Eyelid anatomy and physiology

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1. Anatomy and Physiology of Eyelid Dr. Najara Thapa 1 st year Resident LEI, NAMS

2. OBJECTIVEs To know the process of development of lid structures and the associated developmental defects. To understand the anatomical features and related clinical aspects of eyelid. To have the overview of the physiological aspect of lid structures.

3. contents

4. Introduction The eyelids are the mobile tissue in front of the eyeballs. (ocular appendages) Upper and lower eyelid Functions: Act as shutters protecting eyes from injuries and excessive light Spread the tear film over the cornea and conjunctiva Contribute to the facial feature Information regarding the state of wakefulness and attention

5. Embryology of eyelid Develops from folds of surface ectoderm above and below the developing cornea. The folds enlarge and fuse with each other by 3 rd month A closed space, conjunctival sac is formed in front of the cornea The lid separation starts by 5 th month and completes by 7 th month of intrauterine life

6. 7 th week 8 th week 5-7 th month

7. Connective tissue and tarsal plate : from mesenchymal core. Orbicularis oculi muscle: From mesenchyme of 2 nd Pharyngeal arch. (12wks)

8. Eyelashes develop as epithelial buds from surface ectoderm. [ 1 st arise in upper lid] Glands of Moll and Zeis : from ciliary follicles. Meibomian glands : from columns of ectodermal cells in lid margin.

9. Gross Anatomy Extent Position of eyelids Parts of eyelids Canthi Eyelids Margin Eyelashes Palpebral Aperture

10. Extent: Upper lid: eyebrows to the free margin Lower lid: merges to skin of the cheek below Position of the eyelids: Upper lid covers about 1/6th of the cornea (1.5-2 mm below superior corneal limbus) Lower lid margin just touches the cornea

11. Parts of eyelids: Orbital part horizontal sulcus(or forrow ). Tarsal part Additional folds in lower lid- nasojugal fold medially and the malar fold laterally. These folds limit the spread of blood downward from eyelids to cheek.

12. Canthi (sing. canthus) The upper and lower lids meet at an angle of about 60˚ medially and laterally forming canthus. lateral canthus: 5-7 mm medial to the orbit

13. Medial canthus: separated from globe by lacus lacrimalis . In the center is small pinkish elevation – caruncula lacrimalis . Lateral to it is semilunar fold called plica semilunaris . Racial variation- Mongoloid slant and antimongoloid slant

14. Eyelid Margin: 2 mm wide Covered by cutaneous epithelium Lacrimal papillae (at the center of which is lacrimal punctum) divides the margin into medial 1/6 th and lateral 5/6 th part

15. Eyelid margin contd.. Lacrimal part: medial to punctum rounded devoid of lashes and glands contains lacrimal canaliculi Ciliary part: lateral to punctum rounded anterior and sharp posterior border

16. Grey line: Represents the line of demarcation between the anterior portion of the eyelid formed by the skin and orbicularis muscle (ant. lamina) and the posterior formed by the tarsus and conjunctiva (post lamina). Histologically corresponds to most superficial portion of orbicularis oculi , muscle of Riolan , and to the avascular plane of lid. Surgically Important: For splitting of eyelid with minimal scarring.

17. Palpebral fissure or aperture Space between upper and lower eyelid margin Birth (mm) Adult (mm) horizontal 18-21 28-30 vertical 8 9-11

18. Eyelashes: 2-3 rows Upper lid: 100-150 (forward, upward and backward) Lower lid 50-75 (forward, downward and backward) Lifespan: 3-4 months

19. Trichiasis: Acquired misdirection of eyelashes Pseudotrichiasis : Seen in entropion Madarosis : Decrease in number of eyelashes. Lash Poliosis : Premature graying of the lashes Trichomegaly: Excessive eyelash growth

20. CONGENITAL /DEVELOPMENTAL ANOMALIES Coloboma of lid : notch in the edge of eyelid Cryptophthalmos : partial or complete loss of brows, palpebral fissure, lashes, conjuctiva

21. Ectropion: eversion of eyelid margin Entropion: eyelid margin inversion

22. Euryblepharon : vertical shortening and horizontal lengthening of eyelids. Epiblepharon : lower lid pretarsal muscle and skin ride above the lower lid margin to form a horizontal fold of tissue

23. Ankyloblepharon : partial or complete fusion of eyelids by webs of skin. Symblepharon : adhesion of lid to the gobe .

24. Distichiasis : extra rows of eyelashes Epicanthus: medial canthal fold

25. Blepherophimosis : condition in which palpebral fissure appear to be smaller. Ptosis : drooping of upper lid.

26. Layers of Eyelids

27. Skin Thinnest in the body contains the usual adnexal structures: fine hairs, sebaceous & sweat glands Microscopically epidermis and dermis

28. Subcutaneous Tissue Loose connective tissue arrangement Rich in elastic fibres No fat Applied anatomy - fluid from oedema or haemorrhage rapidly engorges the loose subcutaneous eyelid tissue.

29. Protractors ORBICULARIS OCULI Striated muscle, concentrically arranged Divided anatomically into 2 contiguous parts – Orbital Palpebral

30. Orbicularis oculi Origin Insertion Orbital part Anterior limb of medial canthal tendon Orbital process of frontal bone. Frontal process of maxillary bone infront of anterior lacrimal crest Forms continuous eclipse and inserts just below the point of origin. Pretarsal part Deep origin : medially posterior lacrimal crest ( forms Horners muscle .) Superficial origin : anterior limb of medial canthal tendon Lateral canthal tendon Preseptal part Upper and lower border of medial canthal tendon Lateral palpebral raphe

31. Palpebral portion Pretarsal part Preseptal part Functions for both involuntary and voluntary eyelid movements (blink). Deep heads of pretarsal orbicularis muscle fuse to form a prominent bundle of fibres , near the common canaliculus known as Horner muscle Play a role in drainage of tears (pumping mechanism).

32. Orbital portion Primarily involved in forced eyelid closure Orbicularis fiber extends to lid margin , where there is a small bundle of straited muscle called muscle of Riolan . (forms gray line, play role in meiomian gland discharge, blinking and position of eyelashes).

33. Nerve supply : Temporal and zygomatic branch of facial nerve. APPLIED : Paralysis of the orbicularis oculi muscle leads to : Lagopthalmous - inadequate closure of lids.

34. Orbital Septum thin, fibrous framework, membranous sheet begins anatomically at the arcus marginalis along the orbital rim Separates the eyelid from the contents of orbital cavity

35. Perforated by: Nerves and vessels that exit form the orbital cavity Aponeurosis of levator muscle in upper lid Expansion of the inferior rectus in the lower lid

36. Functions: Holds the orbital fat in position Barrier function- prevent the transmission of infection from lids to orbital cavity and viceversa During the normal ageing process the thining of the septum and the laxity of the orbicularis muscle causes the anterior herniation of the orbital fat.

37. Orbital Fat Upper lid : 2 fat pockets Lower lid : 3 fat pockets Landmark for elective eyelid surgery and lid laceration surgery

38. Retractors Upper lid: Levator palpebrae superioris along with Mullers muscle Lower lid: Capsulopalpebral fascia

39. Levator Palpebrae Superioris Origin: apex of the orbit, just above the annulus of Zinn. Extends as aponeurosis, in upper lid posterior to orbital septum and inserts into anterior surface of tarsus. Muscle = 40mm, Aponeurosis = 14-20mm. Medial and lateral expansion of aponeurosis forms horns . Thin sheet of smooth muscle arise from its inferior surface – superior tarsal muscle / Muller muscle .

40. Insertion : Lateral horn: lateral orbital tubercle. Medial horn : posterior lacrimal crest. In center, aponeurosis continues towards the tarsus and divides into an anterior and posterior portion. (Anterior portion inserts into septa between pretarsal orbicularis and skin – forming upper lid crease.)

41. Whitnall’s ligament (superior transverse ligament) Sleeve of elastic fibers around the LPS muscle located in the area of transition from levator muscle to levator aponeurosis . Functions of whitnall’s ligament: Primarily as a suspensory support for the upper eyelid and the superior orbital tissues. Also act as a fulcrum for the levator

42. Muller muscle : Originates from under-surface of LPS aponeurosis approx. at the level of Whitnall ligament. 12-14mm Inserts in superior tarsal margin of upper eyelid. Provides 2mm elevation of upper eye lid.

43. Action of LPS: raises upper lid Nerve supply : LPS : superior branch of oculomotor Superior tarsal : sympathetic nerves from cervical ganglion APPLIED: Fear and excitement causes contraction of superior tarsal leading to further elevation of eyelid.

44. Applied anatomy Disinsertion of lower lid retractors from tarsus may lead to spastic entropion . Paralysis of LPS [ 3 rd nerve palsy, myasthenia]: Ptosis Loss of superior palpebral fold and Horizontal furrows

45. contd … Paralysis of superior tarsal muscle [ lesion of cervical sympathetic ganglion]: Mild ptosis When associated with miosis , anhydrosis – Horner’s syndrome.

46. Retractors of lower eyelid Capsulopalpebral fascia : Originates from terminal muscle fiber of inferior rectus muscle. Forms lockwood ligament.

47. Tarsal plate : Dense fibrous tissue. Gives shape and firmness to eyelid. In upper lid – larger -- crescentic --11mm in center --Orbital septum and smooth muscle fiber of LPS attached to its upper edge .

48. In lower lid –smaller --4mm at centre --Orbital septum attached to its lower edge. Medially , MPL attaches it to lacrimal crest and frontal process of maxilla. Laterally , LPL attaches it to marginal tubercle on orbital margin formed by zygomatic bone.

49. Conjunctiva Thin mucous membrane lining the eyelids(posterior layer of lids). Composed of non keratinizing squamous epithelium Contains - 1. goblet cells 2. accessary lacrimal glands ( Wolfring and Krause ) At the margin of eyelid – continues into skin along posterior margin of tarsal gland.

50. Subtarsal sulcus : shallow groove on the back of the lid, 2mm from posterior edge of lid margin. APPLIED : site for FB impaction.

51. GLANDS Tarsal or meibomian glands Ciliary glands of Moll Sebaceous glands of Zeis

52. Tarsal ( meibomian ) gland modified holocrine sebaceous glands. lies within the tarsal plates; single row Upper eyelid (30-40); Lower eyelid (20-30). Vertically parallel to each other. The orifice lies just infront of the posterior edge of the lid margin---marks the junction between the skin and conjunctiva.

53. Applied anatomy : a)Meibomian gland dysfunction : dry eye. b) Chalazion or tarsal cyst: -chronic non infectious inflammatory granuloma of meibomian gland. c)Internal hordeolum : -suppurative inflammation of meibomian gland secondary to infection of chalazion

54. Glands of moll modified sweat glands lie in the lid margin between the cilia. more numerous in lower lid. the duct opens between cilia into ciliary follicles or into the glands of Zeis .

55. Gland of zeis modified sebaceous gland. Consists 2-3 lobules. discharge directly into the eyelash follicles. Its secretion (sebum) prevents the lashes from becoming dry and brittle. Applied anatomy: External hordeolum / Stye : Suppurative inflammation of Zeis gland or lash follicle.

56. Accessory glands of wolfring Present along upper border of superior tarsus and lower border of inferior tarsus. 2-5 in upper lid 2-3 in lower lid

57. Fascial spaces Subcutaneous space Submuscular space Pretarsal space Preseptal space

58. Blood supply Internal carotid artery : By ophthalmic artery and its branches (supraorbital and lacrimal) 2. External carotid artery: By arteries of the face (angular and temporal)

59. LATERAL PALPREBRL ARTERY (branch of lacrimal artery) MEDIAL PALPREBRAL ARTERY (direct branch of ophthalmic artery) Each artery divides into 2 branch --- forming 2 arches in upper eyelid: Peripheral arterial arcade Marginal arterial arcade. In lower eyelid : Only single arterial arch

60. Venous Drainage Preseptal Medially: angular vein Internal Jugular Vein Laterally: superficial temporal vein External Jugular Vein Postseptal Orbital veins and facial veins Pterygoid plexus

61. Lymphatic Drainage Lower lid and medial portion drains into submandibular lymph node. Upper lid and lateral portion drains into superficial preauricular lymph node Deeper cervical nodes.

62. Nerve Supply of Eyelids Motor Nerve Supply: Orbicularis oculi muscle - facial nerve (temporal & zygomatic branches) Levator palpebrae superioris - superior division of oculomotor nerve Autonomic Nerve Supply: Superior and inferior tarsal muscle - sympathetic nerve fibers from superior cervical ganglion .

63. upper eyelid - supraorbital, supratrochlear & lacrimal nerves (ophthalmic division) lateral portion of upper eyelid & temple - zygomaticotemporal branch of the maxillary nerve extreme medial portion of both upper & lower eyelid - infratrochlear nerve lower eyelid - infraorbital nerve (maxillary division) lateral portion of lower eyelid - zygomaticofacial branch of the maxillary nerve Sensory supply:

64. Physiology of Eyelid Movements

65. OPENING MOVEMENTS : In upper lid: LPS : primary elevator Frontalis : accessory elevator Superior palpebral muscle of Muller’s : long term adjustment of upper lid in position. In lower lid : Elastic recoil of lower eyelid tissue Traction exerted by attachment of inferior rectus to inferior tarsus. Inferior palpebral muscle .

66. CLOSING MOVEMENTS : Orbicularis oculi Pretarsal fibres : spontaneous blinking and tactile corneal reflex. Preseptal fibres : voluntary blinking and sustained activity. Orbital fibres : forceful closure of eyelid in association with all other fibres . Blepherospasm : involuntary sustained and forcible eyelid closure.

67. PEERING : Act of looking at some object with great interest. Can be voluntarily inhibited. Upper lid moves 2.5mm down and lower lid moves 2.5mm down and 1mm medially.

68. BLINKING : Co – ordinated closing and opening movements of eyelids. 2 types : Voluntary Involuntary spontaneous Reflex blink

69. 1. Voluntary Blinking Coordinated closure and opening of eyelids, carried out as a willed act in both eyes. - Produced by simultaneous contraction of palpebral and orbital part of orbicularis muscle.

70. 2. Spontaneous blinking : Occurs without any obvious stimulus. Occurs at frequent interval Infrequent during first few months of life. Rate: 12-20 /minute, duration: 130 msec

71. Events : Relaxation of levator . Contraction of preseptal fibers of orbicularis against minimal resistance. Synchronous activity occurs in pretarsal and upper lid reaches the limit of its downward excursion. Electrical activity ceases in orbicularis and the concomitant action starts in levator .

72. As the upper lid move vertically downward , the lower lid moves medially in horizontal direction . When upper lid touches the lower lid, the downward movement of upper lid is transmitted to lower lid. After contact, the lower lid moves downward with upper lid. Pupil moves upward just before the upper lid reaches the center of pupil { Bell’s phenomenon}.

73. 3. Reflex blinking : Co –ordinated closing and opening movements of eyelid in response to some direct stimulus. Types : Tactile Optic Auditory Stretch reflex blinking.

74. Hering’s law Law of equal innervation. States “ levator of two eyes act as yoke muscle i. e. get equal innevation during contraction” . Causes symmetric opening movements.

75. Sherrington’s law Law of reciprocal innervation. Levator and orbicularis oculi get reciprocal innervation during eyelid movement. i. e. opening movement of levator gets maximum innervation while orbicularis is inhibited and gets minimum innervation and vice versa.

76. Bell’s phenomenon Co ordinated reflex between facial and oculomotor nuclei , thus on closure of eyelids , eyeball rotates upward and outward. Inverse Bell’s phenomenon – when eyeball rotates downward and outward on eyelid closure.

77. During sleep Tonic muscular activity in the orbicularis combined with a simultaneous inhibition of tonus in the levator

78. References Fundamentals and principals of ophthalmology, AAO, 2016-2017 Clinical anatomy of eye , Richard S. Snell , Michaell A. Lemp [2 nd edition] Wolff’s Anatomy of eye and orbit , eighth edition Clinical Opthalmology – Jack J Kanski and Brad bowling , seventh edition Anatomy and Physiology of Eye, A. K. Khurana, 3 rd edition Parson’s Diseases of the Eye ,22 nd edition Internet sources

79. THANKYOU !!