Atopic ocular surface disease: Implications on tear function and ocular surface mucins

Purpose: To describe tear function, mucin alterations, and ocular surface disorder in patients with atopic diseases. Methods: Subjects underwent corneal sensitivity measurements, Schirmer test, tear film break-up time (BUT) assay, and fluorescein and rose Bengal staining of the ocular surface. Conjunctival impression cytology and brush cytology were also conducted. Impression cytology samples underwent PAS and immunohistochemical staining for MUC5AC. Brush cytology specimens underwent evaluation for inflammatory cell expression and RT-PCR for MUC5AC mRNA expression. Differences related to tear function and ocular surface examination parameters among patients with and without corneal ulceration and healthy control subjects were studied. Results: Mean corneal sensitivity and BUT values were significantly lower in atopic patients with corneal ulcers compared with patients without ulcers and controls (P < 0.001). Brush cytology specimens from patients with corneal ulcers revealed significantly higher expression of inflammatory cells compared with patients without ulcers and controls (P < 0.001). Impression cytology samples from eyes with corneal ulcers showed significant squamous metaplasia and reduction of goblet cell density compared with eyes without ulcers and control subjects. Specimens from eyes with corneal ulcers showed PAS (+) mucin pick up and did not stain positive for MUC5AC. MUC5AC mRNA expression was significantly lower in eyes with corneal ulcers compared with in eyes without ulcers and control subjects. Conclusions: Ocular surface inflammation, tear film instability, and decreased conjunctival MUC5AC mRNA expression are important in the pathogenesis of noninfectious corneal shield ulcers in atopic ocular surface disease.