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Biomedical subjects

Y Robert

Publications and source records attributed to Y Robert.

At least 127 records · Page 7Linked to original sources
PubMed1986

Contrast transfer ratio in normal, cataractous, and intraocular implant lenses. A clinical photopapillometric study.

In order to clinically evaluate the optical performance of the crystalline lens as well as that of intraocular implant lenses, measurements were made of the brightness of two markedly different and easily sited landmarks on the retina (the papilla and the macula) using the photopapillometer. The contrast transfer ratio (CTR) thus generated permitted investigation of three groups of subjects: Normal persons (n = 53) with visual acuity of 1.0 (20/20) from each mature decade of life provided values indicating the age-related changes in eyes not necessarily tending toward lens opacification. Relatively constant CTR values (approximately 2:1) were observed up to 60 years, after which the ratio fell significantly to about 1.5:1 (ranging from 1.41:1 to 1.68:1, depending on the site measured on the papilla). Such a finding in subjects with normal vision was considered to demonstrate the tendency for older lenses to become yellow, which would reduce the CTR. Patients (n = 33) who were being followed clinically for developing lens opacification had their CTRs measured for correlation with their visual acuities. Here, strong correlation (P less than 0.001) was observed. Evaluation of the improvement wrought by the implantation of an intraocular lens in yet another group of patients (n = 38) revealed an increase in the CTR to a virtually normal level (1.97:1). This method provides information about the actual optical efficiency of the lens when the other ocular media are clear, supplementing other methods for evaluating lens density and clarity, and thus further facilitating critical assessment of the progress of lens opacification.

Adult↗
PubMed1986

Respiratory and circulatory influence on photopapillometry.

Respiratory and circulatory conditions that could have an influence on measurements of pallor of the papilla were evaluated with our photopapillometer in a controlled study on canines. The brightness of the papilla rim and the width of the arterioles emerging from the optic nerve head were measured in six anesthetized dogs under normal, hypertensive, and hypotensive circulatory conditions, as well as under various respiratory manipulations, and the parameters were compared for statistical correlation. Both brightness and vessel width remained constant for a wide range of arterial pressures when the rest of the experimental conditions were kept stable at naturally occurring levels. If respiration and circulation were brought to extreme levels, however, there was a statistical tendency for the brightness of the papilla to be dependent on arterial and pulmonary arterial blood pressure. The importance of these findings is discussed with regard to their influence on objective measurements of fundus brightness.

Animals↗
PubMed1986

[Long-term results of Nd-YAG laser iridotomy and indications deriving from it].

Of 132 patients who had undergone Nd-YAG laser iridotomy, 70 were randomly selected for follow-up examinations. Nd-YAG laser iridotomies were subsequently performed on 124 eyes (of these 70 patients), 12 for acute angle-closure glaucoma, 19 fellow eyes of those which had angle-closure glaucoma, 70 for chronic angle-closure glaucoma, and 23 eyes with increasingly narrow chamber angle under miotic therapy. The follow-up period ranged from 1 to 25 months (median = 9 months). Eighty-seven percent of the iridotomies remained visibly open. Of 12 acute glaucomas, 10 were successfully treated, whereas only 2 required a basal iridectomy. In the large group of 106 eyes with a "narrow angle condition," a significant pressure reduction from 20.9 +/- 5.8 to 16.7 +/- 3.4 mm Hg and a significant enlargement of the chamber angle resulted. Since fistulizing procedures involve a risk of malignant glaucoma, Nd-YAG laser iridotomy, which this investigation showed to be risk-free, is the initial procedure of choice in narrow-angle conditions, especially subacute and chronic angle-closure glaucoma, in order to alleviate the angle-closure component in such angle-closure situations, to diagnose its contribution to peak IOP, and to facilitate argon laser trabeculoplasty when needed.

Aged↗
PubMed1986

Influence of pindolol and timolol treatment on the visual fields of glaucoma patients.

In a prospective, multicenter, randomized, double-masked study of glaucoma patients, visual fields, intraocular pressures, blood pressures, and pulse rates were measured after a 4-week wash-out period and after three and six months of treatment with either pindolol 1% or timolol 0.5% twice daily. Both drugs reduced significantly the IOP. The blood pressure was not changed significantly whereas the pulse rate was reduced more in the timolol treated group than in the pindolol treated group. The visual fields of the pindolol group showed on the average a slight tendency towards improvement and in the timolol treated group a very slight tendency for deterioration. The difference between these two trends was statistically significant (p less than 0.05).

Blood Pressure↗
PubMed1985

Delays in the primary vaccination of children.

The results of a population-based survey of 170 children's vaccination records were used to calculate the cumulative distributions of the ages (in months) at which each dose of vaccine had been received. Considerable delays in the administration of measles-mumps-rubella (MMR) vaccine and of the fourth dose of diphtheria-pertussis-tetanus vaccine were observed, particularly in children vaccinated by private physicians rather than at public health clinics. The delay before MMR vaccination causes concern because of the frequency of measles in children aged 1 to 2 years, particularly those attending day-care centres, and the fragility of the herd immunity against this disease. Physicians should follow up patients who have missed appointments for MMR vaccination if a voluntary measles control program is to succeed.

Age Factors↗
PubMed1985

[Evaluation of the effectiveness of beta blockers on the eye].

The authors report on comparative studies of two beta-blockers with regard to various parameters (intraocular pressure, perfusion pressure, and brightness of the papilla). A differential evaluation of these medications shows that measurement of the intraocular pressure alone is not sufficient to elucidate all of their characteristics fully.

Adult↗
PubMed1985

[Photocoagulation-induced macular scotoma and automated perimetry (Octopus)].

The size of macular scotomata is determined numerically by a series of parallel F2 programs of the Octopus Perimeter. As long as useful foveolar fixation is maintained, the results are reproducible within the limits due to fluctuation of the retinal sensitivity. The scotomata can be mapped on a fundus photograph either by direct calculation or after perimetric determination of a reference distance, e.g., foveola-disc or between angioscotomata. This method furnishes useful information which can facilitate evaluation of different types of lasers in macular photocoagulation.

Adult↗
PubMed1985

Multiple cotton wool spots following bone marrow transplantation for treatment of acute lymphatic leukaemia.

Three patients with acute lymphatic leukaemia developed visual impairment due to occlusion of small retinal vessels with multiple cotton wool spots after treatment which included whole body and skull irradiation followed by bone marrow transplantation and cyclosporin A. Withdrawal of cyclosporin A and treatment with corticosteroids was followed by recovery of visual acuity. This retinopathy and the retinal changes seen in the immunodeficiency syndrome are thought to be closely related. The possible role of cyclosporin A is discussed, though cotton wool spots and retinal haemorrhages have never been described in renal transplant patients during treatment with this drug. Withdrawal of cyclosporin A, which is highly effective in preventing graft-versus-host disease, can be fatal. Irradiation of the skull prior to bone marrow transplantation and intrathecal administration of methotrexate may be the most important factors causing the retinal ischaemic signs described here. The inclusion of an ophthalmologist in the team monitoring transplant patients would lead to increased documentation and a better understanding of this disease.

Adult↗
PubMed1985

Fluctuations of light absorption of healthy papillae repeatedly photographed over a long period of time.

In order to distinguish normal, age-related changes of the papilla from changes due to glaucoma, we investigated 7 normal papillae that had been photographed several times over a period of 11 years. By means of digital-image processing techniques, the red- and green-filtered, digitized pictures were compared directly using a subtraction method. The results seem to indicate that normal papillae do not blanch over a long period of time. The difficulties of comparison are discussed.

Aging↗
PubMed1984

Pallor of the optic disc in glaucoma patients with artificial hypertension.

Measurement of four parameters, namely brightness of the unaffected optic disc, brightness of the optic disc under artificially elevated eye pressure, baseline eye pressure, and systolic blood pressure, gives the possibility of discerning glaucomatous eyes from healthy ones, with an accuracy of about 90%. Measuring eye pressure and systolic blood pressure is very simple. If measurement of the optical density could be simplified, an additional practical test for glaucoma could be developed.

Adult↗
PubMed1984

Principles of photometry of the papilla.

To enhance the qualitative information gained by photographing the optic nerve head, we built a silicon photovoltaic detector (photodiode) in the image plane of a fundus camera (Zeiss). It permitted quantitative evaluation of the relative brightness of the illuminated papilla. Following construction of the device and during the early course of more than 260 measurement sessions (on more than 130 subjects), several heretofore unknown sources of error were encountered and subsequently dealt with, resulting in a margin of error for the entire system of between 0.3% and 1.2%. Pallor of the optic nerve head induced by artificial ocular hypertension can be well reproduced by this method.

Humans↗
PubMed1984

Color appearance of the papilla in normal and glaucomatous eyes. A photopapillometric study.

The brightness of the papilla in three groups of subjects (young normal subjects, elderly normal subjects, and patients with glaucoma) was measured with a photopapillometer. By employing a sensor 1.0 mm in diameter with a fundus magnification of X2.5, it was possible to study specific sites on the rim of the papilla. Comparison of the values obtained indicated relatively little difference in the brightness of the two sites measured in the left eyes and an obvious difference in those measured in the right eyes, the temporal side being markedly brighter. This pattern persisted throughout all groups, including that of the patients with glaucoma. There was an interesting correlation between the brightness differences observed in the papilla of the subjects and the relative symmetry of the distribution of their retinal vessels.

Adult↗
PubMed1983

[Prevention, in the contralateral eye, of a giant tear ablation].

In this paper the authors report on 11 patients with giant tear detachment, whose fellow eyes were prophylactically treated with cryopexy or laser coagulation. The patients were followed up for between 4 and 12 years. The prophylactic lesions were located radially or circumferentially (circumscribed or extending through 180 degrees). In 4 out of 11 patients new tears developed during the follow-up period. The tears occurred between 1 month and 7 1/2 years after prophylactic treatment. In one of these cases a giant tear (90 degrees) developed in spite of prophylaxis: this was a case in which the coagulations extended circumferentially for 180 degrees; the new tear originated posteriorly to the scars. In contrast to this only multiple small horseshoe tears were observed in the other 3 patients: in these cases the prophylactic lesions were arranged radially or were circumferential and circumscribed. Some of these horseshoe tears were still attached and were treated with cryopexy or laser coagulation; others were already detached, reattachment was achieved by cryopexy and radial buckling of the tears.

Cryosurgery↗