As in other diseases caused by nascent lymphatic vessels, the VEGF-C/VEGFR-3 pathway also plays a vital role in lymphangiogenesis in pterygium (Fukuhara et al., 2013), and ultraviolet light irradiation upregulates the expression of tumor necrosis factor α (TNF-α), which mediates an increase in the expression of VEGF-C in pterygium and promotes lymphangiogenesis (Dong et al., 2016). This evidence concerns the gene TNF and pterygium.