PURPOSE A classical twin study was performed to examine the relative importance of genes and environment in refractive error. METHODS Refractive error was examined in 226 monozygotic (MZ) and 280 dizygotic (DZ) twin pairs aged 49 to 79 years (mean age, 62.4 years). Using a Humphrey-670 automatic refractor, continuous measures of spherical equivalent, total astigmatism, and corneal astigmatism...

Background: Eyelids have been shown to influence corneal shape. The effects of eyelid pathologies on astigmatism widely investigated. This study aimed determine the correlation between levator palpebrae superioris (LPS) muscle function and with-the-rule (WTR) in university students with normal morphology.Methods: was a cross-sectional sample 58 Chinese origin selected by simple random sampling ...

Primate eyes display considerable oblique off-axis astigmatism which could provide information on the sign of defocus that is needed for emmetropization. The pattern of peripheral astigmatism is not known in the chicken eye, a common model of myopia. Peripheral astigmatism was mapped out over the horizontal visual field in three chickens, 43 days old, and in three near emmetropic human subjects...

AIMS The aim of the present study was to evaluate the cicatricial repair of a corneal artificial perforation in rats with 10-0 nylon suture, N-butyl-2-cyanoacrylate (NBCA) adhesive, or NBCA + methacryloxysulfolane (NBCA-MS) adhesive through microscopic and histological assays. METHODS Twenty Wistar rats were randomly divided into 4 groups each containing 5 rats: (1) control group (corneal tra...

Our purpose was to examine the long-term efficacy of toric intraocular lens (IOL) implantation in cataract patients with high astigmatism due to corneal ectasia, who underwent phacoemulsification cataract surgery. Five eyes of 3 cataract patients with topographically stable keratoconus or pellucid macular degeneration (PMD), in which phacoemulsification with toric IOL implantation was used to c...

PURPOSE To determine the efficacy of the astigmatism correction following toric intraocular lens (IOL) and toric phakic IOL (pIOL) implantation in eyes with no previous ocular surgery and in postkeratoplasty (PKP) eyes. In addition, changes in corneal astigmatism were determined. METHODS Astigmatism was analyzed in 35 eyes with an AcrySof toric IOL, 35 eyes with an Artiflex toric pIOL, 50 eye...

Corneal astigmatism occurs when one corneal meridian has a different refractive power from the orthogonal meridian. In regular astigmatism, the two meridians are at 90o from each other, such as a sphere having a cylinder superimposed on its surface. In irregular astigmatism the two meridians are not at 90o from each other or the cornea curvature is not axially symmetric. Irregular astigmatism c...