Abnormal Eye Size and Position

Question 1

What are the five main causes of abnormal eye size/position?

Answer 1

1. Retrobulbar space occupying lesions
2. Microphthalmia
3. Bupthalmia
4. Glaucoma
5. Lens luxation

Question 2

What are the clinical signs of a space occupying lesion?

Answer 2

Globe displacement
Protrusion of the third eyelid
Changes in facial symmetry

Question 3

What is buphthalmia?

Answer 3

An enlarged eye

Question 4

Why does buphthalmia occur and what are the consequences?

Answer 4

Due to increase IOP (Glaucoma). High IOP leads to globe stretching which is revealed through the following:

• Conjunctival and episcleral vessels
• Corneal oedema
• Haab’s striae (stretch marks in descemet’s membrane)
• Zonular tears
• Corneal ulceration

Question 5

What are the cardinal signs of lens luxation?

Answer 5

Phacodonesis (Lens wobbling)
Iridodonesis (Iris wobbling)
Anterior presentation of the vitreous (Muscous like strands in AC)
Posterior luxation (Lens falls backwards into AC)
Anterior luxation (Pupil blocks causing IOP rocket increase)

Question 6

How would you control IOP?

Answer 6

1. Antihypertensive drops - Timolol (beta blocker) + Dorzolamide (carbonic anhydride inhibitor). In the horse use Latanoprost (PG analogue)
2. Treat underlying cause

Question 7

What is aphakic crescent?

Answer 7

Rupture of zonules due to stretch from buphthalmia when there is high IOP

Question 8

How would you perform an IOP curve?

Answer 8

A measurement series over 30 hours, taking measurements every 3