Ophthalmology Flashcards
What is distichiasis?
Hairs growing in an abnormal site
from the tarsal/Meibomian glands within the tarsal plate and emerging at the lid margin
What is treatment of distichiasis?
- Plucking = regrow
- Electrolysis
- Tarsoconjunctival resection
What solution should be used for the eye?
- Povidone iodine antiseptic solution
What is ectopic (conjunctival) cilia?
- Emerge from the conjunctival surface and impinge directly on the eye
- Much more sporadic and far less common than distichiasis
- Far more painful - can cause shallow ulcers
- Alert - young dog (especially bulldogs) with a severely painful eye, possible shallow ulcer and no obvious cause
How are ectopic cilia treated?
- Easy to deal with = cut out (scalpel / biopsy punch)
-go deep enough
What is entropion? What can it cause?
- In rolling of lid margin = skin hairs impinge on eye
- Can cause corneal damage (masses of corneal granulation tissue)
What is treatment of entropion?
What are consequences of treatment?
- Skin + muscle excision to pull eye margin out
-Hotz-Celsus procedure - Tx can lead to minor post-op ectropion = not a problem
What breeds are predisposed to bad entropion at young age?
What should be done?
- Shar-pei - most need skin + muscle excision on all 4 eyelids eventually
- Tx = do not excise as they will grow
-temporarily ‘tacking’ is advised until mature
-suture good temporarily but cut in + migrate
What breed of dogs have medial entropion with trichiasis?
- Pugs
What breed get upper lid trichiasis syndrome?
Tx?
- Middle aged cocker spaniel upper eyelid syndrome
- Tx = Stades procedure
What is the most common eyelid tumour in dogs?
- Sebaceous adenoma / epithelioma
-arises from tarsal gland
-benign
-require full thickness excision
What is the function of the third eyelid?
- Secretory - 30% of aqueous tears
- Surface protection
- Tear film distribution
- Immunological
What is cherry eye?
- Prolapse of the nictitans gland
How can you manage cherry eye?
- Burying but preserving gland =
-preserves function
-expensive
-can fail - Excision of gland
-cheap + guarantee
-30% of aqueous tear capacity lost
When would you excise the third eyelid?
- Only if neoplasia
What is non-specific ocnjunctivitis?
Tx?
- diffuse redness without corneal, pupillary light reflex
or vision defects - Tx - Fusidic acid (only for STAPHs)
- Tx = Clinagel = Gentamicin (gram +ve & -ve)
Other than conjunctivitis what else can cause red eye?
- Corneal ulcer or trauma
- Glaucoma
- Dislocated lens
- Uveitis
- Dry eye
What produces portions of the tear film?
- Lipid = tarsal gland
- Aqueous = lacrimal + nictitans glands
- Mucus = conjunctival goblet cells
What are causes of dry eye in the dog?
- Immune-mediated inflammation of the glands with secondary loss of function
- Neurological (“Dry eye – Dry Nose” syndrome)
- Sulphonamides / salazopyrin
- Distemper
- Chronic lid abnormalities
- Endocrine abnormalities contributory (hypothyroidism/diabetes)
What are clinical signs of dry eye?
- Chronic conjunctivitis
- Dull appearance to the ocular surface
- Mucopurulent discharge - tenacious and adherent
- Discomfort
- Corneal ulceration (variable)
- Corneal vascularisation and pigmentation
How can you quantify dry eye with tear production?
- 15mm = minimum
- 10-15mm = moderate dry eye
- <10mm = moderate to severe dry eye
What is medical management of dry eye?
- Tear stimulants - cyclosporin (optimmune), Tacrolimus
- Tear film replacements - carbomer gel
How can lacrimal drainage be monitored?
- Fluorescein drainage test =
-apply fluorescein with 2 drops of saline
-should see stain coming out of nose in 3-4minutes or less
What is a corneal ulcer?
- Full thickness defect in epithelium
-causes pain + potential for progression
what are the 4 layers of the cornea?
- Epithelium
- Stroma
- Descemet’s membrane
- Endothelium
What is the stroma susceptible to? what is this referred as?
- Enzymatic digestion =
-proteolysis
-keratomalacia
-collagenolysis
-melting
What can cause release of proteolytic enzymes?
- Bacteria - pseudomonas, B haemolytic streps
- Inflammatory cells
- Corneal cells
- Unexplained / sterile
What are signs of corneal perfortation?
- Sudden pain
- Convex protrusion of brown / black tissue with overlying fibrinous material
- Blood from eye
How does fluorescein work?
- Orange dye, turns green in alkaline conditions
- lipophobic = runs off intact epithelium
- hydrophilic = adheres to exposed stroma
- shows better with blue light
- Must flush with saline after exposure to eliminate false positives
- If depression and clear area in deep ulcer = not good + won’t stain as down to descemet’s membrane
What are primary causes of corneal ulceration?
- Factors causing direct mechanical damage
-eyelids, trauma, foreign bodies - Factors contributing to an unhealthy superficial environment
-dry eye, poor blink - Inherent corneal defects - indolent (boxer) ulcer
- Multifactorial - brachycephalics
What are non-specific medical therapy for corneal ulcers?
- Broad spec AB = gentamycin, ciprofloxacin, chloramphenicol + fluoroquinolone
- Lubricant frequently
- Atropine
- Acetylcysteine - for melting ulcers (anti-collagenase)
What are reconstruction techniques for corneal ulcers?
- Conjunctival pedicle graft
- Corneo-conjunctival transposition
What are indolent ‘boxer’ ulcers?
- Superficial chronic cornea epithelial damage (SCCED)
- epithelial only - not a concavity/crater
- mild oedema and loose under-run edges
- breed helpful - boxers, corgis, Staffies
- stain well with fluorescein
- vascularisation varies from none to extreme
- THEY DON’T HEAL - surgery
What are the 2 types of corneal foreign bodies?
- Adhere to surface
-flat/shallow curvature, little penetration, can be wiped out - Intracorneal (usually thorns)
-easier with reasonable protrusion
-needle for removal
What animals are more prone to pigmentary keratitis?
- Brachycephalics
What breeds tend to get dermoids? (hair growing on eye)
- French bulldogs
What are pannus? breed predisposed? Tx?
- Inflammatory + vascular tissue advances across the cornea always from the ventrolateral direction
- GSD
- Topical cyclosporine / tacrolimus / topical steroids
What does the uvea consist of?
- Iris
- Ciliary body
- Choroid
What are causes of anterior uveitis?
- Spontaneous/idiopathic/immune-mediated
- Deep and/or infected ulcers
- Corneal trauma/laceration
- Remote sites of infection inc. pyometra
- Post intraocular surgery
- Specific intraocular infections
How do you treat uveitis?
- Mydriatics = relieve pain, reduce risk of adhesions
- Topical steroids +/or NSAIDs
- oral steroids / NSAIDs
What is glaucoma? Causes?
- Abnormal rise in intraocular pressure
-always a problem of aqueous flow or drainage not over-production
Why is glaucoma serious?
- Painful
- Rapidly destroys retina + optic nerves
- Main cause of eye removal
What can cause secondary glaucoma?
- Uncontrolled inflammation
- Tumours
- Trauma
- Anterior lens luxation
- Perforations
- Severe intraocular haemorrhage
- Chronic retinal detachment
- Intraocular surgery
What are signs of acute glaucoma?
- Red eye
- Pain & lethargy
- Steamy cornea
- Non-responsive pupil
- Blindness
- Globe hard but normal size
What is tonometry / gonioscopy?
- Tonometry = measure of intraocular pressure
- Gonioscopy = assess drainage angle
What is topical treatment for glaucoma?
- Trusopt, azopt - topical carbonic anhydrase inhibitors
- Prostaglandin analogues - Xalatan
- Also prophylactic treatment of ‘good eye’
