Biomedical subjects

Rui Bernardes

Publications and source records attributed to Rui Bernardes.

4 recordsLinked to original sources

PubMed2005

Mapping the human blood-retinal barrier function.

The aim of the work herein presented is to map blood-retinal barrier function by measuring retinal fluorescein leakage from the blood stream into the human vitreous using a confocal scanning laser ophthalmoscope (CSLO). Existing methods for the assessment of fluorescein leakage into the human vitreous are based on the qualitative evaluation of fluorescein angiographies (FA) and on volume measurements, as performed by the Fluorotron Master. A new procedure is presented capable of measuring fluorescein leakage into the vitreous while simultaneously imaging the retina. The present methodology computes the fluorescein leakage in a fully automated way, based on the three-dimensional fluorescence distribution in the human eye by using a single data acquisition. The processing includes signal filtering, volume alignment and profile deconvolution. The deconvolved profile obeys the established physical model. Representative cases shown are: a healthy eye; an eye with drusen from a nondiabetic person; a photocoagulated eye; and an eye with nonproliferative diabetic retinopathy. The results are in agreement with previous findings and go a step further by making possible its daily usage in a clinical setup based on currently available instrumentation.

Algorithms↗

PubMed2004

Nonproliferative retinopathy in diabetes type 2. Initial stages and characterization of phenotypes.

This review addresses the initial stages of nonproliferative diabetic retinopathy in diabetes type 2. The natural history of the initial lesions occurring in the diabetic retina has particular relevance for our understanding and management of diabetic retinal disease, one of the major causes of vision loss in the western world. Diabetic retinal lesions are still reversible at this stage opening entirely new opportunities for effective intervention. Four main alterations characterize these early stages of diabetic retinopathy: microaneurysms/hemorrhages, alteration of the blood-retinal barrier, capillary closure and alterations in the neuronal and glial cells of the retina. These alterations may be monitored by red-dot counting on eye fundus images and by fluorescein leakage and retinal thickness measurements. A combination of these methods through multimodal macula mapping has contributed by identifying three different phenotypes of diabetic retinopathy. They show different types and rates of progression which suggest the involvement of different susceptibility genes. The identification of different phenotypes opens the door for genotype characterization, different management strategies targeted treatments.

Diabetes Mellitus, Type 2↗

PubMed2003

Alterations of retinal capillary blood flow in preclinical retinopathy in subjects with type 2 diabetes.

BACKGROUND: To identify alterations of retinal capillary blood flow in the papillomacular area in preclinical diabetic retinopathy using the Heidelberg scanning laser Doppler flowmeter. METHODS: Ten eyes from ten patients with type 2 diabetes and no lesions visible on fundus photography (level 10 of Wisconsin grading) and ten eyes from ten healthy subjects of similar age range were examined with the HRF. Intravisit reproducibility of retinal capillary blood flow measurements was assessed in normal subjects and in type 2 diabetic patients, comparing different measurement areas and different analysis procedures: (a) 10x10 pixel box with original software, (b) 10x10 pixel box with SLDF software, and (c) whole-scan analysis with SLDF software (automatic full-field perfusion image analysis). RESULTS: Intravisit reproducibility for the whole-scan analysis in the papillomacular area was 3.52%, 4.81% and 4.60% for volume (VOL), flow (FLW) and velocity (VEL) respectively. Using this method, mean and SD values for retinal capillary blood-flow are 13.25+/-2.87, 214.58+/-55.30 and 0.74+/-0.17, for VOL, FLW and VEL for healthy eyes, comparing with 19.85+/-6.22, 360.87+/-158.70 and 1.20+/-0.48 in eyes with preclinical diabetic retinopathy (P<0.010, P<0.019 and P<0.015 respectively). CONCLUSIONS: The HRF shows acceptable reproducibility when using whole-scan analysis in the papillomacular area. Retinal capillary blood VOL, FLW and VEL were particularly increased in five of the ten diabetic eyes examined, with values over the mean + 2SD of the control population, suggesting that eyes showing increased retinal capillary blood flow may indicate risk of progression.

Adult↗

PubMedDate not supplied

Multimodal macula mapping: a new approach to study diseases of the macula.

Multimodal macula mapping is presented as a combination of a variety of diagnostic tools and techniques to examine the macular region in order to obtain information on its structure and function in a clinical environment. Foundations of macular mapping are reviewed and discussed. New methodologies for multimodal macula mapping based on a combination of scanning laser angiography, retinal leakage analysis, retinal thickness analysis, and visual field testing are presented, demonstrating the potential of macula mapping. Other available detection devices are briefly reviewed considering their potential to be included and utilized in future developments of multimodal macula mapping. Multimodal macula mapping appears to offer unique perspectives and insights that are expected to contribute to improved diagnosis and better understanding of macular diseases.

Diagnostic Techniques, Ophthalmological↗