• Ophthalmic Anatomy is the study of the eye
• The Orbit is a bony fossa separating the eye from the cranial cavity and surrounding structures
• The orbit's size, shape, and position are linked to visual activity and feeding behavior

Aspects of the orbit

• Depth contributes to protection and appearance
• Location governs the visual field

Eye position relative to midline:

• Dogs/cats: 10-20 degrees (enhanced binocular vision)
• Horse: 40 degrees (strong monocular vision)
• Ruminant: 50 degrees (strong monocular vision)
• Rabbits: up to 85 degrees

Orbit completeness:

• Complete orbit: horse, ruminants
• Open orbit: cat, dog, pig

Bones of the orbit (cat and dog)

• Dog: 5/6 bones
• Cat: 6 bones
• Orbital rim: frontal, lacrimal, maxilla, and zygomatic bones, plus a supraorbital ligament (smaller in cats)
• Incomplete floor: sphenoid and palatine bones

Bones of the orbit (equine)

• 5 bones (no maxilla)
• Orbital rim is made up of 4 bones (frontal, lacrimal, zygomatic, and temporal) and a Temporal replacing supraorbital ligament.
• Sphenoid and palatine are other bones

Bones of the orbit (bovine)

• 5 bones
• Orbital rim: frontal, lacrimal, and zygomatic bones without a ligament
• Complete bony rim, zygomatic and frontal are fused without a ligament
• Sphenoid and temporal contribute to the orbit

Orbital Foramina

• Ethmoidal (CN 5): ethmoidal nerve and vessels, branch of trigeminal nerve
• Optic canal (CN 2): optic nerve, internal ophthalmic artery
• Orbital fissure (CN 3, 4, 5, 6): oculomotor, trochlear, abducens, trigeminal (ophthalmic branch)
• Rostral alar foramen (CN 5): Trigeminal nerve (Maxillary branch, lower eyelid, lacrimal gland) found only with a round foramen → alar canal → rostral alar foramen
• Foramen orbitorotundum (cattle): Fusion of orbital fissure and foramen rotundum
• cavernous sinus/middle cranial fossa contains CN3, 4, 5 (ophthalmic and maxillary branch), 6

Orbital Fascia

• Thin, tough connective tissue lining the orbit, divided into three parts:
• Periorbita: Conical fibrous membrane enclosing globe, EOMs, vessels, nerves etc -Thicker laterally in animals with incomplete walls -Divides to merge with facial bone periosteum and tarsal plates -Contains smooth muscle for repositioning
• Fascia bulbi (Tenon's capsule): Connective tissue on the outer sclera, attaching near the corneoscleral junction and is continuous with the EOM fascia -Separated from sclera by Tenon's space (loose connective tissue).
• EOM Fascial Sheaths: Dense membranes attached loosely to muscles via trabeculae -Continuous with Tenon's capsule but not always considered part of it. -Three layers in dogs

Extraocular Muscles info

• The adipose tissue and 3 sheets of orbital fascia cushion the eye and muscles
• Birds and reptiles have little fat
• Orbital fat may position the globe in manatees
• Fat surrounds the optic nerve and separate from retractor muscles in dogs

Extraocular Muscles list

• Four recti, two oblique and retractor bulbi muscle (6 total)
• Dorsal, Ventral, Medial, Lateral
• Originate at orbital apex/annulus of Zinn
• insert ANTERIOR to the equator of globe
• Oblique muscles insert POSTERIOR to the equator and run via a pulley system - originate from medial orbital apex through a trochlea, pulling the dorsal globe medially and ventrally (intorsion). Superior (dorsal) oblique - originate near nasal of medial orbit, passing under, crossing ventral rectus, moving globe medially and dorsally (extorsion). -Ventral (inferior) oblique

Retractor Oculi Muscle

• Surrounds the optic nerve
• Retracts the globe into the orbit
• Is abducens

The nerve supply to the extra occular muscles

• Oculomotor nerve (CN III): innervates the dorsal, ventral, and medial recti, and ventral oblique muscles
• Abducens nerve (CN VI): innervates the lateral rectus and retractor oculi muscles
• Trochlear nerve (CN IV): innervates the dorsal oblique muscle
• LR6SO4 = (lateral rectus =abducens), (superior oblique = trochlear)

Eyelid info

• Eyelids form thin folds of skin continuous with facial skin.
• Palpebral fissure is the opening between the upper and lower lids
• The upper and lower eyelids meet at canthi (medial and lateral)
• Eyelid opening: relaxation of orbicularis oculi (close) muscle and contraction of levator palpebrae superioris (open) muscle.
• Closure: contraction of orbicularis oculi muscle.

Cilia info

• Dogs: Upper has 2-4 rows, lower has no cilia
• Cats: No cilia
• Horses: well defined Cilia on upper lid, absent on lower, lacriminal caruncle @ medial canthus
• Protects eyes from light, spread tear film, direct tear film and remove debris

Eyelid Histology Info

• outer skin layer
• orbicularis oculi muscle layer
• tarsus and stromal layer
• palpebral conjunctiva

Meibomian Glands Info

• Oily
• Part of eyelids
• Near lid magins
• Contribute to tear film
• 20 to 40 per lid in dogs, more in cats Holocrine gland
• Parasympathetic nerves

Conjunctiva Info

• Structure lining inner eye lids
• Transparent and very thin Zones: -palpebral -bulbar -conjunctival fornix

Goblet Cells Info

• Produce mucous
• Vary by species
• High density for Dogs = lower eyes, High for cats = front

CALT

    -arranged in superficial
    -with  superficial plexuses
     -tears. contains effector cells

Nictitating Membrane Info

Large fold of conjunctiva from the medial canthus over the anterior globe surface that is:

• Cartilaginous T-shaped plate(horizontal is parallel, rich is elastic free edge pigmented )
• Stronma supports glands and issues
• Covered nonkaratined layer
• Lg accessory lacrimal gland for each gland prominent accessory lacrimal gland: -serous in horses -mixed sereous in cats
• Cats cross bats are reveresesd haped
• Dogs have a crescent shape

Harderian Gland Info

• Only in pigments
• Function immuno defense
• Movemen= indirect

Lacrimal System Info

• Collects tears
• Pumped to upper and lower eye. Excess leads to a lower cu-de-sac.

Tear layer 3

Tears are required for: 1 is Optical integrity.

2Removal of foreign material.

• 3. Nutrition function / Anti microbal

• Thin oily layer protects from overproducing of tears

• Middle: Aqueus layer protects from bacteria, helps the epithelium with oxygen

• Mucin inner layer helps make surface for a fluid spread and lubrication

Eye Path

• vertiacal away frome eyelid = medial to canal and joins the lacrimal sack

Lacrimal GLAND

produces serous portion of tears Drains into fornik with small ducts Cholinergic stimulate the tears, and drugs reduce them

Globe Info

• 3 basic layers; Fibrous, Vasculature and nervous

Eyeball - size, shape, topography

Size variable due to unknown Three axis - post, trans vers, vertical

Optic Nerve

• Lies inferior and Lateral to the poster pole Blood from short to cillary arteries = travel interscholastically and enter @subcharade

Cornea Facts

• Is transparent, avascular
• Thickness measured via Sd oct Functions:
• Support intracoular const
• Has refraction
• Nourishment and cleansing by lids

Cornea Structure

• Is elliptica and Horizontal dia, thicker, the vertically it is, larger for ungulates
• Lacks pain
• Transparaenct non kertin with pre 24 layers
• basement with lamina = mitos

Surface Cells

• Has a mucro with small surface are for mucins to. attatch to it

Layers

• superiical
• basement and
• stomoal

Stromoal Structure

Transparent with planes, fix and wander

• Cells transform deeper more corneas more scar

Collagen

= most common, has a small sizes striated filbins _ vll are small fiver

Type ||: all are belive for

Tyoes | | | are for development, Proteo, giycoprtien Most are GAC, 75 per water hydrates its

Cornela Transparency

• With a small blood, in keratined,

• Stromo and is Hydo Ando with the Sensitvive to umou GAcs = water bidsg

• BOUWMA = thin cells, some animals

Cornela Endo

• basement

Comelum Endo

• lined up
• some is
• cell

Vessel Retina Information

• vessel are close to cilia
• have for choroid thin with ciliary, Long runs are long to body

Iris Information

• Hightly vascular

• Chorid @ciliary = attaches from

• Iris

• Diaphragm

• Size of pup varies for shape of pupil

• Function: control a pupil for small control size

Divison @irids

Front= pupially to zone The demarcation is a collare. Ciliary for zone with sinous artery

Borde cell

• types- fibroblast: cells processes and layers of melatocytes

Stromo cell of stromo

Collagen for fiber. Melo = lacent or oid

Sphinner muscles helps has 2 muscles- with fibres help -contricated help.

###Posterouis indal surface

2 x epitheal @ ant layer contous & Dilator

Ciliary Body Informtation

• The Heavily pigmented has to protect nutrition and wast. With accommodation
• Triangualar shape witt cord for chorid Has inesr side of cell with glass & outer cell factin sclera

Pars = divide as a cell - plocata: antiorty

And planao = post

Structure cell

inner not pigments with cubodial type

• Outer= cell @ unigulates cuboldiol type

###Cell and funtions

Non = later for cell surfacess

Stromal

• connect tissue with base level, fibre,
• Contrates with the support

Bird Infor

• ciliary msucles types are for skeletal muscles 2 types, at @ cometium = shape, #Bricke for change help. and is by muscle. Help with

Blood cell type

 Cilla, - and from cial and enters  around to vessel

The Uveala informaction

Choridial ( vessel ): vessels join and and the retina. Choridil also needs nutrients.

Les Info

• Cristal clear, and fun
• Help form image with
• less @6. diotors -total ey
• 12 for humans
• held by bodies @e quater
• helps to to retina: -lens _capsilie

Anterior

• a single layer cell contuses
• cell basements & cells @ squamous type

fiber information -

• has cell contouses
• zonule &
• small & some more

lens infomratio

• Lens cells the • In animal with • The vitre

Vessels cell of infomration

• A = not present- • Gac = helps

Acorn cell information

• the most