Open angle usually includes open inner angle and open outer angle. It is to correct and enlarge the inner and outer corners of the eyes by surgery, so as to remove the epicanthus, extend the horizontal length of the eye fissure and achieve the effect of magnifying the eyes. To correct microphthalmia, the medial canthus and lateral canthus must be enlarged, and if necessary, the medial canthus ligament fixation is needed to correct the widening of orbital distance, or ptosis correction is needed. Congenital microphthalmia is characterized by narrow palpebral fissure and serious epicanthus, which is often accompanied by widening epicanthus distance and ptosis. The operation needs to be carried out by stages.

Opening the corner of the eye is used to correct small eyes. Congenital microphthalmia is caused by blepharoptosis and serious epicanthus, often accompanied by widening canthus spacing and ptosis, and the operation needs to be carried out by stages. Simple microphthalmia can be corrected by lateral canthoplasty and Mohs operation at the same time. If accompanied by ptosis, ptosis can be corrected after 6 ~ 12 months.