Term
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Definition
Spherical
Anterior-Posterior (Rostro-caudal) compression in horse and cow |
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Term
| Orientation points of the eye |
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Definition
Poles
Optic Axis
Equator
Meridian(s) |
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Term
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Definition
Cornea
Anterior Chamber
Iris
Posterior Chamber
Lens
Wall has three layers/tunics
Optic Nerve CNII |
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Term
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Definition
External/Fibrous Layer
Middle/Vascular Layer
Internal/Nervous Layer |
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Term
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Definition
Gives shape to eyeball
Resists internal pressure of material in chambers
Gives shape to eyeball
Resists internal pressure of material in chambers
Gives shape to eyeball
Resists internal pressure of material in chambers
Gives shape to eyeball
Resists internal pressure of material in chambers
Gives shape to eyeball
Resists internal pressure of material in chambers
Protective
Complete
Two Parts: Cornea and Sclera (Meet at Limbus) |
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Term
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Definition
Blood Vessels
Smooth Muscle
Nutrient Supply
Control lens and pupil shape and size
Three parts: Choroid, Ciliary Body, Iris |
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Term
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Definition
Translation of visual signal into nerve impulses and transmission to brain
Parts: Retina, Optic Disc |
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Term
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Definition
part of Fibrous Tunic
Main Part: substantia propria
Anterior Epi continuous w/conjunctival epi – contains sensitive nerves, responsible for Corneal reflex
Posterior Epi continuous with anterior surface of iris – supplies nutrients to cornea |
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Term
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Definition
Part of the Fibrous Tunic
Opaque/White: Collagenous and elastic fibres
Entry points for nerves and vessels
Attachments for ocular muscles anterior to equator |
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Term
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Definition
Part of Vascular Tunic
Lines sclera from optic nerve to limbus
Blood vessels in pigmented connective tissue - can be seen with ophthalmascope, supplies nervous tunic
Tapetum Lucidum |
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Term
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Definition
Dorsal avascular layer between capillaries and larger vessels
Reflective Area |
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Term
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Definition
Thickening of tunic area at level of limbus
Thickened ridged ring around lens
Radial ridges (Ciliary Processes) extend zonular fibres to lens
Suspend lens
Smooth muscles control alter lens shape and focusing |
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Term
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Definition
Projects into cavity behind cornea
Easily visible
Pupil: Smooth sphincter (constrictor - parasympathetic) and radial dilator (sympathetic) muscles control pupil size
Shape depends on fibre arrangement (Slit-cats, ovoid-ruminants/horse)
Iridic Granules (horse, ruminant) |
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Term
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Definition
Projections from dorsal border across pupil in Horse, ruminant
Unknown function |
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Term
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Definition
Part of Nervous Tunic
Lines choroid from optic nerve to pupillary margin
pars optica retinae
pars ceca retinae
Ora serrata - connection between two |
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Term
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Definition
Posterior 2/3 of retina can be reached by light
Contains receptor cells |
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Term
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Definition
Anterior 1/3 of retina has no receptors
Continues onto iris |
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Term
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Definition
Choroid
Pigmented Epithelium (No pigment over tapetum)
Neuroepithelial Cells (Receptor Cells: Rods, Cones)
Bipolar Ganglion Cells
Multipolar Ganglion Cells (Axons pass to optic disc and form optic nerve CNII) |
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Term
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Definition
Part of Nervous Tunic
Entry of Optic Nerve (CN II): No receptor cells, Blind Spot
Easily seen with opthalmoscope |
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Term
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Definition
Focussing of Light through structure of eyeball
Cornea: Major role in refraction of light
Aqueous Humor in Anterior and Posterior Chambers
Lens
Vitreous Body/Chamber |
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Term
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Definition
Clear, watery. Maintains ocular pressure
Continually produced by ciliary process cells
Enter posterior chamber
Enters anterior chamber via pupil
Exits via iridocorneal (drainage) angle
Venous sinuses in sclera
Drainage = Production
Constant Intraocular Pressure
Failure to drain = Glaucoma |
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Term
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Definition
Ability of lens to change power – through ciliary muscles
Thick Lens, close vision
muscles CONSTRICT and RELAX Zonular Fibers
Thin lense, far vision
muscles RELAX and TIGHTENS Zonular Fibers
Less accommodation than in humans |
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Term
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Definition
Maintains contact between retina and choroid
Gel-like mass, High water content = vitreous humor |
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Term
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Definition
Ophthalmoscope: Direct visualisation
Ultrasound: Cheap, simple, Allows assessment of retina
CT and MRI may be useful, but more for orbital disease |
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Term
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Definition
Orbit
Orbital Fasciae
3 conical layers
Ocular Muscles
Eyelids
Conjunctiva
Lacrimal Apparatus |
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Term
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Definition
“Conical” cavity on lateral side of skull
Frontal, Lacrimal and Zygomatic Bones
Orbital ligament in carnivores and pig
Zygomatic process horse and ruminant |
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Term
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Definition
Optic Canal
Orbital Fissure
Ethmoidal Foraminae
Lacrimal Sac Fossa: Leads to nasolacrimal duct |
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Term
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Definition
4 Rectus Muscles: Dorsal, Ventral, Medial, Lateral
2 Oblique Muscles: Dorsal, Ventral
Retractor Bulbi: Not in humans
Originate from optic canal area |
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Term
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Definition
True Eyelids: Palpebrae
Musculofibrous folds
Upper and lower lids
Meet at angles of eye AKA Commissures
Opening = Palpebral Fissure
3 layers: Skin, Musculofibrous, Mucous membrane = Palpebral Conjunctiva |
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Term
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Definition
Palpebral Conjunctiva: Lines lids
Bulbar Conjunctiva: Reflects over sclera, Epithelium anterior to cornea
Space between lids and eyeball: Conjunctival Sac
Medial elevation: Lacrimal Caruncle
Mucous Membrane |
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Term
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Definition
Conjunctival Fold: Central Cartilage, Conjunctiva on both sides, Not true eyelid
Retracted by smooth muscle: Orbitalis
Covers eyeball when retracted into orbit |
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Term
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Definition
Production of lacrimal fluid (tears): Protection, corneal nutrition
Glands: Lacrimal-Dorsolateral wall of orbut
Gland of 3rd Eyelid-Around base of 3rd eyelid cartilage, Deeper gland also in pigs and cattle, AKA Nictitans/Nictitating Gland |
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Term
| Dorsal Oblique Ocular Muscle |
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Definition
Wraps around trochlea (Cartilage in dorsomedial periorbita)
Pulley – changes angle of draw
Rotates dorsal eyeball medially |
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Term
| Ventral Oblique Ocular Muscle |
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Definition
Originates in ventromedial orbital wall
Rotates dorsal eyeball laterally |
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Term
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Definition
Inserts posterior to equator of eyeball
Muscular cone
Not present in humans |
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Term
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Definition
External Ophthalmic Artery (Branch from Maxillary a.)
Venous plexuses in periorbita |
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Term
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Definition
Innervates light receptors of retina: Vision
Meningeal Covering
Seen as optic disc |
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Term
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Definition
Enters via orbital fissure
Levator palpebrae m.
Dorsal, Medial and Ventral Recti mm.
Ventral Oblique m.
Retractor Bulbi (Part) |
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Term
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Definition
Via Orbital Fissure
Dorsal Oblique m. |
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Term
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Definition
Via Orbital Fissure
Retractor Bulbi m.
Lateral Rectus m. |
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Term
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Definition
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Term
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Definition
SENSATION
Ophthalmic Nerve
Maxillary Nerve |
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Term
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Definition
From Cranial Cervical Ganglion
Accompany arteries
Orbital muscle and pupillary dilator: Dilation (mydriasis) of pupil with fear, excitement, pain
Maintain opening of palpebral fissure
Loss of innervation: Horner’s Syndrome and Sunken eye, protrusion of 3rd eyelid, constriction of pupil |
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Term
| Parasympathetic Innervation |
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Definition
Travel with oculomotor
Synapse in ciliary ganglion
Innervate ciliary muscles and pupillary constrictor
Cause miosis (contraction) of pupil |
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Term
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Definition
| L and R optic nerves meet ventral to brain, Rostral to pituitary |
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Term
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Definition
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Term
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Definition
Pupillary Light Reflex
Subcortical reflexes (ie do not involve visual cortex) |
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Term
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Definition
Aversion response (eg blink, head movement) in response to sudden intense illumination of the eye
Testing CNII, part of midbrain, CNVII |
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Term
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Definition
separation of retina from pigment epithelium
means loss of blood supply to retina and rods/cones will start to die unless re-attachment is fairly rapid |
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Term
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Definition
Cones mostly in Fovea
Rods everywhere else
NOTHING in blind spot/optic disc |
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Term
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Definition
| protein that determines the wavelength of light detected |
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Term
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Definition
| Misalignment of the eyes, medially (Cn VI abducens) or laterally (Cn III occulomotor) |
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Term
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Definition
Closing of eye due to threat from physical stumuli (not light) ie. moving hand towards face quickly
CN VII tested with this |
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Term
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Definition
Test technique: Menace, Observation in environment, Visual tests
Test findings: Menace, Inability to negotiate new environment, oblivious to new activities
Neurological elements tested: CN II, Optical cortex, Associated effector systems |
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Term
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Definition
Test technique: Pupil size, Low light environment to stimulate pupil dilation, Light source from a distance and compare tapetal reflections
Test findings: Pupil size, Dilated equally
Neurological elements tested: CN II afferent, brainstem, Autonomic supply to the eye (CN III) |
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Term
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Definition
Test technique: PLR, Bright light into pupil, Not response of both tested and contralateral pupil
Test findings: PLR, Constriction of both tested and contralateral pupil
Neurological elements tested: CN II afferent, brainstem, Autonomic supply to the eye (CN III) |
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Term
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Definition
Test technique: Threatening movement towards eye
Test findings: Blink, Aversion of the head, Retraction of eyeball
Neurological elements tested: CN II afferent, VII efferent, cortex |
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Term
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Definition
Test technique: Stimulate skin of face, Medial / lateral canthus orbit, Cheek, Mandible
Test findings: Response to stimulus, Facial twitching, Head movement
Neurological elements tested: CN V afferent (Opthalmic, Maxillary, Mandibular branches), CN VII efferent |
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