Tears and Lacrimation Flashcards
What are the purposes of the tear film?
Tear film prevents the ocular surface from drying out making sure light refracts through the cornea correctly.
What are the 3 layers to the tear film?
It has 3 components
- Lipid layer from the tarsal gland (this prevents other layers evaporating)
- Middle aqueous layer from the lacrimal gland
- Inner mucus layer from goblet cells on the conjunctiva
What is dacryocystitis?
Dacryocystitis – inflammation of the lacrimal sac usually as a result of blockage of the nasolacrimal duct
How does Dacrocystitis present?
Presents as red very tender swelling at the medial canthus below medial canthal tendon +/- localised cellulitis and history of watery eye.
How is Dacryocystitis managed?
Need high doses of oral antibiotics (co-amoxiclav) and refer to lacrimal clinic. Lacrimal sac abscess may rupture spontaneously and result in a fistula.
What is keratoconjunctivitis sicca?
Keratoconjunctivitis Sicca (dry eyes) Caused by either poor production of tears or rapid evaporation.
What can cause a reduced production of tears leading to dry eyes?
Reduce production Old age Sjorgen’s syndrome Rheumatoid Arthritis Mumps Sarcoidosis Amyloidosis Lymphoma Leukaemia Haemochromatosis Drugs such as antihistamines
What can lead to excessive evaporation of the tear film?
Postexposure keratitis
Mucin deficiency – Schirmer’s test
What is xerophthalmia?
Dry eyes secondary to deficient tear production due to Vitamin A deficiency. Over time this leads to Keratomalacia – thinning of the cornea than eventually leads to ulceration. Most common in children aged 2-5.
How does xerophthalmia present?
Blindness – especially at night (nyctalopia)
Tunnel vision
Dry conjunctiva (xerosis)
How is xerophthalmia treated?
Vitamin A will reverse these changes
What is epiphora?
Epiphora – passive overflow of tears onto the cheek
What can cause decreased drainage of the tear film?
Decreases drainage – punctal stenosis or canaliculitis. Use direct ophthalmoscope to visualise the punctum. Nasolacrimal duct obstruction very common in infants due to imperforate membrane. Usually resolves otherwise probing to burst membrane
What can cause increased lacrimation?
Increased lacrimation – both eyes effected? Causes are environmental triggers, corneal injury or FB. Lubricating drops help.
What can causes a pump failure that leads to watery eyes?
Pump failure – when blinking positive and negative pressure is created in the lacrimal sac which sucks tears into it. Look for causes of pump failure such as entropion or ectropion, myasthenia gravis or CNVII
