Ciliary Body Lymphangiogenesis

With interest we read the recent article by Khan et al investigating the ciliary body for the presence of peritumoral lymphatic vessels in uveal melanoma with and without extraocular extension. This study confirms previous findings by Birke et al on the expression of podoplanin and other lymphatic endothelial cell markers in the human anterior eye segment. Podoplanin immunopositivity was shown to be present in all trabecular cells, the cells of the trabeculum ciliare, and the anterior-most perimysium cells of the ciliary muscle (, available at http://aaojournal.org). The antibody against the human lymphatic vascular endothelial-specific hyaluronic acid receptor (LYVE)-1 stained single dendritiform cells in the ciliary body, the trabecular meshwork, and the iris. The antibodies against the vascular endothelial growth factor (VEGF) receptor (VEGFR)-3 and the product of the prospero-related homebox gene-1 stained no structures in the anterior segment. Therefore, Birke et al concluded, concordant with the literature, that the inner eye is physiologically devoid of “true” lymphatic vessels.