THE GLAUCOMAS 1
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  • 1. THE GLAUCOMAS 1 Dr Russell J Watkins
  • 2. Anterior Chamber Anatomy
    • Chamber volume is about 200  l
    • Chamber depth is about 3.2mm
      • Deeper in myopes
      • Shallows with age
    • Schwalbe’s line marks end of DM
    • Scleral spur receives insertion of the longitudonal ciliary fibres - contraction opens TM spaces
    • TM lined by trabeculocytes which have contractile properties which may influence outflow resistance
  • 3. Anterior Chamber Anatomy
    • Canal of Schlemm is oval in cross-section (200-400  m)
    • Canal is lined by endothelial cells which on inner wall have giant vacuoles
      • Number & size of vacuoles varies with IOP
    • This is the mechanism of the bulk transfer of aqueous to Canal of Schlemm
  • 4. Anterior Chamber Anatomy
    • With age, there is
      • 2-3 fold thickening of trabecular sheets
      • Loss of endothelial cellularity
      • Increase in connective tissue
      • Increased accumulation of TM debris
      • Increased accumulation of GAGs
    • Such changes are exaggerated in OAG
  • 5.  
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  • 8. Autonomic Control of Aqueous Secretion
    • Cholinergic mechanisms probably not involved in control of IOP
    • Adrenergic (  1 ,  1  2 , &  2 ) receptors do regulate IOP
      •  receptor stimulation inhibits AC (  IOP)
        •  aqueous production
        •  PGF 2 
      •  receptor stimulation activates AC (  IOP)
        •  aqueous production
  • 9. Aqueous Humour Drainage
    • ~90% aqueous leaves eye via trabecular meshwork
    • ~10% leaves eye via “unconventional” routes
      • most important = “uveoscleral”
    • Trabecular meshwork modulated by GAGs & Ca 2+ in ECM
    • Inner wall endothelium of Schlemm’s canal provides most of TM resistance to outflow
    • Intrascleral & episcleral venous flow also provides resistance to outflow
  • 10. Aqueous Outflow
  • 11.  
  • 12. Classification
    • All forms of glaucoma are classified into primary & secondary forms based on
      • Gonioscopic findings
      • ONH findings
      • VF defects
    • Major risk factors
      • IOP (the major risk factor but not the whole story)
      • Vascular risk factors
        • Local
        • Systemic
      • Race
  • 13. Classification
    • Associated conditions
      • Ocular
      • Extraocular
    • Additional useful clinical data
      • BP, pulse, blood glucose, blood lipids
      • Migraine, cold hands/Raynaud’s
      • Thyroid disease, neurological diseases
      • History of blood loss, smoking
      • FOH +ve for visual loss
      • FOH +ve for glaucoma
  • 14. Glaucoma Classification
    • Primary Congenital Forms
      • Primary Congenital Glaucoma
      • Primary Infantile Glaucoma
      • Glaucoma associated with congenital anomalies
  • 15. Glaucoma Classification
    • Primary Open Angle Glaucomas
      • Primary juvenile glaucoma
      • Primary open angle glaucoma
      • Normal tension glaucoma
      • Ocular hypertension
  • 16. Glaucoma Classification
    • Secondary Open Angle Glaucoma
      • Pseudoexfoliation glaucoma
      • Pigmentary glaucoma
      • Lens-induced OAG
      • Glaucoma associated with intraocular haemorrhage
      • Uveitic glaucoma
      • et al ++
  • 17.  
  • 18. Glaucoma Classification
    • Primary Angle Closure Glaucomas
      • Pupillary block mechanism
      • Plateau iris mechanism
      • Malignant glaucoma
      • Chronic ACG
  • 19.  
  • 20. Glaucoma Classification
    • Secondary Angle Closure Glaucomas
      • Secondary ACG with pupil block
      • Secondary ACG due to “pulling” of AC
        • NVG
        • Aniridia
        • Inflammatory membrane
        • et al++
  • 21.  
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  • 23. Primary Congenital Forms
    • Primary congenital glaucoma
      • Aetiology is angle dysgenesis
      • Pathomechanism is  aqueous outflow
      • Onset from birth to second year of life
      • Usually sporadic; 10% may be AR with variable penetrance; specific chromosomal abnormalities (1p36 & 2q21)
      • 1 in 10,000 live births
      • M>F (65%:35%)
  • 24. Primary Congenital Forms
    • Primary congenital glaucoma (cont.)
      • Photophobia, tearing, blepharospasm
      • Eye rubbing, EUA for IOP unreliable
      • Buphthalmos (cornea  >11mm)
      • Corneal oedema (±ruptures in DM  Haab’s striae)
      • ONH: pressure distension/uniform enlargement
      • VCDR>0.3
      • Gonio: open angle but poorly differentiated structures; trabeculodysgenesis; anterior iris insertion
  • 25. Primary Congenital Forms
    • Primary infantile glaucoma
      • Probably late onset congenital glaucoma
      • Same aetiology & pathomechanism as PCG
      • Onset 3rd to tenth yr of life
      • Similar genetics to PCG
      • Pain unusual; no buphthalmos or corneal oedema
      • Often presents late with symptomatic VF loss
      • Peak IOP > 24mmHg without Rx
      • ONH shows pressure distension & generalised cup enlargement with diffuse rim damage
      • Gonio as PCG
  • 26. Primary Congenital Forms
    • Glaucoma associated with congenital anomalies
      • Aniridia
      • Sturge Weber syndrome
      • Neurofibromatosis
      • Marfan syndrome
      • Homocystinuria
      • Goniodysgenesis
        • Axenfeld-Rieger syndrome & Peter’s anomaly
      • Rubella
      • Microcornea
      • PHPV
      • et al.
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