Mountain biking is associated with a lot of falls. I do all my bike
riding in spinning classes or an exercise
Most surgeons want you avoid sports like boxing, wrestlying, insiste on eye protection for racquet sports, avoid violent head whipping like roller coasters, amusement type rides.
Remember most retinal detachments are NOT due to trauma but due the vitreous pulling on the retina, or thinned areas of the retina from high myopia, lattice or post cataract surgery.