cataract a doughnut-shaped remnant of lens behind the pupil, occurring after cataract surgery or secondary to trauma as a result of contact between the anterior capsule and the posterior capsule, which traps varying amounts of lens substance peripherally. a developmental cataract in which the primary lens cells fail to develop or are absorbed during intrauterine disease. Later developing subcapsular cells, having no fetal nucleus around which to grow, form doughnut-shaped ring cataracts.
