Vision. Anatomy of the Eye Fibrous tunic – Sclera – Cornea.
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Transcript of Vision. Anatomy of the Eye Fibrous tunic – Sclera – Cornea.
VisionVision
Anatomy of the EyeAnatomy of the Eye
Fibrous tunic– Sclera – Cornea
Anatomy of the EyeAnatomy of the Eye
Vascular tunic = Uvea– Choroid– Ciliary body– Iris– Pupil
Anatomy of the EyeAnatomy of the Eye
Nervous tunic = Retina & optic nerve– Outer pigmented layer– Nervous layer
PhotoreceptorsPhotoreceptors
RodsConesMaculaFovea centralis
Optic NerveOptic discBlind Spot
Anatomy of the Eye – Anatomy of the Eye – Miscellaneous structuresMiscellaneous structures
LensAnterior cavity
– Aqueous humor
Posterior cavity– Vitreous humor
Anatomy – Accessory Anatomy – Accessory structuresstructures
Eyelids = Palpebrae– Tarsal plate– Meibomian glands– Palpebral fissure– Lateral commissure– Medial commissure– Caruncle– Sebaceous ciliary glands
Anatomy – Accessory Anatomy – Accessory structuresstructures
Conjunctiva– Palpebral– Bulbar
Anatomy – Accessory Anatomy – Accessory structuresstructures
Lacrimal apparatus– Function– Lacrimal gland– Lacrimal puncta– Lacrimal canal– Nasolacrimal duct
VisionVision
LightRefractionEmmetropia = Normal vision, light rays
focus on a single point called the Focal Point
Focal Point
Retina
VisionVision
Accommodation– For close vision– Pupils constrict– Eyeballs converge– Near point of vision
VisionVision
Eye movement controlsVoluntary fixation (premotor area)Involuntary fixation (visual area)
VisionVision
Binocular visionDiplopiaStrabismus
Photoreceptors of VisionPhotoreceptors of Vision
Rods– Rhodopsin is photopigment– Numerous – about 120 million– Sensitive to light– Relative lack of color discrimination– Peripheral retina in location– Good for night vision, but poor detail– Convergence
Photoreceptors of VisionPhotoreceptors of Vision
ConesFew – about 6 millionPhotopigments sensitive to differing
wavelengths of light– 400 nm blue– 500 nm green– 600 nm red
Photoreceptors of VisionPhotoreceptors of Vision
ConesHigh level of illuminationNot very sensitive to lightSee in colorPrecise detailLittle convergenceMostly in center of retina, esp. fovea
Neural Components of VisionNeural Components of Vision
Bipolar neuronsGanglion neuronsLateral inhibition
– Horizontal cells– Amacrine cells
Visual AcuityVisual Acuity
Snellen Eye Chart20/20
Light/Dark AdaptationLight/Dark Adaptation
Photopigment concentrationPupillary light reflex
– PNS constricts pupil– Direct – ipsilateral– Indirect = Consensual - contralateral
Cones inhibit rods in bright light
Visual PathwayVisual Pathway
Optic NerveOptic ChiasmaOptic tractsThalamus – lateral geniculate bodyOccipital lobe of cerebral cortex