Ophthalmology I shit Flashcards
eye shit
Identify the lens zonules in a eye ?
Identify the tapetum, choroid, retina and sclera in the eyeball ?
Globe
Within the globe - what does the fibrous tunic, neural tunic and the vascular tunic comprise ?
Globe = eyeball
Fibrous tunic
- sclera and cornea
- collagen dense connective tissue
Vascular tunic
- iris, ciliary body and choroid
- this comprises the vascular unit
Neural tunic
- ciliary , epithelium and retina
- the retina is continuous with the optic nerve
Transparent media
- cornea, aqueous lens and vitreous
Describe the orbit of the eye and ocular cone ?
The eye
Orbit
The bony socket of the skull in which the eye and its adnexa live
+ contents of bony socket
+ extraconal orbital tissue
Orbital cone
- extraocular muscles+ blood vessels + nerves
Eye embryology; Describe the structures which the ectoderm gives rise to ?
Eye embryology ectoderm gives rise to
Neuroectoderm
- optic bud
- optic vessicle
Ocular epithelial tissues = lens
Ectoderm also develops into the lens placode
Describe the development of the neuroectoderm ?
Neuroectoderm (neural tube)
Develops into the optic nerve and the retina
- optic bud, optic vessicle
Differentiation
Optic vessicle forms the optic cup
- collapses
- from the ectoderm becomes the retina
Lens vessicle
- from ectoderm becomes the lens
Corneal epithelium
- modification of ectoderm derived skin
- lens placode
What structures develop from mesoderm in the eye ?
Mesoderm
The mesoderm develops into the ocular subepithelial connective tissue
- vitreal
- vasscular tissue
- primary vitreous
The anterior chamber forms via regression of the mesoderm
- pupillary membrane from mesoderm
- tunica vasculosa lentis derived from mesoderm
- secondary vitreous derived from mesoderm
Describe the Iridocorneal angle ?
Iridocorneal angle
- located between the cornea and iris
- structure responsible for the outflow of aqueous humour from the anterior chamber
What is abnormal about this eye ?
What leads to this abnormality ?
- Dermoid; patch of skin on the surface of the globe
- Failure of ectoderm modification from skin to corneal epithelium.
- What is abnormal about the eye ?
- What leads to this type of abnormality ?
- Persistant papillary membrane
- abnormal iris type tissue in anterior chamber across the pupil.
- membranes may run up the back of cornea causing fibrosis and opacification. - Failure of complete regression of the anterior chamber mesoderm.
What is the adnexa ?
Adnexa
Accessory components of the eye
Lids - skin, muscle, senaceous glands, modified hairs and conjunctival linning
Conjunctiva - lines the lids, sclera and forms nictitans
Lacrimal appartus - tear glands and tear ducts.
Identify this disorder and its cause ?
Developmental condition = Simple entropion
The basic problem is the lid is too long
- rolled in lid margins (irritation as hair may contact cornea)
- may observe excessive lacrimation
- usually occurs on the lower lid
What is this condition and its cause ?
Ectropion developmental condition
Basically the lid is too long
- dose not cause as much irritation as entropion
- turned out lid margin, usually lower lid
Identify this condition and its causes ?
Trichiasis - developmental condition
Normal lid hairs growing in an abnormal direction and contacting the globe.
- tends to affect upper lids
- this occurs especially with age / southward migration of lid
- medial canthus
Identify this condition and its cause ?
Macropalpebral fissure
(developmental condition)
- excessive lid length
- lower entropion / ectropion
- upper trichiasis
- a combination of conditions all occuring at the same time
Identify this condition and its cause ?
Brachycephalic lid disease
(developmental condition)
Poor medial canthus conformation and medial entropion/trichiasis
- secondary changes with age
- a combination of trichiasis and entropion
- in brachy dogs (the bone length is reduced) same amount of skin causing rolling
+ secondary changes may occur due to chronic irritation eg. pigmentation.
Identify this condition and its cause ?
Distichiasis
(developmental condition)
Abnormal hair developing from the lid margins
Identify this condition and describe its causes ?
Ectopic cilia
(developmental condition)
Abnormal hairs erupting through the conjunctival lid surface
- classic in young dogs (severe pain)
- must be treated and removed
Identify this condition and describe its causes ?
Pyoderma
(inflammatory condition of eyelids)
- painful swelling of eye
- overactivity of the immune system, bacterial infection
- impetigo
- papules, pastules red and raised - with a white pus centre
- chronic exposure to moisture
Identify this condition and describe its causes ?
Allergy
(inflammation of eyelids)
- redness, discharge and swelling
- may be seasonal
Identify this condition and describe its causes ?
Meibomian adenitis
(immune mediated inflammation - eyelids)
- lumpy swelling along lid margins
- causes glands to become blocked via thick waxy secretions
- sebacious gland of eyelids release oils onto the cornea
- treat with a warm compress which may assist in removing discharge
- blockage leads to reduced tear film stability and decreased lipid secretion
identify this condition and its cause ?
Meibomian adenoma
(neoplastic condition)
Meibomian gland (sebaceous gland of the eye) = produces oils for the surface of the cornea.
- nodules protruding from the eyelid margin
- common tumour of older dogs
- treatment is via surgical removal
- benign
Identify this condition and its causes ?
Neoplasm of the lid
Potentially
- sarcoma
- carcinoma
- mast cell tumours
- requires an incisional biopsy
Describe the surgical principles of eyelid surgery ?
Eyelid surgery
Correction for ectropion, entropion and tumours
- 5.0 or 6.0 soft non absorbabable, polyglycolic acid suture
- cresents to roll out lid margin
- full thickness wedge 2-4 sides shorten lid or remove tumour
Describe the three potential causes of conjunctivitis ?
Conjunctivitis
Conjunctiva lines the inner surface of the eyelid and covers the first part of the eye.
Conjunctivitis is inflammation of the conjunctiva.
can be caused by
- immune mediated / dry eye
- allergy
- infection / cat
Identify this condition and describe its cause ?
Conjunctivitis Dry eye
Immune mediatedattacks the tear glands
- increased mucin production
- can be congenital in pups
- gunky discharging eye
- red inflammed
- common in dogs with most cases being immune mediated
Use a Schirmer tear test to identify - no tear production
Identify this condition and its cause ?
Conjunctivitis - allergy
- second most common cause of conjunctivitis in dogs
- often tied to atopic dermatitis
Schirmer tear test - normal
Identify this condition and its cause ?
Conjunctivitis - infection
- not common in dogs
- number one rule out in cats, very common in multi cat house holds
Describe the Nictitans and the possible reasons for a third eyelid flap ?
The nictitans “third eyelid”
Essentially a fold of conjunctiva with cartiliginous support in a T shape and tear gland.
- can be used to cover the cornea
- third eyelid flap “sutured”
- deep ulcers for extra protection
What could result in elevation of the third eyelid ?
Elevation of the third eyelid
Occurs with retraction of the globe into the orbit (pulled into the socket)
- some dog breeds may retract for discomfort
- cats Horners syndrome
Identify this condition and its causes ?
Cherry eye
This is a prolapse (lacrimal gland of the third eyelid)
- requires surgery for correction
- if severe cases cartilage deformity may combine with gland prolapse
Describe the three layers of the tear film ?
The three layers of the tear film
Lipid layer
- reduce evaporation
- produced by meibomian glands
Aqueous layer
- middle lacrimal gland
Mucin layer
- assist in sticking the tear film to the cornea (produced by goblet cells in the conjuntiva
- dry eye = increased mucin production
Describe the tear glands of the eye and how they are drained ?
Tear glands
Lacrimal glands, nictitans glands and other small glands
The drainage of tear glands
- lacrimal puntate (two openings which join)
- lacrimal canaliculi
- naso lacrimal duct (nasal punctum)
Identify this abnormality and its cause ?
Excessive tear overflow
- punctal atresia - tear duct abnormally small / sealed
- usually a lid conformational problem
- acquired nasal lacrimal duct blockage
- can be corrected surgically but is a cosmetic procedure.
Identify this abnormality and its cause ?
Dacryocystitits
This is infection of the lacrimal sac.
- pus discharge - yet globe appears healthy
What is the name of this condition and what secondary disease may result ?
What simple diagnostic aids will help in assessment of this eye ?
Q1.
Entropion
- which could lead to corneal ulceration
Q2
Topical anaesthesia
Fluorescein stain
What is the treatment for this condition ?
Q1.
Entropion corrective surgery with lid roll out and shortening.
Identify the five layers of the cornea ?
The five layers of the cornea
- Tear film
- Corneal epithelium
- Corneal stroma
- Descements membrane
- Endothelium (mesoderm)
Identify this condition of the cornea and its potential causes ?
Corneal Oedema
Corneal overhydration
- this leads to increased collagen fibre spacing which interfers with light transmission
- appears stippled blue/grey
- opacity / cloudiness
- in health the collagen spacing is very specific and results in minimal scattering of light - when spacing increases through increased water content there is a increased scattering of light.
Cause
- epithelial damage
- endothelial compromise
- vascular infiltrate
Identify this condition and its cause ?
Neovascularisation of the cornea
This is an inflammatory response to infection / healing or is immune mediated
- grow 1/2 mm per day
Identify this condition and its cause ?
Lipid infiltration of the cornea
- stromal deep layer
- may get crystals of cholesterol in the cornea, causing opacification
- circular or swirly type pattern - axial central cornea
Identify this condition and its cause ?
Corneal calcification
- tends to be irritating and uncomfatable
- superficial to epithelium
- dogs 14yrs and older
Identify this condition and its cause ?
Pigmentation of the cornea
- usually indicates chronic aging change
- irritation to the cornea
- often seen in pugs
Identify this condition and its cause ?
Neoplasia corneal
- conjuntiva tissue - infiltrating and growing into the cornea
Identify this condition ?
Corneal ulceration
(epithelial erosion)
- shallow but dye uptake
- can still be painful due to nerve endings in the stroma
- no crater effect / no indentation
Identify this condition ?
Corneal ulcer - stromal erosion
- crater effect
- melting ulcer
- rapid deepening may be observed to release enzymes/ bacteria/ white cells generating keratosis
- collagen analytic - very rapid
Identify this condition ?
Corneal ulcer - Descemetocoele
basement membrane epithelium
- observe cloudy edge
- crystal clear centre (little tissue no stain take up)
- stains around the edge stroma
- oedematous + vascularisation
Identify this condition ?
Perforated corneal ulcer
- eye will collapse
- wrinkled up cornea and the aqueous rushes out
Identify this condition ?
Iris prolapse
- the eyes puncture repair kit
- iris heads up and plugs the gap
- eyes attempt to reinflate and heal itself
What are the aetiologies of ulcerative keratitis ?
Aetiologies of ulcerative keratitis
- simple trauma
- secondary (dry eye, lid disease, foreign body etc)
- indolent non healing SCCED
- Infected (bacterial, fungal)
- Immune mediated (as pictured below).
Describe the pathology which underlies SCCED ?
Ulcerative kertitis SCCED
SCCED = Spontaneous, chronic, corneal, epithelial, defect
- indolent non healing ulcer
- breed and age related
- boxer, staffy > 8yrs of age
- epithelial defect - six months of treatment and still not heal is a strong sign
Describe your management strategies for ulcerative keratitis ?
Management strategies for ulcerative keratitis
First point os to identify the cause
Simple trauma
- prevent infection (antibiotics and allow time to heal).
Secondary
- treat the primary disease and prevent infection
- antibiotics
NON healing ulcers (SCCED)
- promote healing and prevent infection (topical antibiotics)
- requires surgery
Infected
- treat infection and promote healing first
Immune mediated
- can utilise corticosteroids usually contraindicated.
Describe the varous types of non ulcerative keratitis ?
Non ulcerative keratitis
Keratitis is inflammation of the cornea
These are various types of non ulcerative keratitis
Pannus
Pigmentary keratitis
Lipid infiltrate
Calcification
Describe the consequence of corneal endothelial degeneration ?
Oedema
infiltrate of fluid into the cornea
Identify this condition and describe its pathology ?
Pannus
Non ulcerative kertitis/ inflammation of the cornea
- chronic superficial keratitis
- immune mediated condition almost exclusive to German Sheppards and occassionally grey hounds
- there is a genetic component + immune mediated component and UV component
Identify this condition and describe its aetiology ?
Episcleritis / Scleritis
Pink lumps on the eye
- inflammatory
- nodular granulomatous
- poorly defined connective tissue between the collagen of the Sclera and conjunctival epithelium
Identify this condition ?
Neoplasia
Haemangiosarcoma / haemangioma tumour within the cornea
- common Nrth QLD
- tumours on the surface of the globe - vasculature
- sometimes on the surface of the nictitans
Identify this condition ?
Neoplasia on the cornea
Limbal melanoma
- pigmented cells of the limbus - junction of the sclera and cornea
- surface of the eye
- benign
- easy treatment via freezing
Identify this condition ?
Neoplasia of the cornea
Squamous cell carcinoma
- arise from corneal epithelium
- very common in horses
- excision / freezing
Describe the surgical principles for the cornea ?
Cornea
non healing ulcer - requires debridement
- cotton bud debridement
- diamond spur debridement
- grid keratotomy
- superficial keratotomy
Support
- nicitans flap
- potential temporary tarsorrhaphy (suturing the lids together)
Graft (specialist)
- magnification and microinstrumentation
What corneal condition is likely present in this painful eye ?
Describe simple diagnostic aides ?
Describe treatment for this condition ?
Answer
1. Corneal ulcer
- Topical anaesthesia and Fluorescein stain
- Topical antibiotics and consider surgery
- debridement
- support
- graft
Identify this condition and describe its features ?
Anterior uveitis
Classification is based on the part of uvea involved - iris and ciliary body
- miosis (pupil constriction)
- bulbar hyperaemia (vasodilation in the eye)
- ‘Flare’ Tyndall effect, increased protein and cells pick up of the particles through the anterior chamber.
- keratic precipitates
- hypopyon
- iris neovascularisation
- posterior synechiae (adhesions of the iris to the lens).
Describe the anatomy of the Uvea ?
Uvea = the vascular tunic of the eye comprising of
Iris - controls light entry
Ciliary body - nutrition + lens shape
Choroid - nutrition for retina, absorbs light
What are the five classifications of uveitis ?
Identify and describe this condition ?
Congenital heterochromia iridis
(Non inflammatory condition of the uvea)
- incidental normal
- eg one blue and one brown eye
Identify and describe this condition ?
Iris cyst
(degeneration of the uvea).
- spherical brown structure
- may need to alter view 3D effect to identify
- between lens and cornea, sitting in anterior chamber
Identify and describe this condition ?
Iris atrophy
degeneration of the uvea
- moth eaten appearance to iris, thread bear, thinning out
- small older bred dogs
Identify this condition and describe its features ?
Posterior Uveitis
(choroid and retina)
Distinguishing features
- perivascular exudate
- subretinal exudate
- exudative retinal detachment
Identify this condition and describe its features ?
Pan uveitis (both anterior and posterior segment)
Identify this condition and describe its features ?
Endophalmitis
(pan uveitis and intraocular fluids)
- spread to intraocular fuids (sclera and cornea)
Identify this condition and describe its features ?
Panophthalmitis
(endothalmitis + the fibrous tunic)
- fibrous tunic = sclera and cornea
What conditions could lead to secondary uveitis ?
Sequelae of Uveitis
- glaucoma
- pthisis bulbi (eye shrivels and ciliary body can not produce sufficient aqueous humour).
- cataract
- retinal damage
Describe the aetiologies of uveitis ?
Describe the general therapy principles for uveiitis ?
Therapy for uveitis
- Treat any associated disease, neoplasia, ulcer, infectious agents
- topical anitinflammatories with anterior uveitis
- posterior antiinflammatories with posterior uveitis
- mydriatic atropine to affect
Avoid the use of corticosteroids with any systemic disease.
Identify and describe this condition ?
Uveal melanocytoma
Primary tumour
- uveal
- benign
- iris
- heavily pigmented bulging mass formed on the surface of the iris
Identify this pathology ?
Ciliary body adenoma, adenocarcinoma
Primary tumour
- non pigmented coming off the ciliary body’
- benign but may end up as a nucleation
Identify and describe this condition ?
Lymphoma
Secondary tumour
- tends to be bilateral
- subtle thickening of tissue in both eyes with enlarged lymph nodes
- ocular involvement is not a good prognostic for the animals recovery
Identify this pathology ?
Metastatic tumour
Secondary tumour
Describe what is the posterior segment ?
What is the fundus ?
Fundus
The part of the posterior segment which is visable with an opthalmoscope.
Identify this pathology ?
Optic nerve hypoplasia
(congenital conditions)
- reduced in size and lost its myelin
- in health the optic nerve has a triangular shape due to the myelin
Identify this pathology ?
Collie eye anomaly
congenital condition
Abnormal choroid or retina tissue lateral to the optic nerve.
Identify this pathology ?
Retinal dysplasia
(congenital condition)
- strange folds in the retina may appear like worms
Identify this pathology ?
Exudative retinal detachment
Identify this pathology ?
Optic neuritis
Inflammatory condition
- Inflamed optic nerve - sort of fuzzy
- swollen appearance
Identify this pathology ?
Asteroid hyalosis
(degenerative condition)
- speaks observed in vitreous
- age related change / older dogs
Identify this pathology ?
Vitreal degeneration and rhegmatogenous retinal detachment.
(degenerative disorder)
- common in older dogs
- certain breeds labs
- moonscape effect
What is SARDS ?
SARDS
Sudden acquired retinal degeneration syndrome
- often the retina appears completely normal - will observe degeneral changes later on
- middle age to older dogs
- zero electrical response from retina
- change observed within 7 days
What do you call this change in the anterior chamber of the eye ?
What dose this change suggest ?
- Hyopyon
- Anterior uveitis
If you have a bilateral change as pictured what else should you be assessing in this patient ?
Define a cataract and its sequalae ?
Cataract
An opacity or loss of transparency of the lens as a result of tissue breakdown and protein clumping degenerative.
Sequaelae
- congenital
- hereditary ‘primary’
- secondary to uveitis, trauma, diabetes
Identify the five stages of the cataract ?
The five stages of the cataract
incipient
immature
mature
hypermature
reasorbing
Incipient cataract
- small bubbles of degenerative change in the lens
- < 10% of lens lost opacity
- the majority of the tapedal reflex still present
Identify and describe this pathology ?
Immature cataract
- many clumps of opaque material
- retro illumination appear as black shadows
- 50% of lens black shadows
Identify and describe this pathology ?
Mature cataract
- the entire lens has lost its opacity
- complete black out of tapedal reflex
Identify and describe this pathology ?
Resorbing cataract
- rare
- all the contents of the capsule dissolve with degeneration
- left with crystals within the lens capsule
- may regain vision and tapedal reflex
Identify this pathology ?
Primary Lens luxation
aphasic cresent
premature breakdown of collagen making up the lens zonule
there is genetic testing available
