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M.N. Menke, F. Berisha, C.L. Trempe, G.T. Feke; Different Patterns of Retinal Nerve Fiber Loss in Patients With Normal Tension Glaucoma versus Patients With Inflammatory Optic Neuropathy Demonstrated With OCT . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1082.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies have shown an early thinning of retinal nerve fiber layer (RNFL) predominately inferior temporal to the disc in patients with glaucomatous optic neuropathy. The reason for this distinct RNFL loss pattern is still a matter of controversy. Inflammatory optic neuropathy (ION) can also lead to RNFL loss with functional impairment. The different histopathology of ION compared to glaucoma might result in a different pattern of RNFL loss. In this study OCT 3 was used to identify patterns of RNFL loss in normal tension glaucoma (NTG) and in ION due to systemic infection.
Seven patients with NTG (mean age 61 ± 9 years), 7 patients with chronic ION (mean age 64 ± 9 years) and 7 healthy controls (mean age 65 ± 7 years) were included. RNFL thickness and optic nerve head (ONH) parameters were measured using OCT. Average and segmental (4 quadrants) RNFL thickness values and cup–to–disc ratios were compared among the three groups using ANOVA with post hoc tests.
Average RNFL thickness was lower in the NTG (p=0.0006) and ION (p=0.0068) groups compared to controls, but no significant difference in average RNFL thickness was found between the NTG and ION groups. However, RNFL at the inferior quadrant in the NTG group was significantly reduced compared to both the ION group (p=0.001) and controls (p=0.0003). In the ION group, RNFL was reduced in the superior quadrant compared to both NTG patients (p=0.0005) and controls (p<0.0001). RNFL was also reduced in the nasal quadrant of the ION group compared to controls (p=0.0054). NTG patients showed significantly increased vertical and horizontal cup–to–disc ratios compared with both ION patients and controls (p<0.003). No significant differences in the ONH parameters were found between ION patients and healthy controls.
Our findings are in agreement with results of previous studies indicating an early RNFL loss in the inferior quadrant in patients with glaucomatous optic neuropathy. In addition, our study showed a different pattern of RNFL loss in patients with ION, indicating a reduction of RNFL predominately in the superior and nasal quadrants. The mechanism leading to the different patterns of RNFL loss in the two disease entities needs to be explored.
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