Ophth - Conjunctiva, third eyelid, lacrimal system Flashcards
What makes up the third eyelid?
T shaped hyaline cartilage
What is another name for the third eyelid?
Nictitating membrane
What make up the normal conjunctival microenvironment?
Gram positive aerobes - staph, bacillus, strep
What are some clinical signs associated with conjunctival diseases?
Hyperaemia, chemosis, exudation, follicular hyperplasia
What is hyperaemia?
Branching bright red vessels
Redness of the conjunctiva
What is chemosis of the eye?
Conjunctival oedema
More seen in cats
What is exudation of the eye?
Discharge - serous, mucoid or purulent
Where does follicular hyperplasia occur in the eye?
Inner aspect of the third eyelid
Upper fornix
What causes conjunctivitis?
Usually secondary - irritants, chemicals, drugs
Abnormal eyelid conformation
Aberrant hairs
Keratoconjunctivitis sicca
Trauma/Foreign body
What can cause primary conjunctivitis?
Follicular conjunctivitis
Juvenile conjunctivitis
Viruses - distemper, herpes, adenovirus
Parasites - thelazia, leishmania
Allergic conjunctivitis
How can you treat conjunctivitis?
Topical antibiotics - chloramphenicol
Topical anti-inflammatories - NSAIDs
Lubrication
Cleansing/warm compresses
What are some causes of third eyelid protrusion?
Enophthalmos/exophthalmos
Inflammation of third eyelid
Neoplasia of third eyelid
Horners syndrome
Scrolled cartilage of third eyelid
Prolapsed gland or third eyelid - cherry eye
What is cherry eye?
Red, homogenous mass arising from the bulbar aspect of the third eyelid due to prolapse of the third eyelid gland
How should you treat cherry eye?
DO NOT remove the gland - secondary keratoconjunctivitis sicca
Can use medical treatment to reduce inflammation but corrective surgery usually required
What is the corrective surgical technique for cherry eye surgery?
Modified Morgan pocket technique - bury the gland in conjunctival pocket
What is the prognosis of cherry eye surgery?
80% success rate
What are the 3 layers that make up the composition of the pre-corneal tear film?
Deep mucin layer
Intermediate aqueous layer
Superficial lipid layer
What is the function of the superficial lipid layer of the precorneal tear film?
Prevents evaporation of the tear film
What two structures produce the aqueous layer of the precorneal tear film?
Orbital lacrimal gland (2/3)
The third eyelid gland (1/3)
What produces the lipid portion of the precorneal tear film?
Meibomian glands
What produces the mucous portion of the precorneal tear film?
Conjunctival goblet cells
What is the name for the holes in the eyelid that the tears exit the eye through?
Puncta
What are the tubes that transmit the tears to the nasolacrimal duct?
Canaliculi
What is the function of the lipid layer of the tear film?
Prevents evaporation
Aids tear film distribution
What is the function of the aqueous layer of the tear film?
Supplies corneal nutrition
Antibacterial properties
Removal and remodelling - proteases
What is the function of the mucous layer of the tear film?
Lubrication
Refractive properties
Anchors aqueous layer to the cornea
What is keratoconjunctivitis sicca (KCS)?
Dry eyes
What are the clinical signs of KCS?
Strings of adherent mucus
Poor corneal clarity/shine
Low Shirmer tear test reading
Conjunctivitis
Ocular pain
Decreased vision
Corneal vascularisation
What are the two different types of KCS?
Quantitative - amount of tears produced is reduced
Qualitative - poor quality of tears but amount is normal
What causes the majority of quantitative KCS cases?
Immune mediated adenitis - immune system attacks the lacrimal gland
What are some other causes of quantitative KCS?
Iatrogenic - anaesthetics, atropine, drug toxicity
Neurogenic - facial nerve, trigeminal nerve
Trauma to eyelids and third eyelid
What can cause qualitative KCS?
Inflammation of the meibomian glands
Abnormal goblet cells
How do you test for qualitative KCS?
Tear film break up time (can be subjective)
Add fluorescein into eye, then observe with a blue light and see if it breaks up
How do you treat qualitative KCS?
Treat the identified cause
Frequent lubrication
Immunomodulation - topical cyclosporine, optimmune
Use antibiotics to treat secondary infections
What are the signs of impaired drainage through the nasolacrimal duct?
Epiphora
Mucopurulent ocular or nasal discharge
Swelling in medial canthus
Conjunctivitis
How do you test for impaired nasolacrimal drainage?
Jones test
Apply fluorescein to both eyes
Observe at nostrils - should normally emerge within 5 mins
