NEUR30003 Lecture Notes - Lecture 9: Retinitis Pigmentosa, Tunnel Vision, Peripheral Vision
13 Aug 2020
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Lecture 3. 2 the visual system 1 (the retina) 45 year old: trouble seeing at night, trips over her children"s toys, has had many car accidents over the last 2 years, can read ok. Losing her rods -> can"t see at night. 3 layers: cornea -> sclera: outer layer for strength and protection, middle = nutrition layer, retina - inner = neuronal layer (5/6th of the eyeball) What fundamentally limits visual acuity: neural factors, optical factors (how well can light go through the eye to stimulate the neurons in the retina) Pupil size: bright light -> small pupil -> better vision. Clarity of optical media (structures that light passes through: cataracts, corneal opacities. No: myopia (short-sightedness cant see far away), hypermetropia (eye ball too small - long-sightedness), astigmatism (oval shaped instead of sphere), presbyopia. Photoreceptors are at the back of the retina. Ratio of rods: cones = 20:1 (rod dominated) Less sensitive: pigments that pick up the wavelength of light.
