Percentage of degranulated mast cells in vernal conjunctivitis and giant papillary conjunctivitis associated with contact-lens wear.

Using light microscopy, we determined the percentage of granulated and degranulated mast cells in sections of tissue from ten persons with vernal conjunctivitis, ten with giant papillary conjunctivitis associated with contact-lens wear, and ten normal subjects. Tissues from both groups of patients had a significantly higher percentage of degranulated mast cells (greater than 80%) than did normal tissue (less than 25%). The fully granulated mast cells in the three groups did not appear morphologically different, nor did the degranulated mast cells in the three groups. The percentage of degranulated mast cells in vernal conjunctivitis did not differ significantly from that in giant papillary conjunctivitis associated with contact-lens wear. The histamine level in the tears of patients with vernal conjunctivitis, which is four times higher than that of normal subjects and that of patients with giant papillary conjunctivitis associated with contact-lens wear, cannot be explained by a difference in the percentage of degranulated cells detectable by light microscopy.