How would the absence of the enzyme photodiesterase (PDE)affect vision in the vertebrate eye?

Question

Quizplus · Accepted Answer

The absence of the enzyme photodiesterase (PDE) would prevent the breakdown of cGMP in the photoreceptor cells. As a result, the cGMP-gated sodium channels in the outer segments of rod cells would remain open, continuously depolarizing these cells and releasing glutamate at the synapses with bipolar cells. This would inhibit the activity of ON-center bipolar cells and excite OFF-center bipolar cells, leading to a decrease in visual sensitivity and a loss of contrast between light and dark areas. The brain would not detect light absorbed by the rod cells, leading to impaired vision in dim light. The absence of PDE would not affect the differentiation of opsins in cones or the lens adjustment for focusing.

How Would the Absence of the Enzyme Photodiesterase (PDE)affect Vision