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Visual System Introduction
Visual impairment results from a deviation from normal in one or more of the three primary functions of the eye.
1. Near and far acuity
2. Visual fields
3. Motility (presence of diplopia)
The primary functions are not equally important, but perfect vision requires the coordination of all three.
Second and subordinate functions are:
1. Color vision
2. Light/dark adaptation
3. Accommodation
4. Iridoplegia
5. Entropion
6. Ectropion
7. Epiphora
8. Lagophthalmos
9. Scarring (globe)
If these secondary impairments are present and do not contribute to the impairment of primary functions, they must be evaluated independently under the appropriate body system and the respective impairments added to the impairment of the visual system.Tertiary impairments must be calculated as contributing an additional 5 to 10% impairment to the involved eye. Such are:
1. Vitreous opacities
2. Nonreactive pupil
3. Light-scattering abnormalities
Skeletal or soft-tissue abnormalities that do not alter ocular function should be considered individually and may contribute up to 10% of whole-person impairment.
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