PDE6C and glycogen storage disease VI: Ophthalmic investigations revealed that five of the eight participants had high myopia, with refractive errors of −10.25 D/−11.00 D, −10.50 D/−11.00 D, −14.00 D/−14.50 D, −11.00 D/−12.00 D, and −9.00 D/−9.75 D. Alongside the association with high myopia, 4 of the patients with PDE6C-associated achromatopsia were found to have outer retinal atrophy, which is a significant finding as PDE6C disease has been associated with progressive cone and cone-rod dystrophies [51].