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Glaucoma & Glaucoma test

Refraction. Glaucoma & Glaucoma test. Degree of cell packing in retina. Intrinsic Muscles of the Eye: The Iris. Iris circular.....constricts radial.....…dilates Dilating pupil for eye exam: how to do it?. Pharmacology of pupillary dilation: Atropine.

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Glaucoma & Glaucoma test

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  1. Refraction Glaucoma & Glaucoma test

  2. Degree of cell packingin retina

  3. Intrinsic Muscles of the Eye:The Iris • Iris • circular.....constricts • radial.....…dilates • Dilating pupil for eye exam: how to do it? Pharmacology of pupillary dilation: Atropine

  4. Intrinsic Muscles of the Eye:Ciliary Muscle • Ciliary muscle relaxed = tension on zonular fibers = tension on lens = flattened lens = distant focus • Ciliary muscle contracted = tension on zonular fibers reduced = less tension on lens = lens becomes more spherical =near focus • Eye strain Using a Microscope or Binoculars

  5. Accommodation animation • DemonstrateConvergence • Measure NPA With Convergence

  6. NPA Left eye _______________mm NPA Right eye ______________ mm Sex of subject ___ Age in months___ with corrective lenses/contacts? yes/no

  7. Presbyopia

  8. Disorders of Focus • Myopia = nearsighted • eyeball too long, cornea/lens to “strong” • image focused in front of retina • correct with concave lens • Hyperopia = farsighted • eyeball too short, cornea/lens to “weak” • image focused behind retina • correct with convex lens • Astigmatism • irregular surface of lens or cornea

  9. Cataract

  10. Strabismus= misalignment of eyes Extraocular muscles • Actions of extraocular muscles • Motor innervation by CN III, IV, VI Storytime

  11. Visual reflexes: Accomodation, Saccades, Tracking, Pupillary reflex Suprachiasmatic Nucleus for diurnal cycling Aka. Area 17 and V1

  12. Evolution ofBinocular Vision Mapping the boundary of each visual field

  13. Retinotopy

  14. Goliath?

  15. The Retina • Photoreceptors • Rods • Cones • Bipolar cells • Ganglion Cells • axons converge at optic disk • axons constitute optic nerve • Horizontal cells • Amacrine cells

  16. Importance of abundantmembrane

  17. Visual Acuity • 120,000,000 rods and 6,000,000 cones per retina • 1,200,000 retinal ganglion cells & axons • 105:1 convergence ratio • Fovea: cones only, 1:1 highest visual acuity but poor sensitivity Counting fingers andReading the Writing on the Wall

  18. Demonstrationof Blind Spot (diagram)

  19. Differences due to opsin: 4 types

  20. Trichromatic Theory of Color Vision Web-based color deficiency test

  21. StargazingFinding your car in a dark parking lotChoosing socks

  22. “Bleaching” of photopigments Visual Purple

  23. The Dark Current

  24. Phototransduction • In the DARK, rod is depolarized due to influx of Na+ (called dark current) • In the LIGHT, rod is hyperpolarized • cGMP keeps Na+/Ca++ channels open • Light results in decrease of cGMP and thus closure of ion channels, and • Hyperpolarization of cell, and • Reduced release of Neurotransmitter Glutamate

  25. Properties of Cortical Neurons • Simple • respond to stationary bar of light in certain orientation • Complex • respond to moving bar of light in certain orientation • Hypercomplex • respond to moving bar of light of a certain length in a certain orientation

  26. Parallel Processing in the Cortex • Motion sensitive • Color and shape sensitive Story of woman atstreet crossing

  27. Why so much emphasis on the Visual System?

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