Détermination de la tortuosité pour la détection des rétinopathies vasculaires sur les images d''angiographie rétinienne

Les rétinopathies vasculaires peuvent être accompagnées d'une modification de la forme des vaisseaux. Les patients atteints courent le risque de perdre la vue. Jusqu'ici, les méthodes utilisées par les ophthalmologistes pour analyser ces modifications sont qualitatives. Nous proposons une méthode nouvelle d'analyse de la tortuosité des vaisseaux de la rétine en vue d'élaborer par la suite un outil d'aide au diagnostic des rétinopathies vasculaires. La première étape de la méthode est une représentation symbolique de la structure vasculaire de la rétine. La deuxième étape appelée reconstitution 2D est la classification des entités vasculaires en gros vaisseaux (artères ou veines) et en petits vaisseaux (artérioles ou veinules) en utilisant la moyenne du diamèetre et du niveau de gris des segments de vaisseau comme paramètres discriminants. La dernière étape consiste à calculer l'excentricité des vaisseaux pour décrire leur tortuosité. Pour s'assurer de la capacité de l'excentricitéà décrire les petites modifications de forme, un second paramètre a été défini à titre comparatif. Les résultats obtenus permettent de quantifier les modifications de forme des vaisseaux.     

Espace phobique et levier thérapeutique

Introduction

The spatial experience in phobic disorders needs to be better understood in order to account for the pathogenic effect of a local phobogenic situation on the whole subjective world. Such an understanding could be useful for the treatment of resistant phobias which are hampered by therapeutic blocks that require a global restructuration of the subjective world.

Objectives

Three objectives are addressed in this paper: (1) a clarification of the experience of space in phobic disorders; (2) an account of the impact power of the phobogenic situation; (3) an analysis of levers in cognitive psychotherapy that may help to overcome therapeutic blocks in resistant phobias. To tackle these objectives, we bring in the conceptual framework of representational spaces that proposes some tools to describe a subjective world as grounded in the spatial experience. According to the model of phobic disorders that we build up in this framework, the phobogenic situation behaves like a probe that reveals some strains disturbing in depth the subjective representational space. These strains depend on past traumatic situations that have resulted in the development of phobic cores. Thus, the phobogenic situation materializes some dimensions of the representational space that makes it vulnerable to a traumatic agent. In this framework, a therapeutic lever can be defined as a key-situation that favors a global reorganization of the representational space from a local work on it. Three conditions appear to be necessary to the works of such a lever: (1) the key-situation needs to resonate through the representational space with a central phobic core; (2) the patient should actively grasp the processes of the symbolic structuration of his/her space; (3) the therapeutic lever should only be operated at the suitable time of the therapeutic course by taking account of the subjective defences.

Patient and method

Our model is exemplified with a case study that describes the behavioral and cognitive therapy of a patient that suffers from a phobic disorder since his adolescence. The technical method notably uses a work on the cognitive schemas that starts from the patient story.

Results

The method used to overcome therapeutic blocks reveals some phobic cores that are related to traumatic situations in childhood and adolescence. Therapeutic levers are operated when key-situations relative to the familial story can be addressed and elaborated by an active work of the patient, with a feeling of global restructuration of his psychic space.

Conclusions

The conceptual framework of the representational spaces is interesting to clarify the spatial experience in phobic disorders and to explain the impact of the phobogenic situation. Moreover, in complex phobias, this framework offers some useful tools to conceptualize the therapeutic levers that could be efficient to move the whole subjective world. Such levels can only be used during a long-term therapy.     

Schémas dépressogènes et espace subjectif

The concept of schema used in cognitive psychotherapy is an heuristic tool that has more a metacognitive value than a psychological value: it doesn't involve directly the cognitive processes and the representations in memory. Therefore, the understanding of the therapeutic action is limited and insufficient for a satisfying account of the complex clinical data observed during the course of treatment of resistant depression. To overcome this problem, we propose a conceptual framework that describes a subjective universe as a representational space that is displayed from memory. From this point of view, depression is equivalent to a retraction of the subjective space. This retraction is primed by the reactivation of some past traumatic events. We show the influence of early painful situations on the Home Image, which is an essential area for the unification of the representational space. This conceptual framework allows us to define the representational structures underlying the cognitive model of learned helplesness of Abramson et al. [1]. Two levels of schemas are specified: (1) the symbolic structures that constitute the “web” of the subjective space and correspond to the schemas of the cognitive psychology; (2) the metaschemas that are the constructs of the therapist. The formation of the depressogenic schemas during the personal story is linked to the development of metaschemas of vulnerability, gratitude, and control. A therapeutic block is defined as a closing of the therapeutic space - that is, the intersubjective world constructed between the patient and the therapist. Such a block indicates the necessity of a global restructuration to release the memory from a depressogenic metaschema. In this case, the therapeutic strategy requires a technical adaptation to mobilize the mass of the subjective space. The therapeutic medium needs to resonate with the core of the depressogenic metaschema that is deeply buried in memory. The patient should also actively grasp the processes of the symbolic structuration of his/her subjective space. This conceptual framework allows us to account of the concept of insight as a spatial feeling of unification and widening that is associated to a restructuration. Thus, a cognitive therapy can be analyzed as a succession of phases that mirrors in reverse order the development of the depressogenic metaschemas. A case study confirms the relevance of this approach and we underline the crucial function of the therapist's creativity to overcome the therapeutic blocks. We insist also on the carefulness that is necessary to approach the early painful situations deeply buried in memory.