Glaucoma/Lens

Question 1

Glaucoma in horses (and cats) is almost always

Answer 1

Secondary

Question 2

When would it be contraindicated to check IOP in horses?

Answer 2

Deep corneal ulcers / descemetocele
Corneal or scleral lacerations / perforations

Question 3

What are the guidelines to tonometry?

Answer 3

Performed before pupil dilation
Performed after auriculopalpebral nerve block
Pressures should be obtained standing with head above heart
IV sedation may decrease IOP

Question 4

What is normal IOP in horses?

Answer 4

10-20 mmHg
Should be <30 mmHg at all times

Question 5

What are the most common causes of secondary glaucoma in horses?

Answer 5

ERU - most common
Intraocular neoplasia
Blunt trauma
Lens luxation
Following cataract surgery

Question 6

What are the topical medical therapy options for horses with increased IOP?

Answer 6

Dorzolamide/Timolol (Cosopt)
Dorzolamide 2%
Timolol 0.5%
Not Latanoprost

Question 7

What should you not use if you have glaucoma?

Answer 7

Mydriatics (dilation causes worse drainage)

Question 8

What are the complications to surgical therapy?

Answer 8

Corneal edema
Worsening uveitis
Corneal ulceration
Fibrosis around implant
Uncontrolled glaucoma

Question 9

What are the pros to enucleation?

Answer 9

Eliminates need for continued therapy
Fast recovery period
Low complication rate
Allows for histopathologic evaluation

Question 10

What is an expected complication (cosmetic) that occurs with chemical ciliary body ablation?

Answer 10

Phthisis bulbi

Question 11

What breeds might you see inherited congenital cataracts?

Answer 11

Rocky Mountain
Thoroughbreds
QH
Morgans

Question 12

How much of the lens is affected with incipient cataracts?

Answer 12

<10-15%
Visual

Question 13

What would you expect the menace to be with an immature cataract?

Answer 13

Positive

Question 14

What would you expect the menace to be with a mature cataract?

Answer 14

Negative

Question 15

What is often present with hypermature cataracts?

Answer 15

Uveitis

Question 16

What is brunescence?

Answer 16

Increased yellow discoloration of lens
Occurs as normal part of aging
Apparent in some equine cataracts

Question 17

What is the most common cause of cataracts?

Answer 17

Inflammation

Question 18

What are sequelae to cataract formations?

Answer 18

Visual impairment
Lens-induced uveitis
Lens subluxation/luxation
Glaucoma
Retinal detachments

Question 19

What medical therapy options are available for cataracts?

Answer 19

Topical NSAIDs (diclofenac, flurbiprofen, ketorolac)
Does not improve vision
Helps control lens-induced uveitis

Question 20

What is the only therapy available to restore vision with cataracts?

Answer 20

Phacoemulsification
High frequency vibrations emulsify cataract and remove it by aspiration through a small corneal incision

Question 21

What should be considered with cataract surgery in horses?

Answer 21

Overall poor success rates
Horses with ERU are not appropriate candidates
Foals with congenital cataracts may be better candidates
Extensive and prolonged post op care
Vison after surgery should be considered compromised

Question 22

What are the post op complications with cataract surgery?

Answer 22

Corneal ulceration
Persistent uveitis
Endophthalmitis
Glaucoma
Retinal detachment