w/c 5/5/14 Opthamology Flashcards
What is nuclear sclerosis?
Normal aging process affecting the refractive index of the lens. Gives the nucelus of the lens a hazy look
How to differentiate nuclear sclerosis and cataracts
Distant direct opthamoscopy. The tapetal reflex would not be observed with cataracts but would be with nuclear sclerosis
LOOK THROUGH OPTHALMASCOPY. DON’T CONFUSE WITH INDIRECT OPTHALMOSCOPY= FUNDUS IMAGE
Lymphoid follicles on the bulbar side of the third eyelid are indicitive of…
Young animals, allergies. Accompanied by hyperaemia. Can also occur on the palprebral side.
Conjuncitval pattern of BV’s =
Sequale=
Dictomatous branching. Dilation of vessels and seperation of endothelial cells leads to Hyperaemia and Edema (chemosis)
Define chemosis
Oedema of the conjunctiva
Conjunctival pattern of BV= dilation of vessels and seperation of endothelial cells leading to hyperaemia and chemosis.
Episcleral pattern is indicitive of
No dichotomous branching, larger, meander. Signal intraocular disease (uveitis or glycoma)
What % of tear film is provided by lacrimal gland?
30% therefore do not excise cherry eye! Reposition…
4 layers of cornea
Epithelium
Stroma
Descemet’s membrane
Endothelium
Cornea epithelium (hydro____, has or had not got BV?)
The cornea epithelium is hydrophobic and does not have blood vessels. it does have non-myelinated nerves
Cornea stroma (hydro___) stays _________
Cornea stroma is hydrophillic. It stays relatively dehydrated through the action of epithelium and endothelium which actively pumps fluid back into AC
Corneal stroma overhydration is known as
Corneal oedema
Name a specific disease for loss of the corneal epithelium
Corneal ulcer
Name a specific disease for damage to the endothelium
Glacoma, uveitis, lens luxation, primary endothelial degen.
Name a speicif disease for vasculaisation (leakage)
Any irritating problem of the cornea (KCS, LPI, ulcers etc)
What structures define the anterior chamber?
Corneal endothelium, anterior iris and lens, Iridocorneal angle
Purpose of the aqueous humour that fills the anterior chamber?
Establises IOP, feeds posterior cornea and anterior lens.
Route of aqueous humour
Comes from cillary body, into POSTERIOR chamber, goes through pupil into AC and exits through the iridocorneal angle/ uvea
Which two diseases affect the anterior chamber?
Uveitis (inflamm of uvea) and Glaucoma
How does Uveitis affect IOP ( through its affect of the aqueous humour)
Inflamm of the uvea (uveitis) decreases IOP because it increases uveoscleral outflow.
Chronic uveitis can lead to keratic precipitates blocking the flow of aqueous humour and therefore RAISED OCCULAR PRESSURE
Uveitis can lead to
- Miosis= iris spasm
- Endothelial cell seperation leading to leakage of blood components
- Posterior synechia
- Development of PIFMs
What are posterior synechia
Adhesions of iris to the anterior lens. Commonly causes by uveitis
What are PIFMs? Apperance of them
Preiridal fibrovascular membranes. Commonly caused by uveitis. Grow over iris and in pale iris visible as rubeosis iridis. May lead to bleeding in eye= hyphema or closure of the ICA = secondary glaucoma
An undilating pupil can be an indication chronic uveitis and is caused by the formation of
Posterior synechia (adhesions between iris to anterior lens)
Why do keratitic precipitates, hypopion and hyphema occur in uveitis?
Due to endothelial cell seperation leading to leakage of blood components
Define epiphora
Cause of epiphora
Excessive tearing. 1) Trigeminal (CN V) irritation or 2) drainage problems (prolpased gland, eye lid abnormality, blockage of nasolacrimal system)
If eyelid mass affects less than ___% wedge resection. if more then consider referral
<25% = wedge resection then figure of 8 knot.
Treatment of Spastic entropion
When eye is closed tightly (blepharospasm) can lead to spastic entropion. Apply 1 drop of proxymetacaine (topical anaesthetic) if entropion persistas needs surgical correction if disappears investigate source of opthalmic pain
Difference between Strabismus and Nystagmus
Strabismus: Deviation in the position of the globe (congenital, neurologic or extraocular muscle abnormality)
Which nerves supply the extraocular muscles (and subsequent damage produces specific strabismus)
Strabismus = deviation of the globe. Most muscles innervated by oculomotor (CN III)
Abducens: Lateral rectus (ALR)
Trochlear: Superior Oblique (TSO)
Nystagmus= involuntary oscillatory movement of the eyes
Which breed of cats are predisposed to congenital strabismus?
Siamese cats.
What is a coloboma?
Congenital absence of tissue within the eye or adnexa. Normally lahteral part of eyelid in cat.
Can have eyelid coloboma
Define ankyloblepharon
Aklyoblepharon is normally in kittens/puppies up to 10-14 days old.
Pathogeneisis and treatment of Opthalmia neonatorum
Development of a purulent conjunctivitis prior to eyelid opening. Swelling of the fused lids.
Eyelids need to be surgically opened early to avoid corneal damange. Broad spec topical antiobiotics.
Inflammation of the eyelids is known as
Blephritis
Define symblepharon
Seqalae to conjunctivitis which conjunctival adhesions form. Common result of feline herpes virus-1.
Which virus is associated with corneal oedema in dogs?
Canine adenovirus is associated with corneal oedema, (so is anterior uvetitis) forms immune-complexes on corneal epithelium preventing pumps removing fluid
Breed predisposition for plasmoma
Plasmoma - inherited in GERMAN SHEPHERD DOGS.
Thickened irregular boarder. IM disease therefore ciclosporin.
Related condition to Chronic superficial keratitis/ pannus. but PLASMOMA only AFFECTS THIRD EYELID
Aeitiology and treatment of Episcleritis
Episcleritis is an immune-mediated disease of the episclera. Responds to corticosteroids e.g. Azothiaprine.
Left eye is known as…
Oculus sinister (the left eye) OD= right eye OU = Both eyes.
Young golden retriever with bilateral, non painful exophalmos is likely to have
Extraocular polymyositis. Systemic corticosteriods +- Azothiaprine (immunosuppressive)
What is the probably cause of corneal oedema in a Daschund
Inherited endothelial dystrophy in boston terriers, chihauhuas, dauchunds, english springer spaniels
Aetiology of sequestrum
Major cause of black/brown corneal lesions in cats. Consists of necrotic corneal stroma and often surrounded by a ring of inflammatory cells. Can be unilat or bilat. Often associated with herpes
Sequestrum in cats often associated with what virus
Herpes virus.
Define Lagophtalmos
Inability to close the eye completely.
Where do the first lesions of CSK appear?
CSK is Chronic superficial keratitis and is an immune mediated disease aka ‘Pannas’ aka lymphocy..plsmocytic..
It first appears in the VENTROLATERAL quadrant
Exposure to ___ is known to be a predisposing factor for CSK /Pannus/LPI
UV light.
What does the third eyelid normally have a roughened appearance?
Due to the lymphoid tissue
What are Habbs Striae
Stretch marks ‘breaks in Descemet’s membrane
Aqueous flare is pathopneumonic for
Uveitis
Treatment for Glucoma
Glucoma (40-60 mmHg = clinc signs of bupthalmia
Miotics (constrict pupil) e.g. Pilocarpine
Mannitol
Beta-blockers
Carbonic anhydrase inhibitors
Normal Schirmer tear test for dogs
> 15mm/min
TSS-1 = NO ANAESTHIC (dogs have less corneal nerves)
TSS-2 = WITH ANAESTHETIC
When would you use blue light?
Blue light: Fluorescein Green light (aka red free): Differentiate blood from pigment
Type of image with indirect opthalmoscopy
Used for wide field of view of fundus
Inverted virtual Left to Right image.
Don’t confuse with DDO (used for tapetal reflex/ cataracts vs nuc sclerosis)
Where do you place STT strip?
Use STT-1 (no anaesthetic) LATERALLY (doesn’t interfer with third eyelid)
BEFORE USE LIGHT EXAMINATION
>15mm/min = good but if ulcer could be pain?
Persistant Papillary Membranes
Remnants of normal prenatal vascular network.
Not uncommon in dogs
Presence of pigmented strands from one side of iris to the other
ARISE FROM THE IRIS COLLARETE
Can cause CORNEAL and LENS opacity
Close direct ophthalmology
<2cm from patient!
Look for optic disk. Make big picture.
All vessels lead to optic disk. Divide into 1/4s
Jones test
Use Fluorescein staining but do not wash.
Check nasolacrimal duct patency.
Should flow in <4minutes
Examine with BLUE light
Normal IOP range
12-22 (24)
Glucoma vs Uveitis
Ectopic cilia
Associated with meibioum glands but not through openings (c.f. Distichiasis)
Bulbar surface of eye - nearly always central upper eyelid
Normally one hair, one location.
Normally <1.5 years.
Also affects horses
Distichiasis
Hairs are normally multiple (upper and lower eyelids of one or both eyes)
Sprout through meibioum gland openings
Eosinophillic keratitis- what species?
Mainly cats but also horses and rabbits.
Red/pink cellular infiltrate
Canine Lymphocytic Plasmacytic Infiltrate commonly affects _____ area first
Dorsolateral conjuncitva affected first
Cellular infiltrate and vasculisation
Diagnosis of Canine Lymphocytic Plasmacytic Infiltrate
Cytology.
Proxymetacaine (topical anaesthetic), decrease blink, increase dryness= cytobrush and diffquick
Treatment of LPI
Dogs: Cyclosporin. Dogs in temperate climates respond well. Sunny climates do not
Cats (EK): Topical steroid (dexamethasone)
START WITH 4-6 x daily
Taper very very slowly!
Treatment of KCS
Topical ciclosporin.
PERSERVATIVE FREE viscous tears
Lipid infiltrate; how to differentiate primary and secondary form
DEGREE OF VASCULARISATION
Primary: (dystrophy) no vasculisation. King Charles Spaniels, Huskies
Secondary: Degeneration, HAS vasculisation. Associated with chronic corneal problems. Hypothyroidism?
How to differentiate lipid deposits and calcium deposits?
Lipid deposits: Primary or secondary (vascularisation) but both ARE REFLECTIVE
Calcium deposits: NON-reflective crystals, reticulated pattern. Vascularisation.
Pathogenesis of Corneal Abscess and likely progression
Accumulation of WBC. Enzymes can lead to rapid collagen melting.
Not a pocket of fluid (cannot be drained)
Pathogenesis of Sequestra
Prodominately cats.
Normally affects medial cornea (most vulnerable part)
Spontaneous but commonly associated with chronic irritation
Where is the limbus
Where the cornea meets the white of the eye.
Where would you find the Lacrimal gland?
Produces 30% of aqueous portion of tear film.
Found in the third eyelid (along with T shaped cartilage)
Can become inflammed ‘Cherry eye’
What makes up the a) Anterior uvea b) Posterior uvea
Anterior uvea: Iris/Cillary body
Posterior uvea: Choroid
Pathogenesis of secondary glucoma resulting from anterior uveitis
Anterior uveitis: Can development of PIFMs (Preiridal fibrovascular membranes) which grow over iris and pale it = rubeosis iridis which can lead to hyphema but also block the ICA therefore rasing intraoccular pressure (normal is 12-22/24)
Panuveitis
Inflammation of the anterior part AND POSTERIOR part of the uvea (posterior uvea= choroid)
Can lead to reinal detachment.
Retina overlies choroid (i.e. retina is most internal)
Meibioium glands produce
Lipid
Reduces evaporation of tears
Entropion in 20 day old puppy. Treatment?
Entropion is INVERTION of eyelid.
Tacking sutures after eyelid opening - too young to undergo surgery
Treatment of entropion
Check if spastic entropion - apply 1 drop proxymetacaine. to check if spastic entropion (i.e. pain)
If entropion = surgery
Cause of entropion
Brachycephalic breeds skull deformity.
Or cats: Eldery cats= skin laxity or loss of retrobulbar fat.
Euryblepharon
(= macroblepharon
Enlargement of eyelid i.e. more of the sclera is visible than it should be
e.g. blood hounds
How to look for hypopion
= Accumulation of WBC in anterior chamber can lead to blindness.
Push down lower eyelid (gently!) as POOLS at bottom
Appearance of posterior synechia
Adhesion of iris to cornea.
Will appear as a distorted pupil (i.e. not round/ smooth )
Pathogenesis of Lens Induced Uveitis
Treatment of cataracts in dogs is photoemulsification and implantation of news lens. leaking lens can lead to a secondary glucoma by blocking the ICA.
Regular monitoring and occasional use of steroids and
3 infectious agents that are reported to affect uvea
1/ Toxoplasmosis 2/ Leishmania 3/ Cryptococcus 4/ FelV/FIV HYPERTENSION????
How can uveitis cause cataracts
Cataracts can cause uveitis (phacolytic - intact capsule. phacoclastic- rupture of lens capsule)
Uveitis sequale can be cataracts due to poor nourishment of the lens and altered aqueous humour
How does cataract colour differ between direct illumination and retroillumination
Direct illumination: (Distant direct opthal) = white
Retroillumination= dark
Congenital cataracts are always
Heritability?
Nuclear (in centre)
Congenital but RARELY INHERITED
Pathogenesis of Diabetic cataracts
Glucose in anterior chamber Sorbitol Water Something happens.. Look it up
What type of cataracts form during progressive retinal atrophy
Secondary to retinal degeneration
• Retina when degenerates releases toxins (glutamate)
that lead to cataracts
PRA: Night blindness progresses to day blindness
Often starts middle aged
No treatment, not painful
Senile cataracts tend to be
Wedge shaped. Generally affect the cortex
Presentation of PRA
Hyperreflective tapetum due to thinning of retina
Thinning of retinal vessels
Late stage: Cataracts
Most common neoplasia of optic nerve
Meningioma
Infectious diseases that affect optic nerve:
distemper, ehrilichia, cryptococcus
Collie Eye Abnormalty
INHERITED
Combination of 2 diseases
Choroidal hypoplasia (genetic test avaliable)
Optic nerve head coloboma
SARDS test
Sudden Aquired Retinal Degeneration Syndrome
Test: ERG (electroretingraphy)
plr may or may not be present
High doses of which antibiotic can lead to retinal toxicity in cats?
Enrofloxacin
Can also cause neurological clinical signs
Bupthalmia vs Exophtalmos
Bupthalmia: enlargement of eye due to increased IOP
Exophtalmos: anterior displacement of eye
What other changes would you expect with Bupthalmia
Enlargement of eye due to increased IOP. (Norm is 12-22mmHg)
Increased IOP i.e. glucoma leads to secondary opthalmic changes such as episcleral congestion, corneal oedema, Habb’s striae (breaks in Descements membrane)
Which ophthalmic condition are terriers especially predisposed to
Primary lens luxation which can lead to secondary glaucoma.
Lantanoprost
Prostaglandin analogue that increases outflow of aqueous humour therefore decreases IOP.
Lantanoprost also causes miosis therefore can help in cases of lens luxation (miosis prevents moving anteriorly)
Doens’t work in cats, works in horse
Retina has ___ layers
1 epithelial layer
9 neural layers (with rods, cones and ganglion cells)
total of 10 layers
ganglion axons make up optic nerve
Two types of gluacoma, which is most common in dogs?
Open angle and Closed angle (rapid onset, most common in dogs)
How do signs of glucoma differ between a) moderate->high IOP b) high to very high IOP
a) Moderate-> High: Mid dilated non-responsive pupils, episcleral congestion, negative menace
b) High to very high IOP: CORNEAL OEDEMA, Habbs straie (breaks in Descemet’s membrane)
Aphakic Crescent =
A crescent shaped gap that forms between pupil and lens
Secondary to tears of the zonules and lens movement away from it.
Three typical signs of retrobulbar disease
Globe displacement, TE protrusion and
change in facial symmetry
What is an IOP curve
Careful serial measurement of IOP q3hr
over a 30hr period (approximately)
Two causes of microphthalmia
- Usually small eye from birth (normally bilateral)
- Destruction of the cillary body (cyclodestruction)
Sequalae to inflammation, Pthiasis Bulbi (severe uveitis)
Infectious diseases that can cause secondary glucoma in cats (4)
Mostly associated with uveitis (normally decrease IOP but if chronic can lead to increase IOP and glaucoma)
FIV, FeLV, FIV and Toxoplasma.
In which cat species is there thought to be a primary glaucoma condition?
Burmease.
Also secondary forms exist: FIV, FeLV, FIP, Toxoplasma.
Relevance of primary over secondary glaucoma with respect to longer term prognosis
Primary: Second eye WILL be affected. Guarenteed.
Secondary: Might be less of a worry; MONITOR
Can you breed from animals with glaucoma?
Burmease: Primary Glucoma is inherited!
Primary: NO as dysgenesis of ICA is inherited
Secondary: CAN BREED (EXCEPT LENS LUXATION=Terriers!)
Treatment of Glaucoma, 3 types
- Beta-blockers e.g. timolol, reduce production of aqueous
- Carbonic Anhydrase Inhibitors
- Prostaglandin analogue (Lantanoprost)- Increases uveoscleral outflow.
How does Timolol work?
Tx for Glaucoma.
Timolol is a beta blocker that works but reducing production of aqueous humour.
How does Dorzolamide work?
Tx for Glaucoma.
Dorzolamide is a Carbonic Anhydrase inhibitor which works but reducing the production of aqueous humour
i.e. similar to the beta blocker Timolol
Works well with beta blocker.
Carbonic Anhydrase is the treatment of choice for ___ and ___
cats and horses.
e.g. Dorzolamide
Works by reducing the production of aqueous humour
Latanoprost side effects
Prostaglandin analogue that works by increasing outflow.
Doesn’t work in cats, works in horses.
MEDIATOR OF INFLAMMATION!! Can cause uveitis
Strongest (c.f. beta blockers, carbonic anhydrase inhibitors)
Phacodonesis
tremulousness or vibration of the lens with eye movement
Often due to lens subluxation.
Breaks in zonular fibres.
Phaco= lens
c.f: Iridodonesis : Vibration of iris with movement
What clinical signs can be an early sign of subluxation
Phacodonesis (lens vibration)
Iridodonesis (iris vibration)
Anterior presentation of viterous
Sequalae of posterior luxation
Cataract formation
Lens induced uveitis
Lens adhesion to retina
Sequalae to anterior luxation
Pupil block glaucoma
Also damages cornea leading to corneal oedema.
Endolaser cyclophotocoagulation
Cyclo= referring to cillary body
Want to remove part of it to decrease aqueous humour production.
leave 30% intact to avoid phtsis bulbi
Difference between Basal cells and Wing cells of cornea
Basal cells: Transient amplyfying cells, capable of mitosis. Stemp cells at limbus
Wing cells: No longer mitotic 2 to 4 layers
Final most exterior layer is the squamous non-keratinised epithelium
Wound healing of Cornea process
First sliding post abrasion (doesn’t reach basal lamina)
THEN basal cell mitosis, movement upwards. Takes 1 week/cycle.
THEN Centripetal movement -from limbus to centre; affects every layer.
WOUND HEALING DEPENDS ON EXISTANCE OF BASAL LAMINA
Significance of Centripetal movement in corneal wound healing
First sliding (doesn't affect basal lamina) then upwards movement from basal cells mitosis. THEN Centripetal movement from limbus to centre. Clin Signif: Pigment proliferation associated with irritation can migrate centrally over pupil.
How can vascularisation be an indicator of chronicity
Lag time of 2 to 4 days to bud.
Then 1mm/day approx
During corneal wound healing what is the first GAG to form
Change of concentration of GAGs.
First GAG to form is HA. Then HA decreases as other glycoproteins increase in concentration
Shape of the endothelium / wound healing
Exagonal in a chicken wire pattern.
Intracellular Na+K+ATPase pumps to keep corneal stroma relatively dehydrated
Endothelial cells: very sensitive cells with poor ability to regenerate.
Medical treatment for corneal ulcer
Protection from self harm=COLLAR Antibiotic cover= protection Atropine for comfort= mydriasis Ciclosporin will NOT intefer with healing NO STEROIDS/NSAIDS
Tarsorrhaphy
Horizonal mattress suture through eyelids .
Use stents to protect eyelid.
Alternatively Nicititating membrane flap but not recommended over a bandage lens/ tarsorrhaphy.
Medical Tx for Corneal Melting
Serum eyedrops - antiproteases
Frequent application every 30 minutes
How long until need to re-examine corneal ulcer
3-4 days
Healing is AIDED by vascular growth.
Desmatocele
Right before perforation occurs. Partial bulging of Decemet’s membrane. Does not uptake fluorescein (surrounding edematous stroma does)
CLEAR CENTRE as no stroma.
SURGICAL EMERGENCY
Pathogenesis of KCS causing perforation of cornea
Diseased cornea. Irritant still present, increased thick mucoid discharge leads to a change in the bacterial flora, inflamm cells on surface leading to Collagenolysis.
How does SURGICAL treatment of KCS vary depending on where lesion is
a) Central lesions: CLCT: Corneolimboconjunctival transposition
Clears over time
b) Peripheral lesions: Conjunctival pedicle graft . Slightly faster.
Conjunctival pedicle doesn’t clear much over time but as peropheral doesn’t matter.
Medical treatment of KCS
Ciclosporin.
Does not interefere with corneal healing.
Viscous free tears.
Topical antibiotic e.g. Chloramphenicol (broad spec, good penetration)
Spontaneous chronic corneal epithelial deficits:
CATS/DOGS Under running of fluroe scein dye= Pulsed saline test. Loose epithelial edges Tx: Keratectomy (cats beware SEQUESTRUM!) No superficial grid scraping in cats
Corneal thickness
0.5mm
FHV-1 lives in..
Trigeminal ganglion and corneal tissue.
Usually infected in kitten-hood.
Associated with symblepharon in kittens.
Corneal ulcerative disease can be severe.
Recrudencent disease during periods of stress.
Tx: Interferon (decreased cytopathic effects) and L-Lysine (reduced replication)
Feline Acute Bullous Keratopathy
Acute development of corneal oedema.
Risk of melting/ perforation is very high.
REFER
Tx for Facial n. paralysis
Loss of blink.
Treat underlying cause (FHV-1, Otitis media, ear canal neoplasia etc) = myrinectomy to investigate.
treat with Tarsorrhaphy for 2-3 months (horizonal mattress suture)
Most common type of neoplasia of the iris. How does it differ in cats and dogs
Melanocytic neoplasia.
Dogs: normally localised/ diffuse. BENIGN. Melanocytoma Cats: normally diffuse melanoma (very slowly malignant)
Swinging light test; still SOME constriction.
What is the result of a lesion affecting the
left optic tract?
Loss of vision on right .
Marcus Gunn sign
How can you differentiate this from unilateral glaucoma?
Prechiasmal (i.e. before optic chiasm, closer to eye), unilateral afferent lesion (ipsilaterally affected if prechiasmal!)
Can differentiate from unilateral glaucoma as with glaucoma affected eye will not dilate even with indirect PLR (due to increased IOP damaging iris)
Menace response for prechiasmal lesion OS
If PRECHIASMAL lesion would not have a menace response is UNILATERAL eye.
I.e. lesion OS, no menace OS
PLR for prechiasmal lesion
No direct PLR response.
Indirect affected to unaffected= no response
Will have PLR indirect from unaffected to affected.
