Ophtalmologie : organe de la Societe francaise d'ophtalmologie最新文献

The purpose of the present study was to evaluate the electroretinophysiological effects of streptozotocin-induced diabetes in the rat. More specifically, both B wave amplitudes and implicit times generated with various intensities of light stimulation were examined in diabetic animals adapted to either scotopic or photopic conditions. Results indicate that B wave amplitudes, but not implicit times, were differentially affected by these two conditions of light adaptation: amplitudes were significantly enhanced but markedly decreased under photopic and scotopic conditions respectively. The possible functional relationships between these specific ERG changes and our previous observations of selective alterations in retinal dopaminergic systems in this animal model of diabetes are discussed.

A previous study showed the good tolerance of the human type IV collagen lenses implanted by epikeratoplasty in 8 monkeys. It also showed type IV collagen is a good material for the reepithelialization. But we have been interested in the stability of the epithelial healing. The ultrastructural study found anchoring structures. However these were inconstant. So the authors try to understand better the mechanisms of this synthesis of the anchoring structures and describe the future ways of this experimental study.

The Pseudomonas aeruginosa slime-glycolipoprotein (GLP) is considered as one of the principal pathogenetical factors of the bacterium. A single dose of 100 micrograms of the P. aeruginosa slime-GLP was injected in rabbit corneas intrastromally. Light microscopy showed that 4 hours after the injection, polymorphonuclear leucocytes (PMNs) began to infiltrate the anterior stroma. 24 hours after the intrastromal injection, PMNs had infiltrated full corneal thickness followed by multiple absceses formation, loss of epithelial and endothelial cells, disorganisation of normal collagen fibres and hyperplasy of fibroblasts. These morphological observations are very similar to those observed during experimental P. aeruginosa keratitis and show that the P. aeruginosa slime-GLP is at least in part responsible for the characteristic liquefaction necrosis of the keratitis induced by the P. aeruginosa.

Despite its name, Vasoactive Intestinal Peptide (VIP), a 28-amino acid peptide, is widely distributed in the eye where it is thought to play a physiological role, particularly in aqueous humor dynamics or retinal neurotransmission. Localization and pharmacological properties of VIP binding sites were investigated in eyes from albino rabbit and rat using an in vitro autoradiographic method. 125I-VIP was used as ligand and unlabelled VIP was used to displace labelled VIP. Autoradiograms were generated by apposing the slides to 3H-Ultrofilm or autoradiographic emulsion and analysed using an image analysis system. Specific binding represented about 85% of total binding. Kinetic studies showed that equilibrium was reached after 140 min incubation at room temperature. Biochemical investigations demonstrated that 125I-VIP bound to a population of sites with high affinity (Kd = 2.95 +/- 0.5 nM). Inhibition of 125I-VIP binding with VIP and related peptide gave a rank order of potency: VIP greater than peptide histidine isoleucine greater than secretin greater than human growth hormone-releasing factor, glucagon, VIP1-14, VIP14-28. In both species, specific binding were found in conjunctiva, iris, ciliary processes, choroid and retina. Quantitative analysis of autoradiograms revealed that the highest densities of binding sites were localized in the ciliary epithelium in rabbits and in the inner retina in rats.

MR T2 Weighted sequences on the brain demonstrate disseminated "high signal zones" (HSZ) in patients with Multiple Sclerosis; these morphological alterations are corresponding to the plaques. From the very beginnings of MR in 1981, everybody recognizes the main importance of this fact. MR appears as the most sensible exploration in patients with M.S. But the signal alteration is not specific; the clinical considerations and the evolution are requested. The aim of this work is to give a reference tool for evolutive evaluation of the disease. A work station with a specially developed software are presented. The HSZ thresholding is partially automatic. The edition of a cerebral mapping is developed. These results are discussed.

We report on the results obtained in the treatment of inflammation of the cornea by means of the saturation of free radicals, using chemiluminescence. The experiment was conducted on the Alloxan model of corneal inflammation caused by the freeing of free radicals in the stroma. We compared the action of steroidal and non-steroidal antiinflammatory substances, and also specific saturators of free radicals.

Hypercapnia causes vasodilatation of retinal arterioles. Prostaglandin E1, injected close to retinal arterioles from the vitreal side cause vasodilatation apparently similar to that caused by hypercapnia. An inhibitor of prostaglandin synthase (indomethacin) was injected into the ocular circulation. There was a reversible inhibition of the retinal vasodilatation normally induced by hypercapnia. Indomethacin injected close to retinal arterioles from the vitreal side causes reversible vasoconstriction and inhibits the vasodilatory effect of hypercapnia. It is concluded that prostaglandin E1 satisfies three criteria for a candidate for a mediator of hypercapnia-induced arteriolar dilatation.

We study capillary microcirculation on the optic nerve head and its interrelation with blood rheological modifications. The mean maximal velocity has been evaluated in the capillaries of the rabbit optic nerve with a laser doppler velocimeter, in physiological conditions and after intravenous Dextrane 250 injections. Dextrane 250 increases red blood cells aggregation and induces blood hyperviscosity at low flow rates. This hyperaggregation is determined with a reflectometric method. Experimental results show a significant reduction of blood velocity when blood viscosity increases. In our present study, we compare blood capillaries flow rate in the optic nerve, between two groups: healthy humans and subjects suffering from glaucoma. The aggregation level is simultaneously measured for the two groups. First results seem to prove that blood flow rate decrease is associated with red blood cells aggregation increase for the second group.

In a study concerning 124 eyes, we have considered the frequency of superficial deposits on gas-permeable contact lenses in extended wear. On the whole this is not a serious problem when a regular and complete upkeep is made. The new materials made with fluor have proven to be superior to materials made with silicones.

Keratoconus may present a difficult therapeutic challenge when it becomes impossible to adapt Contact Lenses. Penetrating Keratoplasty is sometime difficult to perform and the result is often altered by important astigmatism. Other solutions have been tried with variable results. We treated 26 eyes with Keratoconus that were unadapted to CL bud didn't have central opacities, with Non Freeze Epikeratoplasty. 14 of them are analysed (more than 3 months after suture ablation). 13 increased visual acuity without correction. All of them increased best corrected VA. Medium astigmatism was 3 dioptries, always regular. No major complications were observed. The comparison with an equivalent group treated with Penetrating Keratoplasty showed that the results were equivalent. Epikeratoplasty can be a reasonable alternative in central or large KC without central opacities. It's extraocular and always reversible. The Non Freeze procedure is less aggressive for the graft tissue.