OCT is used for examining the macula and optic nerve head of the retina. It is a non-destructive, non-contact method that performs cross-sectional scanning of the ultrastructure on the retina. It primarily replaces ultrasound by using light waves to drive sound waves, conducting tomographic scans on biological tissues with low coherence, and displaying the results in forms of graphics and numbers. In this context, it is mainly used for diagnosing macular lesions and optic nerve head lesions. For cataract examinations, this method is generally not used; instead, ocular B-ultrasound and slit lamp microscopy are sufficient for detection.