The cause of the low-vision can be often considered as congenital or linked to some important illnesses of the eye. If the low-vision for the young and very young people is linked to a congenital condition; for the adults, the optical illnesses are the first cause of the reduction of the eyesight.
The low vision patients can belong, according to the symptoms of their optical handicap, to four groups: people with central scotomas (for example senile speckled degeneration), people with serious difficulties in the control of the eyes movement (for example nystagmus), people with limited peripheral vision, but with partially conserved central vision (for example glaucoma), people with secondary amblyopia with refracted defects and diabetic retina illness.
The most frequent illnesses that can be the cause of the low vision are the senile speckled degeneration, the diabetes, the glaucoma, the inoperable cataract and the traumas.
The patients who have a speckled degeneration and glaucoma should periodically control their optical field of view with the Amsler test.