Tear function and ocular surface changes in keratoconus

Abstract

Purpose To describe the ocular surface disorder in patients with keratoconus. Design A prospective, case-controlled study. Participants Seventy-five eyes of 38 patients with keratoconus seen at Uludag University School of Medicine, Department of Ophthalmology, from March 2000 through April 2001, and 80 eyes of 40 normal control subjects were studied. Intervention The subjects underwent routine ophthalmic examinations, corneal sensitivity measurements, Schirmer test, tear film breakup time (BUT), fluorescein and rose bengal staining of the ocular surface, and conjunctival impression cytology. Main outcome measures Patients and control subjects were compared for corneal sensitivity, tear function, ocular surface staining parameters, goblet cell density, and squamous metaplasia grade. The relation of these parameters to the severity of keratoconus progression was also investigated. Results The mean corneal sensitivity was significantly lower in keratoconus patients compared with control subjects ( P < 0.001). The BUT values were also significantly lower in the keratoconus group. Patients with keratoconus had significantly higher fluorescein and rose bengal staining scores ( P < 0.001). Corneal sensitivity and tear function changes seemed to get worse with advanced stages of keratoconus. Impression cytology showed goblet cell loss and conjunctival squamous metaplasia, both of which again related to the extent of progression of keratoconus. Conclusions The ocular surface disease in keratoconus is characterized by disorder of tear quality, squamous metaplasia, and goblet cell loss, all of which seem to relate to the extent of keratoconus progression.