Key Terminology & Definitions - EYE Flashcards
Fundus
Interior surface of the eye opposite the lens and includes the retina, optic disc, macula, fovea, and posterior pole.
Tigroid fundus
Normal fundus to which a deeply pigmented choroid gives the appearance of dark polygonal areas between the choroidal vessels, especially in the periphery.
Adnexal structures
Structures related to the eye, external to the globe - eyelids, nictitating membrane (third eyelid), lacrimal + accessory glands
Entropion
Internal rolling in of eyelid
Ectropion
External rolling out of the eyelid
Trichiasis
Eyelashes grow inwards toward the eye + rub against the cornea, the conjunctiva, and the inner surface of the eyelid, more than one misdirected cilia (congenital defect)
Distichia
Abnormal hairs arising from the Meibomian gland and exiting out of the eyelid margin
Ectopic cilia
Abnormal hairs arising from the Meibomian gland but exiting out of the palpebral conjunctiva, common in dogs
Trichomegaly
Excessively large cilia
Blepharitis
Inflammation of the eyelids +/- conjunctivitis - general/local
Meibomian glands
Run along inside of conjunctiva (sebaceous glands)
Chalazion/meibomianitis
Sterile granulomatous inflammation in response to the leakage of Meibomian secretion
Sty
Suppurative inflammation of the adnexal glands
Prolapsed third eyelid
Also known as cherry eye - pathognomic appearance, due to loosening of / congenital laxity in connective tissue anchoring the nictitans gland to the cartilage of the third eyelid - gland moves
Immune-mediated keratoconjunctivitis sicca (KCS)
Body recognises self-antigens in lacrimal gland -> dry eye
Schirmer tear test (STT)
Diagnostic in dogs for immune-mediated keratoconjunctivitis sicca (KCS), checks tear production
Dacryoadenitis
Inflammation of lacrimal gland - result from involvement in orbital cellulitis/orbital trauma from severe intraocular inflammation/incidental involvement in systemic disease
Retained spectacles
When spectacle doesn’t come off w/ reptile’s shed skin
Does the cornea have blood vessels?
No = no leucocytes, can’t truly undergo primary inflammation
Corneal oedema
Hazy blue-white material on lesion
Corneal endothelium function
Pumps fluid from cornea into anterior chamber, against osmotic gradient - wants to maintain partly dehydrated state of cornea to maintain transparency
Limbal disease
Occurs rapidly after injury - results from imbibition of lacrimal water through damage corneal epithelium absorption of anterior chamber water at site of endothelium or failure of pump
Red corneal opacity
Blood vessels
Blue corneal opacity
Oedema (water)
Crystalline white corneal opacity
Lipid
Black corneal opacity
Pigment
Corneal ulceration
Loss of epithelium - can have loss of stroma + Descemet’s membrane -> interaction of growth factors, leucocytes, cytokines within epithelium, stroma
Normal corneal epithelium
Stratified squamous epithelium
Kerato-
Cornea
Malacia
Abnormal softening of a biological tissue
Keratomalacia
Melting ulcer
Descemetocele
Stromal liquefaction that reaches Descemet’s membrane -> forward bulging of Descemet’s membrane, can heal with fibrin plugs from aq humour
Feline herpesvirus (FHV-1)
Most common cause of superficial corneal ulcers in cats = infectious (dogs = non-infectious)
Corneal sequestrum
A piece of cornea that has died off and is taking on a brownish discolouration.
Spontaneous Chronic Corneal Epithelial Deficit (SCCED)
Clinical syndrome - distinctive, characterised by shallow central corneal erosion w/ scant oedema, no vascularisation initially
Persistent pupillary membrane (PPM)
Failure of anterior chamber - goes from fibrovascular mesenchyme to atrophy; persistence of membranous tissues (connective tissues + blood vessels not regressed completely) (congenital disease)
Uveal cysts
Fluid accumulation within iris or ciliary body - common in old dogs, less common in old cats, seen in horses
Hypopyon
Inflammatory cells in the anterior chamber of the eye. It is an exudate rich in white blood cells, seen in the anterior chamber, usually accompanied by redness of the conjunctiva and the underlying episclera. (Purulent material)
Uveitis
Inflammation of uveal tract (iris. ciliary body, choroid), results from ocular trauma, noxious chemicals, infectious agents, neoplasia/immunologic events
Blepharospasm
Twitching of eye
Synechiae
Adhesions that are formed between adjacent structures within the eye usually as a result of inflammation - could be adhesion of iris to cornea
Hyphaema
Collection of blood inside front of eye between cornea and iris - bleeding within eye, indicates breakdown of blood-aqueous barrier
Miosis
Contraction of pupil stimulated due to inflammatory mediators within the eye
Aqueous flare
Serous effusion - particles (proteins) within anterior chamber that shouldn’t be there, light picks up the particles and reflects the back
Serous uveitis
Protein-rich fluid exudation, sometimes with fibrin, immigration of neutrophils in the iris.
Protein-rich fluid readily percolates (filters) through the loose stroma to enter the anterior chamber ->aqueous flare.
Suppurative uveitis
Reflects a bacterial pathogenesis.
Usually bilateral when it is a reflection of haematogenous localisation.
Can see clumps of material adhering to the corneal endothelium as keratic precipitates or settling eventually as hypopyon (inflammatory cells within anterior chamber), so you can see clumps of neutrophils in there.
Granulomatous uveitis
Characterised by granulomatous inflammation and lymphoplasmacytic uveitis. Most common type of uveitis encountered in enucleated globes
Rubeosis iridis
Abnormal neovascularisation of iris
Endophthalmitis
Purulent inflammation of the intraocular fluids (vitreous and aqueous) usually due to infection - of the retina (inner layers + chambers)
Immune privilege
Limited local immune and inflammatory responses to preserve vision. Body doesn’t react to antigens
Glaucoma
Pathophysiologic state characterised by an increase in intraocular pressure sufficient to cause functionally significant injury to the optic nerve and retina (flow of fluid through ciliary body + out through trabecular meshwork)
= Decreased drainage of fluid
Buphthalmia
(Buphalos/megaloglobus) Increased globe size, occurs with corneal stretching -> rents in Descemet’s membrane due to inc in pressure, visible as corneal striae
Len subluxation/luxation
Lens can’t bulge so comes loose/dislocated w/ enlarged eye
Phthisis bulbi
Pressure-induced atophy of ciliary processes -> dec aqueous production -> dec globe size
Scleral thinning
Eye is getting bigger + stretching -> sclera stretches + thins
Hypotony
Low intraocular pressure (IOP)
Mydriasis
Dilated/larger pupil
Cupping of optic disc
Pathogonomic lesion of glaucoma (its absence doesn’t rule out glaucoma)
Primary glaucoma
Open/normal angle (human glaucoma) or narrow/closed angle (veterinary patients) - due to pectinate ligament dysplasia
Secondary glaucoma
Blockage somewhere along aqueous humour pathway
Iris bombe
Bowing of iris due to collection of aqueous humour in posterior chamber (secondary glaucoma)
Pectinate ligament dysplasia
Abnormal arrangement of pectinate fibres, if angle >75% = inc risk of developing glaucoma/passing it to the next generation
Microphakia
Small lens
Senile nuclear sclerosis
Arises with age - continual production of lens epithelial cells leading to compression of lens nucleus, nucleus appears blue/grey
Cataracts
An opacification of the normally optically clear lens or its capsule, most common disorder of lens
Subluxation
Partial displacement of lens, from hyaloid fossa or central visual axis
Luxation
Total displacement from hyaloid fossa into the anterior chamber vitreous - lens may damage the corneal endothelium/vitreous -? oedema + liquefaction
Retinal detachment
Separation of the retinal pigment epithelium (RPE) and the neurosensory retina (photoreceptors) by cleaving its photoreceptors from their interdigitations w/retinal pigment epithelium (developmental condition)
Coloboma
Area of hypoplasia = hole/hollowed out in one of the structures of the eye, such as the iris, retina, choroid, or optic disc
Collie eye anomaly/choroidal hypoplasia
Abnormal mesodermal differential due to deletion of NEHJ-1 gene, optic nerve head coloboma, retinal detachment + posterior segment haemorrhage (developmental condition)
Retinal degeneration
Extensive loss + thinning of outer plexiform layer -> blending of two nuclear layers
Chorioretinitis
Unlikely to have inflammation of the retina without having inflammation of the choroid
Sudden acquired retinal degeneration syndrome
Enigmatic (mysterious), rapidly progressing, photoreceptor degeneration - histologically identical to inherited progressive retinal atrophies, rapid photoreceptor apoptosis -> loss of vision, dogs between 6-9 years, more common in females
Chalazions
Glands within adenoma burst + see accumulation of macrophages + lipid association (meibomian gland becomes blocked)
Squamous cell carcinoma
Arises from conjunctive epithelium of limbus, third eyelid in cattle, horses, cats + dogs, develops through premalignant stages epidermal plaques and papilloma (from actinic dermatitis) - carcinoma in situ -> invasive carcinoma, fully developed carcinoma invades across BM
Benign melanocytoma
Originate in the skin at the eyelid margin, deep within the limbus, in the anterior uvea + within the choroid
Locally invasive + potentially metastatic melanomas
Occur in the conjunctiva, rarely within the anterior uvea
Ophthalmia
Globe of eye too large = indicator of glaucoma
Corneal endothelium
Epithelial layer responsible for maintaining the dehydration of the cornea when the epithelial layer is injured due to uveitis/glaucoma/direct injuries/genetic malfunctions -? cornea becomes oedematous -> haze/opacity
Keratitis
Presence of inflammatory cells within cornea
Keratinocytes
Long, spindle/mesenchymal cells of corneal stroma
Goniodysgenesis
Cocker Spaniels predisposed (autosomal-recessive condition) - associated with defective drainage angle (pectinate ligament never rarified to the point that it should be in development) -> 1^y glaucoma
Lamina cribrosa
Band of eosinophilic fibres within the optic nerve head
Optic nerve head
One of the most senstive places in globe - when aq drainage is impeded, pressure pushes on delicate neural tissue + starts to cavitate inflammatory cells activated from microglial cells (residents of CNS), start to phagocytes tissue, optic nerve head cup (pretty much pathognomic of glaucoma)
Ciliary body
Functions to hold up the lens, should be triangular on histo
Limbus
Junction of peripheral cornea and anterior sclera
Diffuse iris melanoma
Most common primary occular neoplasm in cat + common cause of secondary glaucoma
Cortical cataract
Lamellar pattern on cortex - fibres have become liquefied - have less fibres degenerate + cause an opacity if they aren’t perfectly arranged + healthy (can’t stay clear)
Nuclear cataract
Similar histologically to cortical cataract but harder to identify
Subcapsular cataracts
Migration/proliferation of cells along lens/posterior capsule where they shouldn’t be, may even deposit fibrous matrix in some cases
Panophthalmitis
When all layers of eye including fibrous tunic + orbit are affected
Morgadnian globule
Lesion of cataracts - when lens fibres swell + become more distinct + individualised. If identified with a nucleus = bladder cells
Corpora nigra
Normal structures within the horse’s eye, are seen suspended from the pupil margin. They are believed to be involved in reducing glare from bright light to improve the horse’s vision.
