The retinal nerve fiber layer (RNFL) is the anatomical structure most sensitive to glaucoma injury. Before a functional loss such as a visual field defect is displayed, a large number of nerve fibers can be damaged. However, there are glaucoma patients in which an apparently normal RNFL coexists with evident visual field defects. A total of 54 eyes affected with primary open-angle glaucoma were studied. Visual field was examined with the Humphrey Field Analyzer (Zeiss) using program 30-2. The Nerve Fiber Analyzer II (Laser Diagnostic Technologies) was used to study the RNFL of these patients. Mean deviation of the visual field ranged from 6 to 31 dB in all eyes that were examined. The average thickness of the RNFL ranged from 20 to 90 μm. According to our previous experience 75 μm was fixed as the cutoff between normal and pathological values of RNFL thickness. We identified 5 eyes with a RNFL thickness over 75 μm and a visual field with a mean deviation over 6 dB; 9% of the studied eyes were found to have a visual field defect with no changes in RNFL. We conclude that not all subjects have the same number of fibers at birth and that it is therefore possible to underestimate the RNFL changes. Our study illustrates that the concept of normal and altered has to be considered as a relative one for all the aspects characterizing the glaucomatous disease.

Hoyt VF, Newman NM: The earliest defect in glaucoma? Lancet 1972;i:692–693.
Tjon-Fon-Sang MJ, De Vries J, Lemij HG: Measurement by nerve fiber analyzer of retinal nerve fiber layer thickness in normal subjects and patients with ocular hypertension. Am J Ophthalmol 1996;122:220–227.
Tuulonen A, Lehtola J, Airaksinen J: Nerve fiber layer defects with normal visual fields: Do normal optic disc and normal visual field indicate absence of glaucomatous abnormality? Ophthalmology 1993;100:587–598.
Hoh ST, Ishikawa H, Greenfield DS, Liebmann JM, Chew SJ, Ritch R: Peripapillary nerve fiber layer thickness measurement reproducibility using scanning laser polarimetry. J Glaucoma 1998;7:12–15.
Gluck R, Rohrschneider K, Kruse FE, Volker HE: Detection of glaucomatous nerve fiber damage: Laser polarimetry in comparison with equivalent visual field loss. Ophthalmologe 1997;94:815–820.
Zangwill L, Berry CA, Garden VS, Weinreb RN: Reproducibility or retardation measurements with the nerve fiber analyzer II. J Glaucoma 1997;6:384–389.
Caprioli J, Miller JM: Measurement of relative nerve fiber layer surface height in glaucoma. Ophthalmology 1989;96:633–641.
Quigley HA, Addicks EM: Quantitative studies of retinal nerve fiber layer defects. Arch Ophthalmol 1982;100:807–814.
Tjon-Fo-Sang MJ, Van Strik R, De Vries J, Lemij HG: Improved reproducibility of measurements with the nerve fiber analyzer. J Glaucoma 1997;6:203–211.
Junghardt A, Schmid MK, Schipper I, Wildberger H, Seifert B: Reproducibility of the data determined by scanning laser polarimetry. Graefes Arch Clin Exp Ophthalmol 1996;234:628–632.
Marraffa M, Mansoldo C, Morbio R, De Natale R, Tomazzoli L, Bonomi L: Does nerve fiber layer thickness correlate with visual field defects in glaucoma? A study with the nerve fiber analyzer. Ophthalmologica 1997;211:338–340.
Sommer A, Katz J, Quigley HA: Clinically detectable nerve fiber atrophy precedes the onset of glaucomatous field loss. Arch Ophthalmol 1991;109:77–83.
Airaksinen J, Drance SM, Douglas GR, Mawson DK: Diffuse and localized nerve fiber loss in glaucoma. Am J Ophthalmol 1984;98:566–571.
Copyright / Drug Dosage / Disclaimer
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.
You do not currently have access to this content.