TY - JOUR
T1 - The relationship between retinal ganglion cell axon constituents and retinal nerve fiber layer birefringence in the primate
AU - Pocock, Ginger M.
AU - Aranibar, Roberto G.
AU - Kemp, Nate J.
AU - Specht, Charles S.
AU - Markey, Mia K.
AU - Rylander, H. Grady
PY - 2009/11
Y1 - 2009/11
N2 - PURPOSE. To determine the degree of correlation between spatial characteristics of the retinal nerve fiber layer (RNFL) birefringence (ΔnNFL) surrounding the optic nerve head (ONH) with the corresponding anatomy of retinal ganglion cell (RGC) axons and their respective organelles. METHODS. RNFL phase retardation per unit depth (PR/UD, proportional to ΔnRNFL) was measured in two cynomolgus monkeys by enhanced polarization-sensitive optical coherence tomography (EPS-OCT). The monkeys were perfused with glutaraldehyde and the eyes were enucleated and prepared for transmission electron microscopy (TEM) histologic analysis. Morphologic measurements from TEM images were used to estimate neurotubule density (ρRNFL), axoplasmic area (Ax) mode, axon area (Aa) mode, slope (u) of the number of neurotubules versus axoplasmic area (neurotubule packing density), fractional area of axoplasm in the nerve fiber bundle (f), mitochondrial fractional area in the nerve fiber bundle (xm), mitochondria-containing axon profile fraction (mp), and length of axonal membrane profiles per unit of nerve fiber bundle area (Lam/Ab). Registered PR/UD and morphologic parameters from corresponding angular sections were then correlated by using Pearson's correlation and multilevel models. RESULTS. In one eye there was a statistically significant correlation between PR/UD and ρRNFL (r =0.67, P = 0.005) and between PR/UD and neurotubule packing density (r = 0.70, P = 0.002). Correlation coefficients of r = 0.81 (P = 0.01) and r = 0.50 (P = 0.05) were observed between the PR/UD and Ax modes for each respective subject. CONCLUSIONS. Neurotubules are the primary source of birefringence in the RNFL of the primate retina.
AB - PURPOSE. To determine the degree of correlation between spatial characteristics of the retinal nerve fiber layer (RNFL) birefringence (ΔnNFL) surrounding the optic nerve head (ONH) with the corresponding anatomy of retinal ganglion cell (RGC) axons and their respective organelles. METHODS. RNFL phase retardation per unit depth (PR/UD, proportional to ΔnRNFL) was measured in two cynomolgus monkeys by enhanced polarization-sensitive optical coherence tomography (EPS-OCT). The monkeys were perfused with glutaraldehyde and the eyes were enucleated and prepared for transmission electron microscopy (TEM) histologic analysis. Morphologic measurements from TEM images were used to estimate neurotubule density (ρRNFL), axoplasmic area (Ax) mode, axon area (Aa) mode, slope (u) of the number of neurotubules versus axoplasmic area (neurotubule packing density), fractional area of axoplasm in the nerve fiber bundle (f), mitochondrial fractional area in the nerve fiber bundle (xm), mitochondria-containing axon profile fraction (mp), and length of axonal membrane profiles per unit of nerve fiber bundle area (Lam/Ab). Registered PR/UD and morphologic parameters from corresponding angular sections were then correlated by using Pearson's correlation and multilevel models. RESULTS. In one eye there was a statistically significant correlation between PR/UD and ρRNFL (r =0.67, P = 0.005) and between PR/UD and neurotubule packing density (r = 0.70, P = 0.002). Correlation coefficients of r = 0.81 (P = 0.01) and r = 0.50 (P = 0.05) were observed between the PR/UD and Ax modes for each respective subject. CONCLUSIONS. Neurotubules are the primary source of birefringence in the RNFL of the primate retina.
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U2 - 10.1167/iovs.08-3263
DO - 10.1167/iovs.08-3263
M3 - Article
C2 - 19494208
AN - SCOPUS:78649413493
SN - 0146-0404
VL - 50
SP - 5238
EP - 5246
JO - Investigative Ophthalmology and Visual Science
JF - Investigative Ophthalmology and Visual Science
IS - 11
ER -