Comparative evaluation of lymphatic vessels in primary versus recurrent pterygium.

PURPOSE: To compare lymphangiogenesis in primary versus recurrent pterygium.

METHODS

Tissues from 88 excised primary and 34 recurrent pterygia were evaluated, and tissues from 7 nasal epibulbar conjunctivae segments were used as controls. The lymph-vascular area (LVA), lymph-microvascular density (LMD), and lymph-vascular luminal diameter (LVL) were examined and compared between the primary and recurrent pterygia. In addition, the expression of VEGF-A and VEGF-C in the primary and recurrent pterygia were determined by ELISA and real-time PCR. The relationships between the mRNA level and LVA, LMD, and LVL were clarified.

RESULTS

Although there was no significant difference in quantification of LVL between primary and recurrent pterygia, the quantification of LVA and LMD in recurrent pterygia dramatically increased in comparison with primary pterygia (both P-values <0.01). Compared with primary pterygia, the VEGF-A and VEGF-C mRNA levels were up-regulated significantly in recurrent pterygia (both P-values <0.05). There was a significant relationship between VEGF-C mRNA and LVA, LMD, and LVL, while VEGF-A mRNA was only closely correlated with LMD in recurrent pterygia.

CONCLUSIONS

Lymphangiogenesis develops in recurrent pterygium, for which transient up-regulation of VEGF-C might be responsible.