Purpose: To evaluate the presence of snake-like chromatin (SLC) cell protein (related to eye rubbing) in patients with keratoconus or allergic conjunctivitis and in controls.
Materials and methods: Prospective experimental study included 193 eyes of 193 patients between January 2015 and July 2016; 86 had a diagnosis of new keratoconus, 88 were controls, and 19 had a diagnosis of allergic conjunctivitis and underwent impression cytology (IC). Specimens were stained with a combination of periodic acid-Schiff (PAS) and Gill\'s modified papanicolaou stains to detect the presence of SLC cell protein and morphological characterization of dry eye and allergic conjunctivitis. A questionnaire regarding eye-rubbing habits was administered.
Results: Of the patients, 56.97% (49/86 eyes) in the keratoconus group, 84.21% (16/19 eyes) in the allergy group, and 10.11% (9/89 eyes) in the control group reported rubbing their eyes. The SLC was detected in 24.41% (21/86), 73.68% (14/19), and 3.37% (3/89) of the keratoconus, allergy, and control groups respectively, who reported rubbing their eyes. In contrast, SLC was detected in 2.32% (2/86), 0% (0/19), and 1.12% (1/89) of the keratoconus, allergy, and control groups respectively, who reported not rubbing their eyes.
Conclusion: The presence of SLC cells was higher in keratoconus, allergy, and control group patients who reported rubbing their eyes. Keratoconus is independent of eye-rubbing habits and the presence of SLC cells.