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PurposeConjunctiva-associated lymphoid tissue (CALT) is thought to play a key role in initiating ocular surface related immune responses. This study was planned to get first profound insights into the function of CALT related to development, cellular dynamics and morphological alteration using a novel mouse model.MethodsExpression and morphology of CALT were investigated using BALB/c mice kept under different housing conditions, after topical antigen-stimulation and following lymphadenectomy and splenectomy. Particles and bacteria were applied topically to study antigen-transport. Intravital visualization was performed using two-photon microscopy.ResultsPostnatal development and ultrastructure of CALT in the mouse is similar to humans. Topical antigen-challenge significantly alters CALT expression. Bacterial translocation is demonstrated via lymphoepithelium whereas cellular velocities within follicles were approximately 8 µm/min.ConclusionsCALT in the mouse is an immunological interface of the ocular surface, featuring dynamic processes such as morphological plasticity, particle/bacteria transport and cellular migration.

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Immunologic graft rejection is the main complication after corneal transplant into pathologically prevascularized so‐called high‐risk eyes. The aim of this study was to evaluate whether ultraviolet (UV) light crosslinking can regress pathologic corneal blood and lymphatic vessels and thereby improve subsequent graft survival. Using the murine model of suture‐induced corneal neovascularization, we found that corneal crosslinking with UVA light and riboflavin regressed both preexisting blood and lymphatic vessels significantly via induction of apoptosis in vascular endothelial cells. In addition, macrophages and CD45+ cell counts were significantly reduced. Consistently, corneal crosslinking reduced keratocyte density and corneal thickness without affecting corneal nonvascular endothelial cells, iris, and lens depending on the crosslinking duration. Furthermore, using the murine model of corneal transplant, long‐term graft survival was significantly promoted (P < .05) and CD4+ CD25+FoxP3+ T regulatory cells were upregulated (P < .01) in high‐risk eyes preoperatively treated with crosslinking. Our results suggest UV light crosslinking as a novel method to regress both pathologic corneal blood and lymphatic vessels and to reduce CD45+ inflammatory cells. Furthermore, this study demonstrates for the first time that preoperative corneal crosslinking in prevascularized high‐risk eyes can significantly improve subsequent graft survival and may become a promising novel therapy in the clinic.

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