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

If beta-blockage does not cause lowering of aqueous humor secretion, in itself responsible for the maintenance of intraocular pressure, what is the mechanism of action? The antagonism for indolamines, recently measured in aqueous humor, the absence of nocturnal effect, and the amplitude diminution of diurnal variations thus produced suggest that beta-blockers could interact with indolamines, since the latter are probably responsible for intraocular pressure regulation. Aqueous humor secretion depends to a major extent on the sodium-potassium pump and its enzyme, Na+K(+)-ATPase. Serotonin, known for its activating action on Na+K(+)-ATPase, is present in the greatest amounts in the morning, precisely when the aqueous humor secretion is the highest. Moreover, timolol is a potent antagonist of serotonin, suggesting that beta-blockers could decrease the secretion by antagonism with serotonin at the level of Na+K(+)-ATPase. Since serotonin is metabolized to melatonin during sleep, beta-blockers might simulate a state of sleep of the ciliary epithelium.

Two fluorophotometric methods, by instillation and oral route, allowed the aqueous humor flow measurement and apparent outflow resistance calculation in normal and hypertensive subjects. There was no statistically significant difference between the two methods in the aqueous humor flow of hypertensive patients and normal subjects. On the contrary, there was an increase of the outflow resistance in hypertensive patients in relation to normal subjects. Finally, oral route fluorophotometry allowed the individualization and calculation of a coefficient of aqueous humor production from the iris, which is statistically increased in hypertensive in comparison with normal subjects. Subsequent studies thanks to this fluorophotometric method by oral route, which interest is certain in treated hypertensive patients, should allow to determine the action site of the drug and to quantify its efficiency.

Modern anomaloscopes with four independent light channels (i.e. Besançon-Anomalometer which was presented in 1979 at the SFO Congress) allow accurate examinations of color vision. In our routine clinical examination, we use two metameric equations: the red-green Rayleigh equation and the blue-green Moreland equation. This so called Two-Equation-Method enables the diagnosis of congenital and acquired color vision defects in a precise qualitative as well as quantitative way. For both equations the goal of the examination is to measure the absolute matching range. Abnormal color vision is diagnosed if the absolute matching range is shifted and/or enlarged in one or both of the two metameric equations. In congenital colour vision deficiencies, the results are similar to those obtained with the Nagel anomaloscop. The different types of acquired defects are compared with the types of Verriest's classification. A computer controlled clinical examination of color vision, which will make the procedure simplier and shorter for the patient is actually being developed.

The subjective aniseiconia was measured with spatial eiconometer on 51 isometropic and unilateral pseudophakic patients in relation with the post-operative anisometropia. The median value of subjective aniseiconia is 2-3% for anisometropia minus or equal to 5 diopters, without statistic correlation, related to a probably "sensorial brain adaptation". So error of intra-ocular lens power calculation less than 7.5 diopters may be accepted.

We have treated 62 recently post-operative eyes with non functioning trabeculectomies at the site of the failed bleb with one to four ultrasound applications each of five seconds duration and at an intensity level of 10 kw/cm2; 32 eyes were phakic, 7 aphakic, and 23 pseudophakic (anterior or posterior chamber). The two groups of patients showed the best response when the ultrasound treatment was performed three to twelve weeks after the last trabeculectomy; 82% are success in the phakic group, and 68% in the aphakic or pseudophakic group after three months. After the ultrasound treatment, 5FU subconjunctival injections seem to be effective in the very bad cases with a low rate of complications.

In 54 consecutive cases of glaucoma triple procedure, a trabeculectomy was systematically performed at six o'clock. By separating the order and the locations of the incisions as well as their placement in limbo-corneal sites, haemorrhages are minimized. A watertight, controlled running suture avoids post-operative flat anterior chamber, and permits rapid tonometric normalisation. The results of these first cases are: a mean post-operative ocular pressure (O.P.): 15.1 mmHg, mean drop of O.P.: 36%; tonometric normalisation and visual-functional improvement above 90%.

A 32 years old patient died seven months after a radial keratotomy. The histologic study of one cornea is realized. The wound of anterior stroma varies from 0.08 to 0.13 mm; it is filled of epithelial cells with eosinophile cytoplasm and a round nucleus. Near this epithelial ingrowth Bowman's membrane is interrupted and the fibres of stroma lose their parallel direction in comparison with the epithelial plane. These histopathologic results are compared with the other publications; and in reference with the mechanism of the healing, an histogenesis of the corneal healing is proposed.

The proliferation of new vessels originating from the choriocapillaris, constitute the turning point in Age Related Macular Degeneration. Vaso-proliferative, or better vaso-modulator, factors have an effect upon the subsequent steps of angiogenesis. Receptors especially for the fibroblast growth factor have been identified on ocular vascular endothelial cells. Basement membranes are the storage site of the factor. In vitro, vaso-proliferative factors, as Fibroblast growth factors, and vaso-inhibitor factors, as Transforming Growth Factor B, were identified in cell cultures of pigment epithelium. On the other hand, proliferations of pigment epithelium cells surround the neovascular sprouts and induce involution of experimental subretinal new vessels. Experimentally and clinically, inflammatory cells are found in the vicinity of the new vessels. Their effect could add or initiate new vessel proliferation. Angiogenesis is an extremely complex phenomenon but results of research on the role of pigment epithelium and vaso-modulators factors help to clarify it partially.

Daunomycin action on human lens epithelial cells has been tested in vitro, with different exposure times. A clinical study on 30 eyes, operated on by the same surgeon, has been carried out according to the Cologne protocol. Cell cultures, with different techniques were grown. This demonstrates that Daunomycin can destroy the lens epithelial cells. We can not currently say what dosage and protocols are necessary to achieve a prevention of secondary cataract.

Using proton beams for treatment of malignant tumors of the eye allows high dose irradiation of the tumor volume with negligible irradiation of the surrounding critical structures. Actually, the clinical results reported from the Boston or Villigen groups which have experience of such a technique, are impressive. In France, it is planned to use soon 200 MeV proton beams from the Orsay synchrocyclotron 20 km from Paris. Therefore, a feasibility study has been conducted during year 1988, consisting of a dosimetric analysis of the characteristics of the Orsay proton beams. It was concluded that only simple modifications were necessary to make the beam clinically available for protontherapy and more specifically for treatment of uveal melanomas.