Contributions
Abstract: P1091
Type: Poster
Abstract Category: Pathology and pathogenesis of MS - OCT
Background: Experimental autoimmune encephalomyelitis (EAE) is the mostly used preclinical model for multiple sclerosis (MS). Thinning of the retinal nerve fiber layer (RNFL) in EAE due to degeneration of optic nerve can be measured using optical coherence tomography (OCT). However, axonal loss may be masked by edema in the acute phase. Reflectance, which may related to changes of the cellular skeleton, is an intrinsic optical property and has been found reduced in MS patients. Also, the reflectance of RNFL showed decrease before the thickness changes in a glaucoma model. The results imply the potential of using reflectance to monitor the neuronal loss during the acute phase. Here we aimed at exploring the usefulness of reflectance as a marker of underlying structural deformation of RNFL of EAE.
Materials and methods: Five dark Agouti female rats with EAE induced through myelin oligodendrocyte glycoprotein immunization were compared to six healthy controls. They all underwent bilateral circular peripapillary OCT scans at four time points after EAE onset, occurring 10 days post immunization-p.i. (day 21, 35, 42, and 56 p.i.). RNFL thickness (RNFLT) were measured and its reflectance (NRI) calculated as signal intensity of RNFL normalized with the intensity of retinal pigment epithelium. For each rat, edema was identified as the changing rate of thickness exceeding 10.4% (95% percentile) found in controls.
We compared RNFLT and NRI among four conditions: Pre-edema, edema, post-edema, and eyes of controls.
Results and discussion: Repeated measures ANOVA showed a significant effects of group by time interactions of RNFLT and NRI (both p < 0.001). Post-hoc analyses revealed that NRI was significantly decreased in the pre-edema period (p = 0.001), when only two eyes had delayed VEPs. On the other hand, RNFL thickness was not decreased in the edema phase (when 3 VEPS were delayed, 2 absent) and only decreased in the post-edema phase (p < 0.001), when three eyes had delayed and one absent VEPs.
Reflectance, which in EAE precedes the occurrence of RNFL edema, might be a potential marker for detecting early sign of RNFL damage which should further be validated exploring mechanisms of axonal dysfunction preceding axonal loss and conduction block, as demonstrated by relatively spared bioelectrical conduction.
Disclosure: The authors have nothing to disclosure.
Abstract: P1091
Type: Poster
Abstract Category: Pathology and pathogenesis of MS - OCT
Background: Experimental autoimmune encephalomyelitis (EAE) is the mostly used preclinical model for multiple sclerosis (MS). Thinning of the retinal nerve fiber layer (RNFL) in EAE due to degeneration of optic nerve can be measured using optical coherence tomography (OCT). However, axonal loss may be masked by edema in the acute phase. Reflectance, which may related to changes of the cellular skeleton, is an intrinsic optical property and has been found reduced in MS patients. Also, the reflectance of RNFL showed decrease before the thickness changes in a glaucoma model. The results imply the potential of using reflectance to monitor the neuronal loss during the acute phase. Here we aimed at exploring the usefulness of reflectance as a marker of underlying structural deformation of RNFL of EAE.
Materials and methods: Five dark Agouti female rats with EAE induced through myelin oligodendrocyte glycoprotein immunization were compared to six healthy controls. They all underwent bilateral circular peripapillary OCT scans at four time points after EAE onset, occurring 10 days post immunization-p.i. (day 21, 35, 42, and 56 p.i.). RNFL thickness (RNFLT) were measured and its reflectance (NRI) calculated as signal intensity of RNFL normalized with the intensity of retinal pigment epithelium. For each rat, edema was identified as the changing rate of thickness exceeding 10.4% (95% percentile) found in controls.
We compared RNFLT and NRI among four conditions: Pre-edema, edema, post-edema, and eyes of controls.
Results and discussion: Repeated measures ANOVA showed a significant effects of group by time interactions of RNFLT and NRI (both p < 0.001). Post-hoc analyses revealed that NRI was significantly decreased in the pre-edema period (p = 0.001), when only two eyes had delayed VEPs. On the other hand, RNFL thickness was not decreased in the edema phase (when 3 VEPS were delayed, 2 absent) and only decreased in the post-edema phase (p < 0.001), when three eyes had delayed and one absent VEPs.
Reflectance, which in EAE precedes the occurrence of RNFL edema, might be a potential marker for detecting early sign of RNFL damage which should further be validated exploring mechanisms of axonal dysfunction preceding axonal loss and conduction block, as demonstrated by relatively spared bioelectrical conduction.
Disclosure: The authors have nothing to disclosure.