Retinitis Pigmentosa. The only one I can think of right off is retinitis pigmentosa, and inherited degenerative disorder of the retina. There are probably other retinal disorders that can cause blindness, but most serious conditions you might think of such as cataract and glaucoma are treatable.
Usually genetic. Such conditions as retinitis pigmentosa, leber's hereditary optic rophy, tay-sachs disease, albinism, and others. We do not yet have answers to these conditions. That is why it is important to choose your parents very carefully.
See below. Glaucoma and macular degeneration.
Chlamydia. One example of this is trachoma, which is chlamydia in the eye. The chlamydia organism infects the eyelids, causing the eye lashes to turn in. This rubs against the cornea, leading to eventual blindness if not properly treated.