Study design
DRY EYE, EYE, DRY EYE
A 6-month prospective, non-randomized, longitudinal cohort study was conducted at the Refractive Surgery Center of the Eye Hospital at the First Affiliated Hospital of Harbin Medical University. The study was conducted in accordance with the tenets of the Declaration of Helsinki and approved by the First Affiliated Hospital of Harbin Medical University Ethics Committee. Dry eye indices and VIP were measured before surgery and 1 day, 1 week, and 1 month post-surgery and recorded as 1, 2, 3, and 4 in chronological order. Some data were not measured 1 day after surgery to minimize the risk of damage to operated eyes, which could not affect statistical results. The severity of dry eye and increase in VIP concentration were recorded as 3 − 1, 1–3, 4 − 1, and 1–4, which indicates the difference between the values at two time points; 1 represents pre-operation, 3 represents 1 week post operation, and 4 represents 1 month post operation.