[Avulsion of the optic nerve: two case studies]. / L'avulsion du nerf optique. A propos de deux cas.

Avulsion of the optic nerve is a rare and serious injury. The authors report two cases of optic nerve avulsion. The first one concerns a 5-year-old boy who presented ocular trauma after falling on the handlebars of a bicycle. His visual acuity was light perception in the right eye, and his right pupil was unresponsive to light. The anterior segment was normal. The ophthalmoscopic examination showed a total separation of the optic nerve head from the sclera with peripapillary hemorrhage. The second case concerns a 30-year-old man who was hit in the right eye with a stick. On admission, he had no light perception in the right eye, a right afferent pupil defect, a small laceration of the right lower eye lid and no abnormalities on the anterior segment. The fundus examination showed a mild vitreous hemorrhage. Ocular ultrasonography showed vitreous hemorrhage coming directly from the optic nerve head in a mushroom pattern. A CT scan of the orbit revealed a thickened optic nerve. Color Doppler ultrasonography documented slowing of blood flow in the central retinal artery. The two patients received 1 mg/kg/day of prednisone for 2 weeks. No improvement was noted. Optic nerve avulsion is often caused by sudden and forceful rotation of the eye with tearing of the optic nerve as it exits the globe. The nerve can be partially or totally avulsed. The prognosis is usually poor.

Quick methods to control compliance of plastic materials with food packaging regulations.

A general strategy is presented, aiming to provide plastics manufacturers, food industries and enforcement laboratories with quick methods to check whether migration from materials for food contact will be acceptable during the time of use. The strategy involves several steps, with increasing time demand and cost. Monitoring extraction kinetics allows both the optimization of the extraction time, and the selection of conditions where extraction is more severe than migration. The influence of the extracting solvent is discussed. It may give rise to specific non-extraction of some migrants, which may change the conclusions when the solvent is used in replacement of a fatty food simulant. Factors ruling this effect at a given temperature are identified: the affinity to the solvent with the migrant (selectivity), its ability to reach molecules entangled in the polymeric network (accessibility) and its interaction with the polymer (penetration). The kinetic parameters of the penetration of olive oil into polypropylene have been determined by the determination of profiles of concentration.

Migration from plasticized poly(vinyl chloride) into fatty media: importance of simulant selectivity for the choice of volatile fatty simulants.

An investigation was carried out to determine whether isooctane and ethanol behave like sunflower oil as fatty simulants for overall and for specific migration from PVC containing aromatic plasticizers (bis-2-ethylhexyl phthalate and tris-2-ethylhexyl trimellitate). In these films, the partition coefficients of migrants between simulant and polymer play a major role. The affinities of isooctane and of sunflower oil to all migrants were similar and isooctane can be considered as an alternative fatty simulant for plastized PVC. In contrast ethanol displays a different selectivity, and is not an adequate fatty simulant. Guidelines for the selection of solvents to be used as fatty simulants for migration testing are discussed. The scope of spectroscopic methods (FTIR and 1H-NMR) to monitor migration of aromatic plasticizers is presented.