Seminar: The Red Eye

Question 1

3 steps to thinking through ophthalmology cases

Answer 1

1. Where, What and HOW (pathophysiology)
2. Work up
3. Treatment Plan

Question 2

3 areas to think about with possible pathophysiology? Other things to think about?

Answer 2

1. tissue affected
2. its parts
3. its relationship to other tissues
   - anything related but not directly visualised involved?
   - occular v systemic disease

Question 3

What are the 3 steps of the workup?

Answer 3

1. diagnositcs
2. Ddx
3. further diagnostics necessary

Question 4

3 steps of treatment plan in general practice?

Answer 4

1. diagnostics and advice
2. treat what you feel confident about
3. refer to the right specialist

Question 5

Where can redness be seen?

Answer 5

• eyelids
• conjunctiva/episclera/sclera
• TE
• cornea
• anterior chamber
• anterior uvea
• posterior uvea/retina and retrobulbar area not directly visualised

Question 6

What is the uvea?

Answer 6

• “grape”
• a mesh of blood vessels, heavily pigmented
• iris, ciliary body and choroid

Question 7

What can leaky vessels d/t inflammation lead to?

Answer 7

flare

• keratic precipitates
• hypophema
• posterior synechia

Question 8

How can eyelids be affected -> redness? What may occour 2* to eyelid damage?

Answer 8

• 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

Question 9

Which layers of blood vessels may be seen as hyperaemic?

Answer 9

> 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)

Question 10

How do vascular patterns in cats differ from dogs?

Answer 10

less aggressive looking and red and angry, more subtle

Question 11

What does the sclera consist of ?

Answer 11

white of the eye

• fibrous tunic continuous with cornea via limbus
• collagen fibres, fibroblasts and emisaria (holes for BVs and nerves)

Question 12

How may the TE be affected by inflammation?

Answer 12

> 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)

Question 13

What are the 4 layers of the cornea?

Answer 13

• 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)

Question 14

What happens if protection of storm is lost or damaged? 3 causes

Answer 14

• overhydration = corneal oedema

- d/t epithelial damage, endothelial damage or vascularisation of the cornea

Question 15

What structures define the AC?

Answer 15

• corneal endothelium
• anterior surface of iris and lens
• irial corneal angle (outflow of aqueous humour)

Question 16

Where is aqueous formed and where does it travel?

Answer 16

• ciliary body
• posterior chamber to anterior chamber through pupil
• exits via iridial corneal angle

Question 17

What 2 diseases affectt the AC?

Answer 17

• glaucoma (ICA closure/clogging - ^ IOP)

- uveitis (^ uveoscleral outflow - v IOP, if chronic -> clogged 2* glaucoma)

Question 18

What sections make up the uvea?

Answer 18

• anterior uvea (ciliary body, iris; muscles (constrictor and dilator, CB musculature) anterior blood ocular barrier)
• posterior uvea (choroid; tapetum lucidum)

Question 19

What can uveitis result in?

Answer 19

• 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)

Question 20

When may rubiosus iridis be seen?

Answer 20

FIP/FIV/FeLV

Question 21

What is the cause of anterior synechia?

Answer 21

• sudden decompression -> iris prolapse and adherence to cornea

Question 22

Which parts of the eye cannot be seen directly? What may occur d/t damage to these?

Answer 22

> 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

Question 23

What do retrobulbar problems lead to?

Answer 23

• 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

Question 24

Ddx remembering thingy

Answer 24

DAMNIT (C)

• developmental, degenerative
• autoimmune, acquired
• metabolic
• neoplastic, nutritional, neurological
• immune, infection, inflammation, iatrogenic, inherited
• trauma, toxins
• congenital