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Glaucoma

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Samoyed. Springer spaniel. Pectinate ligament dysplasia. Samoyed. Springer spaniel. Flat Coated Retriever. Secondary glaucoma. Anterior uveitis ... – PowerPoint PPT presentation

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Title: Glaucoma


1
Glaucoma
  • Björn Ekesten
  • Department of Clinical Sciences, SLU
  • 2006

2
What is glaucoma?
  • A condition with elevated, abnormal intraocular
    pressure (IOP)?
  • The abnormal IOP damages different ocular
    structures
  • Impaired function
  • An optic neuropathy with a certain type visual
    field loss?
  • Elevated IOP is only a risk factor

3
Aqueous humor
  • Transparent
  • Ultrafiltrate of plasma
  • Very few cells
  • Low protein content
  • Function
  • Nutrition
  • Eliminates wastes
  • Maintains the shape of the globe
  • Required for normal refraction

4
Production
  • Formed in the ciliary body
  • Diffusion
  • Lipophilic substances
  • Ultrafiltration
  • Passage over a cell membrane hydrostatic
    pressure
  • Active secretion
  • Carbonic anhydrase
  • Rate of formation
  • Dog 2,5 µl / min
  • Cat 15 µl / min

5
Elimination
  • Conventional outflow
  • Bulk flow - plexus aqueous
  • Normal dog 85
  • Normal cat 97
  • Non-conventional (uveoscleral) outflow
  • Normal dog 15
  • Normal cat 3
  • Glaucomatous dog 3
  • What is the normal rate of elimination / min?

6
Kammarvinkeln
7
Intraocular pressure (IOP)
  • (Pa-Pi) Cin (Pi-Pe) Cout U
  • Cin inflow facility µl / min / mm Hg
  • Cut outflow facility µl / min / mm Hg
  • Pa ciliary artery pressure mm Hg
  • Pi intraocular pressure (IOP) mm Hg
  • Pe episcleral venous pressure mm Hg
  • U uveoscleral outflow µl / min

8
Glaucoma
  • Cause of elevated IOP
  • Impaired aqueous outflow
  • Not increased production
  • Primary - without predisposing ocular disease
  • Secondary - complication to other ocular diseases

9
Pupillary block
  • Primary
  • Relative pupillary block (angle-closure glaucoma)
  • Sekundary
  • Total posterior synechia / iris bombé (seclusio)
  • Inflammatory debris in the pupil (occlusio)
  • Fakomorfic (intumescent catarakt / swollen lens)
  • Lens(sub)luxation, vitreous prolaps

10
Closed iridocorneal angle
Iris touches the corneal endothelium
  • Primary
  • Angle-closure glaucoma (effect of the relative
    pupillary block)
  • Secondary
  • Iris bombé (together with pupillary occlusion)
  • Anterior uveitis - peripheral anterior synechiae
  • Forward displacement of peripheral iris -
    neoplasia, iridociliary cysts?

11
Reduced opening to ciliary cleft
  • Primary
  • Angle-closure glaucoma (collapse of ciliary
    cleft)
  • Dysplasia of the pectinate ligamentet
  • Secondary
  • Anterior uveitis / preiridal membranes
    (predisposed individuals)
  • Neoplasia

12
Pectinate ligament dysplasia
  • Increased risk for glaucoma if excessive PLD
  • 100 90 risk
  • 75 11 risk
  • 50 0,2 risk
  • Polygenic inheritance
  • Triggering factor?

13
Outflow block inside the ciliary cleft
  • Primary
  • Open-angle glaucoma
  • Sekundary
  • Anterior uveitis - inflammatory debris
  • Intraocular hemorrhage
  • Melanocytosis / neoplastic cells
  • Viscoelastics

14
Primary glaucoma
  • Open-angle glaucoma
  • Beagle (AR)
  • Norwegian Elkhound
  • Angle-closure glaucoma
  • Samoyed
  • Springer spaniel
  • Pectinate ligament dysplasia
  • Samoyed
  • Springer spaniel
  • Flat Coated Retriever

15
(No Transcript)
16
Secondary glaucoma
  • Anterior uveitis
  • Peripheral anterior synechiae
  • Posterior synechiae
  • Debris
  • Lens associated
  • Catarakt
  • Luxation / subluxation
  • Intraocular neoplasias
  • Intraokular hemorrhage
  • Intraokular melanocytosis
  • Iridociliary cysts

17
Acute glaucoma
  • Sudden onset and dramatic
  • Signs of pain
  • Blepharospasm
  • Epiphora
  • Altered behaviour
  • Episcleral congestion
  • Corneal changes
  • Cloudiness / edema
  • Striae
  • Mydriasis - no response to light
  • Impaired vision
  • Elevated IOP

18
Sequels - short-term
  • Ganglion cell damage
  • Optic nerve head excavation and cupping
  • Visual impairment
  • Secondary uveitis
  • Synechiae formation
  • Rapid!

19
Open-angle glaucoma
  • Insidous!
  • Obvious clinical signs rare initially
  • Visual field loss
  • Slightly - moderately elevated IOP (30 mm Hg)
  • Optic nervehead alterations
  • Obvious signs when ciliary cleft has collapsed

20
Chronic glaucoma
  • Chronic pain
  • Impaired vision / blindness
  • Buphthalmos
  • Chronic uveitis
  • Cataract
  • Lens luxation
  • Retinal degeneration
  • Elevated IOP

21
Diagnosis
  • Eye examination
  • Tonometry
  • Gonioscopy
  • Primary / secondary?

22
Treatment
Medical
Filtration surgery
Cyclo- destructive surgery
23
Acute medical treatment
  • Mannitol 1-2 g/kg iv
  • Transient decrease in IOP
  • Not horse
  • Miotics (topical)
  • Pilocarpine 2 x 3-4
  • Avoid in horses
  • Beta blockers (topical)
  • Timolol 0,5 x 2
  • Prostaglandins (topical)
  • Latanoprost x 1-2
  • Not in horses
  • Carbonic anhydrase inhibitors (topical)
  • Dorzolamid
  • Brinzolamid

24
Maintenance
  • Miotics (topical)
  • Pilocarpine 2 x 3-4
  • Avoid in horses
  • Beta blockers (topical)
  • Timolol 0,5 x 2
  • Prostaglandins (topical)
  • Latanoprost x 1-2
  • Not in horses
  • Carbonic anhydrase inhibitors (topical)
  • Dorzolamid x 2-3
  • Brinzolamid x 2-3
  • Surgical intevention?

25
When is surgery needed?
  • When medical treatment is insufficient
  • Does it help
  • Shunts
  • Cyclodestructive treatments
  • Laser
  • Cryo
  • Enucleate if the IOP cannot be controlled properly

26
Gonioscopic findings in ESS
27
Selective breeding
28
Summary
  • Several mechanisms
  • Primary / secondary
  • Mode of inheritance?
  • No DNA-tests available
  • Emergencies!
  • Guarded prognosis, at best.
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