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      • Article: found

      Influence of Cycloversions Induced by Head Tilt on Scanning Laser Polarimetry Parameters

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          Abstract

          Objective: To study the influence of cycloversions induced by head tilt on parameters of scanning laser polarimetry. Methods: Five left and five right eyes of 9 normal subjects were measured in seven different head tilt positions by one examiner using a scanning laser polarimeter (Nerve Fiber Analyzer, NFA II, LDT Inc., San Diego, Calif., USA). Images were acquired for the following head tilt positions: upright, 10, 20, 30° to the right, and 10, 20, 30° to the left. For each position five to eight images of the peripapillary area were recorded. Objective cycloversions were determined trigonometrically on the fundus pictures provided by the scanning laser ophthalmoscope. Parameters acquired for different head positions were compared using a Friedmann’s two-way analysis of variance. Results: Average objective cyclodeviations were 5.9° for the 10° head tilts, 11.2° for the 20° head tilts, and 18.9° for the 30° head tilts. Head tilts to the right in left eyes and to the left in right eyes (both of them corresponding to an incycloposition) induced a significant increase in several parameters (p < 0.05). Head tilts to the left in left eyes and to the right in right eyes (both corresponding to an excycloposition) showed no influence on parameters (p > 0.05). Conclusions: Ocular incycloposition has a significant influence on several scanning laser polarimetry parameters. Therefore, evaluation is limited in patients having an incyclorotation of the nonfixating eye with the head in an upright position or in patients having a head tilt inducing an incyclorotation.

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          Effect of corneal polarization axis on assessment of retinal nerve fiber layer thickness by scanning laser polarimetry.

          Scanning laser polarimetry uses an anterior segment compensating device that assumes a fixed axis of corneal birefringence, which we call the corneal polarization axis. The purpose of this investigation was to establish the distribution of corneal polarization axes among a population of normal eyes and to evaluate the relationship between corneal polarization axis and posterior segment retardation. We constructed a noninvasive slit lamp-mounted device incorporating two crossed linear polarizers and an optical retarder in order to measure the slow axis of corneal birefringence. Normal subjects underwent corneal polarization axis measurement. A subset of eyes underwent scanning laser polarimetry of the peripapillary retinal nerve fiber layer (n = 32) and macula (n = 29), and retardation measurements were evaluated in each group. One hundred eighteen eyes of 63 normal subjects (35 female, 28 male) underwent corneal polarization axis measurement (mean age, 45.5 +/- 17.1 years). Six eyes (5.1%) demonstrated unmeasurable corneal polarization. In the remaining 112 eyes, the mode of the corneal polarization axis distribution was 10 to 20 degrees nasally downward (range, 90 degrees nasally downward to 54 degrees nasally upward). A significant (P <.0001) correlation was observed between fellow eyes (R(2) =.52), with a mean difference of 11.2 +/- 10.5 degrees (range, 0-52 degrees). Corneal polarization axis was significantly associated (R(2) =.52-.84) with retinal nerve fiber layer and macula summary retardation parameters (average thickness, ellipse average, superior and inferior average, superior and total integral; P <.0001 for all groups). The mean corneal polarization axis among normal corneas is nasally downward; however, considerable intraindividual and interindividual variability exists. The linear relationship between corneal polarization axis and posterior segment retardation parameters is responsible, in part, for the wide distribution of retinal nerve fiber layer thickness data generated by scanning laser polarimetry.
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            Differentiating patients with glaucoma from glaucoma suspects and normal subjects by nerve fiber layer assessment with scanning laser polarimetry.

            A study was conducted to determine normative data for nerve fiber layer measurements as obtained by scanning laser polarimetry with the Laser Diagnostic Technologies Nerve Fiber Analyzer II, identify factors affecting the measurements, and identify parameters capable of differentiating normal subjects from patients with glaucoma and patients suspected of having glaucoma because of ocular hypertension or because of a large cup-to-disc ratio (GS-disc). A case series. Four hundred normal subjects, 35 patients with ocular hypertension, 42 patients with glaucoma, and 17 glaucoma suspects based on optic disc appearance participated. Nerve fiber layer thickness assessments were determined in normal subjects (with normal-appearing optic nerves and normal visual fields). The results were compared to measurements from samples of age-matched patients with ocular hypertension (with normal visual fields), patients suspected of having glaucoma based on enlarged cup-to-disc ratios, and patients with open-angle glaucoma who had visual field loss. The majority of the parameters derived from the measurements showed no significant relationship to age, although some parameters tended to decrease with increasing age. Multiple parameters showed statistically significant differences between normal subjects and patients with glaucoma. In particular, the intraellipse sector variability, an indirect measure of the shape of the nerve fiber layer in an ellipse surrounding the nerve head, showed statistically significant differences between normal subjects and patients with glaucoma as well as between glaucoma suspects and normal subjects. Similar results were seen with the superior maxima, the average thickness assessment value of the 1500 thickest points in the superior bundle. Assessments of nerve fiber layer thickness as determined by scanning laser polarimetry can differentiate patients with glaucoma from normal subjects and may identify otherwise undetected damage in glaucoma suspects.
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              Bielschowsky head-tilt test—I. Ocular counterrolling and Bielschowsky head-tilt test in 23 cases of superior oblique palsy

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                Author and article information

                Journal
                OPH
                Ophthalmologica
                10.1159/issn.0030-3755
                Ophthalmologica
                S. Karger AG
                0030-3755
                1423-0267
                2003
                October 2003
                20 August 2003
                : 217
                : 5
                : 311-314
                Affiliations
                aPrivate Practice, Zürich, bDepartment of Neurology, University of Bern, Inselspital, Bern, and cDepartment of Neuro-Ophthalmology and Strabismus, Kantonsspital, St. Gallen, Switzerland
                Article
                71343 Ophthalmologica 2003;217:311–314
                10.1159/000071343
                12913318
                b43e16bd-c81b-429b-a3bd-0ab58cba1b2a
                © 2003 S. Karger AG, Basel

                Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

                History
                : 30 September 2002
                : 09 January 2003
                Page count
                Figures: 1, Tables: 2, References: 17, Pages: 4
                Categories
                Original Paper

                Vision sciences,Ophthalmology & Optometry,Pathology
                Scanning laser polarimetry,Counterrolling,Cycloversions,Head tilt,Ocular

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