Glaucoma Flashcards
Where is aqueous produced?
Which enzyme allows for active secretion of aqueous?
What is the formula for this? And how does this work?
Non pigmented epithelium of the ciliary body
Carbonic anhydrase
(Formula in photo)
Movement of bicarbonate ions into the posterior chamber creates osmotic gradient, drawing in water from ciliary stromal vasculature
In regards to aqueous drainage, where does conventional drainage occur?
And unconventional drainage?
Which is the main drainage?
Conventional drainage (main) iridocorneal angle
Unconventional drainage (minor) uveoscleral outflow
Does IOP increase or decrease with age?
Decrease
Does GA increase or decrease IOP?
Decrease
What are the major structures of the drainage apparatus (trabecular mesh work) for aqueous?
Trabecular meshwork- pectinate ligament + ciliary cleft
Why does mydriasis occur in glaucoma?
Pressure induced paresis/ paralysis of the iris sphincter.
Why does corneal oedema happen in glaucoma?
High IOP interferes with the corneal endothelial pump (normally moving water out of the corneal stroma) and then excess water disrupts the stromal lamellae
Is the third eyelid likely to be up or down in globe enlargement?
In exophthalmos?
Globe enlargement- down
Exopthalmos - up
What are descemets fractures/ Haabs striae pathopneumonic for?
Chronic glaucoma
Why can glaucoma cause lens luxation?
Globe enlarge can cause stretching and tearing of the zonular fibres, loosening the lens
In general does primary lens subluxation cause the aphachic crescent to go ventro laterally or dorsally?
And in secondary lens luxation?
Primary- dorsal
Secondary- ventrolaterally
What happens to the optic disc when there is glaucoma?
Cupping- bows backwards
Then optic nerve head atrophy
What happens during glaucoma to the -retina?
-retinal vessels?
Are these effects reversible?
Retina- thinning causing hyper reflectivity
Retinal vessels- attenuated
No- not reversible!
What are equatorial staphylomas caused by?
Glaucoma- scleral thinning and stretching.
Pressure induced atrophy of what can cause a normal pressure in a glaucomatous eye?
Ciliary processes
Is the Norwegian Elkhound predisposed to
A) pectinate ligament abnormality/goniodysgenesis
OR
B) open angle glaucoma
B
Is the flat coat retriever predisposed to
A) pectinate ligament abnormality/goniodysgenesis
OR
B) open angle glaucoma
A
Is the Petit Basset Griffon Vendeen predisposed to
A) pectinate ligament abnormality/goniodysgenesis
OR
B) open angle glaucoma
B
Is the Fauve de Betagne predisposed to
A) pectinate ligament abnormality/goniodysgenesis
OR
B) open angle glaucoma
B
Is the Basset Hound predisposed to
A) pectinate ligament abnormality/goniodysgenesis
OR
B) open angle glaucoma
A & B!!
Is the English & Welsh Springer, and English cocker spaniel predisposed to
A) pectinate ligament abnormality/goniodysgenesis
OR
B) open angle glaucoma
A
Is the Siberian Husky predisposed to
A) pectinate ligament abnormality/goniodysgenesis
OR
B) open angle glaucoma
A
Is the Welsh Terrier predisposed to
A) pectinate ligament abnormality/goniodysgenesis
OR
B) open angle glaucoma
A
Is the Great Dane predisposed to
A) pectinate ligament abnormality/goniodysgenesis
OR
B) open angle glaucoma
A
Is the Hungarian Viszla predisposed to
A) pectinate ligament abnormality/goniodysgenesis
OR
B) open angle glaucoma
A
Is the Dandie Dinmont predisposed to
A) pectinate ligament abnormality/goniodysgenesis
OR
B) open angle glaucoma
A
Is the Border Collie predisposed to
A) pectinate ligament abnormality/goniodysgenesis
OR
B) open angle glaucoma
A
Is gonioscopy useful in open angle glaucoma?
No (drainage angle is normal)
Is pectinate ligament abnormality/goniodysgenesis congenital or acquired?
Congenital
What is the main breed for primary lens luxation?
Terriers
Occasionally Border collie
Is it more common to get glaucoma with an anterior or posterior lens luxation?
Anterior
In uveitis the iris can become swollen causing glaucoma because it blocks what?
The drainage angle
What are the most common intraocular neoplasias? (3)
Uveal melanoma
Lymphoma
Primary ciliary body adenoma/ adenocarcinoma
What breed gets ocular Melanosis/ pigmentary glaucoma?
What age bracket?
Is there any tx to halt the pigment?
Cairn terriers
Middle- old age
No
What is more effective in cats with glaucoma?
Dorzolamide (trusopt)
Brinzolamide (azopt)
Dorzolamide (trusopt)
What is a possible side effect of Dorzolamide (trusopt) in cats?
Hypokalaemia
Which one stings less?
- Dorzolamide (trusopt)
- brinzolamide (azopt)
Dorzolamide (trusopt)
What should be frequency of CAI (Dorzolamide, trusopt and brinzolamide, azopt) in;
- dogs
- cats
Dogs q6-8h
Cats q12h
What % can CAIs reduce IOP by?
50%
How do prostaglandin analogues increase outflow?
Unconventional (uveoscleral outflow)
When are prostaglandin analogues contraindicated? (2)
Uveitis
Lens luxation
In acute management of glaucoma how often and how many times can you use prostaglandin analogues?
q15mins for 4-6 doses
How often do you give prostaglandin analogues for chronic management?
Latanoprost (Xalatan)
Travaprost (travatan)
SID
How beta adrenergic blockers work in glaucoma?
Decrease aqueous production
May increase outflow too
When is Betoxalol, a beta adrenergic blocker, useful?
Delaying the development of glaucoma in cases of PLA/ goniodysgenesis
How often is cosopt (Dorzolamide and timolol) given?
q12h
What is the process of cyclocryoablation?
How does it treat glaucoma?
Destroys ciliary processes and ciliary epithelium via freezing
Decreasing aqueous humour formation
What happens to the IOP immediately post surgery?
Increases
For how long after performing cyclophotocoagulation should medical tx be continued?
4weeks
How can fibrosis and scarring soon after filtration devices have been placed for cases of glaucoma be prevented (2 ways)?
Antifibrotic agents
Beta irradiation during surgery
What drug is used for pharmacoablation in cases of glaucoma?
How does it work?
What are the risks with this technique?
Why is this contraindicated in cats?
Gentamicin
Destroys the ciliary body epithelium and retina so reduces aqueous humour formation
Intractable uveitis resulting in phthisis bulbi
Risk of feline post traumatic sarcoma
What coloured eyes does cyclophotocoagulation not work in?
Where do you avoid in this technique?
Blue iris
3 and 9 o’clock position as that’s where blood vessels are
What does cyclophotocoagulation use to work?
What does it destroy?
Laser energy (Nd-YAG and diode lasers)
Ciliary processes
Is glaucoma in cats normally primary or secondary?
Secondary
Cats with an anteriorly luxated lens doesn’t always have an increase in IOP, why is this?
Cats have large anterior chambers
Aqueous misdirection (Aqueous flows in to the vitreous) can cause glaucoma in cats, what is the treatment for this? Is it uni or bilateral?
Vitrectomy with lens removal
Bilateral
What is the most common cause of feline glaucoma?
Anterior uveitis
Is latanaprost useful in feline glaucoma?
No
Will cause miosis
What are the lines on the cornea?
What is this pathognomonic for?
Haabs striae
Chronic glaucoma
Which breed does pigmentary and cystic glaucoma happen in in the USA?
Golden retrievers
What dose of mannitol should be used in acute glaucoma?
1-2g/kg iv over 20-30mins
When using a prostaglandin analogue in acute glaucoma how often should you use it?
Every 15mins 4-6 doses
When is beta blockers useful in glaucoma?
Cats
Open angle glaucoma
Not in PLA in dogs
What needs to be removed in endolaser?
Lens
How can you diagnose aqueous misdirection syndrome in cats?
Treatment?
Shallow anterior chamber
Lendectomy
