AIM: To study the effects of long-term use of clozapine on tear film stability and ocular surface tissue structure.METHODS: Case-control study was conducted on 45 patients(group 1)who were diagnosed with schizophrenia and treated with clozapine for 3.45±0.72a between March 2021 and December 2021. Another 45 healthy subjects(group 2)served as controls, whose demographic characteristics were similar to those of group 1. Patients' dry eye symptoms were investigated using OSDI questionnaire, tear secretion was detected by the Schirmer I test, ocular surface damage was assessed by the ocular surface staining score, and comprehensive ophthalmic examination was performed on all patients through LipiView ocular surface interferometer, ocular surface integrated analyzer, corneal confocal microscope and slit lamp photographic system.RESULTS: Slit-lamp photography showed diffuse grayish-white spot-like opacification in the corneal stroma of group 1, accompanied by brown star-like opacification in the center of the anterior capsule of the lens. OSDI scores were 38.00(31.50, 48.50)and 15.00(9.00, 19.50)in the two groups respectively. Schirmer test showed that the group 1 was 5.27±2.18mm/5min, while group 2 was 15.62±3.05mm/5min. Corneal fluorescein staining score: 4.00(2.50, 5.00)for group 1 and 1.00(0.00, 1.50)for group 2. The lissamine green staining score for the conjunctiva was 9.00(6.50, 10.00)and 3.00(2.00, 3.50)for the two groups, respectively. LipiView detected lipid layer thickness(LLT), suggesting that the results of group 1 and group 2 were similar, respectively 75.91±15.51 and 77.24±12.11nm; and the results were similar for the lid gland deficiency score, with 1.37±0.26 and 1.29±0.31 points, respectively. The mean tear meniscus height in group 1 was 0.13±0.06mm, which was lower than 0.23±0.04mm of group 2. Non-invasive breakup time(NIBUT)was 6.04±2.62 and 11.4±2.74s in group 1 and group 2 respectively. OSDI score, Schirmer Ⅰ test, ocular surface staining score, tear meniscus height and NIBUT were significantly different between the two groups(P<0.05). Confocal corneal microscopy suggested decreased corneal nerve fiber density with stromal layer inflammatory cell infiltration and pigmentation in group 1.CONCLUSION: The antipsychotic drug clozapine can induce dry eye with a range of ocular surface injuries such as corneal pigmentation, and patients who taking such drugs should be routinely examined by an ophthalmologist.