Basic Ocular Anatomy

1. Basic Ocular Anatomy www.battalionaidstation.com

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3. General Overview • The eye is arguably the most complicated organ we have. Unless its studied in an organized, structured manner, its anatomy can easily confuse even the best students. This slideshow will help guide you through a quick survey of the basic anatomy of the eye.

4. Anterior and Posterior • A gross dissection of the eye will divide it into three main sections: the anterior and posteriorsegments. Some anatomists also refer to a small intermediate section, pictured below.

5. Review #1- The eye is broken down into how many major segments?

6. Review #1- The eye is broken down into how many major segments? Anterior and Posterior Segments

7. Anterior and Posterior Breakdown Anterior SectionPosterior Section

8. Anterior Segment Evaluation(as seen through with a handheld light source or slit lamp evaluation) • From front to back: • Lids & lashes • Conjuctiva • Cornea • Anterior chamber • Iris • Lens

9. Review #2- From front to back, what are the parts of the anterior segment of the eye? #1- The eye is broken down into how many major segments? Anterior and posterior Segments

10. Review #2- From front to back, what are the parts of the anterior segment of the eye? Lids and lashes, conjuctiva, cornea, anterior chamber, iris, and the lens. #1- The eye is broken down into how many major segments? Anterior and posterior Segments

11. Lids and Lashes • Main function is the lubrication and protection of the eye • Contain muscles for opening and closing eyes (orbicularisoculi & superior levatorepalpebrae) • Contain several glands for producing tears and coating the lashes • Lacrimalpuncta in each eyelid for drainage of tears

12. Review #3- Tears drain into what structure in the eyelids? #1- The eye is broken down into how many major segments? Anterior and posterior Segments #2- From front to back, what are the parts of the anterior segment of the eye? Lids and lashes, conjuctiva, cornea, anterior chamber, iris, and the lens

13. Review #3- Tears drain into what structure in the eyelids? Lacrimalpuncta #1- The eye is broken down into how many major segments? Anterior and posterior Segments #2- From front to back, what are the parts of the anterior segment of the eye? Lids and lashes, conjuctiva, cornea, anterior chamber, iris, and the lens

14. Conjuctiva • The conjuctiva is a highly vascular mucous membrane covering the lids and sclera • Most people know it as the part of the eye that’s irritated during “conjuctivitis,” or “pink eye” • It’s main function is to ensure smooth movement of the eyelids over the globe • Extends from lid margin to edge of cornea • Bulbar conjunctiva - covers globe • Palpebral conjunctiva - covers inside of eyelids

15. Review #4- What is the conjuctiva’s main function? #1- The eye is broken down into how many major segments? Anterior and posterior Segments #2- From front to back, what are the parts of the anterior segment of the eye? Lids and lashes, conjuctiva, cornea, anterior chamber, iris, and the lens #3- Tears drain into what structure in the eyelids? Lacrimalpuncta

16. Review #4- What is the conjuctiva’s main function? Ensure smooth movement of the lids over the globe #1- The eye is broken down into how many major segments? Anterior and posterior Segments #2- From front to back, what are the parts of the anterior segment of the eye? Lids and lashes, conjuctiva, cornea, anterior chamber, iris, and the lens #3- Tears drain into what structure in the eyelids? Lacrimalpuncta

17. Cornea • Main function of the cornea is to focus light onto the retina • Clear and avascular tissue but contains high concentration of nerves on its surface layer • Takes its oxygen directly from the atmosphere and its nutrients from the body’s tears • Five layers: Epithelium, Bowman’s, Stroma, Descemet’s, Endothelium

18. Review #5- Why is continuous wear of contact lenses a major source of irritation for the cornea? The cornea gets its oxygen directly from the air and its nutrients directly from tears. Contact lenses form a barrier that prevent it from getting oxygen and nutrients #1- The eye is broken down into how many major segments? Anterior and posterior Segments #2- From front to back, what are the parts of the anterior segment of the eye? Lids and lashes, conjuctiva, cornea, anterior chamber, iris, and the lens #3- Tears drain into what structure in the eyelids? Lacrimalpuncta #4- What is the conjuctiva’s main function? Ensure smooth movement of the lids over the globe

19. Review #5- Why is continuous wear of contact lenses a major source of irritation for the cornea? The cornea gets its oxygen directly from the air and its nutrients directly from tears. Contact lenses form a barrier that prevent it from getting oxygen and nutrients #1- The eye is broken down into how many major segments? Anterior and posterior Segments #2- From front to back, what are the parts of the anterior segment of the eye? Lids and lashes, conjuctiva, cornea, anterior chamber, iris, and the lens #3- Tears drain into what structure in the eyelids? Lacrimalpuncta #4- What is the conjuctiva’s main function? Ensure smooth movement of the lids over the globe

20. Anterior Chamber • Located between the cornea and the lens • Filled with clear liquid • Determines intraocular pressure and is measured to determine presence of glaucoma • Supplies the cornea and the lens with nutrients

21. Review #6- Where is the anterior chamber located?

22. Review #6- Where is the anterior chamber located? Between the cornea and the lens Cornea Iris Lens/Pupil Anterior Chamber (As seen through slit lamp exam)

23. Iris • The iris is the multicolored tissue that dilates and constricts in reaction to light • More unique to every individual than their fingerprints • Functions to limit the amount of light that enters the eye • Two main muscles • Sphincter muscle constricts pupil • Dilator muscle dilates the pupil

24. Review #7- What is the function of the iris? #6- Where is the anterior chamber located? Between the cornea and the lens

25. Review #7- What is the function of the iris? Limits the amount of light that enters the eye #6- Where is the anterior chamber located? Between the cornea and the lens

26. Lens • The lens receives the light from the iris • Main function is accomodation (focusing) • Begins clear but gets cloudier with time • Advanced cloudiness is referred to as cataracts

27. Review #8- A cloudy lens, present in almost everyone over age 65, is commonly referred to as what? Cataracts #6- Where is the anterior chamber located? Between the cornea and the lens #7- What is the function of the iris? Limits the amount of light that enters the eye

28. Review #8- A cloudy lens, present in almost everyone over age 65, is commonly referred to as what? Cataracts #6- Where is the anterior chamber located? Between the cornea and the lens #7- What is the function of the iris? Limits the amount of light that enters the eye

29. Posterior Segment Evaluation(As seen through direct ophthalmoscopy. These slides will also give a basic guide through a basic opthalmoscopy in order to assist in finding the landmarks listed below) • Vitreous • Vessels • Optic nerve • Retina • Macula • Peripheral Retina - (not observable with direct ophthalmoscope)

30. Vitreous Humor • Translucent (clear) gel-like material that fills the posterior chamber of the eye. • The main function of the vitreous is to protect the retina by absorbing shock from injuries and day-to-day activities. Prevents retinal detachment. • In early life it’s about four times as thick as water. It loses viscosity with age, becoming more liquid as we age.

31. Review #9- What is the main function of the vitreous and how does it’s structural makeup help it do it? Main function is to protect the retina. It’s gel-like consistency helps it absorb shock. #6- Where is the anterior chamber located? Between the cornea and the lens #7- What is the function of the iris? Limits the amount of light that enters the eye #8- A cloudy lens, present in almost everyone over age 65, is commonly referred to as what? Cataracts

32. Review #9- What is the main function of the vitreous and how does it’s structural makeup help it do it? Main function is to protect the retina. It’s gel-like consistency helps it absorb shock. #6- Where is the anterior chamber located? Between the cornea and the lens #7- What is the function of the iris? Limits the amount of light that enters the eye #8- A cloudy lens, present in almost everyone over age 65, is commonly referred to as what? Cataracts

33. Vessels • When looking through the opthalmoscope you will first see the back of retina reflected through the pupil if you’re standing about 1 foot away. It should be an orange-reddish color. This is known as the red reflex. • Look around the back of the retina until you find a blood vessel. Check to see that there are no signs of bleeding or AV nicking. • Find a vessel and follow it in one direction. If it gets smaller as you travel in that direction, stop and go the other way. The vessel should get larger and larger until you reach the optic disc.

34. Review #10- When starting the opthalmoscope exam, how far away should you be from the patient in order to see the red reflex? One foot away

35. Review #10- When starting the opthalmoscope exam, how far away should you be from the patient in order to see the red reflex? One foot away

36. Optic Disc • All vessels converge at the optic disc • It’s main purpose is to carry the retinal signal from the eye to the brain • The terminal point of the second cranial nerve • Appearance should be pink with white cup in the middle, distinct margins

37. Review #11- What is the optic disc? Where all vessels of the retina converge The terminal point of CN II Pink with a white cup in the center. Distinct margins. #10- When starting the opthalmoscope exam, how far away from the patient should you be in order to see the red reflex? One foot

38. Review #11- What is the optic disc? Where all vessels of the retina converge The terminal point of CN II Pink with a white cup in the center. Distinct margins. #10- When starting the opthalmoscope exam, how far away from the patient should you be in order to see the red reflex? One foot

39. Retina • Innermost layer of eye (sclera is outermost, choroid is central layer) • Reddish-orange color • Allows for peripheral vision

40. Review #12- What are the three layers of the eye, from innermost to outermost? Retina, choroid, sclera #10- When starting the opthalmoscope exam, how far away from the patient should you be in order to see the red reflex? One foot #11- What is the optic disc? Where all vessels of the retina converge The terminal point of CN II Pink with a white cup in the center. Distinct margins

41. Review #12- What are the three layers of the eye, from innermost to outermost? Retina, choroid, sclera #10- When starting the opthalmoscope exam, how far away from the patient should you be in order to see the red reflex? One foot #11- What is the optic disc? Where all vessels of the retina converge The terminal point of CN II Pink with a white cup in the center. Distinct margins

42. Macula • The macula is located in a slight depression located in the center of the retina • The center of the macula is known as the “fovea centralis,” which is the spot of clearest vision. • Responsible for detailed central vision and color • Darker pigment than the rest of the retina

43. Review #13- Describe the different parts of the eye that are responsible for different types of vision. Retina- Inner layer of eye. Responsible for peripheral vision Macula- Allows for central vision. The lens and iris focus vision onto the macula Fovea centralis- Located in the center of the macula.

44. Review #13- Describe the different parts of the eye that are responsible for different types of vision. Retina- Inner layer of eye. Responsible for peripheral vision Macula- Allows for central vision. The lens and iris focus vision onto the macula Fovea centralis- Located in the center of the macula.

45. Extraocular Muscles (EOM) • Six muscles attached to the outside of the internal section of the globe, responsible for movement. • Lateral Rectus muscles. Responsible for abduction, innervated by the sixth cranial nerve • Medial Rectus muscles. Responsible for adduction, innervated by the third cranial nerve • Superior Rectus muscles. Responsible for supraduction, innervated by the third cranial nerve • Inferior rectus responsible for infraduction, innervated by the third cranial nerve • Inferior oblique responsible for torsional movements, innervated by the third nerve • Superior oblique responsible for torsional movements, innervated by the fourth nerve

46. Review #14- What are the nerves that innervate the extraocular muscles? Cranial nerves three, four, and six #13- Describe the different parts of the eye that are responsible for different types of vision. Retina- Inner layer of eye. Responsible for peripheral vision Macula- Allows for central vision. The lens and iris focus vision onto the macula Fovea centralis- Located in the center of the macula.

47. Review #14- What are the nerves that innervate the extraocular muscles? Cranial nerves three, four, and six #13- Describe the different parts of the eye that are responsible for different types of vision. Retina- Inner layer of eye. Responsible for peripheral vision Macula- Allows for central vision. The lens and iris focus vision onto the macula Fovea centralis- Located in the center of the macula.

48. Questions?