Figure 1. Slit-lamp photos of different grades of pterygium and results of lymphatic vessel endothelial hyaluronan receptor 1 immunohistochemistry for the three grades of pterygia: A and D: Grade 1; B and E: Grade 2; C and E: Grade 3. Microvessels were dramatically increased in Grades 2 and 3 pterygia. Lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1) was positive for lymphatic vessels but negative for blood vessels. Red arrows point to lymphatic vessels and blue arrows, blood vessels (original magnification=100X).