Ophthalmology (1-9) Flashcards
name the spaces of the orbit
- intraconal space
- extraconal space
name 7 possible clinical signs of orbital disease in dog
- exophthalmos
- incr. resistance to digital retropulsion
- Strabismus
- pain on opening mouth
- TEL protrusion
- Lagophthalmos & exposure keratopathy
- Conj. hyperaemia/chemosis/congestion
name the term
protrusion of a normal sized globe
exophthalmos
name the term
deviation of the gobe
strabismus
name 2 common differential diagnoses of exophthalmos
- retrobulbar cellulitis or abscess
- retrobulbar neoplasia
what is the most common retrobulbar neoplasm?
nasal adenocarcinoma
what is the mean age of dogs with masticatory myositis
3 years
how to treat masticatory myositis
corticosteroids systemically (weeks)
what 2 breeds are most typically affected by extraocular polymyositis
- labradors
- golden retrievers
name the condition
exophthalmos but NO 3rd eyelid protrusion;
no pain;
swollen & hyperechoic extraocular mm on U/S;
respond to corticosteroids
extraocular polymyositis
name the condition
protrusion of the globe with eyelids behind equator of globe;
caused by trauma
traumatic proptosis
name 2 positive prognostic indicators for vision following traumatic proptosis
- brachycephalic conformation
- positive direct or indirect pupillary light reflexes
name 4 negative prognostic indicators for vision following traumatic proptosis
- cats
- severe intraocular trauma
- rupture of multiple extraocular muscles
- obvious optic nerve damage
name the 2 steps of replacement of proptosed globe
- preparation and canthotomy
- closure - temporary tarsorrhaphy
what is done during replacement of proptosed globe to release tension on the eyelids and allow them to be drawn forward over the cornea
lateral canthotomy (scissors)
sutures should be left in place for at least this long following replacement of a proptosed globe
at least 2 weeks
name 4 indications for enucleation
- a non-visual eye with intractable pain
- irreparable damageto the globe or optic nerve
- proptosis with optic nerve transection
- neoplasia that cannot be removed without sacrificing the globe
name 4 major disadvantages of loupes
- lack of variability in magnification
- limited magnification
- small field of view
- limited depth of field
what is the ideal product for patient positioning for an enucleation?
keeps patient insulated from cold table; resistant to commonly used disinfectants; radiolucent; vacu-support shaped to fit patient
Kruuse - Buster pillows
(vacuum positioning)
what is the main consideration during enucleation of a cat or brachycephalic bulb
short optic nerve
(do NOT clamp or ligate - risk injury to other nerve via optic chiasm)
what is the main consideration during enucleation of a rabbit
large orbital venous sinus
(risk for hemorrhage)
name the procedure
removal of globe, eyelids and conj. sacs in one unit ;
eyelids sutured together or held by Allis tissue forceps
transpalpebral enucleation
what part of the eye should NOT be penetrated during a transpalpebral enucleation?
conjunctival sac
describe the 7 steps of a transpalpebral enucleation
- elliptical incision around eyelid margins
- blunt dissection around globe
- posterior sclera reached beyond conj. reflection
- dissect under EOM insertions and cut
- ensure all conjunctival tissue removed
- close subcuticular layer (vicryl - watertight)
- close skin layer
name 5 possible complications of enucleation
- excessive bruising
- infection
- retention of conjunctiva
- orbital emphysema
- contralateral blindness optic nerve traction
name the condition
eyes sinking deeper in eye socket
enophthalmos
name 4 causes of enophthalmos
- ocular pain causing globe retraction
- conformation
- atrophy of orbital tissue (cachexia, muscle loss)
- Horner’s syndrome (loss of smooth muscle tone in the orbit)
name the term
the protective and supporting structures of the eyeball (globe) and optic nerve
adnexa
what 5 things make up the adnexa of the eye
- external eyelids
- third eyelids
- conjunctiva
- lacrimal system
- orbit
what 3 things does the middle layer of the eyelids contain
- glands
- muscles
- connective tissue
what does the inner layer of the eyelid contain
palpebral conjunctiva
this is a small pink nodule at the medial canthus of the eye;
it is external to the third eyelid and can bear fine hairs
caruncle
name the tendon
short, tethers the medial canthus to the frontal bone
medial canthal tendon
name the tendon
longer, attaching the lateral canthus to the orbital ligament
lateral canthal tendon
what muscle closes the eyelids
orbicularis oculi mm (VII)
what dye is applied topically to detect any corneal ulceration and to check for nasolacrimal patency;
can highlight distichiasis or facial hairs in contact with the pre-ocular tear-film
fluorescein dye
name 3 conditions involving eyelid cilia
- distachiasis
- conjunctival cilia (ectopic cilia)
- trichiasis
name the condition
very common in dogs;
cilia emerge from lid margin;
bother some dogs more than others;
treat those with evidence of discomfort
distichiasis
name 3 signs of discomfort with distichiasis
- lacrimation
- incr. blink rate
- blepharospasm
name the condition
uncommon (young dogs);
hair emerges through conjunctiva of upper lid;
really painful;
cornea frequently ulcerated opposite hair
conjunctival/ectopic cilium
name the condition
normally located hairs which are abnormally directed to contact and irritate/damage the ocular surface
trichiasis
this is when the lid margin turns inward towards the cornea, so the upper and lower lid margins do not meet perfectly when blinking;
skin hairs in contact with the cornea causes PAIN
entropion
name 4 signs of ocular pain
- blepharospasm
- lacrimation
- globe retraction
- photosensitivity
name 6 things that might cause a patient to have entropion
- excessively long eyelids
- abnormal canthal attachments
- excess skin folds
- painful process causing globe retraction
- loss of retrobulbar contents
- loss of skin elasticity
this is typically seen in brachycephalic dogs with a misdirected/tight medial canthal ligament ;
generally not in pain and cornea does not usually ulcerate, but chronic irritation causes corneal pigmentation ;
may be tear overflow by functional obstruction of the lower lacrimal punctum
medial canthal entropion
name 7 eye troubles with brachycephalics
- prominent globes cannot readily retract
- macropalpebral fissure & lagophthalmos
- medial canthal entropion
- hairy caruncle
- nasal folds with hair contacting cornea
- tear film evaporation
- reduced corneal sensation
this is a surgical procedure usually done for brachycephalics which shortens the length of the palpebral aperture and reduces corneal exposure
medial canthoplasty
what does entropion often cause?
severity is variable & most will heal uneventfully on medical management
corneal ulceration
what dog breed is predisposed to entropion;
puppies present with pain almost as soon as the lid open - must address promptly with temporary tacking procedure
sharpei
this is a simple technique that corrects entropion only while sutures are in place;
protects the cornea, giving time for problem to be self corrected (or a safe delay in performing permanent procedure)
temporary tacking with vertical mattress sutures
this is the definitive surgical correction of entropion;
involves the removal of an ellipse of skin below the lid margin at the affected site and the wound closed with simple interrupted sutures
Hotz-Celsus repair
this affects the lower lid and is only a cosmetic concern so NO treatment is needed;
it can, however, be responsible for repeated exposure conjunctivitis and should be treated with simple lid shortening
ectropion
this is upper and lower entropion laterally and ectropion of mid lower lid so it kinks in upper and lower lids
“diamond eye” conformation
name the term
face lift
rhyditectomy
name the term
inflammation of the eyelids
blepharitis
this is the rupture of meibomian gland → release of lipid meibum into tissues → pyogranulomatous response ;
warm compress may be useful in the early stages ;
topical antibiotics 7-10 days
chalazion
what is the 2 most common eyelid tumours in older dogs
- tarsal gland adenoma or adenocarcinoma
- melanoma
what are the 2 most common eyelid tumours in younger dogs
- viral papilloma
- histiocytoma
name the eyelid tumour
very common in dogs;
warty/cauliflower appearance;
evert lid, may see thickened ridge/bulge on conjunctival surface over tarsal gland;
may obstruct meibomian gland opening
tarsal gland adenoma
what closure should be used for eyelid mass excision?
allows knot to be placed at safe distance from cornea & align lid margin accurately
figure 8 suture
what is the normal appearance of the ocular surface
- moist
- clear cornea
- uninterrupted reflection of light
this is a fold of conjunctiva, supported internally by T shaped cartilage;
lots of lymphoid tissue;
nictitans glad at base of cartilage contributes to aqueous portion of tear film
third eyelid
(nictitating membrane/nictitans)
name 5 causes of third eyelid prominence
- orbital mass lesions (extraconal)
- retraction of globe
- reduction in globe size
- reduction in orbital contents
- alteration to nervous control
this is the common name for a prolapsed nictitans gland
cherry eye
this is plasma cell infiltration of the third eyelid (GSD and collies);
‘depigmentation’ appearance due to pink/tan fleshy tissue covering the pigment;
treated with long-term topical cyclosporine;
UV exposure exacerbates
nictitans plasmacytic conjunctivitis/plasmoma
name the 4 layers of the cornea
- epithelium
- stroma
- descemet’s membrane
- endothelium
name the corneal layer
sheets of collagen in a glycoprotein matrix
stroma
name the corneal layer
the basement membrane for the endothelium
Descemet’s membrane
name the corneal layer
monolayer of cells, in contact with the aqueous
endothelium
name the term
full thickness defect of the epithelium, exposing underlying stroma
corneal ulceration
name the type of corneal ulcer
only the epithelium is lost
superficial ulcer
name the type of corneal ulcer
the ulcer is deeper than just the epithelium, with varying degrees of stromal loss
stromal ulcer / deep ulcer
name the type of corneal ulcer
an ulcer that reaches Descemet’s membrane
Descemetocoele
name the type of corneal ulcer
full thicknes corneal defect!
perforated/ruptured ulcer
name 6 signs of corneal ulceration
- pain
- conjunctival hyperaemia
- localised corneal oedema
- irregularity of surface contour
- neovascularization and cellular infiltration
- reflex uveitis
what 2 tests should be performed to assess a corneal ulcer
- STT Test (Schirmer Tear Test)
- Fluorescein stain
name 8 causes of corneal ulcers
- trauma/foreign body
- hair/lash trauma
- infection (secondary)
- tear film abnormalities
- SCCED/’Boxer’ ulcer
- exposure keratopathy
- rupture of bullae secondary to endothelial dysfunction
- erosion by cholesterol or calcium deposits
will fuoroscein staining be more or less intense for a corneal ulcer when there is corneal oedema
less intense
what is the most common cause of a ventromedial corneal ulceration
foreign body under third eyelid
what is the most common cause of a dorsal, vertically orientated corneal ulceration
ectopic cilium
what medication potentiate enzymatic degradation of corneal ulcers - resulting in progressive stromal loss
topical corticosteroids
what causes progressive stromal loss causing the corneal ulcer to deepen?
enzymatic degradation
what medication should be given to an animal with a “melting” ulcer (extreme stromal ulcer)
broad spectrum antibiotics
(assume infected)
what is the treatment for a superficial ulcer (epithelial loss only)
- topical broad spectrum antibiotic
(+/- systemic NSAID for analgesia & atropine if reflex uveitis)
(reassess to ensure healing - heals quickly)
name the type of corneal ulcer
superficial ulcers;
rarely infected;
failure of adhesion of epithelium to underlying stroma;
underrun edges;
middle aged to older dogs
spontaneous chronic corneal epithelial defect (SCCED)
(“Boxer ulcer”)
name 4 medical treatment options for a SCCED (spontaneous chronic corneal epithelial defect)
- analgesia
- topical antibiotics
- atropine if reflex uveitis
- autologous serum
name 5 surgical treatment options for a SCCED (spontaneous chronic corneal epithelial defect)
- debride with cotton buds
- keratotomy (grid or punctate)
- diamond burr debridement
- phenol cautery
- superficial keratectomy
name the SCCED (spontaneous chronic corneal epithelial defect) treatment
25G needle used to produce superficial scratches in a grid pattern;
scarring may result
superficial grid keratotomy
(NOT IN CATS!!!!)
name the SCCED (spontaneous chronic corneal epithelial defect) treatment
23G needle used to produce superficial scratches;
less likely to cause scarring
superficial punctate keratotomy
what are the only corneal ulcers you can treat with debridement
SCCED (spontaneous chronic corneal epithelial defect)
name the 6 steps of treatment for a stromal or malacic corneal ulcer
- cytology +/- C&S
- topical antibiotics
- autologous serum
- systemic NSAIDs
- +/- atropine
- re-assess q25-48h
name 4 features of a corneal ulcer that indicate it is a SCCED and can be debrided
- middle aged-older dog
- superficial
- no obvious inciting cause or infection
- loose epithelial edges/under-running of fluorescein
name 6 causes of corneal opacities
- oedema
- cells (‘infiltrate’)
- blood vessels
- pigment
- scarring (fibrosis)
- lipid
this occurs mostly in German Shepherd Dogs;
a typically rough, fleshy looking infiltrate of inflammatory tissue, vessels and sometimes pigment;
advances towards the central cornea from the lateral limbus
Chronic Superficial Keratitis (CSK)
name the part of the eye
this is the structures in front of and including the lens
anterior segment