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Biomedical subjects

A Bechetoille

Publications and source records attributed to A Bechetoille.

48 records · Page 3Linked to original sources
PubMedDate not supplied

Regulation of optic nerve head blood flow in normal tension glaucoma patients.

PURPOSE: To investigate the regulation of the optic nerve blood flow (Fonh) in response to an increase of the perfusion pressure (PPm) in normal tension glaucoma (NTG) patients and in age-matched normal volunteers. METHODS: Measurements were performed in 16 eyes of NTG patients and in 10 eyes of age-matched controls. Laser Doppler flowmetry (LDF) was applied to calculate the relative flux of red blood cells at the temporal rim of the optic nerve head (ONH) in response to increases in PPm. PPm was raised through an increase in systemic blood pressure induced by isometric exercise. Before being tested, all patients had 3 weeks of washout of any local medication. RESULTS: In the NTG group, mean ophthalmic arterial blood pressure increased during isometric exercise from 73 to 89 mmHg (22%), resulting in a 29% increase of the PPm. This increase did not induce any significant change in mean Fonh. For the control group, the 28% increase of PPm also did not significantly affect Fonh. There was a trend for a greater increase in vascular resistance during isometric exercise in the NTG than in the normal control group (47% versus 25%). CONCLUSIONS: The LDF parameters, measured in the ONH, did not indicate an abnormal Fonh regulation in response to an increase of the PPm in either normal subjects or NTG patients. The maintenance of constant blood flow is achieved by an increase in local vascular resistance. Our data show a greater percent increase in vascular resistance in the NTG patients compared to the normal subjects for a similar percent increase in PPm in both groups during squatting. This suggests some alteration of the vessel tone regulatory mechanisms in NTG patients.

Aged↗
PubMedDate not supplied

[Tonometry yesterday and today].

Instrumental tonometry was developed in the second half of XIX century, especially when local anesthesia of the cornea became available. Imbert-Fick mathematical law and the building, 75 years later, of the excellent Goldmann tonometer were the principal steps of aplanation tonometry; however, this technique is now limited by the difficulties encountered in updating and automatizing the evaluation of aplanated surface. In the other hand, there are some evidence that the ocular tension, as evaluated with Goldmann tonometer, could be different of manometric intraocular pressure in the vitreous cavity, especially when the cornea is abnormal. New tonometers utilizing electric deformimeters technology might be developed particularly to perform continual eye pressure monitoring.

Humans↗
PubMedDate not supplied

[Asymmetrical forms of primary open angle glaucoma].

PURPOSE: The goal of this study is to describe asymmetrical forms of primary open angle glaucomas in black african originated patients. MATERIAL AND METHOD: Data of 514 glaucomatous patients (1022 eyes) followed between 1993 and 1997, and attending our hospital eye department are retrospectively analysed. All the participants were diagnosed as primary open angle glaucomas; asymetry was defined as a difference of 0.2 at least between the vertical cup disc ratio of the same patient. RESULTS: The mean age of all 514 glaucoma patients was 34.52 +/- 15.55 years; 254 patients (49.40%) had no differences between cup disc values while 260 remaining others had asymmetric glaucomas (50.58%). Of them, 189 (72.69%) had a difference of 0.2 between both eyes; 49 (18.8%) had 0.3 difference; 7 (2.69%) had 0.4 difference; 4 (1.53%) had 0.5 difference, and 11 (4.23%) a difference of 0.6. Besides, 114 eyes (11.15%) had a vertical ratio of 0.9 at the first diagnosis. CONCLUSION: Carefully recognition of asymmetric cup disc ratios is of great diagnostic value in the the early stages of primary open angle glaucoma because 50% of all patients presented with this clinical form in our experience. This strategy would improve early diagnosis of glaucoma in our areas.

Adolescent↗