When the central vision is affected, people have difficultiy recognizing faces and seeing small details such as reading letters. The central sight is affected by for example age related macular degeneration. An estimated 2% of untreatable blindness in the elderly is caused by macular degeneration.
There are also vision disorders (for example glaucoma) where people have tunnel vision. People can then still read but not walk without help because they cannot orient themselves in a space. The most common causes of untreatable blindness in the elderly in Zambia are; glaucoma (damage to the optic nerve by an eye pressure that is too high) 30%, corneal injury (trachoma or trauma) 15%.