Development of ex vivo organ culture models to mimic human corneal scarring

PURPOSE: To develop ex vivo organ culture models of human corneal scarring suitable for pharmacological testing and the study of the molecular mechanisms leading to corneal haze after laser surgery or wounding. METHODS: Corneas from human donors were cultured ex vivo for 30 days, either at the air-liquid interface (AL) or immersed (IM) in the culture medium. Histological features and immunofluorescence for fibronectin, tenascin C, thrombospondin-1, and α-smooth muscle actin were graded from 0 to 3 for control corneas and for corneas wounded with an excimer laser. The effects of adding 10 ng/ml transforming growth factor-β1 (TGF-β1) to the culture medium and of prior complete removal of the epithelium and limbus, thus preventing reepithelialization, were also analyzed on wounded corneas. Collagen III expression was detected with real-time PCR. RESULTS: Wounding alone was sufficient to induce keratocyte activation and stromal disorganization, but it was only in the presence of added TGF-β1 that intense staining for fibronectin and tenascin C was found in the AL and IM models (as well as thrombospondin-1 in the AL model) and that α-smooth muscle actin became detectable. The scar-like appearance of the corneas was exacerbated when TGF-β1 was added and reepithelialization was prevented, resulting in the majority of corneas becoming opaque and marked upregulation of collagen III. CONCLUSIONS: THE MAIN FEATURES OF CORNEAL SCARRING WERE REPRODUCED IN THESE TWO COMPLEMENTARY MODELS: the AL model preserved differentiation of the epithelium and permits the topical application of active molecules, while the IM model ensures better perfusion by soluble compounds

Blanc périveinulaire isolé révélant une intolérance à l’hypoxie : à propos d’un cas

International audienc

Incidence of Cystoid Macular Edema After Descemet Membrane Endothelial Keratoplasty

International audienc

Migration en chambre antérieure de l’implant intravitréen de dexaméthasone Ozurdex® chez le pseudophake : à propos de trois cas

Introduction. - Intravitreal implantation of Ozurdex (R) (Allergan Inc., Irvine, CA, USA) is being used widely for the treatment of macular edema secondary to retinal vein occlusion and in the setting of non-infectious posterior uveitis. We describe a complication little reported in the literature until now: migration of the dexamethasone implant into the anterior chamber. Patients and methods. - We report three cases of migration in two pseudophakic patients with iris claw lenses (on the anterior and posterior aspects of the iris) and in one pseudophakic patient with a posterior chamber IOL and zonular rupture. Discussion. - The risk of anterior chamber migration of the Ozurdex (R) implant is increased in cases of prior vitrectomy (three cases), prone positioning and dilation of the pupil (mydriasis). Clinical tolerability of the implant in the anterior chamber is poor in all cases, with diffuse corneal edema. Endothelial cell loss occurs, as demonstrated by specular microscopy performed in two of our patients. Removal or repositioning of the Ozurdex (R) implant into the posterior segment must be performed without delay because of the risk of endothelial toxicity. Conclusion. - Patients without perfect zonular/posterior capsular integrity present a high risk of anterior chamber migration of the Ozurdex (R) implant. In such cases, anti-VEGF therapies should be discussed as an alternative. (C) 2012 Elsevier Masson SAS. All rights reserved