Physiology of the Eye. 1. Refraction The bending of light as it travels from less dense medium into a more dense medium

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Physiology of the Eye

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1. Refraction

The bending of light as it travels from less dense medium into a more dense medium.



2. Divergence

Light rays spread out; Occurs with concave lenses



3. Convergence

Light rays come together; Occurs with convex lenses



4. Human Eye

Lens is Biconvex



5. Image on the retina

Upside down & reversed (inverted)



6. AccommodationThe ability of the lens to change its shape; helps to achieve sharp focus at close range (<20 ft)



7. Stereoscopic vision

The ability to see objects in three dimensions; important when driving, parking, climbing stairs, etc.



8. Peripheral vision

The ability to see to the sides without moving the head

The parts of the retina associated with peripheral vision do not contain cones, so sharp vision & color vision are not possible



9. Photoreceptor responsible for vision in dim light

Rods



10. Night blindness

Vitamin A deficiency can contribute to night blindness because it is responsible for converting retineene into rhodopsin; without enough Vitamin A, there is a slow return of dark adaptation





11. Bright light causes pain

Intense light bleaches rhodopsin & eyes need time to recover & become light adapted





12. Photoreceptor for fine focus & color vision

Cones



13. 3 primary colors of vision

Red

Green

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14. True

• There are 3 types of cone receptors, each of which contains its own photochemical sensitive to one of the three wavelengths of primary colors.



15. True

• Equal stimulation of the 3 types of cones is perceived as white light.



16. Purkinje shift

Shift from light adaptation (cone reception) to dark adaptation (rod reception) at dusk & vice versa



17. Afterimages+ Afterimages: carryover of visual impressions is exactly the same as the original stimulus pattern

- Afterimages: carryover of visual impressions appear in a complementary color of the original

18. Visual AcuityThe sharpness or degree of detail the eye can see

Influenced by: brightness or intensity of light, size of object, color of object, and retinal area on which the image of the object falls

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Physiology of the Eye. 1. Refraction The bending of light as it travels from less dense medium into a more dense medium