multipass absorption cell, based on an astigmatic variant of the off-axis resonator (Herriott) configuration, has been designed to obtain long path lengths in small volumes. Rotation of the mirror axes is used to obtain an effective adjustability in the two mirror radii. This allows one to compensate for errors in mirror radii that are encountered in manufacture, thereby generating the desire...

Purpose: Comparison of astigmatic correction and visual acuity outcomes in patients implanted with toric intraocular lenses following cataract surgery reference marked pre-operatively manually with a pen or with YAG laser, in conjunction with the Sunalp YAG Laser Lens. Methods: 16 eyes from 16 patients were divided into two groups of 8 patients each. Pre-operativelly, the eye of one group was r...

Attempts to describe normal corneal shape and to represent corneal topography by an array of discrete points have limited usefulness. A quantitative photogrammetric method that produces indices to describe corneal shape was developed. Four indices depict the departure of keratographic rings from circularity, and two indices express the trends and consistencies of all the rings from one keratogr...

An optical vortex, produced at one point in an optical beam, would propagate through an optical system to another point where the vortex can be used for some purpose. However, asymmetrical optical elements in such a system can cause astigmatism or at least distroy the rotational symmetry of the beam, which may affect the propagation of the vortex in an undesirable way. While an optical vortex i...

In the first part of this chapter, the optical condition of astigmatism is defined. The main causes and available classifications of ocular astigmatism are briefly described. The most relevant optical properties of image formation in an astigmatic eye are analysed and compared to that of an emmetropic eye and an eye with spherical ametropia. The spectacle prescription and axis notation for asti...

purpose: controversy has recently risen about the presence of compensatory ocular countertorsion (coct) after head tilt. this study was performed to define the functional range of this phenomenon. methods: cycloplegic autorefraction was performed on 80 eyes with regular astigmatism 2d. objective autorefraction was performed in normal position, right and left head tilt positions of 5º, 10º, 15º,...