What disease can make you go blind?

Many. The most common causes of blindness around the world include cataracts, macular degeneration, and glaucoma. Of those 3, cataracts are highly treatable. Improvements in vision with macular generation is largely limited to about 15% of cases which are the 'wet' form. Glaucoma damage is preventable but not restored with treatment. Parasitic eye disease (eg river blindness) occurs in the 3rd world.