Disorders of the Equine Lens

Question 1

What is the difference between nuclear sclerosis and a cataract?

Answer 1

Nuclear sclerosis = lens nucleus becomes densely packed with normal fibers
Cataracts = an opacity on or within the lens associated with ABNORMAL lens fibers

Question 2

A 15 year old TB gelding presents to your clinic for a routine annual exam. You take a quick look at the eyes and notice a diffuse opacity throughout the entire lens. His menace is still intact and PLRs are normal. What is your diagnosis?

Answer 2

Nuclear sclerosis

Question 3

How much of the lens does an incipient cataract obscure?

Answer 3

< 15%

Question 4

How much of the lens does an immature cataract obscure?

Answer 4

15-99%

Question 5

How much of the lens does a mature cataract obscure?

Answer 5

100% - you will NOT see a tapetal reflection through these

Question 6

What is characteristic of a hypermature cataract?

Answer 6

Signs of resorption (wrinkles with sparkling white crystal appearance, can start to see tapetal reflection again)

Question 7

What is the most common cause of cataracts in the horse?

Answer 7

Inflammatory/post-inflammatory

Question 8

What kind of cataracts do not progress?

Answer 8

Nuclear cataracts that DO NOT extend to the cortex

Question 9

What are the clinical implications of cataracts?

Answer 9

They can scatter light, distort images, and decrease acuity

Question 10

When (in what patients) is cataract surgery success the highest?

Answer 10

Foals less than 6 months of age

Question 11

What type of sight will an aphakic horse have?

Answer 11

Hyperopic (far-sighted - can’t see up close, can see things far away)