Week 4 Flashcards
(145 cards)
What is surrounding the eye?
Densest collagen in the body on the outside- sclera and cornea anteriorly
What is the most common eye injury we will see?
Mechanical injury- transfer of kinetic force to the eye. Blunt (closed eye injury, remains intact) or sharp trauma (eye ruptures). Penetrating injury doesn’t always get through the cornea or sclera or it can perforate.
** coup and countre coup injury can occur in the eye as well

Chemosis- the swelling of the conjunctiva (surrounds the sclera)– conjunctiva is full of lymphatics and conjunctiva. Chemosis is a non- specific response to injury.

Conjunctival haemorrhage (can occur with chemosis)

Blepharospasm

Epiphora- either overproduction of tears or inadequate drainage

Corneal oedema- endothelium is important in maintaining the transparancy of the cornea because it pumps fluids out. Can be localized or diffuse.
What happens to the eye with this type of trauma?

May see a rim of pigment left behind on the rim, you will see the angles change– you are impeding the drainage of the aqueous humour–> intra-occular pressure rises–> cause deformation of the eye–> can cause serious problems at the junction between the cornea and the sclera.. very sensitive to shear forces–> ANGLE RECESSION, ANGLE TEARING = HAEMORRHAGE


Hyphaema- pressure dropping, which causes this problem. The amount of blood in the eye can impede the oxygenation of the tissues. Gradually drains out but can block the drainage and cause problems with pressure.
(Closed eye blunt trauma)

Corneal blood staining

Traumatic cataract- effect on the lens, damaging anterior lens capsule from blunt trauma, star burst opacity. Closed eye blunt trauma. Cataract= clouding of the lens (lens is made of epilthelial cells- if you get damage to the equilibrium, fibres can break down– leading to loss of transparency– age and increasing density– cataract is a pathological phenomenon where fibres are degrading– can be focal or diffuse… some cataracts are breed related, and found in specific parts of the lens)

Lens luxation from blunt trauma (closed eye). Rupture of zonula fibres… can be forwards (through the pupil into the anterior chamber- sitting in the chamber blocking fluid flow- eye has no lymphatic drainage- it relies on the flow of aqueous humour from the ciliary body– if you block the angles– serious problems of pressure and hypoxia) or backwards (into vitreous). Posterior chamber is in front of the lens- between the iris and the lens.
What is the picture? What is flare?

Rubeosis iridis (won’t see most of the time because their eyes are brown- the delicate fine vessels are not supposed to be there)
Anything that causes hypoxia in the eye causes blood vesselts to proliferate due to release of VEGF and other factors.
Flare= protein leakage in the aqueous humour
(Closed eye blunt trauma)

When can retinal atrophy occur?
* Blunt trauma can actually transmit a shock wave through the vitreous (it is a gel)- and can shear the photoreceptor segments. The shock wave of the vitreous body can damage soft tissue. It can repair. You may never know it happened in veterinary medicine. Sometimes it doesn’t repair. If the choroid is damaged (supplies nutrition to the retina) then the retina will atrophy
Possible consequences of blunt eye trauma


Iris Prolapse

Ruptured globe- most common site of rupture is the temporal limbus (versus nasal– different directional terms due to horses and cattle can’t use lateral and medial).
** if you rupture the eye- the fluid will come out and it can take the uvea out with it. It can take the iris out as well since it is floating around. Entire intra-occular contents can be expelled- you don’t need a big hole either (e.g. 3 mm hole in humans).
** loss of barrier of epithelium = loss of protection for infection… plugging the whole with the uvea does not protect against infection– it does not replace the cornea in that regard
What can penetrating injury cause?
* Penetrating injury is usually more focused- energy in a pointed way that may or may not perforate the eye
** oedema
** can carry the epithelium in with the object

Epithelialisation- epithelium travels inside the eye with the penetrating object. You can culture your own epithelium– it just grows and covers the eye- the normal restrainst to growth are not present. If some of the fibrous stroma also gets in… or fibrous membranes- live behind the iris– you can then get granulation tissue…. they contract in the skinw hich is good BUT in the EYE, the tissues deform… and then can cause RETINAL DETACHMENT

Retinal detachment

Grass seed- moved around in the eye- gets to the back of the eye, bumps up against the orbit and optic n. May not see damage much from the front. lt also takes bacteria in with it. Which completely wrecks the tissues. Can end up full of pus. Common injury in young dogs– cat clawing especially.
Endopthalmitis or Panopthalmitis

How are immune responses different in the eye?
You can’t afford to have a normal immune response in the eye. Sequestered from the immune system (other parts of the body too). You can’t disrupt the delicate balance of the eye system. It means though that when things get in there, they can go wild. It also means that proteins and antigens that get in the eye are “foreign” from the eyes point of view. You can get a lens induced uviitis- not infectious, can be completely sterile but still wreck the eye because of its own proteins.
Open eye trauma- penetrating injury
* Cyclitic (ciliary body) membrane- impede production of vitreous humour and the eye becomes hypotonic (fluid mechanics)
* traumatic injury to the lens of a cat may cause a focal post traumatic lens sarcoma (neoplasm) derived from the lens epithelium (name is off)- more common in the US so possibly a genetic component

Capacity of regeneration and repair in the eye
Cornea is the only part that can regenerate
* Repair:
* Retina: Muller cells, retinal pigment epithelium (only possible with these two types of cells)
* Lens: epithelium- limited
* Uvea- limited
* Sclera- limited
(function is rarely restored back to normal, which sometimes does not matter)












































































