After the first 1-month treatment period, patients who had conventional PFAT treatment were switched to AS treatment and the patients who had AS treatment in the first 1-month treatment period were switched to conventional PFAT treat- ment in the second 1-month treatment period, according to the study's crossover nature. The examining ophthalmologist (Uğur Yılmaz) that performed tear function and ocular surface evaluations was blinded to the type of eye drops given to each patient. In addition, the patients were blinded to which treatment they were receiving.