Rescuing axons from degeneration does not affect retinal ganglion cell death

After a traumatic injury to the central nervous system, the distal stumps of axons undergo Wallerian degeneration (WD), an event that comprises cytoskeleton and myelin breakdown, astrocytic gliosis, and overexpression of proteins that inhibit axonal regrowth. By contrast, injured neuronal cell bodies show features characteristic of attempts to initiate the regenerative process of elongating their axons. The main molecular event that leads to WD is an increase in the intracellular calcium concentration, which activates calpains, calcium-dependent proteases that degrade cytoskeleton proteins. The aim of our study was to investigate whether preventing axonal degeneration would impact the survival of retinal ganglion cells (RGCs) after crushing the optic nerve. We observed that male Wistar rats (weighing 200-400 g; n=18) treated with an exogenous calpain inhibitor (20 mM) administered via direct application of the inhibitor embedded within the copolymer resin Evlax immediately following optic nerve crush showed a delay in the onset of WD. This delayed onset was characterized by a decrease in the number of degenerated fibers (P<0.05) and an increase in the number of preserved fibers (P<0.05) 4 days after injury. Additionally, most preserved fibers showed a normal G-ratio. These results indicated that calpain inhibition prevented the degeneration of optic nerve fibers, rescuing axons from the process of axonal degeneration. However, analysis of retinal ganglion cell survival demonstrated no difference between the calpain inhibitor- and vehicle-treated groups, suggesting that although the calpain inhibitor prevented axonal degeneration, it had no effect on RGC survival after optic nerve damage.

Using ImageJ to Evaluate Optic Disc Pallor in Traumatic Optic Neuropathy

PURPOSE: To evaluate optic disc pallor using ImageJ in traumatic optic neuropathy (TON). METHODS: This study examined unilateral TON patients. The optic disc was divided into 4 quadrants (temporal, superior, nasal, and inferior), consistent with the quadrants on optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness maps. Optic disc photography was performed and disc pallor was quantified using gray scale photographic images imported into ImageJ software. The correlation between optic disc pallor and RNFL thickness was examined in each quadrant. RESULTS: A total of 35 patients (31 male, 4 female) were enrolled in the study. The mean participant age was 34.8 +/- 15.0 years (range, 5 to 63 years). Overall RNFL thickness decreased in 6 patients, with thinning most often occurring in the inferior quadrant (28 of 35 eyes). There was a significant correlation between optic disc pallor and RNFL thickness (superior, rho = -0.358, p = 0.04; inferior, rho = -0.345, p = 0.04; nasal, rho = -0.417, p = 0.01; temporal, rho = -0.390, p = 0.02). The highest level of correspondence between disc pallor and RNFL thickness values outside of the normative 95th percentiles was 39.3% and occurred in the inferior quadrant. CONCLUSIONS: Optic disc pallor in TON was quantified with ImageJ and was significantly correlated with RNFL thickness abnormalities. Thus, ImageJ evaluations of disc pallor may be useful for evaluating RNFL thinning, as verified by OCT RNFL analyses.

Comparison between retinal nerve fiber layer and macular thickness measured with OCT detecting progressive axonal loss following traumatic optic neuropathy / Comparação entre as medidas da espessura da camada de fibras nervosas da retina e da mácula pela tomografia de coerência óptica na detecção da perda axonal progressiva decorrente à neuropatia óptica traumática

PURPOSE: To compare the optical coherence tomography retinal nerve fiber layer and macular thickness measurements for detection of progressive axonal loss following acute traumatic optic neuropathy in a longitudinal study. METHODS: Three patients with unilateral traumatic optic neuropathy were evaluated sequentially after trauma. Macular and retinal nerve fiber layer thickness measurements were obtained using optical coherence tomography weekly for five weeks and around the twelfth week after trauma. RESULTS: All patients showed progressive macular and retinal nerve fiber layer thickness reduction. The mean retinal nerve fiber layer thickness on the first week was 114 μm and reduced sequentially over the first five weeks and was 46 μm on the twelfth week. For macular parameters, the mean average thickness on the first week was 248 μm and also reduced over the first five weeks and was 218 μm on the twelfth week. When compared to the initial measurement, macular thickness average reduction rate at the 12th week was 14 percent while peripapillary retinal nerve fiber layer thickness average reduction rate was 59 percent. CONCLUSIONS: Although both measurements reduce significantly after trauma, retinal nerve fiber layer thickness measurements show greater and faster retinal neural reduction if compared to macular thickness measurements in traumatic optic neuropathy.

OBJETIVO: Comparar as medidas da espessura da camada de fibras nervosas da retina e macular obtidas pela tomografia de coerência óptica na detecção da perda axonal progressiva após neuropatia óptica traumática aguda e durante o seguimento clínico. MÉTODOS: Três pacientes com neuropatia óptica traumática unilateral aguda foram avaliados sequencialmente após o trauma. Medidas da espessura macular e da camada de fibras nervosas da retina foram obtidas pela tomografia de coerência óptica semanalmente por 5 semanas consecutivas e ao redor da décima segunda semana após o trauma. RESULTADOS: Todos os pacientes apresentaram redução progressiva dos valores da espessura macular e da camada de fibras nervosas da retina. A espessura média da camada de fibras nervosas da retina foi de 114 μm na primeira semana e reduziu sequencialmente ao longo das primeiras cinco semanas e foi de 46 μm na décima segunda semana. Para parâmetros macular, a espessura média foi de 248 μm na primeira semana, e também reduziu ao longo das primeiras cinco semanas e foi de 218 μm na décima segunda semana. Quando comparado às medidas iniciais, a taxa de redução das médias da espessura macular foi 14 por cento na décima segunda semana após o trauma, enquanto que a taxa de redução das médias da espessura da camada de fibras nervosas da retina foi 59 por cento. CONCLUSÕES: Os valores da espessura da camada de fibras nervosas da retina apresentaram uma redução maior e mais rápida se comparada às medidas da espessura macular na neuropatia óptica traumática.

Analysis of 84 ocular disability cases in traffic accident / 法医学杂志

OBJECTIVE@#To study the injury modes, the injury characteristics, the disability grade assessments and other relative problems in eye injuries after traffic accidents.@*METHODS@#Eighty four ocular disability cases after traffic accidents collected from March 2007 to March 2009 in our institute were retrospectively analyzed. Then to study the ocular disability reasons, the assessment time and methods.@*RESULTS@#The main cause of ocular disability is visual dysfunction, and the other causes for example eyeball missing, injury of eyelid, injury of lacrimal apparatus, traumatic cataract and defect of visual field were rare relatively. Most ocular injuries happened to single eye. The disability grades were often from VII to X.@*CONCLUSION@#The accuracy of visual function expertise could be improved by using some tests and visual electrophysiological measurements. The vision and ophthalmology data before the injury of the wounded who has intrinsical disease should be provided. The assessment time should be delayed for people whose visual function still may change.

Changes of retinal ganglion cells and expression of Bad after optic nerve crush in rats / 法医学杂志

OBJECTIVE@#To observe the change of retinal ganglion cells (RGCs)and the expression of Bad after optic nerve injury, so as to study the changes of optic function level on morphology and molecular.@*METHODS@#The experimental models of optic nerve crush were established in fifty Wistar rats. At the different time after injuries (from one to twenty-eight day), the changes of RGCs were observed under microscope. Immunohistochemiscal technique and computer image analysis methods were performed to observe the changes of Bad in RGCs in rats.@*RESULTS@#The number of RGCs was reduced significantly according to partial lesion of optic nerve crush. An initial loss of RGCs densities was accelerated in one week after nerve crush, two weeks later the trend mitigated. After four weeks, no obvious change were observed. The expression of Bad increased in 3 days, reached peak in 5 days, and declined one week later. No obvious changes were observed after two weeks.@*CONCLUSION@#The expression of Bad lead to the loss of RGCs following optic nerve crush. This is the important reason of loss optic function. The identification on optic nerve injuries should be done at least four weeks later.

Watery and dark axons in Wallerian degeneration of the opossum's optic nerve: different patterns of cytoskeletal breakdown?

In this paper we report a qualitative morphological analysis of Wallerian degeneration in a marsupial. Right optic nerves of opossums Didelphis marsupialis were crushed with a fine forceps and after 24, 48, 72, 96 and 168 hours the animals were anaesthetized and perfused with fixative. The optic nerves were immersed in fixative and processed for routine transmission electron microscopy. Among the early alterations typical of axonal degeneration, we observed nerve fibers with focal degeneration of the axoplasmic cytoskeleton, watery degeneration and dark degeneration, the latter being prevalent at 168 hours after crush. Our results point to a gradual disintegration of the axoplasmic cytoskeleton, opposed to the previous view of an "all-or-nothing'' process (Griffin et al 1995). We also report that, due to an unknown mechanism, fibers show either a dark or watery pattern of axonal degeneration, as observed in axon profiles. We also observed fibers undergoing early myelin breakdown in the absence of axonal alterations