Decrease in vitamin C concentration in human lenses during cataract progression.

Cataract formation is believed to result from an oxidative insult which decreases the antioxidant defense of the lens, particularly the vitamin C concentration. Upon oxidation, vitamin C contributes with glucose to protein glycation. It also favours tryptophan oxidation, resulting in fluorescent peptide cross-links and protein insolubilisation. The relationship between cataract and lenticular vitamin C was analysed in 48 cataractous lens nuclei classified into four severity grades, considering the sum of the colour and opacity. Ascorbic and dehydroascorbic acids were quantified by HPLC-fluorescence. The Amadori product was measured by means of furosine, advanced glycation end products by their fluorescence and tryptophan concentration by HPLC-UV. The lens vitamin C concentration significantly decreased with cataract severity, but mostly in severe brown cataracts (around 88 mumol/100 g lens in mild cataracts, and 50 mumol/100 g in dark brown lenses). The dehydroascorbic acid concentration was always low and stable (1.9 +/- 0.9 mumol/100 g), as was the furosine concentration (0.4 +/- 0.1 mumol/g). The fluorescence of insoluble advanced glycated end products was significantly higher in severe cataracts than in milder ones. The peptide tryptophan content was stable but the tryptophan to tyrosine ratio decreased and was highly correlated to the ascorbic acid concentration. Vitamin C content appears to be a good indicator of cataract severity, suggesting that oxidation could take part in cataract progression.

Molecular genetics of open-angle glaucoma, moving from gene localization to predictive testing.

It has long been suspected that genetic factors play a role in open-angle glaucoma. Only recently, however, has the molecular basis of such factors begun to be established, with the primary localization of the GLC1A locus for juvenile-onset and early-onset autosomal dominant open-angle glaucoma on chromosome 1q. These findings are clinically significant in that they allow familial screening of individuals at risk for glaucoma before the onset of irreversible visual impairment. A physical map of the GLC1A genomic region is now available, and the actual GLC1A gene might be identified in the near future. Nevertheless, open-angle glaucoma is a genetically heterogeneous entity, and additional loci have been mapped or proposed. Identification of open-angle glaucoma genes should provide invaluable clues to the disorder's pathophysiology. It could also aid in conceiving novel therapeutic agents and broadening the screening of at-risk subjects.

[Positive diagnosis of Leber's hereditary optic neuropathy using molecular genetics]. / Diagnostic positif de neuropathie optique héréditaire de Leber par génétique moléculaire.

INTRODUCTION: Leber's hereditary optic neuropathy (LHON) is a bilateral optic atrophy, more common in males than in females. No specific clinical feature or biologic test exists to evidence LHON. We report here the case of a man affected with a nonfamilial bilateral optic atrophy, whose diagnostic remained uncertain for 17 years. PATIENT AND METHODS: This patient was hospitalized at the age of 27 in order to establish diagnosis. He had an ophthalmologic examination once a year. He was also affected with chronic renal failure. Detection of the G to A mutation at position 11778 of the DNA was assessed by restriction enzyme digestion of amplified genomic DNA. RESULTS: The 11778 mitochondrial DNA mutation was evidenced, in homoplasmic condition in white blood cells. DISCUSSION: Molecular biology allows to substantiate the diagnosis of LHON and is relatively easy and cheap. Assessment of mitochondrial DNA provides a useful diagnostic tool for nonfamilial or atypical cases of LHON.

MR imaging and CT of surgical materials currently used in ophthalmology: in vitro and in vivo studies.

PURPOSE: To assess methods of imaging postoperative changes in the eyeball by performing in vitro and in vivo studies of the main solid and fluid materials used in the treatment of cataract and retinal detachment. MATERIALS AND METHODS: The samples were analyzed in vitro with computed tomography (CT) and magnetic resonance (MR) imaging performed at 0.5 T. In vivo studies were performed in seven patients who underwent lens implantation (n = 1), scleral buckling with hydrogel or silicone (n = 6), and retinopexy with gas or silicone oil (n = 6). The attenuation and signal intensity of the materials were compared with values for anatomic structures. RESULTS: Lens implants were difficult to visualize. Each scleral buckling and retinopexy material was easily differentiated from the others and from anatomic structures at both CT and MR imaging. CONCLUSION: Postoperative CT or MR imaging may be useful after retinal detachment surgery, particularly when ultrasound is not reliable after intravitreous gas-fluid interchange.

[Optic correction of myopia]. / Correction optique de la myopie.

Correction of myopia by optics is still the most widely used method of visual rehabilitation. It raises visual acuity to levels that permit a normal life in a world where vision is particularly important. This success of glasses and lenses is most perfect for mild or moderate myopia. For subjects with severe myopia glasses are not without problems and contact lenses are preferable, but the results sometimes remain mediocre due to organic disorders resulting from excessive lengthening of the eyeball.

[Local treatment by epidermal growth factor after epikeratoplasty. A double-blind clinical trial]. / Traitement local par facteur de croissance épithélial après épikératoplastie. Etude clinique à double insu.

Epidermal growth factor is a protein which stimulates epithelial cell growth. We conducted a randomized double blind study between patients treated with PHZ102 (Inpharzam SA, Cadempino, Switzerland) containing EGF, and placebo eyedrops as topical treatment following epikeratoplasty, to evaluate the effect of EGF on corneal reepithelialization. The patients of the EGF group recovered earlier (1 to 4 days) than the patients in the placebo group (3 to 15 days). Therefore, the results obtained confirmed that EGF may reduce the time normally required for complete reepithelialization of the cornea.

[Epithelial and stromal healing after radial keratotomy. Scanning electron microscopy analysis]. / Cicatrisation épithéliale et stromale après kératotomie radiaire. Analyse en microscopie électronique à balayage.

A study of corneal healing after radial keratotomy was conducted under scanning electron microscopy in 28 papio-papio baboons. The appearance of the incisions after follow-ups ranging from one hour to three and a half years postoperatively permits to emit some hypotheses regarding the precise mechanisms of action of radial keratotomy, as well as those governing any functional or anatomical complications susceptible to occur after the operation.