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Retinal Nerve Fiber Layer Loss After Traumatic Optic Neuropathy Detected by Scanning Laser Polarimetry

Retinal Nerve Fiber Layer Loss After Traumatic Optic Neuropathy Detected by Scanning Laser... A 19-YEAR-OLD man was admitted to the emergency department after a motor vehicle crash. His visual acuity was hand motions OD and 20/20 OS, with moderate periorbital edema and ecchymosis in his right eye. Slitlamp examination disclosed only a mild subconjunctival hemorrhage. The ocular motility was normal, and intraocular pressure was 16 mm Hg OU. Pupillary examination showed a 3+ relative afferent defect in his right eye. Dilated funduscopic examination revealed normal optic nerve with a cup-disc ratio of 0.4 OU. A computed tomographic scan of the head and orbits detected a fracture through the right optic canal. The patient was treated with steroids, and visual acuity improved to 20/400 OD. Retinal nerve fiber layer (RNFL) measurements using scanning laser polarimetry (SLP) (Gdx; Retinal Diagnostic Technologies Inc, San Diego, Calif) were taken at 15 days (Figure 1), 30 days (Figure 2), 45 days (Figure 3), and 90 days (Figure 4) after injury. There was a progressive loss of nerve fibers as shown by the double-hump curve, deviation from normal values, and GDx parameters. This was consistent with optic nerve atrophy revealed by ophthalmoscopy 45 days after injury. During the 90 days of follow-up there was no change of the cup-disc ratio. Figure 1. View LargeDownload Scanning laser polarimetry printout 15 days after injury. The examination results were completely normal. Figure 2. View LargeDownload Scanning laser polarimetry printout 30 days after injury. The "superior/nasal" ratio is the first parameter to become abnormal. Figure 3. View LargeDownload Scanning laser polarimetry printout 45 days after injury. The parameter "the number" is greater than 30, and "ellipse modulation" is outside normal limits. Figure 4. View LargeDownload Scanning laser polarimetry printout 90 days after injury. Diffuse loss of nerve fibers is evident. Comment Scanning laser polarimetry is a noninvasive method that provides in vivo quantitative assessment of the peripapillary RNFL. This technique measures the change in the state of polarization of an illuminating laser beam known as retardation, which is caused by the birefringence of the RNFL. Retardation is linearly correlated with RNFL thickness in monkey eyes1 and corresponds with known properties of the RNFL in normal and glaucomatous human eyes.2 Measurable changes in the RNFL retardation signal as determined by SLP are evident in this patient, and the first parameters to become abnormal were the "superior-nasal" ratio, followed by "the number" (≥30) and "ellipse modulation." It is interesting that the number and the superior/nasal ratio were also the best parameters for detecting glaucomatous damage according to other authors.3-5 Later a greater decrease in the retardation signal, probably related to a more generalized loss of nerve fibers, is evident. As there is a more diffuse loss of nerve fibers, the ratios returned to normal values. It is likely that the global parameters only later became positive owing to the wide range of values in the normal population given by the instrument. To our knowledge, this is the first time that progression of RNFL loss has been shown with SLP after optic nerve trauma. Reprints: Felipe Andrade Medeiros, MD, Glaucoma Service, Department of Ophthalmology, University of São Paulo, Ave Brig Luis Antonio 3030/905, 01402-000 São Paulo, Brazil (e-mail: fmedeiros@uol.com.br). References 1. Weinreb RNDreher AWColeman AQuigley HAShaw BReiter K Histopathologic validation of Fourier-ellipsometry measurements of retinal nerve fiber layer thickness. Arch Ophthalmol. 1990;108557- 560Google ScholarCrossref 2. Weinreb RNShakiba SZangwill L Scanning laser polarimetry to measure the nerve fiber layer of normal and glaucomatous eyes. Am J Ophthalmol. 1995;119627- 636Google Scholar 3. Susanna RTakahashi WYNakamura NKF Sensibilidade e especificidade da avaliação da camada de fibras nervosas examinada através da polarimetria a laser. Rev Bras Oftalmol. 1998;5717- 22Google Scholar 4. Paczka JAQuigley HAFriedman DSBarrón YVitale S Capabilities of frequency-doubling technology, scanning laser polarimetry and nerve fiber layer photographs to distinguish glaucomatous damage [ARVO abstract]. Invest Ophthalmol Vis Sci. 1999;40S841Google Scholar 5. Weinreb RNZangwill LBerry CCBathija RSample PA Detection of glaucoma with scanning laser polarimetry. Arch Ophthalmol. 1998;1161583- 1589Google ScholarCrossref http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Ophthalmology American Medical Association

Retinal Nerve Fiber Layer Loss After Traumatic Optic Neuropathy Detected by Scanning Laser Polarimetry

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References (6)

Publisher
American Medical Association
Copyright
Copyright © 2001 American Medical Association. All Rights Reserved.
ISSN
0003-9950
eISSN
1538-3687
DOI
10.1001/archopht.119.6.920
Publisher site
See Article on Publisher Site

Abstract

A 19-YEAR-OLD man was admitted to the emergency department after a motor vehicle crash. His visual acuity was hand motions OD and 20/20 OS, with moderate periorbital edema and ecchymosis in his right eye. Slitlamp examination disclosed only a mild subconjunctival hemorrhage. The ocular motility was normal, and intraocular pressure was 16 mm Hg OU. Pupillary examination showed a 3+ relative afferent defect in his right eye. Dilated funduscopic examination revealed normal optic nerve with a cup-disc ratio of 0.4 OU. A computed tomographic scan of the head and orbits detected a fracture through the right optic canal. The patient was treated with steroids, and visual acuity improved to 20/400 OD. Retinal nerve fiber layer (RNFL) measurements using scanning laser polarimetry (SLP) (Gdx; Retinal Diagnostic Technologies Inc, San Diego, Calif) were taken at 15 days (Figure 1), 30 days (Figure 2), 45 days (Figure 3), and 90 days (Figure 4) after injury. There was a progressive loss of nerve fibers as shown by the double-hump curve, deviation from normal values, and GDx parameters. This was consistent with optic nerve atrophy revealed by ophthalmoscopy 45 days after injury. During the 90 days of follow-up there was no change of the cup-disc ratio. Figure 1. View LargeDownload Scanning laser polarimetry printout 15 days after injury. The examination results were completely normal. Figure 2. View LargeDownload Scanning laser polarimetry printout 30 days after injury. The "superior/nasal" ratio is the first parameter to become abnormal. Figure 3. View LargeDownload Scanning laser polarimetry printout 45 days after injury. The parameter "the number" is greater than 30, and "ellipse modulation" is outside normal limits. Figure 4. View LargeDownload Scanning laser polarimetry printout 90 days after injury. Diffuse loss of nerve fibers is evident. Comment Scanning laser polarimetry is a noninvasive method that provides in vivo quantitative assessment of the peripapillary RNFL. This technique measures the change in the state of polarization of an illuminating laser beam known as retardation, which is caused by the birefringence of the RNFL. Retardation is linearly correlated with RNFL thickness in monkey eyes1 and corresponds with known properties of the RNFL in normal and glaucomatous human eyes.2 Measurable changes in the RNFL retardation signal as determined by SLP are evident in this patient, and the first parameters to become abnormal were the "superior-nasal" ratio, followed by "the number" (≥30) and "ellipse modulation." It is interesting that the number and the superior/nasal ratio were also the best parameters for detecting glaucomatous damage according to other authors.3-5 Later a greater decrease in the retardation signal, probably related to a more generalized loss of nerve fibers, is evident. As there is a more diffuse loss of nerve fibers, the ratios returned to normal values. It is likely that the global parameters only later became positive owing to the wide range of values in the normal population given by the instrument. To our knowledge, this is the first time that progression of RNFL loss has been shown with SLP after optic nerve trauma. Reprints: Felipe Andrade Medeiros, MD, Glaucoma Service, Department of Ophthalmology, University of São Paulo, Ave Brig Luis Antonio 3030/905, 01402-000 São Paulo, Brazil (e-mail: fmedeiros@uol.com.br). References 1. Weinreb RNDreher AWColeman AQuigley HAShaw BReiter K Histopathologic validation of Fourier-ellipsometry measurements of retinal nerve fiber layer thickness. Arch Ophthalmol. 1990;108557- 560Google ScholarCrossref 2. Weinreb RNShakiba SZangwill L Scanning laser polarimetry to measure the nerve fiber layer of normal and glaucomatous eyes. Am J Ophthalmol. 1995;119627- 636Google Scholar 3. Susanna RTakahashi WYNakamura NKF Sensibilidade e especificidade da avaliação da camada de fibras nervosas examinada através da polarimetria a laser. Rev Bras Oftalmol. 1998;5717- 22Google Scholar 4. Paczka JAQuigley HAFriedman DSBarrón YVitale S Capabilities of frequency-doubling technology, scanning laser polarimetry and nerve fiber layer photographs to distinguish glaucomatous damage [ARVO abstract]. Invest Ophthalmol Vis Sci. 1999;40S841Google Scholar 5. Weinreb RNZangwill LBerry CCBathija RSample PA Detection of glaucoma with scanning laser polarimetry. Arch Ophthalmol. 1998;1161583- 1589Google ScholarCrossref

Journal

Archives of OphthalmologyAmerican Medical Association

Published: Jun 1, 2001

Keywords: optic nerve injuries

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