Abstract
Purpose: :
Dense congenital cataracts are surgically removed within a few months after birth in developed nations. In congenital cataract patients from the villages of India, the infants often do not undergo cataract surgery. They remain blind for several years due to lack of education, medical resources, and cost of surgery. Congenital blindness, if treated within a few months after birth, usually leads to near normal development of vision. According to a strict interpretation of the critical period hypothesis, plasticity in the brain requires early sensory stimulation. After age 6 or 7, the brain may not be able to regain functional vision. Our patients with congenital blindness are studied longitudinally after cataract surgery to test for recovery of visual acuity.
Methods: :
Patient WA is a 14 y/o female who presented with bilateral congenital cataracts. Visual acuity was measured by assessing light perception, hand motion, finger counting and Landolt C before and after cataract surgery. Face recognition and object recognition were also assessed after surgery. Cataract surgery was done on the left eye first followed after one to two weeks by the right eye. Corroborative data from 3 younger congenital cataract subjects will also be presented.
Results: :
Preoperatively, WA had light perception, hand motion recognition and was able to accurately counting fingers at 40 cm (right eye) and 10 cm (left eye). On consecutive days post-operatively after both cataract surgeries, WA counted fingers at 110 cm, 125 cm and 160 cm (right eye) and 170 cm, 170 cm and 180 cm (left eye). At post-op day 5, WA recognized 1 of 10 objects and 14 of 21 faces. Five days later, she recognized 4 of 10 objects and 17 of 21 faces.
Conclusions: :
WA showed gradual improvement during the week following surgery. The brain retains plasticity even after the ‘critical period’ for plasticity. Our long-term goal is to find whether there is an upper age limit for the treatment of late-stage blindness.
Keywords: cataract • visual development: infancy and childhood • low vision