CAS PS 222 Chapter Notes - Chapter 3: Photon, Opsin, Snellen Chart
10 Aug 2018
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Document Summary
Visual acuity is measure by a snellen chart. Accommodation: focusing on nearby objects by changing lens. Focused in front of the retina instead of on the retina. Hyperopia: far-sightedness shorter than normal eyeball, light focused behind the retina. Electromagnetic spectrum: energy is described by wavelength, spectrum ranges from short wavelength, visible spectrum: 400 nm to 700nm. Visual stimuli are picked up by rods and cones, the photoreceptors, info sent from optic nerve to brain (first the thalamus then to visual cortex, then to corpus collosum for high processing ) We see a reflection of light, not direct light; reflected light hits rods and cones. The cornea which is fixed accounts for 80$ of focusing. The lens which adjusts its shape for objects accounts of 20% of focusing. The rear of the eye where rods and cones convert light into neural impulses. Rods: located in the peripheral area of retina, 120 million, shape and black and white vision, lower light.
