To compare the pharmacokinetic behavior of azithromycin eye drops in the tear with the original azithromycin eye drops, and evaluate the release behavior of both in the eye.

There are 48 patients will divided into group A and group B randomly . subjects of Group A will given the first test drug, elution after the control drug; Subjects of Group B will given the first control drug, elution given to the test drug.

Inclusion Criteria:

• 18 to 65 years old, male or female;
• BMI in the range of 19 to 28;
• eyes corrected visual acuity should be ≥ 1.0, intraocular pressure, slit lamp and fundus examination were normal, tear secretion function is normal;
• Good compliance and voluntarily signed consent.

Exclusion Criteria:

• Have eye disease or systemic disease;
• physical examination, laboratory tests, ECG and chest X-ray examination abnormalities and has clinical significance;
• HBsAg, anti-HCV and HIV positive;
• those who used eye drops two weeks before the test and who used any dosage form of azithromycin;
• known to azithromycin or macrolide-related varieties of allergies or serious adverse reactions;
• need to wear contact lenses during the test;
• history of internal surgery or laser surgery history;
• participated in other drug clinical trials in the past three months;
• pregnant women and lactating women, or in the growth period without taking effective contraceptive measures, menstrual period women;
• mental illness or alcohol, history of drug abuse or inability to collaborate;
• Any other circumstances that the investigators consider are unfit to participate in this study.