Abstract: Objective To compare the chronotype of young dry eye patients and healthy controls, and to evaluate the relationship between different chronotypes and dry eye symptoms and signs. Design Case-control study.  Participants A total of 400 young dry eye patients who visited Beijing Tongren Hospital, and 200 age- and gender-matched healthy controls were included. One eye was randomly selected for each patient for the analysis.  Methods Dry eye-related indicators were collected from all participants, and differences in chronotypes between the dry eye group and the control group as well as differences in dry eye symptoms and signs among patients with different chronotypes in the dry eye group were compared. Main Outcome Measures Ocular surface disease index (OSDI), fluorescein breakup time (FBUT), Schirmer I Test (SIt), corneal fluorescein staining (CFS), and meibomian gland loss score. The Chinese version of the morningness-eveningness questionnaire-5 (MEQ-5) was used to assess participants' circadian rhythm types.  Results In the dry eye group, the predominant chronotypes were definite evening type and moderate evening type, whereas in the control group, definite morning type and moderate morning type were predominant, with statistically significant differences between the two groups (Z=66.36, P<0.001). Among dry eye patients with different chronotypes, the OSDI score of evening type patients (42.0) was significantly higher than that of neutral  (32.0) and morning type patients (23.0) (H=70.33, P＜0.001). The SIt in evening type patients  (3.0 mm) was significantly lower than in neutral (5.0 mm) and morning type patients (6.0 mm) (H=81.76, P＜0.001); the proportion of moderate to severe meibomian gland loss was significantly higher in evening type patients than in neutral and morning type patients (H=10.80, P=0.029). Conclusion Compared with healthy controls, young dry eye patients exhibit a trend toward evening-type chronotype. Within the dry eye patient group, evening-type patients had more severe dry eye symptoms and signs compared to morning-type patients. (Ophthalmol CHN, 2025, 34: 202-206)

Key words: young subjects, dry eye, chronotype