Low vision is defined as irreversible visual impairment caused by eye disease which cannot be corrected or improved with regular eyeglasses, contact lenses, medicine or surgery.
It also includes loss of peripheral field of vision, reduced contrast sensitivity, increased glare or difficulty with daily activity.
1.Structural abnormality or abnormal development of external or internal structures of
- Corneal opacities
- Congenital cataract especially long standing untreated ones
- Lack of Iris (pupil) –Aniridia
- Nystagmus –Constant, involuntary movement of eyeballs.
- Retinal dystrophies
2. Genetic disorders:
- Retinitis pigmentosa (black Pigments/ white pigments all over retina)
- Oculocutaneous albinism (red eyes with extremely fair skin)
- Stargardts disease (mottled retina with flecs)
- Congenital glaucoma: Huge Bull eyes
II Age Related:
- Metabolic namely Advanced Diabetic Retinopathy
- Age –Related macular Degeneration
1) Ocular injuries
2) Brain injuries
Uncorrected refractive errors, squints leading to amblyopia
IV Cerebral Visual Impairment:
It is defined as vision loss resulting from damage to neural pathways in absence of any eye disease.
- Birth hypoxia or hypoxia in womb
- Genetic disorders associated with multiple disabilities
- Optic atrophy
- Maternal intake of drugs
- Congenital neurological malformations
- Congenital structural malformations like
- Cardiac / Respiratory arrest C Common:
- CNS infections
Since there is no treatment possible for these disorders; so as to help the individuals restore functional ability and improve the quality of life & independence in an individual; visual rehabilitation comes in the picture.