What unique physical characteristic do Bengal cats with PRA-b exhibit?

Bengal cats with PRA-b (Progressive Retinal Atrophy type b) exhibit excessively enlarged pupils as a unique physical characteristic. This condition leads to changes in the retina, which can hinder the normal functioning of the eye. One of the responses of the eye to reduced light sensitivity, which is a result of retinal degeneration, is the dilation of the pupils. Enlarged pupils can occur as the eye attempts to allow more light to enter in an effort to compensate for the deteriorating retinal function.

While the other options reference various ocular or visual impairments, they do not accurately describe the specific characteristic linked to PRA-b in Bengals. Reduced vision acuity relates to overall vision quality but does not pinpoint the specific physical change in the eyes, while total color blindness and irregular eye shape describe different conditions not inherently associated with PRA-b. Thus, excessively enlarged pupils are the key observable feature in affected Bengal cats.