As William grew older, Ethan and Elizabeth found that their lives revolved around their young son. They both doted on him and took pride in every milestone he achieved. They watched as William began to crawl, then walk, and finally speak his first words. Ethan was especially delighted when William began to use his senses more to understand and experience the world around him.

But with each new discovery, Ethan also felt the ache of his blindness more deeply. He could not take in the colors of the sky or watch William’s smile light up with wonder as he saw something new. Ethan longed to experience these things himself, but...