Download Ocular Odyssey

 Ocular Odyssey
 The Eyelashes and Beyond:
 Shane R. Kannarr, OD
 [email protected]
Ocular Appendages
Eyelids
Protect from light
Distribute tears
Key Anatomy
Meibomian glands
oil glands mark
the junction of skin and conjunctiva
Gray line—between eyelashes and glands
Punctum Lacrimale
Located superior and inferior nasally in both eyes
Drainage structure
Eyebrows
Protective
Keep old men busy
Conjunctiva
A thin mucous membrane that lines the eyelids and sclera forms a space called
the conjunctival sac
Palpebral—lining of the eyelids
Bulbar—lies in contact with the eyeball
Lacrimal Caruncle—medial angle colorless hairs/accessory lacrimal gland
Lacrimal System
Lacrimal Gland—
Orbital—larger section
Palpebral—smaller section
12 ducts in to the superior fornix
Numerous small accessory glands
Tears
Defense against microorganisms
Regulate epithelial turnover
Hormones to support lacrimal secretion/suppress immunology activity
Tears
Work to:
Keep the eye moist to aid in refraction
Lubricate with lipids for movement
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)
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
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
Why do you care?
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
The Eyeball
Tenon’s Capsule
Thin membrane that separates the eye from orbital fat
Eyeball Dimensions
Anterior-Cornea-1/6
Posterior-Sclera 5/6
24mm anterior to posterior diameter
Fibrous Layer
Cornea
Epithelium- 5 layers turns over every 7 days
Basement membrane
Bowman’s layer-merges with the stroma
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
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
Clear as can be
Sclera/Choriod
3 layers thick
1 mm thick
Choriod—thin lining of the inner surface of the sclera
Nourishes the outer retinal layer
Ciliary Body
Two sections
Pars Plicata-anterior ridges
Ciliary processes
Anterior secretes aqueos
Posterior-zonules
Pars Plana-smooth
Ciliary MuscleMoves the ciliary body forward for accomodation
Iris
Pupillary margin-around the pupil
Ciliary margin-root of the iris
2 major muscles
Sphinter-miosis
dilator-mydriasis
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
Aqueos Drainage
90% leaves by
Trabecular meshwork to
Canal of Schlemm to
Collector Channels to
Aqueos veins
Meets metabolic needs for avascular regions
Lens
4mm thick (thicker as we age)
15D of power (eye 58D)
Anterior and Posterior poles
Center points
Equator-circumference
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
Y sutures anterior are erect
Y sutures posterior are inverted
Lens cortex area with recently formed fibers
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
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
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
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
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
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
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
Superior Rectus-elevator
Inferior Rectus-depressor
Medial Rectus-adductor
Lateral Rectus-abductor
Inferior oblique-elevates/abducts/extorsion
Superior oblique-depresses/abducts/intorsion
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
Muscles/Innervation
Superior rectus-Oculomotor
Inferior rectus-Oculomotor
Medial rectus-Oculomotor
Inferior oblique-Oculomotor Lateral rectus-abducents
Superior Oblique-Trochlear
Blood Supply
Ophthalmic Artery
Branch of the Carotid
Veins
Superior and Inferior ophthalmic
2 anterior ciliary arteries go to each rectus muscle