1. anatomy and physiology eye

Human eye is the biological structure which enable the sense of light. the Eyes are the windows to the wonders of the world.

1. MEDICAL SURGICAL NURSING- II UNIT – II NURSING MANAGEMENT OF PATIENTS WITH DISORDERS OF EYE TOPIC : REVIEW OF ANATOMY AND PHYSIOLOGY OF EYE Mrs. Soumya. M 1 PRESENTED BY Mrs. SOUMYA SUBRAMANI, M.Sc.(N) LECTURER, MSN DEPARTMENT CON- SRIPMS, COIMBATORE.

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5. Eye s are th e paire d orga n s tha t det e ct ligh t and convert it int o electro-chemic a l impulses i n n eurons. EY E : Th e organ o f VIS I ON Mrs. Soumya. M 5

6. Types o f eye: Sim p le eye i s presen c e in all chord a tes Compound eye i s presen c e in ca s e of ar t hop o ds Mrs. Soumya. M 6

7. P arts of EYE mainly div ide d into Mrs. Soumya. M 7 parts

8. 1.Eyebal l Three layer s : Fibr o us outer l a y er Sc l e r a Cornea V as c ular middle l a y er Choroid, Ciliary bod y and Iris Th e inne r ner v ous l a y er R et i na Pupil Structur e s i n side the e y eball a r e t he lens , aqueous fluid and vitre o us bod y . P arts of EYE Mrs. Soumya. M 8

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10. 2 . Acc esso r y structu r es • Co n junct i v a • E y elid • E y el a shes • Lacrimal gl a nd • Ext r ao c ul a r muscl e s P arts of EYE Mrs. Soumya. M 10

11. S c ler a “Wh i te p a rt of the e y e ” Ma i nta i ning th e shape and form of th e ey e ba ll . Con t a i ns B Vs and i nse r t i on s i t e for e xtr i nsic ey e musc l e s. Cornea Thin , t r anspa r e nt e p i the l i um A ll ow th e fr e e e ntry of li ght. Act as r e f r act i v e m e d i a. Fibr o us outer l ay er Mrs. Soumya. M 11

12. CORNEA Transparent avascular tissue with 5 distinct layers. Function is to allow light rays to enter the eye. Surrounded by a vascular layer known as the limbus which nourishes the cornea. Should be smooth and clear. Mrs. Soumya. M 12

13. Layers of the Cornea 1. Epithelium (5-6 layers of cells) 2. Bowman's layer 3. Stroma (about 90% of the thickness) 4. Descemet's layer (clear membrane) 5. Endothelium (1 cell layer) Mrs. Soumya. M 13

14. Choroid Pi gm ented to abso r b e x ce s s li g ht Sup plie s th e r e tin a with n u trient s and o x y gen via bloo d sup p ly Iris “ Colo r ed par t ” of the e y e w h ic h c ontains pi g ment cells, l o o s e c o n necti v e tissu e and pu p illar y muscle.  Ad j usts th e pu pil  R egu l ates amount of li g ht V as c ular mid d l e l ay er Mrs. Soumya. M 14

15. V as c ular mid d l e l ay er Mrs. Soumya. M 15 C i lia r y Bo dy R i ng of sm o oth musc l e a r ound l e ns  R e gu l at e s th e shape of the l e ns for acc o m m od a t i on S u spe n sato r y Ligaments – A ttac h th e c ili a r y b o d y t o th e l e ns

16. The Uveal Tract Composed of the choriod , ciliary bodies and the iris. Middle vascular layer of the eye. Divides the sclera and the retina and the anterior and posterior sections of the eye. Mrs. Soumya. M 16

17. The inner nervou s layer Mrs. Soumya. M 17 Retina i s a li g h t -sensiti v e l a y er of tissue , li n in g the i n ner sur f ace of the e y e . Fun c tions It helps in  Ph otopic visi o n Scoptic visi o n  Mesopic visi o n  Ster o sc o pi c visi o n Acui t y of vi s ion  Colo r visi o n  P e r ception of m o v ement

18. The inner nervou s layer Mrs. Soumya. M 18 Ce l ls of retin a - Photo r e c eptor c e lls Bipolar cells III . H o ri z o ntal cells IV.Amacrine cells V. Gan g lio n cells Th e pho t o r e c ep t or c ells a r e 2 ty p es - The c o n e c ells (2)The r od c ells

19. RETINA Thin semitransparent multi-layered sheet of neural tissue that lines the inner layer of the posterior section of the globe of the eye. Mrs. Soumya. M 19

20. Layers of the Retina (from the outside to the inner layer) Bruch’s membrane Retinal pigment epithelium Photoreceptor cells layer (Rods and Cones) External limiting membrane Outer nuclear layer Inner plexiform layer Ganglion cell layer Nerve fiber layer Internal limiting membrane Mrs. Soumya. M 20

21. Layers of the Retina Mrs. Soumya. M 21

22. The inner nervou s layer Mrs. Soumya. M 22 Th e ma cula lute a / Yellow spot F o v ea cent r alis Th e blin d spot / Optic disc R etinal blood v es s els . pigment epithelium cells Photoreceptor cells M acula lut e a Vein Optic di s c A r te r y Specia l Area s of the Retina i s an o v a l -shap e d hi g hly p i g me nted ye ll ow spot ne a r the c e nter of th e r e t i na Fove a c e nt ralis ( fovea) i s a depression, l oc a te d i n the c e nter of th e m a cula r e g i on of th e r e t i na. T h e m a cul a

23. Macula That area of the retina that is responsible for central detailed vision. Most concentrated area of visual sensitivity is the fovea. No blood vessel pass through the macula. Nourishment comes from the Retinal Pigment Epithelium (RPE) Mrs. Soumya. M 23

24. The Optic Nerve and Disk Consists of over 1 million axons from the nerve fiber layer of the retina. 80% consists of visual fibers synapse on axons that terminate in the occipital lobe of the brain. Part of the Central Nervous System Will not regenerate if severed. Mrs. Soumya. M 24

25. Photoreceptor Cells Transfer light and images to nerves that convert images to electrical impulses that are sent to the occipital lobe of the brain and translated into images that we see. Two types: Rods and Cones Mrs. Soumya. M 25

26. Photoreceptor Cells: Cones Concentrated in the macula and fovea Responsible for central, fine, detailed vision Responsible for ability to see color Require good light to work effectively Bundled with a one to one correspondence to nerve endings that transmit light and images to the brain. Mrs. Soumya. M 26

27. Photoreceptor Cells: Rods Require little light to work effectively and at night gives a primarily grayish image Generally do not give clear vision Relatively Sensitive to Light Responsible for peripheral vision Bundled in groups of 30, 40 or 100 to nerves that transmit image to the brain. Mrs. Soumya. M 27

28. Difference bet w eem CON E cell and ROD cell Property Con es Rods L oc a t i on In the fo v ea O utsid e the fo v ea Resoluti on and v isual acu ity Large S mall To t al num b e r of elem e nts 5 mill ion 1 2 mill ion Col o r sensi t i v i t y Y e s No Brightness sensiti v i t y S mall , fo r daylight v is i on Larg e , fo r nigh t v is i on Fi g ure Mrs. Soumya. M 28

29. Veins and Arteries Central Retinal Vein Branch Retinal Veins Central Retinal Artery Branch Retinal Arteries When occluded the retina turns pale and yellowish and lacks oxygen. Mrs. Soumya. M 29

30. The in n e r nervou s layer  Is a hole located in the ce n te r of the iri s .  It helps to pass the ligh t into the e y e. Pupil Mrs. Soumya. M 30

31. Structures insid e th e e y eball Mrs. Soumya. M 31  Th e lens and cil i ary body divide the e y e into two c a vities.  Th e a nte r io r c a vi ty  Th e po s terio r c a vi ty  Closel y - pac k ed c o n c en t ric c o lum n ar cells  F o c uses i mage on the retina.

32. CAVITIES OF THE EYE ANTERIOR CAVITY- Both the  anterior  and  posterior chambers  are located within the  anterior cavity , POSTERIOR CAVITY -while the vitreous chamber is located in the  posterior cavity . Mrs. Soumya. M 32

33. CHAMBERS OF THE EYE ANTERIOR- Between iris and cornea POSTERIOR- Between iris and lens VITREOUS- Located behind the lens and in front of the optic nerve. Mrs. Soumya. M 33

34. Contain s aque o us h u mor whic h is se c reted b y cilia r y bo d y Mai n tain s s h ape of a n terio r e y e. aque o us h u mor c ons tantly pr o du c e d - le a v es e y e th r ough ca n al tha t ca r ries it to blo o dst r eam. Anter i or Chamber of Eye A n t er i or Ch a m b e r Mrs. Soumya. M 34

35. Contain s vitreo u s h u mor M a intai n s s h ape of po s terio r e y e. R ef r acts ligh t r a ys. Is n ot c o n s tantly being pro d uced . It is not become replenished if some is Los t . Posterior Chamber of Eye Posterior Chamb er Mrs. Soumya. M 35

36. The vitreous chamber is the largest of the three chambers and is located behind the lens and in front of the optic nerve. This chamber is filled with a thick, clear gel-like substance called the  vitreous humor  (also vitreous body).  Vitreous Chamber of Eye V itreo u s Chamb er Mrs. Soumya. M 36

37. Aqueous and Vitreous Humor Aqueous Humor is the clear liquid in the anterior chamber (front) of the eye. Aqueous humor is produced by the ciliary bodies and it flows from the posterior chamber through the pupil into the anterior chamber. Vitreous Humor is the clear gelatinous fluid in the posterior chamber (back 2/3) of the eye .   vitreous humour  is derived from embryonic mesenchyme cells, which degenerate after birth. Mrs. Soumya. M 37

38. Flow of Aqueous Humor Secreted by the cilliary bodies into the posterior chamber (between the iris and the lens). Flows from the posterior through the opening of the iris (pupil) into the anterior chamber Then flows through the trabecular meshwork into the canal of Schlemm Then flows through the aqueous veins unto the surface of the eye, where is functions, in part, as a lubricant. Mrs. Soumya. M 38

39. Tears Normal Tears Lubricant Protect from bacterial infections Contain an enzyme called lysozyme Reflect Tears Mostly water Back-up for irritation, emotions and dryness Mrs. Soumya. M 39

40. Make-Up of Normal Tears Mucin , which is a mucus like substance, produced by goblet cells that help adhere the tears to the eye and are produced deep inside the eyelids. Water , which makes up about 90% of the tear, is produced by the lacrimal glands located under the brow of the eye. Fatty oils called lipids , which are the outside layer, slow down the evaporation of the tears and are produced by the meibomian glands on the edge of the eyelids. Mrs. Soumya. M 40

41. Lacrim al gl a nd Th e l ac r i m a l g l ands a r e t h e s i te s of te a r pr o ducti o n.  T e a r s functi o n t o k ee p t h e c o njunc ti v a and c o rn e al e p i the li um m o i st and w ash a w a y for ei g n m a te r i al from th e eye . Acce s so r y st r uctures Mrs. Soumya. M 41 Lacrim al app a ratus Sec r etes and d r ains tear s fr om the e y e

42. Acce s so r y st r uctures Mrs. Soumya. M 42 Eye l ashes Ey el ash e s a r e short ha i rs of ey e that m a y occur i n d oub l e or tr i p l e r o ws.  The y functi o n t o pr o tec t th e ey e fr o m d e b r i s. Lash e s m a y a l so h a v e d i ffer e nt l e ngt h s and d i a me te r s t o one anothe r .

43. Acce s so r y st r uctures Mrs. Soumya. M 43 Conju nctiva Th e c o njunct i v a r e f e rs t o th e li n i ng of the eye . It has 2 pa r ts  P a l p e b r al con j unct i v a  B ul b ar con j unct i v a  It he l p s l ubr i cate th e ey e b y s e cr e t i ng muc o us, and s e r v e s as a pr o tect i v e ba r r i e r ag ai n mi cr o b e s.  It conta i ns m a n y gob l e t ce ll s w hich s e cr e t e a co m pon e nt of th e te a rs that b a t h th e e y e .

44. Acce s so r y st r uctures Mrs. Soumya. M 44 Eye l id Th e m a i n functi o n of th e eye li d i s t o pr o v i de t h e ey e with pr o tect i on. Ther e a r e s eve r al t ypes of g l ands i n the eye li ds , i nclud i ng t a r sal g l ands tha t p r o d uce a s e b a c e ous s e cr e t i on tha t r e sults i n an o il y surface of th e te a r f i l m to pr eve nt th e e v ap o r at i on of the nor m al te a r l a ye r .

45. Acce s so r y st r uctures Mrs. Soumya. M 45 Extraocula r Muscles R e c tu s do r s a lis R ectus v ent r alis R ectus med ialis R e c tu s late r alis Obli q us dor s alis Obli q us v ent r alis

46. Fun c tio n s o f Extrao c ular Musc l es Mrs. Soumya. M 46 IO SR IO / SR SR/IO SR IO LR MR MR LR SO I R  SO / L IR e ft and I R/ SO I R SO  Ri g ht. Th e r e maining tw o m MR u s c le s c o M R ntr o l th e adjustments i n v ol v ed i n c o u n te r acting head m o v ement. CO NV ER G E N CE  Thes e six m u scles r e sponsib l e f o r e y e m o v ement. F our r e ctus m u s c le s c o ntr o l th e m o v ement of th e e y e i n the four ca r di n al directions:  U p ,  D o wn,

47. PHYSIOLOGY OF EYE Mrs. Soumya. M 47

48. Visua l Pathway Mrs. Soumya. M 48 P at h w a y of LIGHT

49. The Optic Pathway Begins at the optic nerve. Impulses cross and partially split at the optic chiasm. After the chiasm, it becomes the optic tract. Lateral geniculate bodies (sensory way stations) Some fibers go to the colliculus (located in the mid brain) TI The other fibers fan out into the visual cortex which is located at the top and back of the brain. Mrs. Soumya. M 49

50. The Brain and Vision ( cont ) Temporal Lobes center for visual learning recognition by sight Midbrain -- Limbic sector emotional responses to visual stimuli Midbrain -- Superior Colliculus -- guides visual attention Mrs. Soumya. M 50

51. R e f r act i on i s t h e pheno me non w poss i b l e b y th e ey e as we l l as b l e nses. h i ch m a k e s i m a ge for m at i on y ca me r as and other syste m s of Th e eye , i s opt i ca ll y e qu i v a l e nt t o th e usual photog r aph i c ca me r a. Th e l e ns system of th e ey e i s co m pos e d of four r e f r act i v e i nterf a c e s. F o rm a tion of an Ima g e on the R etina. Th e l e ns system of th e ey e can focus an i m a ge on th e r e t i na. Th e i m a ge i s i n ve rt e d and r eve rs e d wit h r e sp e ct t o th e ob j e ct. H o we v e r , th e m i nd perc e i ve s ob j e cts i n the upr i gh t p o s i t i on b e cause th e b r a i n i s t r a i ned t o cons i d e r an i n ve rt e d i m a ge as the nor m a l . Refraction Mrs. Soumya. M 51

52. Ac c om m odation Mrs. Soumya. M 52 Th e pro c ess of changing the shape of th e len s w h ile fo c using on an obje c t is terme d as ac c ommodati o n. A t r est fo c used on dist ant objec t s, needs to increase fo c al powe r tha n f ocus on cl o se objec t s. Th e c i lia r y mu s c l es c o nt r a c t and re l ease tensi o n in the ligament s and th e l ens becom es rounder in c ase of cl o se objec t s.

53. Ther e a r e four t ypes of photop i g me nt s , one i n th e r o d s and one i n e ach of three t ypes of con e s.  Th e p i g me nt i n th e r o d s i s ca ll e d rho d op si n .  Rhodo ps i n abs o rbs a l l v i s i b l e w a ve l e ngt h s, so tha t r o ds pr o v i de v i s i on on l y i n shad e s of gr e y b y d e tect i ng d i ffer e nt i ntens i t ie s r ather tha n co l our s .  Th e three t ypes of con e s - red , gree n and blue ph o topsin , can r e spond s e l e ct ive l y to v a r i ous w a ve l e ngt h s of li ght, g i v i ng r i se t o co l our v i s i on. Photopigments Mrs. Soumya. M 53

54. Rhodopsin Mrs. Soumya. M 54 ed b y r h o d ops i n. le cu l e tig h t l y - pac k ed i n the bi l l i o n r h o d op s i n m ole cu les, um p hoton capture r ate Th e pho t on i s a b s o rb T he li g ht r ec e p t or mo dis k mem b r anes On e r o d c ontai n s 10 w h ic h ensures an optim Rhodopsi n has 2 c om p onents R etinal - V i ta m i n A a l d e h y de Opsi n - s i ng l e po l ypept i de conta i ning 7 t r ans me m b r ane do m a i ns

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56. V i tam i n A i s pre s ent both i n the cyto p l asm of the ro d s and i n the p i g ment l a y er of the r e tina. Th e r e fore, v i tam i n A i s norma l l y a l w a ys a v a il a b l e to form new r e t i nal when ne e d e d . Co nv er s e l y , whe n there i s e x c e ss r e t i nal i n the r e t i na, i t i s co n v er t e d ba c k i nto v i tam i n A, thu s re d uc i ng the am o unt of li g h t - s e nsiti v e p i g ment i n the r e t i na. N i ght bl i ndn e ss. Mrs. Soumya. M 56

57. Th e reti n a th e ref o re si g n a l s the br a in Li g h t st im u l a tion thr o u g h a n in h i b itory res p o n se i n vo l vi n g a s e ri e s of p h y si o l o g i cal re a ctio n s Acti o n p o te n tia l s, Only or i g i n ate i n t h e g a n g l i o n ce l ls, Th e first n e u ro n s i n t h e ch a i n th a t carry the vis u a l stimu l i to the br a i n . V is i o n occurs This p r o c e s s is calle d p h ot o tra n sducti o n . Phot o transduction Mrs. Soumya. M 57

58. N Mrs. Soumya. M 58 Astigmatis m – de f ecti v e cur v ature of th e corn e a or len s of th e e y e. Presb y o p i a – impai r ed vision of th e co r n e a or len s of the e y e, associated w i th a g ing. Hyperopi a – ca n ’ t see cl o se objects, r a ys of l i gh t focus be h in d r etina Myopia- ca n ’ t see f a r aw a y objects, r a ys of l i gh t focus i n front of the

59. The Miracle of Vision! Mrs. Soumya. M 59

60. TEACHER’S REFERENCE Tortora DJ. Principles of anatomy and physiology.14 th edition. England: John Wiley and sons publication; 2014. Mrs. Soumya. M 60

61. TEACHER’S REFERENCE Mrs. Soumya. M 61 Ghosh BD. Human anatomy for students: Jaypee publication ; 2007

62. STUDENT’S REFERENCE Mrs. Soumya. M 62 Chauracia BD. Human Anatomy. Volume 2.4 th edition. New Delhi: CBS publication; 2008.

63. STUDENT’S REFERENCE Ashalatha PR. Text book of anatomy and physiology for Nurses.2 nd edition: Jaypee publication; 2010. Mrs. Soumya. M 63

64. STUDENT’S REFERENCE Mrs. Soumya. M 64 Chauhan R. Anatomy for B.Sc. Nursing: APC Publication; 2007.

65. What is the primary (most powerful) focusing structure of the eye? cornea Mrs. Soumya. M 65

66. Which type of photoreceptor is best able to process bright light and color ? CONE CELLS Mrs. Soumya. M 66

67. Which eye structure determines a person’s eye color ? IRIS Mrs. Soumya. M 67

68. Which eye structure is comparable to the film of a camera because it senses light focused on it? RETINA Mrs. Soumya. M 68

69. What is the point of sharpest, most distinct visual acuity within the eye? fovea centralis Mrs. Soumya. M 69