OPTN and glaucoma: Since transplants are challenging to perform and must be done before knowing whether the transplanted cells will express the transgenes, and the intermediates are short-lived, these studies were conducted mainly for axons expressing the glaucoma-associated M98K OPTN mutation, as these animals had the greatest number of stopped OPTN in both F0 and F1 analyses (Figure 2E, Figure 2—figure supplement 1A).