The upper eyelashes in vernal keratoconjunctivitis (VKC) patients have been reported to be longer than in healthy age- and gender-matched subjects. Eyelash length positively correlated to the severity of the disease and negatively to the employment of cyclosporine eye drops, suggesting that specific humoral factors could be involved in both ocular inflammation and elongation of the eyelashes. The aim of the present study is to evaluate a possible relationship between eyelash length and the duration of topical cyclosporine treatment. The length of the upper eyelashes of 34 VKC patients never treated with topical cyclosporine (Cyc-NT) was matched with that of 58 VKC patients treated with cyclosporine (Cyc-T). The latter group was divided into three subgroups, depending on the duration of therapy: 1-6 months (group 1; 21 subjects) , 7-12 months (group 2; 19 subjects), greater than 12 months (group 3; 19 subjects). Cyc-NT patients eyelashes were significantly longer than those of VKC patients treated for 1-6 months (group 1). No significant difference was found between Cyc-NT and Cyc-T patients in group 2 and group 3. The differences between Cyc-T patients and group 1 and 2, group 2 and 3, and group 1 and 3 were not statistically significant. The eyelash shortening observed seems directly related to the rapid improvement of ocular symptoms induced by the treatment. A receptor down-regulation by mediators of ocular inflammation may explain this data, although different cytokines, hormones or other humoral mediators could be expressed on the ocular surface at different stages of the disease, mainly in periods of rapid change of the clinical course.