Outcome measures
tear-film
Pooled basal tears from the eye of the subject without previous topical anesthesia were collected by inserting dry sharp-tip microsponges (Alcon Lab. Inc., Fort Worth, TX) into the inferior conjunctival fornix for 30 s, followed by storage at − 80 °C for further analysis [The ocular surface assessment comprised tear-film breakup time (TBUT), ocular staining, and ocular surface disease index (OSDI). TBUT and corneal staining were observed using a slit- lamp microscope with a cobalt filter after corneal fluorescein staining. The test result is the time from a complete blink until the first signs of a break in the tear film, which was repeated thrice and averaged. Corneal staining was performed using the Oxford grading scale as reference [