Lacrimal System Flashcards
Go over cards for first part of lecture
this is your reminder to just do it
Action of cyclosporine and tacrolimus
- Interfere with interleukin 2 produced by T helper cells
- They are immunosuppressive and should only be applied in small amounts
- Act by suppressing the immune disorder affecting the lacrimal gland as well as direct stimulation of tears
Cyclosporine and tacrolimus with corneal ulcers
- In contrast to steroids, they do NOT interfere with corneal healing and can be used with corneal ulcers
Tear replacements for KCS
- There are a number of replacements
- She prefers the ones with hyaluronic acid
- Have to get the gunk out of the eye first
- Solution before ointment
What are goals of tear replacements?
- Keep cornea moist and reduce surface tension
- Prevent corneal pigmentation
- Protect
- Nourish
- Comfort
- Aid in vision (remember decreased tear production will blur your vision)
Topical steroids in patients with KCS
- DO NOT DO IT
N-acetylcysteine with KCS
- Can be added to break up the mucus in the gunk
Referring patients with KCS
- When advanced or non-responsive to traditional therapies, refer to an ophthalmologist
Which drug would you use for neurogenic KCS, and how would you administer it?
- Pilocarpine 2%
- 1 drop per 20# on FOOD
- Systemic action
Can increase oral dose very slowly until GI signs appear, then reduce
How does pilocarpine act to help KCS?
- Stimulates parasympathetic input to lacrimal gland
Parotid duct transposition - when to do?
- Salvage procedure after all treatment options have failed
What are some caveats for parotid duct transposition?
- Must have normal salivary gland function
- Minerals from saliva may irritate cornea, and the pH is different
How common is KCS in cats?
- Not common
Schirmer tear test normal in cats
- 12-25mm/min
- HOWEVER, she doesn’t really like to do STT in cats because theirs fluctuate
Usual cause of KCS in cats
- USUALLY NOT IMMUNE-MEDIATED
- Usually associated with inflammation (herpes virus infection) and resolves when inflammation resolves
Treatment for KCS in cats
- Keep eye moist
- Don’t put on cyclosporine
KCS in horses - what causes generally?
- Trauma to Cranial nerve VII
STT in horses
- Variable
- May be very high or as low as 12 mm/min
When might you clinically be suspicious of KCS in a horse?
- Corneal ulcer without epiphora
Fornix
- Cul de sac between the palpebral conjunctiva and bulbar conjunctiva
Limbus
- Corneal/scleral junction
What is conjunctivitis?
- It is NOT a diagnosis
- MUST find the underlying cause
Chemosis
- Edema
Conjunctival hyperemia
- congestion of the capillaries
What type of disease does conjucntival hyperemia suggest?
- surface diseases
- Allergen, distichia
Subconjunctival hemorrhage - what does it suggest?
- Some sort of coagulopathy
How can you differentiate surface vs intraocular disease with episcleral injection?
- Larger, more angry vessels suggests intraocular disease
- Surface vessels suggest surface disease
What are the two most common causes of conjunctivitis in dogs?
- KCS
- Allergies/irritants
Other causes of conjunctivitis in dogs
- KCS and allergies/irritants are the MOST COMMON!
- Foreign body
- Corneal ulcer, aberrant cilia, retrobulbar disease
- Dental/oral disease
- Infectious agent
- CHV1
Most common causes of conjunctivitis in cats?
- INFECTION
- Herpesvirus FHV1-
- Chlamydia
Other causes of conjunctivitis in cats
- bartonella, calici, mycoplasma
- Trauma
- Corneal ulcer (usually viral)
- FB
- Allergies (consider if you’ve ruled out everything else
- Dental/oral disease
What history questions should you ask for conjunctivitis?
- Duration
- Current or prior medications**
- Change in diet or environment
- Concurrent illness (HAC, DM)
Diagnostic steps for conjunctivitis
- History***
- Ocular exam (look for conformational abnormalities, distichia, trichiasis, masses, and ectopic cilia)***
- STT (in a dog)***
- Fluorescein stain***
- Explore conjunctival sac and behind TEL (proparacaine needed)
- Nasolacrimal flush
- Collect samples for cytology, culture, and sensitivity
- Examine oral cavity
- Biopsy of conjunctival tissue
- R/o Systemic disease
- Response to treatment
Who gets follicular conjunctivitis?
- Dogs under 24 months of age
What should you rule out prior to diagnosing follicular conjunctivitis
- Everything
- Distichia, ectopic cilia
- Foreign body
- Entropion, KCS
Causes of follicular conjunctivitis?
- Immune stimulation and possible allergies in the diet
Clinical signs of follicular conjunctivitis?
- Mild discomfort
- Ocular discharge
- Cobblestone appearance behind the third eyelid
How does follicular conjunctivitis respond to topical abx and steroid?
- Responds well, but will recur when treatment stops
Treatment for follicular conjunctivitis?
- RULE OUT UNDERLYING CAUSE OR ULCER FIRST
- Start with BNP-HC or NSAID (diclofenac)
- May need NPDex if not responsive (start out high then taper to lowest effective interval)
- Exclusion diet like Z/D may be helpful
If a horse has conjunctivitis, what should you assume until proven otherwise?
- CORNEAL ULCER
- 9/10 there will be a corneal ulcer, so you MUST LOOK FOR IT
- It will be hard to see
Conjunctivitis and periodontal disease - appearance
- The eye might look fine (no hyperemia)
- Pus coming out of the skin near the eye but the eye looks okay
Retrobulbar abscess/cellulitis appearance
- Periorbital swelling, elevated 3rd eyelid, pain opening mouth
Retrobulbar neoplasia appearance
- Periorbital swelling, elevated 3rd eyelid, +/- painful
How to diagnose abscess vs neoplasia for retrobulbar?
- May need imaging to try and differentiate
- For neoplasia, ultimately biopsy
Retrobulbar cellulitis causes
- Tooth root abscess
- Foreign body
- Bony orbit is soft, and the teeth are quite close
Retrobulbar cellulitis signs
- Conjunctivitis
- Swelling and redness behind last molar
Diagnosis for retrobulbar cellulitis
- Examine mouth for dental disease
- Dental radiographs
Treatment for retrobulbar cellulitis
- Treat the underlying problem
- Topical and broad spectrum abx and NSAIDs
Hemorrhage in the conjunctiva- what to look for?
- Immune mediated disease like hemolytic anemia
- Can look for trauma
- Look for anticoagulant rodenticide
Infectious causes of canine conjunctivitis
- Canine distemper virus
- Canine adenovirus CAV 1 (not usually seen)
- Canine herpes virus CHV1
- Bacterial infections usually secondary
Ocular signs seen with canine distemper virus?
- Inflammation
- copious suppurative exudate
- KCS
- SYstemic illness
What to do if a patient has conjunctivitis as well as signs of allergies (foot licking, pruritus, otitis)?
- Treat the derm issues first
- Often have blepharitis
- Consider exclusion diet, fatty acids, NSAIDs, antihistamine, dermatologist referral
Treatment options for allergic conjunctivitis in dogs
- Topical steroids (BNP-HC might be best as it’s a weak steroid vs NPDex
- NSAIDs (diclofenac)
- Antihistamines (ketotifen)
Steroids for treatment of conjunctivitis - precautions ** KNOW THIS FOREVER ***
- Hydrocortisone can be used for conjunctival inflammation
- Steroids SHOULD NOT BE USED WITH CORNEAL ULCERS
- Dexamethasone and pred acetate are more potent, penetrate the cornea, and promote corneal melting if an ulcer is present
Topical steroids in cats
- AVOID AVOID AVOID
- Conjunctivitis in cats usually caused by an infectious agent
- HUGE PROBLEMS
FVRCP intranasal treatment for Feline Herpes
- Intranasal FVRCP thought to give a local IgA response
Why do cats with herpesvirus end up getting conjunctivitis?
- It hangs out in the trigeminal ganglion
- Immunosuppression –> immune signs in the eye
Rabbits with conjunctivitis
- Dacryocystitis from dental disease needs to be ruled out as the primary cause
Differentials for diffuse subconjunctival hemorrhage and tiny pupil
- Trauma, coagulopathy, neoplasia, immune-mediated condition
Differentials for a pale conjunctiva with chemosis
- Might be stomach worms leading to hypoproteinemia?
What are reasonable differentials for epiphora? in a white poodle
- Imperforate punctas
- Trichiasis
- Meibomian gland dysfunction (lipid layer)
Differentials for a dog with excessive tearing and blepharospasm and inspissated Meibomian glands?
- loss of lipid layer
- Not sure?
