differences of tear function and ocular surface findings in patients with atopic keratoconjunctivitis and vernal keratoconjunctivitis

The pathogenesis of the ocular surface disease in atopic keratoconjunctivitis (AKC) and vernal keratoconjunctivitis (VKC) has not been fully understood. We tried to clarify the differences in the ocular surface status in patients with AKC, VKC, and healthy control subjects. Twenty-four eyes of 12 AKC patients, 12 eyes of six VKC patients, and 20 eyes of 10 normal control subjects were studied. The subjects underwent corneal sensitivity measurements, Schirmer test, tear film break-up time (BUT), vital staining of the ocular surface, conjunctival impression and brush cytology. Impression cytology samples underwent periodic acid Schiff staining for goblet cell density, squamous metaplasia grading, and immunohistochemical staining for MUC1, 2, 4, and 5AC. Brush cytology specimens underwent staining for inflammatory cell counting and Real Time PCR for MUC1, 2, 4, and 5AC mRNA expression. The mean BUT, corneal sensitivity, and conjunctival goblet cell density values in AKC patients were significantly lower compared with VKC patients and control subjects. The squamous metaplasia grades in eyes with AKC were significantly higher compared to eyes with VKC and controls. The inflammatory cell response in brush cytology specimens was different between patients with AKC and VKC. Eyes with AKC showed significantly higher MUC1, 2 and 4 and lower MUC5AC mRNA expression compared to eyes with VKC. Differences of the infiltrates, higher level of tear instability, lower corneal sensitivity, up-regulation of MUC1, 2, and 4, and down regulation of MUC5AC were important differential features of the ocular surface disease in AKC compared with VKC.