title: Intraoperative semiquantitative keratometry using the keratoscopic astigmatic ruler.
abstract: Intraoperative keratometry enables the surgeon to set an appropriate amount of corneal astigmatism with the suture tension. Errors in estimating or measuring the astigmatism can occur with hand-held keratometers because the distance an object is held from an astigmatic cornea influences the shape of the elliptical image. Thus hand-held instruments should be held at a calibrated distance. We have designed a new hand-held keratometer, the keratoscopic astigmatic ruler, to assess the magnitude of corneal astigmatism. It consists of a rack of elliptical keratoscopic lenses corresponding to increasing magnitudes of astigmatism and is made from inexpensive autoclavable injection-molded plastic. The ruler's keratoscopic lenses refract light, creating a real aerial image above the cornea that produces a bright and easily determined corneal reflection. The ruler incorporates a sight to allow the user to hold the ruler at the correct distance.
authors.affiliation: Department of Ophthalmology, University of New South Wales, Australia.
authors.forename: N
authors.initials: N
authors.lastname: Morlet
authors.forename: P A
authors.initials: PA
authors.lastname: Lindsay
mesh_terms: D001251:Astigmatism / Q000175:diagnosis* / Q000209:etiology; D002387:Cataract Extraction; D006801:Humans; D007432:Intraoperative Period; D009885:Ophthalmology / Q000295:instrumentation*; D011183:Postoperative Complications; D013536:Suture Techniques