The Blind Eye

Question 1

What is Symblepharon?

Answer 1

where the bulbar and palpebral conjunctiva form an abnormal adhesion to one another

Question 2

Give an example of a disease that may lead to Symblepharon?

Answer 2

Feline Herpesvirus Type I
The virus destroys the conjunctiva leading the 3rd eyelid to adhere to the conjunctiva of the eyelid

Question 3

What is Keratitis?

Answer 3

Inflammation of the Cornea

Question 4

What structures are involved in Uveal Disease?

Answer 4

any area with blood vessels e.g. iris, ciliary

Question 5

What are the clinical signs of Uveitis? (5)

Answer 5

Aqueous Flare (Tyndall Effect)
Hypopyon (white blood cells in the anterior chamber)
Hyphema (red blood cells in the anterior chamber)
Synechia (iris adheres to the iridocorneal angle
Decreased IOP

Question 6

Adhesions of the iris lead to what pathology of the cornea and why?

Answer 6

Anterior Synechiae adhesion of the anterior surface of iris to the endothelium of the cornea > corneal perforation

Question 6

In cases of Hyphema, what diagnostic investigations should be undertaken to rule out differentials (3)?

Answer 6

ELISA/ Faecal to rule out Lungworm
Blood pressure readings to rule out Systemic Hypertension
Blood Test to rule out Thrombocytopenia

Question 7

When the iris adheres to the lens, this leads to…

Answer 7

Posterior Synechiae- Anterior Synechiae adhesion of the posterior surface of iris to the lens

Question 8

What are Persistent Pupillary Membranes (PPMs)?

Answer 8

a developmental abnormality involving the originate strands of the iris collarete that should have regressed

Question 9

What do PPMs lead to?

Answer 9

Corneal Opacity
Lens Opacity

Question 10

What are some common complications of Uveitis?

Answer 10

Corneal Oedema
Cataracts
Synechiae (anterior and posterior)
Pre-iridal Fibrovascular Membranes
Retinal Detachment
Lens luxation
Glaucoma

Question 11

What causes Uveal Disease? (4)

Answer 11

Systemic Hypertension
Infectious causes such as FIV, toxoplasma, angiostrongylus, pyometra bacteria
Immune Mediated
Neoplastic e.g. lymphoma

Question 12

How is Uveal Disease treated? (3)

Answer 12

1. Treat the cause first
2. Systemic anti inflammatories e.g. prednisolone, meloxicam
3. Topical anti inflammatory treatment e.g. steroid eye drops

Question 13

What are the signs of systemic hypertension?

Answer 13

Intraocular haemorrhages
Bullous retinal detachment
Iridal haemorrhages
Tortuosity (twisting) of retinal vessels

Question 14

What is ERU?

Answer 14

Equine Recurrent Uveitis
Heterogenous, immune mediated disease (several route causes) that causes recurrent inflammation

Question 15

What are the three types of ERU?

Answer 15

Classic
Insidious
Posterior

Question 16

What is classic ERU?

Answer 16

Active Inflammatory episodes followed by periods of minimal ocular uveitis

Question 17

ERU can progress to…

Answer 17

Glaucoma

Question 18

What is Insidious ERU?

Answer 18

Low grade immune response that continues and slowly progresses to chronic clinical signs of Uveitis

Question 19

Which breeds are predisposed to Insidious ERU?

Answer 19

Appaloosa and draft breed horses

Question 20

How is ERU treated medically?

Answer 20

Reduce ocular inflammation- with topical steroids, NSAIDs, Atropine
In severe cases intravitreal steroid injections are administered

Question 21

What surgery treatment options are available for ERU?

Answer 21

1. Suprachoroidal cyclosporine implants
2. Pars plana Vitrectomy (very advanced!)
3. Enucleation (removal of eye)

Question 22

How does Cataracts cause Uveitis?

Answer 22

Causes Phacolytic Uveitis- an inflammatory condition caused by leakage of lens protein from a cataract through a grossly intact lens capsule

Question 23

How does Uveitis cause Cataracts?

Answer 23

due to poor nourishment of the lens & altered chemistry of the aqueous humour

Question 24

Cataracts appear ______ on direct illumination and ______ on retroillumination

Answer 24

white on direct
dark on retro

Question 25

Give an example of a metabolic cause of cataracts?

Answer 25

Diabetes

Question 26

How does diabetes cause cataracts?

Answer 26

Glucose accumulates in the lens > converted to Sorbitol > Sorbitol is a large molecule and cannot diffuse across the lens capsule therefore it builds up to form an opacity on the lens

Question 27

What is Progressive Retinal Atrophy (aka PRA)?

Answer 27

Degeneration of the retina which releases toxins and leads to cataracts

Question 28

What is a senile cataract?

Answer 28

cataracts caused by old age- generally affects the cortex and is wedge shaped

Question 29

Who is more predisposed to Vitreal Diseases?

Answer 29

seen in young patients with Dobermans & Staffies more predisposed

Question 30

What is Retinal Dysplasia?

Answer 30

Folding or complete detachment of the retina

Question 31

What are the three stages to PRA?
(progressive retinal atrophy)

Answer 31

Hyperreflective Tapetum (thinning of retina)
Vascular attenuation (thinning of retinal vessels)
Cataracts

Question 32

What is Retinal Toxicity?

Answer 32

Induced by high doses of enrofloxacin in cats causing neurological signs

Question 33

How is SARDS diagnosed?

[Sudden acquired retinal degeneration syndrome]

Answer 33

ERG (Electroretinography)

Question 34

What are the two types of Retinal detachment?

Answer 34

Inflammatory- retina is pushed by fluid causing detachment from retinal pigment
Disinsertional- retina loses its peripheral attachments causing it to detach from the retinal pigment

Question 35

Name one Ophthalmic Neoplasia

Answer 35

Melanoma (most common eye tumour seen)

Question 36

What is Collie Eye Anomaly?

Answer 36

Combination of 2 diseases- Choroidal hypoplasia and Optic nerve head coloboma [INHERITED]
Causing retinal detachment & Vitreal haemorrhage