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Abstract #5595 Published in IGR 2-1
Visual field defects and normal nerve fiber layer: may they coexist in primary open-angle glaucoma?
De Natale R; Marraffa M; Morbio R; Tomazzoli L; Bonomi LOphthalmologica 2000; 214: 119-121
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 6-31 dB in all eyes that were examined. The average thickness of the RNFL ranged from 20-90 μm. According to the authors' previous experience, 75 μm was fixed as the cutoff between normal and pathological values of RNFL thickness. They identified five 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. The authors conclude that not all subjects have the same number of fibers at birth, and that it is therefore possible to underestimate the RNFL changes. This 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.
Dr. R. De Natale, University Eye Clinic, Ospedale Borgo Trento, Piazzale Stefani, I-37126 Verona, Italy
Classification:
2.13 Retina and retinal nerve fibre layer (Part of: 2 Anatomical structures in glaucoma)
6.6.2 Automated (Part of: 6 Clinical examination methods > 6.6 Visual field examination and other visual function tests)
