Blindness has many causes. For instance, cataracts occur when the lens loses its transparency. If untreated, cataracts can lead to blindness. Blindness can also result from a genetic defect $($RPE$65$ deficiency$)$ that causes the rods and cones to die. A new gene therapy causes the connecting neurons in the retina to convert into light$-$sensing cells. Which of these forms of blindness could be treated by this therapy? Follow the procedure in the One Step at a Time box to answer this question, and demonstrate your understanding of the steps in the visual pathway.

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