This study intends to use a hospital-based multi-center cross-sectional study to understand the disease composition of "red-eye" patients in Chinese ophthalmology clinics. This study will provide important clinical diagnosis and treatment data for common eye diseases in China with "red eye" as the main performance.

Red eye is a common sign of eye diseases. Eye diseases such as ocular surface inflammation, glaucoma, and uveitis can be expressed as red eyes. The disease with red eye as the main complaint is the most common condition that clinicians need to identify. It is not uncommon to be misdiagnosed and missed clinically. The collection and analysis of the disease composition of the "red eye" in Chinese ophthalmology clinics will help to understand the current status of "red eye" related diseases and provide a systematic and comprehensive clinical basis for the differential diagnosis of red eye.

Inclusion Criteria:

• Confirmation of signs under the slit lamp is red eye

Exclusion Criteria:

• The investigator believes that there are any unsuitable reasons for participating in the trial.

Patients with "red eye".