The blurring of the black-white eye junction site at the pupil margin is usually due to the following causes: 1. caused by senile ring, which is not a disease but a physiological phenomenon. as we age, the corneal tissue ages and lipid deposits appear at the corneal margin near the black-white eye junction site, thus forming a grayish-white ring structure that makes the corneal margin blurred. 2. caused by limbal corneal degeneration This is an autoimmune disease that causes a ring-shaped ulcerated foci with a white color near the border of the black and white eyes, thus blurring the edge. 3. The corneal limbus type of allergic conjunctivitis, caused by spring cataract conjunctivitis, causes tissue edema at the corneal limbus, thus blurring the border. 4. adhesions and thus deformation, resulting in blurred margins.