1. PHYSIOLOGY OF VISION Prof. Vajira Weerasinghe Dept of Physiology, Faculty of Medicine, University of Peradeniya

23. PHYSICS OF VISION OPTICS

26. f = focal length power of a lens = 1 ---------- f (m) f = 1 m: power = 1 D f = 2 m: power = 0.5 D f = 0.5 m: power = 2 D + 1 D: converging lens - 1 D: diverging lens

35. emmetropia: unaccommodated eye emmetropia: accommodated eye myopia: distant objects, forms in front of retina correction: - lens, decreases power MYOPIA

37. emmetropia: unaccommodated eye emmetropia: accommodated eye hypermetropia: image forms behind the retina correction: + lens, increases power HYPERMETROPIA

39. emmtropia: unaccommodated eye emmtropia: accommodated eye presbyopia: lack of accommodation presbyopia: + lens, increases accommodation PRESBYOPIA

44. Neural activity

49. a rod outer segment inner segment in light when light strikes the outer segment, Na+ channels close Na+ influx ceases inner segment pumps Na+ out leads to hyperpolarised membrane Na + Na + Na + - 80 mV Na + in dark Na + Na + Na + membrane potential - 40 mV

52. wavelength 400 700 500 600 light absorption spectrum Ultra violet violet indigo blue green yellow orange red Infra red visible spectrum rods

56. 0 10 20 30 40 50 1 10 100 1000 10000 100000 cone adaptation rod adaptation minutes in dark retinal sensitivity

57. 0 10 20 30 40 50 minutes in dark retinal threshold

62. Colour Vision

66. visual field retina optic nerve optic chiasma optic tract lateral geniculate body occipital cortex

69. Left Right normal visual fields left eye blindness bitemporal hemianopia right homonymous hemianopia right homonymous hemianopia