The Opaque Eye - Intraocular Disease

Question 1

What is found at the centre of the lens?

Should you be able to see it in the normal eye?

Answer 1

Nucleus

No

Question 2

What is the lens attached to?

Answer 2

The ciliary body

Question 3

What causes nuclear sclerosis?

Answer 3

Lens nucleus becomes compact and dense with aging

DOES NOT CAUSE BLINDNESS

Question 4

What clinical signs are associated with lens disease?

Answer 4

Decreased transparency - cataract

Phacodenesis - lens luxation
Iridodonesis - trembling iris
Aphakic crescent - lens subluxation

Question 5

What can cause diseases of the lens ?

Answer 5

Congenital abnormalities
Cataract
Lens induced uveitis
Lens luxation

Question 6

What congenital abnormalities can cause lens disease?

Answer 6

persistent blood vessels
Microphakia - small lens
Lens coloboma - hole in lens

Question 7

Define the term cataract

Answer 7

Any non-physiologic opacity in the lens

Question 8

What is the most common cause of cataracts?

Answer 8

Diabetes Mellitus

DOGS usually develop within 2y of diabetes diagnosis

Question 9

What is the second most common cause of cataracts?

Answer 9

Progressive Retinal Atrophy (PRA)

Retina degenerates releasing toxins (glutamate) -> cataract formation

Question 10

What drug could prevent the formation of diabetic cataracts?

Answer 10

ALDOSEREDUCTASE

Prevents sorbitol formation

Question 11

What is key on exam to detect and identify cataracts?

Answer 11

Retro illumination

- defects appear black against light background

Question 12

What is an incipient cataract?

Answer 12

Less than 10-15% lens volume

Y shape

Vision minimally affected

Question 13

What are immature cataracts?

Answer 13

Nuclear and cortical regions affected (more than 30% affected)

Tapetal reflex still visible

Decreased vision especially at night

Question 14

What are mature cataracts?

Answer 14

Complete opacity of the lens - marble white appearance

NO TAPETAL REFLEX

BLIND

Question 15

What is a hyper mature cataract?

Answer 15

Small crystalline particles from degraded lens

Wrinkled anterior lens capsule
Lens may decrease in size

Question 16

What is a morgagnian cataract?

Answer 16

Advanced lysis and liquefaction of lens fibres

Solid nucleus might gravitate centrally - DROPPED nucleus

Question 17

What causes lens-induced uveitis?

Answer 17

Proteins leak through lens capsule during cataract maturation

CS - reduced IOP
Resistance to pharmacological dilation
Iris dark colour

Tx early cataracts with antiinflammatories

Question 18

What type of uveitis may be seen in advanced cataracts ?

What cause makes this more likely?

Answer 18

PHACOLYTIC
- spontaneous lens rupture (RARE)

Diabetic

Question 19

What is a potential downside to cataract surgery in dogs?

Answer 19

Need life long anti-inflammatory pos surgery

Question 20

When do you see iridodonesis?

Answer 20

If the lens isn’t there to give it stability

Question 21

What causes primary lens luxation?

Answer 21

Anomalous zonules

Terriers

Question 22

What causes secondary lens luxation?

Answer 22

Chronic inflammation
Glaucoma
Intra ocular mass
Trauma

Question 23

What is pathognomonic of a lens luxation on retroillumination?

Answer 23

Aphakic crescent

Question 24

what is the goal of glaucoma treatment ?

Answer 24

To prolong to process- will eventually go blind as it is IRREVERSIBLE

Question 25

Why does glaucoma occur?

Answer 25

Blocked outflow - problem with aqueous drainage - primary - genetic - secondary to ocular disease

Question 26

What concurrent ocular diseases can lead to glaucoma ?

Answer 26

Uveitis Lens luxation Intraocular tumour Cataract - can leak and cause inflammation

Question 27

What clinical signs are associated with acute glaucoma ?

Answer 27

``` Corneal oedema Episcleral congestion Conjunctival hyperaemia Epiphora MYDRIASIS Aqueous flare Absent menace ```

Question 28

Why is MYDRIASIS associated with glaucoma?

Answer 28

increased intraocular pressure

Question 29

What clinical signs are associated with chronic glaucoma ?

Answer 29

``` Corneal oedema Optic nerve head cupping Hab’she striae (Stretch marks on eye) Bupthalmia Lens subluxation Episcleral congestion Conjunctival hyperaemia Epiphora MYDRIASIS Aqueous flare ABsent menace and blindnes ```

Question 30

What is buphthalmos ?

Answer 30

Enlargement of the eye

Question 31

What is gonioscopy?

Answer 31

Direct viewing of the drainage angle

Question 32

What can you give to patients with uveitis to prevent glaucoma?

Answer 32

ATROPINE Opens pupil and stops iris getting stuck to lens

Question 33

How can pupil size help differentiate between uveitis and gaucoma?

Answer 33

Small pupil - uveitis | Large - glaucoma

Question 34

How can you medically manage glaucoma?

Answer 34

Prostaglandin analogues to increase out flow (drops) Carbonic anhydrase inhibitors to reduce aqueous production by ciliary body

Question 35

How can you surgically manage glaucoma?

Answer 35

Laser cyclophotocoagulation Aqueous shunt placement Enucleation

Question 36

If there is wobbling inside the eye what should you consider?

Answer 36

Lens luxation

Question 37

Why is there less of an inflammatory response in the eyes of cats in general?

Answer 37

Have a better blood aqueous barrier