Assessment of Retinal Nerve Fiber Layer Internal Reflectivity in Eyes With and Without Glaucoma Using Optical Coherence Tomography

Abstract

To assess the internal reflectivity of the retinal nerve fiber layer in normal, ocular hypertensive, and glaucomatous eyes using optical coherence tomography. Methods: All patients underwent complete ophthalmic examination and achromatic automated perimetry. Intraocular pressure was 21 mm Hg or less for low-tension glaucoma and normal eyes and at least 25 mm Hg on 2 separate occasions in ocular hypertensive and high-tension glaucoma eyes. All glaucomatous eyes had characteristic glaucomatous optic neuropathy and associated achromatic automated perimetry defect. Relative retinal nerve fiber layer internal reflectivity was measured on optical coherence tomography images using a software program of our own design. Results: We enrolled 98 eyes (19 normal, 34 ocular hypertensive, 17 high-tension glaucoma, and 28 lowtension glaucoma). Relative internal reflectivity was less in eyes with glaucoma than in normal (PϽ.001, t test) and ocular hypertensive eyes (PϽ.001, t test). There was no difference in relative internal reflectivity between normal and ocular hypertensive eyes (P=.32) and between eyes with high-tension glaucoma and low-tension glaucoma (P = .43). Internal reflectivity correlated with mean deviation on achromated automatic perimetry (r 2 = 0.49, PϽ.001, quadratic regression analysis). Conclusion: Relative retinal nerve fiber layer internal reflectivity may provide useful information about the extent of retinal nerve fiber layer injury in glaucoma.

A Simple Subjective Evaluation of Enface OCT Reflectance Images Distinguishes Glaucoma From Healthy Eyes

“…Although published data were generated with dissimilar approaches to the one used here, previous studies have shown strong correlations between RNFL thickness and reflectance. 22,31,43,46 Our analysis also showed strong relationships between enface parameters and corresponding RNFL thickness (Fig. 5), in concordance with the literature.…”

“…15,31,50 Irrespective of the analysis performed, reflectivity of the RNFL was reduced in eyes with glaucoma compared to healthy eyes, and increasingly so with more severe disease. 15,31,43,50 Diagnostic performance of enface indices was excellent in many ONH sectors (Table 2), yet statistically similar to corresponding RNFL thickness parameters. The high accuracy of conventional cpRNFL thickness suggests that glaucomatous defects in this sample were already well captured by the typical morphological OCT analysis.…”

A Simple Subjective Evaluation of Enface OCT Reflectance Images Distinguishes Glaucoma From Healthy Eyes

“…Although published data were generated with dissimilar approaches to the one used here, previous studies have shown strong correlations between RNFL thickness and reflectance. 22,31,43,46 Our analysis also showed strong relationships between enface parameters and corresponding RNFL thickness (Fig. 5), in concordance with the literature.…”

“…15,31,50 Irrespective of the analysis performed, reflectivity of the RNFL was reduced in eyes with glaucoma compared to healthy eyes, and increasingly so with more severe disease. 15,31,43,50 Diagnostic performance of enface indices was excellent in many ONH sectors (Table 2), yet statistically similar to corresponding RNFL thickness parameters. The high accuracy of conventional cpRNFL thickness suggests that glaucomatous defects in this sample were already well captured by the typical morphological OCT analysis.…”

The Effect of Glaucoma on the Optical Attenuation Coefficient of the Retinal Nerve Fiber Layer in Spectral Domain Optical Coherence Tomography Images

“…The model was based on the reflectivity of the RNFL and the RPE, on interaction between light and the tissue and on the thickness of the RNFL. This novel analysis confirms earlier conclusions (i.e., that the optical scattering properties of the RNFL change in glaucoma) 27 (van der Schoot J, et al IOVS 2010;51:ARVO E-Abstract 212). In this current study, the attenuation coefficient was examined, because it is based on relative measurements of the reflectivity.…”

Reflectance Spectrum and Birefringence of the Retinal Nerve Fiber Layer With Hypertensive Damage of Axonal Cytoskeleton

“…This contrasts with the use of intrinsic reflectance, the internal RNFL reflectance seen on OCT, which several studies showed might provide sensitive detection of RNFL damage. 8–10,12 The measured value of RNFL reflectance is strongly affected by directional reflectance, as shown in Figure 3A and our earlier studies. 7,13 Clinical imaging systems do not simultaneously view all bundles at on-peak reflectance due to the change of bundle orientation around the ONH, introducing substantial variation into measurements of intrinsic reflectance.…”

A Simple Subjective Evaluation of Enface OCT Reflectance Images Distinguishes Glaucoma From Healthy Eyes

“…Although published data were generated with dissimilar approaches to the one used here, previous studies have shown strong correlations between RNFL thickness and reflectance. 22,31,43,46 Our analysis also showed strong relationships between enface parameters and corresponding RNFL thickness (Fig. 5), in concordance with the literature.…”

“…15,31,50 Irrespective of the analysis performed, reflectivity of the RNFL was reduced in eyes with glaucoma compared to healthy eyes, and increasingly so with more severe disease. 15,31,43,50 Diagnostic performance of enface indices was excellent in many ONH sectors (Table 2), yet statistically similar to corresponding RNFL thickness parameters. The high accuracy of conventional cpRNFL thickness suggests that glaucomatous defects in this sample were already well captured by the typical morphological OCT analysis.…”

The Effect of Glaucoma on the Optical Attenuation Coefficient of the Retinal Nerve Fiber Layer in Spectral Domain Optical Coherence Tomography Images

“…The model was based on the reflectivity of the RNFL and the RPE, on interaction between light and the tissue and on the thickness of the RNFL. This novel analysis confirms earlier conclusions (i.e., that the optical scattering properties of the RNFL change in glaucoma) 27 (van der Schoot J, et al IOVS 2010;51:ARVO E-Abstract 212). In this current study, the attenuation coefficient was examined, because it is based on relative measurements of the reflectivity.…”

Reflectance Spectrum and Birefringence of the Retinal Nerve Fiber Layer With Hypertensive Damage of Axonal Cytoskeleton

“…This contrasts with the use of intrinsic reflectance, the internal RNFL reflectance seen on OCT, which several studies showed might provide sensitive detection of RNFL damage. 8–10,12 The measured value of RNFL reflectance is strongly affected by directional reflectance, as shown in Figure 3A and our earlier studies. 7,13 Clinical imaging systems do not simultaneously view all bundles at on-peak reflectance due to the change of bundle orientation around the ONH, introducing substantial variation into measurements of intrinsic reflectance.…”

A Simple Subjective Evaluation of Enface OCT Reflectance Images Distinguishes Glaucoma From Healthy Eyes

“…Although published data were generated with dissimilar approaches to the one used here, previous studies have shown strong correlations between RNFL thickness and reflectance. 22,31,43,46 Our analysis also showed strong relationships between enface parameters and corresponding RNFL thickness (Fig. 5), in concordance with the literature.…”

“…15,31,50 Irrespective of the analysis performed, reflectivity of the RNFL was reduced in eyes with glaucoma compared to healthy eyes, and increasingly so with more severe disease. 15,31,43,50 Diagnostic performance of enface indices was excellent in many ONH sectors (Table 2), yet statistically similar to corresponding RNFL thickness parameters. The high accuracy of conventional cpRNFL thickness suggests that glaucomatous defects in this sample were already well captured by the typical morphological OCT analysis.…”

The Effect of Glaucoma on the Optical Attenuation Coefficient of the Retinal Nerve Fiber Layer in Spectral Domain Optical Coherence Tomography Images

“…The model was based on the reflectivity of the RNFL and the RPE, on interaction between light and the tissue and on the thickness of the RNFL. This novel analysis confirms earlier conclusions (i.e., that the optical scattering properties of the RNFL change in glaucoma) 27 (van der Schoot J, et al IOVS 2010;51:ARVO E-Abstract 212). In this current study, the attenuation coefficient was examined, because it is based on relative measurements of the reflectivity.…”

Reflectance Spectrum and Birefringence of the Retinal Nerve Fiber Layer With Hypertensive Damage of Axonal Cytoskeleton

“…This contrasts with the use of intrinsic reflectance, the internal RNFL reflectance seen on OCT, which several studies showed might provide sensitive detection of RNFL damage. 8–10,12 The measured value of RNFL reflectance is strongly affected by directional reflectance, as shown in Figure 3A and our earlier studies. 7,13 Clinical imaging systems do not simultaneously view all bundles at on-peak reflectance due to the change of bundle orientation around the ONH, introducing substantial variation into measurements of intrinsic reflectance.…”