PURPOSE To report the outcomes of the correction of mixed astigmatism with non-penetrating femtosecond laser intrastromal astigmatic keratotomy in patients with previous refractive surgery. METHODS One hundred twelve eyes that had low mixed astigmatism after excimer laser surgery, refractive lens exchange, or phakic intraocular lens implantation underwent intrastromal astigmatic keratotomy us...

PURPOSE To evaluate by vector analysis the corneal astigmatic changes occurring in keratoconic corneas during a 3-year follow-up and to determine the relationship between these changes and other clinical changes. METHODS Keratoconic eyes (n = 114) of 75 patients ranging in age from 14 to 70 years were retrospectively reviewed in four different centers. In all cases, a 3-year follow-up was com...

PURPOSE To determine the effectiveness of correcting astigmatism by laser refractive surgery by a vectorial astigmatism outcome analysis that uses 3 fundamental vectors: target induced astigmatism vector (TIA), surgically induced astigmatism vector, and difference vector, as described by the Alpins method. METHODS A data set of 100 eyes that had laser in situ keratomileusis to correct myopia ...

A numerical method for analyzing a folded or ring cavity is presented. Astigmatic compensated parameters, stability regions, and beam parameters inside the cavity or within the gain medium can be obtained numerically as long as the intracavity beam propagation can be expressed by round-trip matrices, no matter how complicated the cavity is. This method is easy to follow, and the results are acc...

We demonstrate generation and frequency doubling of unit charge vortices in a linear astigmatic resonator. Topological instability of the double charge harmonic vortices leads to well separated vortex cores that are shown to rotate, and become anisotropic, as the resonator is tuned across resonance.

The most common means of correcting refractive errors is with spectacles. Spectacles are prescribed and dispensed with corrective lenses that give the best visual acuity and are comfortable. Custom-made spectacles (i.e., made up for each individual) are more expensive, but they are essential in some cases, i.e., when a person requires astigmatic correction or needs diff erent power lenses in ea...