Generally speaking, a large eye and a small eye may be physiological phenomenon or ptosis, congenital glaucoma and other pathological factors. 1. Physiological phenomenon: most people do not have two absolutely equal eyes, this situation is mostly due to congenital development or single and double eyelids, which is a normal physiological phenomenon, if it is not particularly obvious without special treatment, if it is too obvious, you can consider eye surgery to correct it. 2. Ptosis: Ptosis is a common ophthalmologic disease, usually categorized into congenital ptosis and acquired ptosis, because of the ptosis, resulting in the patient’s eyes look smaller. 3. Congenital glaucoma: In children with congenital glaucoma, elevated intraocular pressure can lead to an increase in the size of the affected eye, resulting in the appearance of one eye being large and the other small. It is recommended that patients with different sizes of eyes should consult a doctor to evaluate their condition and follow the doctor’s instructions for treatment.