Glaucoma is an increase in pressure inside the eye that damages the optic nerve
. Macular degeneration is a progressive deterioration of the most sensitive part of the retina. It causes loss of central vision. Trachoma happens when a contagious microorganism known as Chlamydia trachomatis causes inflammation in the eye. The ophthalmologist determines vision impairments three different ways. One is through reading off of an eye chart known as visual acuity test. The second test they do is measure your side vision. The last test to determine visual impairment is a procedure that checks the fluid pressure inside the eye. If a visual impairment is diagnosed to be severe then guide dogs and Braille are used in assisting people with for the vision loss.