Archives: Projects/Publication

Measuring retinal fluorescein leakage into the human vitreous with a modified confocal scanning laser ophthalmoscope.

Bernardes R., Isidoro J., Simões P., Lobo C., Cunha-Vaz J.

A method is described to quantify blood-retinal barrier permeability to fluorescein. Data is collected from the vitreous of the human eye at two elapsed time intervals after intravenous fluorescein administration, using a modified confocal scanning laser ophthalmoscope. Data processing includes fundus image enhancement, image alignment, profile construction, profile filtering and interpolation, exponential fit and integration. Automatic determination of the center of fovea is obtained by a correlation process. Grid overlapping on fundus images and permeability maps allows for matching chorioretinal morphological structures with alterations of blood -retinal barrier permeability to fluorescein.

Proceedings of the European Society of Engineering and Medicine. 1999, 5: 181-182.

1999

Retinal leakage analyzer.

Lobo C., Cunha-Vaz, J., Bernardes R.

Int. J. Metabol. 1999; 2:87-88.

1999

Measuring retinal fluorescein leakage into the human vitreous with a modified confocal scanning laser ophthalmoscope.

Bernardes R., Lobo C., Cunha-Vaz J.

Revista do DETUA. 2000; 3: 180-186.

2000

Evaluation of blood-retinal barrier function from fourier domain high definition optical coherence tomography.

Bernardes R., Santos T., Cunha-Vaz J.

Proceedings of 25/XI IFMBE 2009, World Congress on Medical Physics and Biomedical Engineering, September 7-12, 2009, Munich, Germany.

2009

Computer-assisted microaneurysm turnover in the early stages of diabetic retinopathy.

Bernardes R., Nunes S., Pereira I., Torrent T., Rosa A., Coelho D., Cunha-Vaz J.

Purpose: To assess the reliability of microaneurysm turnover, computed from color fundus photographs, in evaluating diabetic retinopathy in patients with type 2 diabetes and nonproliferative retinopathy.

Methods: A new method (MA-Tracker) was developed to count microaneurysms by mapping their locations through image co-registration. To compute the reliability of microaneurysm turnover, 3 different graders were asked to earmark microaneurysms on the same set of color fundus photographs.

Results: The total numbers of microaneurysms earmarked in each of 5 visits suggest that microaneurysms remain stable over time (p 0.138). However, an analysis of each microaneurysm showed that only 29.4% remained at the same location. By computing the formation and disappearance rates of microaneurysms (2.3 and 1.7 microaneurysms/year, respectively), a significant turnover of microaneurysms was found.

Conclusions: The formation and disappearance rates of microaneurysms obtained from color fundus photographs using MA-Tracker show very good agreement between different graders, and can be used as indicators of microaneurysm turnover in the initial stages of diabetic retinopathy.

Ophtalmologica, 2009; 223(5):284-291.

2009
http://content.karger.com/ProdukteDB/produkte.asp?Doi=213638

Microaneurysm Turnover Is a Biomarker for Diabetic Retinopathy Progression to Clinically Significant Macular Edema: Findings for Type 2 Diabetics with Nonproliferative Retinopathy.

Nunes S., Pires I., Rosa A., Duarte L., Bernardes R., Cunha-Vaz J.

Purpose: To examine the relationship between microaneurysm turnover (formation rate), using a new semi-automatic method (MA-Tracker) based on color fundus photographs, and diabetic retinopathy (DR) progression to clinically significant macular edema (CSME).

Methods: In total, 113 patients/eyes with nonproliferative DR (NPDR) were followed up every 6 months for 2 years as controls of the DR clinical trials, and by conventional general and ophthalmological care for the next 8 years (over a total of 10 years’ follow-up). Microaneurysm turnover for the 2 first years was computed using the MA-Tracker.

Results: The 17 patients that developed CSME over the 10 years of follow-up presented a microaneurysm formation rate of 9.2 ± 18.2 microaneurysms/year (mean ± SD) during the first 2 years, which was statistically higher than the eyes that did not develop CSME (0.5 ± 1.2 microaneurysms/year, p < 0.001). These 17 patients also presented higher HbA_1C levels at baseline (8.5 ± 1.2%) compared to the patients who did not develop CSME (7.3 ± 1.2%, p = 0.001).

Conclusions: A high microaneurysm formation rate on color fundus photographs appears to be a good biomarker for DR progression to CSME in type 2 diabetic patients with NPDR.

Opthalmologica 2009; 223(5):292-297.

2009
http://content.karger.com/produktedb/produkte.asp?typ=fulltext&file=000213639