Glaucoma

Question 1

Glaucoma (2)

Answer 1

1) multifactorial disease
2) elevation of IOP incompatible with ocular health

Question 2

Glaucoma pathogenesis (3)

Answer 2

1) reduced aqueous humor drainage capacity in ALL cases
2) results in progressive IOP elevation
3) irreversible vision loss through optic nerve & retinal ganglion cell death

Question 3

Primary Glaucoma (2)

Answer 3

1) heritable, breed-related abnormality of aqueous drainage angle
2) rarely congenital

Question 4

Secondary Glaucoma (1)

Answer 4

numerous causes of secondary drainage angle obstruction

Question 5

Glaucoma clinical signs in acute disease (5)

Answer 5

1) blepharospasm
2) corneal edema
3) episcleral injection
4) dilated pupil
5) variable vision

Question 6

Glaucoma clinical signs in chronic disease (5)

Answer 6

1) all acute signs possible
2) buphthalmos- swelling of eye
3) Haab’s striae- fracture/break in decimates membrane, streaks across cornea
4) lens subluxation- crescent appearance to lens
5) cupped optic nerve

Question 7

Causes of canine primary glaucoma (4)

Answer 7

1) breed-related/hereditary condition
2) drainage angle abnormality
3) bilateral disease potential
4) one eye affected first then second weeks to months later

Question 8

Causes of canine secondary glaucoma (6)

Answer 8

1) lens luxation
2) uveitis
3) hyphema
4) intraocular neoplasia
5) Melanocytic glaucoma
6) pigmentary uveitis
7) pseudophakia/aphakia
8) trauma

Question 9

Feline glaucoma (4)

Answer 9

1) primary glaucoma is rare
2) secondary similar causes as dogs
3) uveitis common cause of secondary
4) aqueous humors misdirection (unique to cats)

Question 10

Equine glaucoma (2)

Answer 10

1) primary glaucoma is rare
2) most cases secondary to equine recurrent uveitis (ERU)

Question 11

Clinical findings in equine glaucoma (6)

Answer 11

1) usually an insidious disease
2) corneal edema (intermittent or persistent)
3) dilated pupil
4) Haab’s striae
5) lens luxation
6) vision loss

Question 12

Glaucoma diagnosis (4)

Answer 12

1) clinical signs/findings
2) history/signalment
3) IOP measurement
4) Gonioscopy

Question 13

Tonometry (5)

Answer 13

1) measurement of IOP
2) methods: rebound, applanation, indentation
3) 15-25 normal
4) abnormal: IOP differences between 2 eyes
5) important for assessing efficacy of glaucoma therapy

Question 14

Gonioscopy (3)

Answer 14

1) examination of the drainage angle
2) requires specialized lens
3) helps determine likelihood of primary glaucoma based upon angle morphology

Question 15

Goals of therapy (3)

Answer 15

1) maintenance of vision where possible
2) patient comfort in all cases
3) prophylaxis in “at risk” eyes

Question 16

Emergency Management (2)

Answer 16

1) Systemic hyperosmotic medication
2) topical prostaglandin analogue

Question 17

Maintenance medication: Carbonic anhydrase inhibitors (CAIs) (4)

Answer 17

1) very effective
2) can be used in all species and all forms of glaucoma
3) topical and systemic formulation
4) Side effects: GI upset, panting, lethargy

Question 18

Maintenance medication: Miotics 7 prostaglandin analogues (topical) (3)

Answer 18

1) avoid in glaucoma secondary to uveitis or anterior lens luxation
2) reduce aqueous outflow
3) ocular side effects

Question 19

Maintenance medication: Beta blockers (topical) (2)

Answer 19

1) usually no adequate as sole agent
2) side effects

Question 20

Medical prophylaxis (1)

Answer 20

1) significantly delays onset of disease in second eye of dogs with primary glaucoma

Question 21

General treatment principles (6)

Answer 21

1) treat aggressively early in the course of disease
2) target IOP <20 mmHg
3) don’t taper medications in controlled cases
4) consider surgical intervention early in disease course
5) manage underlying disease
6) topical mydriatics are CONTRINDICATED (except horses)

Question 22

Surgical management: Decrease Aqueous production (1)

Answer 22

1) cyclodestructive procedures

Question 23

Surgical management: Increase Aqueous production (1)

Answer 23

1) filtering procedures/aqueous shunts

Question 24

Prognosis (2)

Answer 24

1) long term visual prognosis is poor
2) salvage surgical procedures- reduce pain

Question 25

Salvage procedures (3)

Answer 25

1) enucleation
2) evisceration/intrascleral prosthesis
3) chemical ciliary body ablation