Search results for "Retina"

Protective Effect of Astaxanthin on Primary Retinal Cells of the Gerbil Psammomys Obesus Cultured in Diabetic Milieu

2017

Astaxanthin is a major marine carotenoid with powerful antioxidant and neuroprotective properties. The in vitro protective effect of astaxanthin in adult retinal cells of the type-2 diabetic model Psammomys obesus in hyperglycemic conditions was investigated. Primary retinal cells were cultured in normal (5 mM) or high concentrations of glucose (25 and 40 mM) for 5 days and treated with 1-20 μM astaxanthin for the last 48 h of culturing. Mitochondrial dehydrogenase activity and cell viability were assessed using MTT test and trypan blue exclusion dye. Retinal cells were characterized by immunohistochemistry. The results showed that mitochondrial function increased significantly (P<0.05) …

Polyamines and ripening of photoreceptor outer-segment in chicken embryo.

1995

Polyamines and their related monoacetyl derivatives were studied in rod outer segment (ROS) and cone outer segment (COS) of photoreceptor cells from chick embryo retina during eye development (7th-18th days). Putrescine was found to be necessary, in the second phase of retinogenesis, to sustain both ROS and COS differentiation and, after acetylation, gamma-aminobutyric acid synthesis. On the Other hand, spermidine and even more spermine intervene in the third phase of development when photoreceptors mature. Moreover, the presence of Nl-acetylspermidine already at the 7th day indicates that in the outer segment of photoreceptor cells too, as in the whole retina, putrescine synthesis comes ab…

Retinal neurodegeneration and an innovative nanostructured approach in an iron overload in vivo model

2020

Ocular Drug Delivery Systems per la veicolazione di molecole bioattive al segmento posteriore dell'occhio

Modeling retinal landmarks for medical diagnosis automatization

Graph-based minimal path tracking in the skeleton of the retinal vascular network

2012

This paper presents a semi-automatic framework for minimal path tracking in the skeleton of the retinal vascular network. The method is based on the graph structure of the vessel network. The vascular network is represented based on the skeleton of the available segmented vessels and using an undirected graph. Significant points on the skeleton are considered nodes of the graph, while the edge of the graph is represented by the vessel segment linking two neighboring nodes. The graph is represented then in the form of a connectivity matrix, using a novel method for defining vertex connectivity. Dijkstra and Floyd-Warshall algorithms are applied for detection of minimal paths within the graph…

Human Visual Perception and Retinal Diseases

2010

Retinal diseases are causing alterations of the visual perception leading sometimes to blindness. For this reason, early detection and diagnosis of retinal pathologies is very important. Using digital image processing techniques, retinal images may be analyzed quickly and computer-assisted diagnosis systems may be developed in order to help the ophthalmologists to make a diagnosis. In this paper we described shortly two computer-assisted systems for the detection of retinal landmarks (optic disc and vasculature) together with a brief introduction to the human visual system and to some alterations of the visual perception caused by retinal diseases.

Blood vessels and feature points detection on retinal images

2009

In this paper we present a method for the automatic extraction of blood vessels from retinal images, while capturing points of intersection/overlap and endpoints of the vascular tree. The algorithm performance is evaluated through a comparison with handmade segmented images available on the STARE project database (STructured Analysis of the REtina). The algorithm is performed on the green channel of the RGB triad. The green channel can be used to represent the illumination component. The matched filter is used to enhance vessels w.r.t. the background. The separation between vessels and background is accomplished by a threshold operator based on gaussian probability density function. The len…

Bright Pupil Detection in an Embedded, Real-Time Drowsiness Monitoring System

2010

Driver’s drowsiness is stated as an important cause of road and highway accidents. Therefore, the development of a system for monitoring the driver’s level of fatigue is desirable in order to prevent accidents. The paper presents the design and the implementation of a system able to find and evidence the drowsiness level of a driver in an ordinary motor vehicle, in order to prevent car accidents. The system, made up of a car installed infrared video camera connected to the Celoxica RC203E FPGA based board, is able to perform a real time video stream processing. The system exploits the “bright pupil” phenomenon produced by the retina, that reflects the 90% of the incident light when a radiat…

Optic disc positioning and blood vessels extraction on eye fundus

2009

This paper presents two methods aimed to the optic disc positioning on the retinal images. The first is based on a template of the entire image, while the second is based on the retinal vascularisation. For this second task, also a vessel extraction method is provided. Both the algorithm have been tested on test images of the Drive Database.