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Identifier

000348238

Title

Εξωαγγειακές προσεγγίσεις για τη λύση του θρόμβου σε απόφραξη φλέβας του αμφιβληστροειδή : πειραματική και κλινική μελέτη

Author

Χριστοδουλάκης, Εμμανουήλ Β

Thesis advisor

Τσιλιμπάρης, Μιλτιάδης

Reviewer

Παλλήκαρης, Ιωάννης
Κατσαμούρης, Αστέριος
Βάρδας, Παναγιώτης
Αντιμησιάρη, Σοφία
Βελεγράκης, Γεώργιος
Σιγανός, Χαράλαμπος

Abstract

Venous occlusion is one of the major blood vessel diseases of the eye, with thrombotic episodes to be the second in order of frequency of vascular diseases of the retina, after diabetic retinopathy. Under current therapeutic practice there is no effective treatment for central or branch retinal vein occlusion. AIM This research seeks thrombus dissolution with extravascular – nearby the occluded vessel, administration of recombinant tissue plasminogen activator (rt-PA), in a clinical and experimental case series of retinal vein thrombosis. MATERIAL – METHODS - RESULTS Clinical Study 3 patients with recent central retinal vein occlusion and 3 patients with branch vein occlusion included in this case series. Technique: all patients underwent vitrectomy, fluid – air exchange and finally intravitreal injection of 50 μg t-PA / 0,5 ml. No improvement of the expected natural course of the disease, was noticed in these cases. Although no intra-operative complications were noticed, some safety concerns were arisen about the t-PA intravitreal injections. Experimental Study We developed an experimental rabbit model of superficial ear vein thrombosis with the use of photodynamic therapy (phthalocyanine or verteporfin and proprietary diode laser). We tried to perform thrombus lysis with subcutaneous injection of various concentrations of thrombolytic agent, nearby the occluded vessel. Clinical observation (retro-illumination) and histology results revealed thrombus presence, despite therapy. We developed an experimental rabbit model of photodynamic retinal vein thrombosis and observed its natural course; we injected intravitreally various concentrations of tPA. Clinical examination (fundoscopy) and histology revealed no improvement, and immuno-histochemistry was negative for tPA presence inside the retina or the vascular lumen. Afterwards, we entrapped tPA in liposomes in order to improve its permeability through inner limited membrane and retinal vessel wall, in various techniques, sizes and concentrations. We injected intravitreally this modified drug in the rabbit eye thrombosis model (see above), but no improvement of thrombus course was noticed (fundoscopy, fluorescein angiography). Immuno-histochemistry was negative for liposomal-tPA presence inside the vascular lumen. CONCLUSIONS This clinical study could not show benefit to these 6 patients (3 with central vein occlusion, and 3 with branch vein occlusion), who underwent vitrectomy, fluid – air exchange and intravitreal injection of rt-PA. Experimental research shown no benefit for thrombus lysis, after intravitreal injection rt-PA and rt-PA in liposomes; further more shown that both forms of the drug (with/without liposomes) could not penetrate the vascular wall and recognized into the vessel lumen, following extravascular (intravitreal) administration.

Language

Greek

Subject

Eye Diseases

Ophthalmology retina

Retina

Retinal Vessels

Αμφιβληστροειδής

Αμφιβληστροειδούς αγγεία

Οφθαλμικά νοσήματα

Issue date

2008-04-03