Purchase this article with an account.
A. L. Moura, A. S. Raza, J. Cho, M. A. Lazow, C. G. De Moraes, J. G. Odel, D. C. Hood; Retinal Ganglion Cell and Inner Plexiform Layer Thickness Measured With fdOCT in Regions of Severe Sensitivity Loss in Patients With Ischemic Optic Neuropathy. Invest. Ophthalmol. Vis. Sci. 2010;51(13):659.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Patients with severe visual field loss secondary to ischemic optic neuropathy (ION) were studied to better understand the effects of retinal ganglion cell (RGC) loss on frequency domain optical coherence tomography (fdOCT) measures of RGC and inner plexiform layer (IPL) thickness.
Exp. 1: fd-OCT (3D-OCT 1000, Topcon) 3D macular scans containing 128 lines (B-scans) across a 6 x 6 mm area were obtained from 9 patients with ION and severe visual field loss and from 20 healthy controls. Raw images were exported and the thickness of the RGC layer+IPL was measured along 9 of the B-scans, corresponding to horizontal locations: 0°, ±3°, ±5°, ±8° and ±10°, using a manual segmentation procedure.[1,2] Thicknesses at circular eccentricities of 3°, 5°, 8° and 10° were obtained from the segmented scans. For the patients, only locations with total deviation losses of -15 dB or worse on perimetry (24-2, Humphrey visual fields) were included. Exp. 2: FdOCT (Spectralis, Heidelberg) horizontal midline scans from 30 controls were manually segmented  and the thicknesses of the RGC layer and of the IPL were measured at eccentricities of 3°, 5°, 8° and 10°.
For the patients, in regions of severe visual field loss, the RGC+IPL thickness was approximately constant at all 4 eccentricities (44, 48, 43,41 µm), while it decreased monotonically for controls from 86 µm (3°) to 51 µm (10°). The RGC+IPL thickness for all patients fell below the 95% confidence interval (CI), except at 10°, where for 33% of the patients it fell within the CI. In Exp.2, for controls, the RGC layer thickness decreased with eccentricity from 50 µm (3°) to 22 µm (10°), while the IPL thickness was approximately constant (mean: 40 µm).
The data are consistent with the following hypothesis: Severe RGC loss caused by ION leaves an IPL of relatively normal thickness and perhaps a very thin (<5 µm) residual RGC layer. Because the thickness of the IPL does not change with RGC loss and the RGC layer is relatively thin beyond 8° eccentricity, local RGC loss is best studied within the central ±8°. 1. Hood et al (2009) IOVS. 2. Wang et al (2009) Arch Ophthal.
This PDF is available to Subscribers Only