1. Ocular Odyssey
The Eyelashes and
Beyond:

2. By Shane R. Kannarr,OD

3. Ocular Appendages Eyelids Protect from light Distribute tears
Key Anatomy
Meibomian glands
oil glands mark
the junction of skin and conjuctiva
Gray line—between eyelashes and glands

4. Punctum Lacrimale Located superior and inferior nasally in both eyes
Drainage structure
**Caruncula lacrimalis**

5. Eyebrows
Protective
Keep old men busy

6. Conjunctiva
A thin mucous membrane that lines the eyelids and sclera forms a space called the conjuctival sac
Palpebral—lining of the eyelids
Bulbar—lies in contact with the eyeball
Lacrimal Caruncle—medial angle colorless hairs/acessory lacrimal gland

7. Lacrimal System Lacrimal Gland— Orbital—larger section
Palpebral—smaller section
12 ducts in to the superior fornix
Numerous small accessory glands

8. Tears Contain: Lysozyme IgA Beta Lysin-bactericidal protein Which:
Defense against microorganisms
Regulate epithelial turnover
Hormones to support lacrimal secretion/suppress immonological activity

9. Tears Work to: Keep the eye moist to aid in refraction
Lubricate with lipids for movement

10. Tear Layers
Thin superficial oily layer secreted by the meibomian glands/sebaceous glands(Zeiss)/sweat(Moll)
Watery layer (lacrimal glands)
Mucin layer (conjunctival goblet and lacrimal)

11. Tear drainage Punctum lacrimale Sets atop the papilla lacrimalis
Superior and inferior
Lacrimal Canaliculi
Vertical and horizontal section 10mm long
Ampulla-union of the two

12. During blinking canaliculi are pulled medially and compressed to act as a pump
Lacrimal Sac
Situated in the lacrimal fossa
Nasolacrimal duct-connects lower end of the sac with the inferior meatus of the nose
Plica lacrimalis-keeps air out of nasolacrimal sac

13. Tear Circulation
Lids move tears over cornea/tears do not follow the lid
During sleep the orbicularis Oculi shortens the canaliculi dilating the lacrimal sac and pumping the tears off the eyes

14. The Eyeball Tenon’s Capsule
Thin membrane that seperates the eye from orbial fat
Eyeball Dimensions
Anterior-Cornea-1/6
Posterior-Sclera 5/6
24mm anterior to posterior diameter

15. Fibrous Layer Cornea Epithelium- 5 layers turns over every 7 days
Basement membrane
Bowman’s layer-merges with the stroma

16. Stroma 90% of the thickness Layers or Lamella Run at 90 degrees
Does not rejuvenate
Allows LASIK to work
Descmet’s membrane
Posterior surface basement membrane

17. Tidbits Endothelium-one layer thick Controls corneal hydration
Avascular-gets nutrients from the aqueous and O2 from tears and peripheral vessels
Major refractive surface
Clarity comes from even spacing/fluid is a problem

18. Tidbits Limbus-where cornea and sclera meet
Canal of Schlemm-around the eye at the corneascleral junction. Allows drainage through the trabecular meshwork
Scleral spur

20. Sclera/Choriod 3 layers thick 1 mm thick
Choriod—thin lining of the inner surface of the sclera
Nourishes the outer retinal layer

21. Ciliary Body Two sections Pars Plicata-anterior ridges
Ciliary processes
Anterior secretes aqueos
Posterior-zonules
Pars Plana-smooth
Ciliary Muscle-
Moves the ciliary body forward for accomodation

22. Iris Pupillary margin-around the pupil Ciliary margin-root of the iris
2 major muscles
Sphinter-miosis
dilator-mydriasis

23. Aqueous Flow Aqueous-clear fluid Formed by ciliary processes
Flows between the suspensory ligments through the pupil to the anterior chamber
Moves inferior/anterior to posterior superior
Anterior Chamber-behind the cornea in front of the iris
Posterior Chamber-lens to posterior surface of the iris

24. Aqueos Drainage 90% leaves by Trabecular meshwork to
Canal of Schlemm to
Collector Channels to
Aqueos veins
Meets metabolic needs for avascular regions

25. Lens 4mm thick (thicker as we age) 15D of power (eye 58D)
Anterior and Posterior poles
Center points
Equator-circumference

26. Lens “parts”
Capsule-chief function to mold the lens as the zonules contract
Lens epithelium- move metabolic materials in and out
Makes lens fibers
Lens Fibers
Embryonic-earliest fibers
Fetal
Adult forms after birth always changing

27. Y sutures anterior are erect
Y sutures posterior are inverted
Lens cortex area with recently formed fibers

28. Vitreous Body Occupies 4/5 of the eyeball
Between the lens and the retina
Hyloid fossa-depression for the lens
Dense cortex with a liquid center
98% water
Vitreous base-area where the retina attaches at the ciliary body/pars plana

29. The Retina
The nervous coat is the internal layer of the eyeball. Photochemical transduction creates nerve impulses that are transmitted to the brain for cortical processing. Purple in color in living individuals
Posterior portion is receptive and ends at the orra serrata
Anterior portion is nonreceptive

30. The Retina
Macula lutea-center of the posterior portion. Depressed in the center to form the fovea centralis
RPE-retinal pigmented epithelium single layer of cells Absorb light/aid in the turn over of photoreceptors(absorb light in an antireflective method which stops image degradation. Aid in blood retina barrier

31. Neural Retina Groups of neurons
Bipolar cells-contact cells to ganglion cells
Ganglion cells-second neurons carry info from retina through lamina cribosa
Photoreceptors-rods and cones
Horizontal cells-possible they integrate visual stimuli
Amacrine cells-excite lateral ganglion cells/modulators of photoreceptor signals

32. Retinal Layers 1) Pigmented Epithelium 2) Rods and Cones
3) External limiting membrane
4) Outer nuclear layer
5) Outer plexiform layer
6) Inner nuclear layer
7) Inner plexiform layer
8) Ganglion cells
9) Nerve Fiber layer
10) Internal limiting membrane

33. Lamina cribosa Posterior opening
One larger opening for the central retinal artery and vein
Increased IOP can cause bulging and a cupped disk
3 other opening for one each for:
Anterior Ciliary Arteries
Exit of Vortex Veins
Long and short ciliary nerves

34. 7 Bones of the Orbit Maxilla Palatine Zygomatic Sphenoid Frontal
Ethmoid
Lacrimal
Lateral strongest/floor weakest

35. Sinuses Ethmoidal Frontal Maxillary Sphenoid
Most common site of orbital cellulities

36. Visual Pathway
“The retina, the optic nerve, the optic chiasma, the optic tracts, the lateral geniculate bodies, the optic radiations, and the visual cortex (area 17) make up the pathway.”
From the Clinical Anatomy of the Eye” by Snell and Lemp

37. Tracing the Image Retina-Inferior nasal is Superior temporal
Optic Chiasma-Nasal crosses
Optic tract-Retinal fibers line up
Lateral Geniculate Body-relay and integration
Optic radiation
The retina turns light into an electrical nerve impulse

38. Musculature Primary Position-eye is straight ahead
Secondary-Up/down/lateral/medial
Tertiary- up and out/down and in ect.
Elevator-up
Depressor-down
Adduction-toward the midline
Abduction-away from the midline

39. Superior Rectus-elevator
Inferior Rectus-depressor
Medial Rectus-adductor
Lateral Rectus-abductor
Inferior oblique-elevates/abducts/extorsion
Superior oblique-depresses/abducts/intorsion

40. Innervation Cranial nerves II-Optic Vision III-Oculomotor
Raises eyelids/moves eyeball up/down/medial/contricts pupil/causes accomodation
IV Trochlear-assists in moving eyeball down and lateral
V Trigeminal-branch one is cornea
Adbucent-Moves eyeball laterally

41. Muscles/Innervation Superior rectus-Oculomotor
Inferior rectus-Oculomotor
Medial rectus-Oculomotor
Inferior oblique-Oculomotor Lateral rectus-abducents
Superior Oblique-Trochlear

42. Blood Supply Ophthalmic Artery Branch of the Carotid Veins
Superior and Inferior ophthalmic
2 anterior ciliary arteries go to each rectus muscle