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Biomedical subjects

M Malenfant

Publications and source records attributed to M Malenfant.

10 recordsLinked to original sources
PubMed1996

Myelinated nerve fibers and retinal vascular abnormalities.

BACKGROUND/PURPOSE: Abnormal retinal vessels may develop in a region of myelinated nerve fibers, and these vessels may cause vitreous hemorrhages. METHODS: The clinical histories of seven patients with retinovascular abnormalities in a patch of myelinated nerve fibers are presented. None of the reported patients had other evidence of systemic disease. The cases were traced by a multicentric retrospective study. RESULTS: Retinal vascular abnormalities ranged from mild telangiectasis to frank neovascularization, with or without obstruction of the capillary network and signs of branch artery and vein occlusion. Age at diagnosis ranged from 15 to 68 years. Vitreous hemorrhages occurred in the four youngest patients and occurred at 15, 27, 27, and 43 years of age. Laser photocoagulation was applied in three patients and vitrectomy was performed in one. CONCLUSION: The authors' findings suggest that the abnormal structure of the myelinated nerve fibers and the thickened nerve fiber layer of the affected portions of retina may play a role in the onset of retinal vascular abnormalities and eventually cause telangiectasis, branch artery and vein occlusion, neovascularization, and vitreous hemorrhages. This suggestion is based on the absence of other causes of neovascularization or vitreous hemorrhage in all seven patients, and on the relatively young age of four of the patients with this association.

Adolescent↗
PubMed1995

[Diabetic retinopathy: pathogenesis, risk factors, clinical picture, classification].

Hyperglycemia is the main cause of diabetic complications. High glucose concentration acts directly on pericytes, endothelial cells and basal membrane of small vessels. Non-enzymatic reaction between glucose and proteins gives a substance called AGE (Advanced Glycosylation End Products). This AGE reacts with proteins, lipids, nucleic acids, lymphocytes and macrophages, antioxidants producing microvascular changes related to atherogenesis the high glucose level triggers formation and accumulation of sorbitol and galacticol causing alteration of cell membrane. These changes in vessel walls added to rheologic and hemostatic changes give rise to microthrombosis, ischemia and finally neovascular formation.

Blood Glucose↗
PubMed1995

[Ophthalmological monitoring of Type I and Type II adult diabetics].

In type I-Type II Adult diabetics, the eye-examination ideally should be done by ophthalmologists because experience and specialization of the examiners increase the ability to diagnose proliferative retinopathy. A dilated eye examination is essential and must include mid-periphery examination. In macular oedema, contact lens examination is required tot diagnose a clinically significant macular oedema. Angiography is useful as a guide for treating clinically significant macular oedema. Indications of laser treatment in preproliferative and proliferative retinopathy are revised.

Adult↗
PubMed1989

Canthaxanthin retinopathy. Anatomic and functional reversibility.

Canthaxanthin intake is associated with golden yellow crystalline deposits in the retina around the macula and low static luminance threshold. Our study assesses the anatomic and functional reversibility of canthaxanthin retinopathy. The number of retinal deposits was evaluated in nine patients, two to four times over a mean period of 55 months. There was no significant difference after a nine-month follow-up. A statistically significant decrease in the number of retinal deposits was found after an observation period of 26 months. The deposits disappeared slowly, while some remained even seven years after canthaxanthin therapy was discontinued. Threshold static perimetry performed on eight patients with retinopathy and seven controls did not differ significantly between the two groups at the end of the follow-up period. The results demonstrate that canthaxanthin retinopathy is reversible.

Adult↗
PubMed1988

Static perimetry in canthaxanthin maculopathy.

We performed threshold static perimetry on 19 patients who had ingested canthaxanthin; 11 had maculopathy and eight did not. Patients with no history of canthaxanthin ingestion served as controls. All patients had visual acuity of 6/9 or better. Threshold static perimetry was reevaluated two to three years after cessation of canthaxanthin ingestion. For both testing sessions, patients with maculopathy presented lower retinal sensitivity than controls, while patients without maculopathy did not differ significantly from the control group. These results suggest that canthaxanthin retinopathy can adversely affect the neurosensory retina.

Adult↗
PubMed1986

Ocular toxicity of Anandron in patients treated for prostatic cancer.

Approximately 65% of patients with prostatic cancer treated by the combination therapy using a gonadorelin (LHRH) agonist or orchidectomy in association with the antiandrogen Anandron complained of a delay in recovering vision after bright illumination (sun, television, bright light). Detailed ophthalmological examination revealed an increase in the photostress recovery time to an average of 9 min, while the upper limit of normal is 1 min 20 s. When treatment was changed from Anandron to the other pure antiandrogen flutamide, the value of the photostress recovery time markedly decreased and the visual symptoms rapidly disappeared. Since uninterrupted administration of the antiandrogen is of the outmost importance for the successful therapy of prostatic cancer, the availability of a compound such as flutamide that has no side effect other than those due to hypoandrogenicity should greatly facilitate compliance by the patients and the success of the treatment.

Aged↗
PubMed1984

[Retinopathy due to canthazanthine: 2. Predisposing factors].

A retrospective study of 14 cases of retinopathy due to canthaxanthine, a carotenoid recently used as a skin-tanning agent, revealed that several clinical factors were associated with an increased susceptibility to retinal deposits: focal epitheliopathy, ocular hypertension and, possibly, the concurrent use of beta-carotene. Age has already been established as such a factor.

Adult↗
PubMed1983

[Canthaxanthine retinopathy: 1. Clinical study in 51 consumers].

Canthaxanthine, a non-provitamin A carotenoid, has been marketed in Canada since March 1979 as a skin-tanning agent. Fifty-one individuals who ingested from 3.6 to 66 g of the drug within a 24-month period were ophthalmologically evaluated. Six of them had deposits in the ocular fundus that appeared to be related to ingestion of the substance, but no functional impairment could be detected.

Administration, Oral↗
PubMed1982

[Maculopathy with golden particles].

This article describes two patients with a bilateral maculopathy due to the presence of numerous glistening yellow particles located mainly around the edge of the macular pit. This picture has apparently not been reported before. Further studies are needed to confirm a possibly toxic origin.

Adult↗