Equine lens

Question 1

First and second most important refractive structures in eye

Answer 1

#1 cornea
#2 lens

Question 2

Lens epithelium is present at

Answer 2

equator and lines the anterior lens cortex

Question 3

Three major regions of lens

Answer 3

1. Cortex
2. Nucleus
3. Capsule

Question 4

Most common cause of acquired cataracts in the horse

Answer 4

ERU

Question 5

Classification of adult cataracts (4)

Answer 5

1. Age of onset
2. Etiology/cause
3. Location within the lens
4. Stage of maturity
   - incipient
   - immature
   - mature
   - hypermature

Question 6

When to eval a horse for cataracts (4)

Answer 6

1. ocular exam
2. ALL pre-purchase exams
3. All insurance exams
4. Initial foal exam on newborn

Question 7

Exam of lens (how to)

Answer 7

1. Focal light source DOS, Finoff transilluminator or slit lamp SL-15
2. Mydriasis w/ two doses of 1% tropicamide topically after 5 min
3. Mydriasis in 15-30 min

Question 8

Luxated lens usually becomes

Answer 8

cataractous

Question 9

Iridodonesis

Answer 9

slight vibration/trembling of iris because of a luxated lens posterior (no more support for iris)

Question 10

To see the complete lens it’s necessary to

Answer 10

dilate eye

Question 11

Future directions in equine surgery

Answer 11

1. injectible IOLs
2. determine best diopteric strength of IOLs
3. Post-op vision determination
4. Liability for surgeon if someone is injured by horse post-op