Clinical examination of a patient shows ring scotoma. It is seen in the following condition:

Annular or ring-shaped scotoma is a typical feature of retinitis pigmentosa which corresponds to the degenerated equatorial zone of retina. As the disease progresses, scotoma increases anteriorly and posteriorly and ultimately only central vision is left (tubular vision). Eventually even this is also lost and the patient becomes blind. Ref: Comprehensive Ophthalmology by AK Khurana, 4th edition, Page 268-269.