Professional and Linguistic Assessments Board (PLAB) Practice Exam

The condition characterized by night blindness and tunnel vision is retinitis pigmentosa. This is a hereditary degenerative disease that affects the retina's ability to respond to light.

In this condition, the photoreceptor cells (rods and cones) in the retina are progressively damaged. Rod cells, which are responsible for vision in low-light conditions, are often the first to be affected. This leads to difficulties seeing in dim light (night blindness). As the disease progresses, the peripheral vision decreases, which results in the characteristic "tunnel vision," where peripheral sight is lost while central vision may remain intact for a time.

Understanding retinitis pigmentosa is crucial since it illustrates the relationship between retinal structure and function, providing insights into how specific types of retinal dystrophies can result in particular visual impairments.