Seminar: The Red Eye Flashcards
3 steps to thinking through ophthalmology cases
- Where, What and HOW (pathophysiology)
- Work up
- Treatment Plan
3 areas to think about with possible pathophysiology? Other things to think about?
- tissue affected
- its parts
- its relationship to other tissues
- anything related but not directly visualised involved?
- occular v systemic disease
What are the 3 steps of the workup?
- diagnositcs
- Ddx
- further diagnostics necessary
3 steps of treatment plan in general practice?
- diagnostics and advice
- treat what you feel confident about
- refer to the right specialist
Where can redness be seen?
- eyelids
- conjunctiva/episclera/sclera
- TE
- cornea
- anterior chamber
- anterior uvea
- posterior uvea/retina and retrobulbar area not directly visualised
What is the uvea?
- “grape”
- a mesh of blood vessels, heavily pigmented
- iris, ciliary body and choroid
What can leaky vessels d/t inflammation lead to?
flare
- keratic precipitates
- hypophema
- posterior synechia
How can eyelids be affected -> redness? What may occour 2* to eyelid damage?
- skin, meibomian glands and conjunctiva
- dermatitis
- meibomian glands
- > 2* cornea and tear film affected as intimately associated (loss of protection/loss of oily part of tear film/contact problem)
- > ulcers and epiphora, hyperaemia and vascularisation
Which layers of blood vessels may be seen as hyperaemic?
> conjunctival (dichotomous branching, v senstivie to surface irritation -> hyperaemia and oedema (chemosis))
- line eyelids, sclera and 3rd eyelid, ends at limbus where white meets cornea (stem cells stop conjunctiva taking over cornea)
episcleral (thick, chunky, meandering, connective tissue under conjunctiva)
- only line sclera on eyeball
- may be inflamed 2* to very severe surface disease or more commonly INTRAOCULAR disease (uveitis/glacuoma)
How do vascular patterns in cats differ from dogs?
less aggressive looking and red and angry, more subtle
What does the sclera consist of ?
white of the eye
- fibrous tunic continuous with cornea via limbus
- collagen fibres, fibroblasts and emisaria (holes for BVs and nerves)
How may the TE be affected by inflammation?
> lymphoid folicles on bulbar side + some on palpebral side
- v. prominent young animals and allergies
T shaped cartilagenous core
- can curl and cause outward fold
contains a lacrimal gland
- 30% aqueous tear production
- can prolapse and become inflamed (Cherry eye)
What are the 4 layers of the cornea?
- epithelium (protective barrier, hydrophobic, no BVs if healthy, has unmyelinated nerves)
- stroma (hydrophilic, stays dehydrated d/t epithelium and endothelium [actively pumps fluid back into AC])
- Descement’s membrane
- endothelium (may be damaged d/t uveitis, 1* inflame/infection, glaucoma)
What happens if protection of storm is lost or damaged? 3 causes
- overhydration = corneal oedema
- d/t epithelial damage, endothelial damage or vascularisation of the cornea
What structures define the AC?
- corneal endothelium
- anterior surface of iris and lens
- irial corneal angle (outflow of aqueous humour)
Where is aqueous formed and where does it travel?
- ciliary body
- posterior chamber to anterior chamber through pupil
- exits via iridial corneal angle
What 2 diseases affectt the AC?
- glaucoma (ICA closure/clogging - ^ IOP)
- uveitis (^ uveoscleral outflow - v IOP, if chronic -> clogged 2* glaucoma)
What sections make up the uvea?
- anterior uvea (ciliary body, iris; muscles (constrictor and dilator, CB musculature) anterior blood ocular barrier)
- posterior uvea (choroid; tapetum lucidum)
What can uveitis result in?
- mioisis (iris spasm and pain)
- mydriasis (opposite of miosis)
- endothelial cell separation -> leakage of blood components into the AC (keratin precipitates, hypopion, hyphema, protein) and around the lens (“snow banking”)
- posterior synechia (adhesion of iris to anterior lens)
- development of PIFMs (preiridial fibroaxillar membranes)
> grow over iris (rubiosus iridis)
> may cause bleeding (hyphema)
> blockage of ICA (2* glaucoma)
When may rubiosus iridis be seen?
FIP/FIV/FeLV
What is the cause of anterior synechia?
- sudden decompression -> iris prolapse and adherence to cornea
Which parts of the eye cannot be seen directly? What may occur d/t damage to these?
> posterior uvea
- continuous with anterior urea so often both affected (panuveitis)
- retinal detachement
- hyphema if in anterior chamber too
retrobulbar area
- inflam/infection (dentals, trauma [carnivores and pigs have incomplete orbit] idiopathic, middle ear abscess, haematogenous, parasites, conjunctival FBs migrating… )
- neoplasia (muscle sarcomas, haemoagniosarcoma, nerve gliomas etc., osteosarcomas, lacrimal ducts and salivary glands)
sinuses
something else important look up
What do retrobulbar problems lead to?
- altered position of eye within orbit and relationship w/ eyelids
- ^ pressure around eye
- swelling/infection of surrounding tissues (eg. conjunctiva)
> these may all cause redness of the eye - vision loss (ON)
- pupillary problems
- restricted ocular movement
Ddx remembering thingy
DAMNIT (C)
- developmental, degenerative
- autoimmune, acquired
- metabolic
- neoplastic, nutritional, neurological
- immune, infection, inflammation, iatrogenic, inherited
- trauma, toxins
- congenital
