1. ESye and Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

2. Vision uses visible light which is part of the electromagnetic spectrum with wavelengths from about 400 to 700 nm. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

3. Accessory structures of the eyes include the eyelids, eyelashes, eyebrows, lacrimal (tear-producing) apparatus and extrinsic eye muscles. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

4. 1 inch diameter 5/6 of eyeball inside orbit & protected Eyelashes & eyebrows help protect from foreign objects, perspiration & sunlight Palpebral muscles control eyelid movement and extrinsic eye muscles are responsible for moving the eyeball itself in all directions. Eyeball Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

5.  The conjunctiva is a thin, protective mucous membrane that lines the eyelids and covers the sclera.  The tarsal plate: a fold of connective tissue that gives form to the eyelids. Contains a row of sebaceous glands (tarsal glands/Meibomian glands) that keeps the eyelids from sticking to each other. (sty) Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

6. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

7.  The lacrimal apparatus produces and drains tears. The pathway for tears is:  The lacrimal glands  The lacrimal ducts  The lacrimal puncta  The lacrimal canaliculi  The lacrimal sac  The nasolacrimal ducts that carry the tears into the nasal cavity. Lacrimal Apparatus Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

8. a watery physiologic saline, with a plasma-like consistency, contains the bactericidal enzyme lysozyme; it moistens the conjunctiva and cornea, provides nutrients and dissolved O 2 to the cornea. Lacrimal Apparatus Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

9. Lacrimal Apparatus Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

10.  Six extrinsic eye muscles move the eyes in almost any direction. These muscles include the  4 recti : superior rectus, inferior rectus, lateral rectus, medial rectus,  2 obliques :superior oblique and inferior oblique. Extrinsic Muscles of Eye Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

11. Move eyeball in direction of name Superior rectus, inferior rectus, medial rectus supplied by Occulomotor or Cranial nerve III. Lateral rectus supplied by Cranial nerve VI / Abducens Recti muscles of eye: movement and nerve supply Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

12. Extraocular Muscles Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

13. Superior & inferior - rotate eyeball on its axis Superior rotates inferiorly and laterally Inferior rotates superiorly and laterally Superior oblique supplied by Cranial nerve IV / Trochlear Inferior oblique supplied by Cranial nerve III / Occulomotor Oblique muscles Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

14. The eyeball contains three tunics (coats): the fibrous tunic, outermost (the cornea and sclera) the vascular tunic/uvea, middle(the choroid, ciliary body and iris). the nervous tunic, innermost( retina) Three tunics of Eyeball Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

15. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

16. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

17. Sclera Cornea Fibrous tunic Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

18. “White” of the eye, covers posterior ¾ of the eye Dense irregular connective tissue layer -- collagen & fibroblasts Provides shape & support At the junction of the sclera and cornea is an opening (scleral venous sinus) Posteriorly pierced by Optic Nerve (CNII) Sclera Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

19. Transparent, avascular Helps focus light(refraction); astigmatism 3 layers - nonkeratinized stratified squamous - collagen fibers & fibroblasts - simple squamous epithelium Transplants: common & successful; no blood vessels so no antibodies to cause rejection Nourished by tears & aqueous humor Cornea Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

20. 1.choroid 2. ciliary body ciliary muscle & ciliary process 3. iris radial muscle & circular muscle 4. pupil Middle vascular tunic or uvea Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

21. is a network of blood vessels that supply oxygen and nutrients to the tissues of the eye. located deep to the sclera and is called the "choroid.“ contains a pigmented layer (melanin) that helps absorb excess light anterior to the choroid is a circular structure called the "ciliary body." ciliary body has ciliary muscles that act on suspensory ligaments which suspend the lens in the correct position. Ciliary body is also made up of a ciliary process that makes a fluid called aqueous humor Vascular tunic: Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

22. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

23. The suspensory ligaments are either taut or relaxed based on the action of the ciliary muscles. The tension on the ligaments changes the shape of the lens, depending on the distance of the object being viewed. This process is called "accommodation". The iris is the colored portion of the eye and it is found in front of the ciliary body, Vascular Tunic Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

24. it divides the front portion of the eye into two chambers – the anterior and posterior chambers. the opening in the middle of the iris is called the "pupil," which appears as the dark center of the eye. the iris either dilates or constricts the pupil to regulate the amount of light entering the eye. In bright light the pupil will be small, but in dim light the pupil will be very large to let in as much light as possible. Iris of the Eye - controls the amount of light entering the eye Constriction of pupils - contraction of the circular fibers – parasympathetic, bright light Dilation - contraction of radial fibers – sympathetic, dim light Iris Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

25. The iris (colored portion of the eyeball) controls the size of the pupil based on autonomic reflexes. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

26. posterior ¾ of eye ball only anterior margin – ora serrata retina superficial layer of pigment epithelium: nonvisual portion absorbs stray light & helps keep image clear optic disc – attachment of optic nerve / blind spot, no photoreceptors deeper layer of neurons - rods/cones are photoreceptor layer - bipolar neuron layer - ganglion cell layer Inner sensory tunic/retina Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

27.  The retina lines the posterior three- quarters of the inner layer of the eyeball. It may be viewed using an ophthalmoscope.  The optic (II) nerve is also visible.  The point at which the optic nerve exits the eye is the optic disc (blind spot).  The exact center of the retina is the macula lutea. In its center is the fovea centralis (area of highest visual acuity). Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

28. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

29.  The retina contains sensors (photoreceptors) known as rods and cones.  Rods to see in dim light  Cones produce color vision  From these sensors, information flows through the outer synaptic layer to bipolar cells through the inner synaptic layer to ganglion cells. Axons of these exit as the optic (II) nerve. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

30. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

31. Pathway of light Ganglion cells  bipolar cells  photoreceptor cells Pathway visual impulses Photoreceptor cells  bipolar cells  ganglion cells  optic nerve Visual and light pathways Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

32. Light penetrates retina Rods & cones transduce light into action potentials Rods & cones excite bipolar cells Bipolars excite ganglion cells Axons of ganglion cells form optic nerve leaving the eyeball (blind spot) Retina Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

33. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

34.  The eye is divided into an Anterior Cavity and Posterior Cavity.  The anterior cavity is divided into - anterior chamber and a posterior chamber by the iris (colored portion of the eyeball). anterior chamber (between the iris and cornea) posterior chamber lies behind the iris and in front of the lens the anterior cavity contains aqueous humor  Behind this is the posterior cavity (vitreous chamber) filled with a transparent, gelatinous substance, the vitreous humor. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

35. filled with aqueous humor Aqueous Humor - Continuously produced by ciliary body - Flows from posterior chamber into anterior through the pupil - continually drained by scleral venous sinus or canal of Schlemm / opening in white of eye at junction of cornea & sclera - drainage of aqueous humor from eye to bloodstream Glaucoma increased intraocular pressure that could produce blindness problem with drainage of aqueous humor Anterior Cavity Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

36. (posterior to lens) filled with vitreous body (jellylike) holds retina in place formed once during embryonic life floaters are debris in vitreous of older individuals Posterior Cavity Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

37. Light passes through the cornea, the anterior chamber, the pupil, the posterior chamber, the lens, the vitreous humor, and is projected onto the retina. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

38. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

39. 1. Refraction of light by cornea, aqueous humor, lens & vitreous humor light rays must fall upon the retina 2. Accommodation of the lens changing shape of lens so that light is focused 3. Constriction of the pupil less light enters the eye/ pupil Major Processes of Image Formation Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

40. Light refracts (bends) when it passes through a transparent substance with one density into a second transparent substance with a different density. This bending occurs at the junction of the two substances. Refraction of light Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

41.  Images focused on the retina are inverted and right-to-left reversed due to refraction. The brain corrects the image.  The lens must accommodate to properly focus the object.  The image is projected onto the central fovea, the site where vision is the sharpest. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

42. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

43. The normal (emmetropic) eye will refract light correctly and focus a clear image on the retina. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

44.  In cases of myopia (nearsightedness) the eyeball is longer than it should be and the image converges (narrows down to a sharp focal point) in front of the retina. These people see close objects sharply, but perceive distant objects as blurry.  A concave lens is used to correct the vision. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

45. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

46.  In cases of hyperopia (farsightedness) also known as hypermetropia, the eyeball is shorter than it should be and the image converges behind the retina. These individuals can see distant objects clearly, but have difficulty with close objects.  A convex lens is used to correct this abnormality. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

47. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

48. Astigmatism is a condition where either the cornea or the lens (or both) has an irregular curve. This causes blurred or distorted vision. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

49. Rods and cones, the photoreceptors in the retina that convert light energy into neural impulses, were named for the appearance of their outer segments. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

50.  Rods and cones contain photopigments necessary for the absorption of light that will initiate the events that lead to production of a receptor potential.  Photopigments = opsin (protein) + retinal /vitamin A derivative  Rods contain only rhodopsin.  Cones contain three different photopigments, one for each of the three types of cones (red, green, blue).  Photopigments respond to light in a cyclical process. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

51. Color blindness inability to distinguish between certain colors absence of certain cone photopigments red-green color blind person can not tell red from green Night blindness (nyctalopia) difficulty seeing in low light inability to make normal amount of rhodopsin possibly due to deficiency of vitamin A Color Blindness & Night Blindness Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

52. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

53. Isomerization: light cause cis-retinal to straighten & become trans-retinal shape Bleaching: enzymes separate the trans-retinal from the opsin, colorless final products Regeneration: in darkness, an enzyme converts trans-retinal back to cis-retinal (resynthesis of a photopigment) Physiology Of Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

54. Pigment epithelium near the photoreceptors contains large amounts of vitamin A and helps the regeneration process After complete bleaching, it takes 5 minutes to regenerate 1/2 of the rhodopsin but only 90 seconds to regenerate the cone photopigments Full regeneration of bleached rhodopsin takes 30 to 40 minutes Rods contribute little to daylight vision, since they are bleached as fast as they regenerate. Regeneration of Photopigments Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

55.  Light adaptation occurs when an individual moves from dark surroundings to light ones. It occurs in seconds.  Dark adaptation takes place when one moves from a lighted area into a dark one. This takes minutes to complete.  Part of this difference is related to the rates of bleaching and regeneration of photopigments in rods and cones.  Light causes rod photoreceptors to decrease their release of the inhibitory neurotransmitter glutamate. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

56. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

57. In darkness, rod photoreceptors release the inhibitory neurotransmitter glutamate. This inhibits bipolar cells from transmitting signals to ganglion cells which provide output from the retina to the brain. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

58. In darkness: Na+ channels are held open and photoreceptor is always partially depolarized (- 30mV);  continuous release of inhibitory neurotransmitter onto bipolar cells In light: enzymes cause the closing of Na+ channels producing a hyperpolarized receptor potential (-70mV); release of inhibitory neurotransmitter is stopped;  bipolar cells become excited and a nerve impulse will travel towards the brain Physiology of Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

59. Retinal Processing of Visual Information Convergence one cone cell synapses onto one bipolar cell produces best visual acuity 600 rod cells synapse on single bipolar cell increasing light sensitivity although slightly blurry image results 126 million photoreceptors converge on 1 million ganglion cells Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

60. The neural pathway for vision begins when the rods and cones convert light energy into neural signals that are directed to the optic (II) nerves. The pathway is:  The optic chiasm  The optic tract  The lateral geniculate nucleus of the thalamus  Optic radiations allow the information to arrive at the primary visual areas of the occipital lobes for perception. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

61. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

62. The anterior location of our eyes leads to visual field overlap. This gives us binocular vision. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

63.  The two visual fields of each eye are nasal (medial) and temporal (lateral).  Visual information from the right half of each visual field travels to the left side of the brain.  Visual information from the left half of each visual field travels to the right side of the brain. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

64. Vision Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

65. Visual information in optic nerve travels to occipital lobe for vision Midbrain for controlling pupil size & coordination of head and eye movements Hypothalamus to establish sleep patterns based upon circadian rhythms of light and darkness Processing of Image Data in the Brain Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.