1. The Eye 1

2. Lacrimal apparatus  Lacrimal glands Superior and lateral in each eye Produces tears Several small ducts liberate the tear continually  Excretory ducts Accessory structures of the eye 2

3. Lacrimal Apparatus  Lacrimal canal Medial in each eye  Lacrimal sac  Nasolacrimal duct  Tears Salt solution Contains lysozyme and antibodies Cleanse, protect, moisten and lubricate the eye ball 3

4. Accessory structures of the eye Palpebrae  Lateral canthus  Medial canthus  Caruncle – contains sweat and sebaceous glands 4

5. Accessory structures of the eye  Eyelashes  Ciliary glands Modified sweat glands between the eyelashes  Meibomian or tarsal glands Posterior to the eyelashes. Secrete oil 5

6. Accessory structures of the eye  Sty Acute inflammation of the ciliary or meibomian gland  Chalazio Chronic inflammation of the meibomian gland 6

7. Accessory structures of the eye Conjunctiva  Palpebral  Ocular or bulbar  It is a mucosa that secretes mucus  Conjunctivites Inflamation of the conjunctiva Extrinsic muscles of the eye  Control eye movement 7

8. Internal Anatomy of the eye Outer fibrous tunic  Dense avascular connective tissue  Sclera  Cornea Transparent, anterior most portion 8

9. Internal Anatomy of the eye Middle vascular tunic (uvea) Iris Colored part of the eye Smooth muscle acting as a diaphragm Ciliary body Ciliary muscles – control the shape of the lens Ciliary processes – secretes aqueous humor Suspensory ligaments 9

10. Internal Anatomy of the eye Choroid  Posteriormost part  Contain melanin  Tapetum lucidum (only in animals) Inner sensory tunic (Retina)  Pigmented layer Covers the choroid 10

11. Internal Anatomy of the eye  Neural layer Rods – photoreceptors cells for dim light. Perceives gray tones Cones – photoreceptors cells for color. They need high amount of light Optic disc – blind spot. Emergency of the optic nerve Macula lutea – high concentration of cones. Fovea 11

12. Internal Anatomy of the eye Lens  Held by the suspensory ligaments. Attaches to the ciliary body.  Catarats – lens become opaque and hard 12

13. Internal Anatomy of the eye Anterior segment  Aqueous humor – clear fluid formed by the ciliary process. It provides nutrients for the lens and cornea.  Scleral venus sinus (canal of Schlemm) – absorbs the aqueous humor  Glaucoma – increased intraocular pressure Posterior segment  Vitreous humor – helps to keep the retina in place 13

14. Figure 17.4a, b The Sectional Anatomy of the Eye 14

15. Microscopic anatomy of the retina Pigmented epithelial layer  Located between the choroid and neural layer Neural layer  Photoreceptors – rods and cones  Bipolar neurons  Ganglion neurons 15

16. Microscopic anatomy of the retina 16

17. Visual Pathways to the brain Optic nerve Optic chiasma  It is the crossing of the fibers of the optic nerve Optic tract Thalamus Optic radiation Visual cortex – located on the occipital lobe 17

18. Visual Tests and Experiments Blind Spot  When the image fall on the optic disc 18

19. Visual Tests and Experiments Refraction of the light rays  Cornea  Lens  Vitreous humor Accommodation of the lens  Near-point accommodation Presbiopia – difficult focus for close vision because of decreased lens elasticity 19

20. Visual Tests and Experiments Visual acuity  Snellen chart  Emmetropy  Myopia  Hyperopia Astigmatism  Irregularity in the curvatures of the lens and/or cornea 20

21. Visual Tests and Experiments Color blindness  Three cone types- red, green and blue Binocular vision  Three dimensional vision  Accuracy of locating objects  Depth perception Panoramic vision 21

22. Visual Tests and Experiments Extrinsic muscles of the eye  Convergence Medial eye movements for near vision  Keep moving objects focused on the fovea 22

23. Visual Tests and Experiments Pupillary reflex  Photopupillary reflex Constriction of the pupils when the retina is illuminated by a bright light Intrinsic muscles of the eye  Accommodation pupillary reflex Change of the pupil diameter for near focus 23

24. Eye Dissection WHOLE EYE  Cornea  Sclera  Optic nerve  Extrinsic muscles 24

25. Eye Dissection FRONTAL CUT  Humors: aqueous, vitreous  Lens  Ciliary body  Iris  Pupil  Choroid  Retina  Posterior cavity 25