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Glaucoma

Glaucoma Paul E. Miller, DVM, Diplomate ACVO University of Wisconsin-Madison GLAUCOMA: A diverse group of diseases united by a common theme in which IOP is too high for the optic nerve to function properly resulting in the loss of some or all vision Incidence VMDB over 20 years

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Glaucoma

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  1. Glaucoma • Paul E. Miller, DVM, Diplomate ACVO • University of Wisconsin-Madison

  2. GLAUCOMA: A diverse group of diseases united by a common theme in which IOP is too high for the optic nerve to function properly resulting in the loss of some or all vision

  3. Incidence • VMDB over 20 years • 1 in 119 dogs • 1 in 367 cats • Screening cats > 7 years old • 1 in 111 cats

  4. Aqueous Humor Flow

  5. Intraocular Pressure • Inflow = Outflow • Production • Active Secretion – Energy – 70% • NaK pump • H20+ CO2H2CO3 HCO3- + H+ • Diffusion – Lipid soluble • Outflow • Trabecular Meshwork – Most • Uveoscleral – 3-15% to 50% • Via Iris • Glaucoma is almost always due to impaired outflow

  6. Step 1: Impaired Outflow  Increased IOP • Apoptotic triggers include: • Neurotrophin deprivation - Excess glutamate • Apoptic gene activation - Ischemia • Excess nitric oxide - Free radicals • Lipid peroxidation - Autoimmunity • Helicobacter pylori infection • A vicious cycle may then result Step 2: Ischemia/Deformation Step 3: Necrosis Apoptosis

  7. Clinical Signs: Red Eye

  8. Clinical Signs

  9. Clinical Signs

  10. Chronic Signs

  11. Diagnosis - Tonometry • Indentation - Schiøtz • Use human calibration tables Original Schiøtz

  12. Diagnosis - Tonometry Applanation – Tono-Pen

  13. Diagnosis - Tonometry • Induction-Impact (Tono-Vet) • Species specific calibration • No topical anesthesia • Accurate in normal dogs and horses • Unsure accuracy in disease

  14. Koeppe Diagnosis - Gonioscopy Lovac eyevetclinic.co.uk PLD – Sheets/flow holes Open Slightly Narrow Closed

  15. Evaluation Schemes • Ekesten AJVR 1991 Width and pectinate ligament dysplasia may be separate entitites

  16. Glaucoma Classification Primary - Open-angle - Angle-closure - Congenital Secondary - Lens associated - Uveitis - Hyphema - Neoplastic - Post-surgery - Many others

  17. Primary Open Angle Glaucoma

  18. Primary Angle Closure Glaucoma

  19. PACG Risk Factors • Mid/older age • Stress • Dim light/night • Genetic • • Mid-range pupil • Abnormal angle • Females 2:1 http://www.aacca.net/newsletterimages/old116.jpg

  20. Normal Sheets and flow holes Sheets Goniodysgenesis (Pectinate Ligament Dysplasia)

  21. How PACG Develops - Dogs Normal PACG PLD is only first “hit”

  22. Acute PACG Therapy

  23. GLAUCOMA VISUAL VISUAL OR BLIND ? BLIND Determine primary cause Relieve pain Enucleation Evisceration / prosthesis Cyclocryosurgery Cyclophotocoagulation Evaluate fellow eye PRIMARY OR SECONDARY ? PRIMARY (CLOSED) Medical Therapy 0.005% Latanoprost or if ineffective Mannitol 2% Pilocarpine Methazolamide Recheck IOP in 3-4 hrs Evaluate Fellow Eye SECONDARY Treat 1o Cause Uveitis Lens Luxation Hyphema Neoplasia Evaluate Fellow Eye Prophylactic Therapy Demecarium or Betaxolol IOP q1 mo for 3 mo then q 3 mo IOP > 20 Perform Surgery IOP < 20 Continue Medical Rx Either Sx now or if IOP > 20 mm Hg Surgery Combined Procedures Cyclocryosurgery Cyclophotocoagulation Gonioimplantation

  24. 37 mm Hg, PD: 8.0 mm 13 mm Hg, PD: 2 mm PGF2 Derivatives • Highly species and dose specific • Are current “front-line” drugs in humans • Xalatan doesn’t work in cats •  uveoscleral outflow ( traditional) • Can  aqueous production in dogs • Intense miotic in animals • Can  IOP 50+ mm Hg

  25. PGF2 Unoprostone 0.12%Rescula® Novartis Latanoprost 0.005% Xalatan® Pfizer Bimatoprost 0.03% Lumigan® Allergan Travoprost 0.004%Travatan® Alcon PGF2 Derivatives • Latanoprost best studied • All work  same • Are additive to all other anti- glaucoma drug classes: • BUT: Pilocarpine may reduce efficacy • NSAIDS don’t directly interfere • BUT: Topical PG’s may recruit endogenous PGs to further IOP

  26. Hyperosmotics • Osmotic gradient dehydrates vitreous • Big drop (50-60 mm Hg) in 1-2 hrs • Short-lived effect (1-2 days) • Toxicity limits to potentially visual eyes • BAB breakdown relative contraindication • Not in CHF (both) or DM (glycerin) • Additive to all other anti-glaucoma drugs • 1st choice only in pre-op lens luxation • Now 2nd to PGs in acute PACG

  27. Carbonic Anhydrase Inhibitors •  aqueous humor production • Systemic toxicity – acidosis, K+, panting, vomiting, diarrhea, weakness • Systemics being replaced by topicals ( toxicity) • TID topical  BID systemic after 1 week (dog) • 20-30% IOP  • Maintains IOP lowering ability over time • Often use with a hyperosmotic in acute PACG • First choice in many secondary glaucomas • Additive to all other classes

  28. Topical CAIs • Irritation primary side effect • Dorzolamide 2% (Trusopt®, Merck) • Cosopt®(Merck) = dorzolamide plus timolol • Brinzolamide 1% (Azopt®, Alcon)

  29. Cholinergics • Old (1873) but potent class • 3rd choice to PGs and CAIs in most • Increase outflow via TM • Contracts longitudinal ciliary muscle • Miosis reopens angle/break pupil block • Additive to every class (+/- PGs) Pilocarpus pennatifolius

  30. -Adrenergic Agonists • Been used for 50+ years • 2nd choice to CAIs in some secondary glaucomas • Usually in combination in primary glaucomas • Epinephrine 1-2% q6-12 hrs • Dipivefrin0.1% BID • Pro-drug cleaved in AC  irritation • 10X IOP lowering effect of epinephrine • May  outflow via ß-2 receptors in TM • May  uveoscleral outflow (relax CB, recruit PGs) • NSAIDS may partially block • May  or  aqueous production •  efficacy with time • Adverse effects: Irritation

  31. -Adrenergic Blockers • First-line prior to PGs in humans • Inhibit ß- 2 receptors on ciliary epithelium  aqueous production • 3rd choice in some secondary glaucomas or as prophylactic • Only mild  in animals – sleep/receptors • May outflow dogs/cats (miosis) • Additive to other classes except  agonists

  32. Beta Blockers • Timolol maleate 0.5% q12hr • Non-selective -1 and -2 blocker • Bradycardia possible • May worsen asthma (cats) • Potent miotic (dog/cat) • Betaxolol HCL 0.5% q12hr • Cardioselective (-1)  risk in asthma • <IOP than timolol • Recently shown to be neuroprotective • Mild miosis • Proven PACG prophylactic • Other -1/-2 • Metipranolol, Levobunolol,Carteolol

  33. Glaucoma Drug TherapyCompliance Human anti-glaucoma drug compliance

  34. Surgical Therapy - Implants

  35. Implants

  36. Surgical Therapy - Laser

  37. Therapy - End-stage

  38. PACG – Other Forms • Latent - “at risk” fellow eye • Intermittent – attacks that spontaneously resolve • Acute congestive – sudden attacks that don’t resolve • Post congestive – had an attack but now normal IOP • Chronic – gradual increase • Absolute – end stage

  39. Latent Form • “Normal” fellow eye • At high risk – 50% in 8 months • Abnormal angle/S-shaped iris • Cleft open initially – may close later • Preventative drops lower risk to 50% in 30+ months Possible Course

  40. Glaucoma Prophylaxis

  41. Intermittent Form • 8-yr-old FS Cocker Spaniel • Vague Hx transient red eye at night or with child crying • PLD OU • R L • 8AM 15 17 • 9AM 13 21 • 11AM 16 23 • 1PM 17 41 • 2PM (latano) 16 12 • Cleft Closed on HRUS

  42. Intermittent PACG - Course • Remain normal – rare • Develop acute PACG – most common • Develop chronic PACG - occurs

  43. Anterior Uveitis – Glaucoma

  44. GLAUCOMA VISUAL VISUAL OR BLIND ? BLIND Determine primary cause Relieve pain Enucleation Evisceration / prosthesis Cyclocryosurgery Cyclophotocoagulation Evaluate fellow eye PRIMARY OR SECONDARY ? PRIMARY (CLOSED) Medical Therapy 0.005% Latanoprost or Mannitol 2% Pilocarpine Methazolamide Recheck IOP in 3-4 hrs Evaluate Fellow Eye SECONDARY Treat 1o Cause Uveitis Lens Luxation Hyphema Neoplasia Evaluate Fellow Eye Prophylactic Therapy Demecarium or Betaxolol IOP q1 mo for 3 mo then q 3 mo IOP > 20 Perform Sx IOP < 20 Continue Medical Rx Either Sx now or if IOP > 20 mm Hg Surgery Combined Procedures Cyclocryosurgery Cyclophotocoagulation Gonioimplantation

  45. Hyphema

  46. Lens Luxation

  47. Neoplasia

  48. Feline Glaucoma Uveitis induced LSA Melanoma FAHMS

  49. FelineAqueous Humor Misdirection Syndrome

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