primary%20open-angle%20glaucoma
PRIMARY OPEN-ANGLE GLAUCOMA
Primary open-angle glaucoma (POAG) is a chronic, progressive, irreversible, usually bilateral disease of the eye with an insidious onset.
It is most often characterized by optic nerve damage, defects in the retinal fiber layer and subsequent visual field loss in the absence of underlying ocular disease or congenital abnormalities.
It is generally asymptomatic until it has caused a significant loss of visual field.
Occasionally, patients with very high intraocular pressure may complain of nonspecific headache, discomfort, intermittent blurring of vision or even halos caused by corneal edema.

Laser Treatment

  • While topical medications are the usual first line of treatment, laser trabeculoplasty may be an effective initial treatment option to POAG, especially in cases of a very high IOP, severe glaucoma, need for >2 topical medications, known intolerance or allergy to topical agents, and concerns about patient compliance
  • Reduces IOP by improving aqueous outflow and is performed using argon, diode and frequency-doubled neodymium: yttrium-aluminum-garnet (Nd:YAG) lasers
  • Possible complications include IOP spike, transient iritis, temporary blurring of vision, endothelial burns, corneo-refractive changes, suprachoroidal effusion
Argon Laser Trabeculoplasty (ALT)
  • Works by activation of trabeculocytes to improve trabecular meshwork (TM) function
  • Full effect of treatment may be apparent after 6 weeks
    • Evidence showed comparability of the long-term efficacy of primary ALT with primary medical treatment for patients with open-angle glaucoma
  • Re-treatments in the same area may, however, cause scarring of the TM and raised IOP
  • Less successful in eyes without pigmentation of the TM

Micropulse Laser Trabeculoplasty (MLT)

  • Uses extremely short duration pulses of laser delivering thermal energy to the TM
  • No damage and visible tissue reaction compared to ALT and selective laser trabeculoplasty (SLT)
  • Comparable efficacy with other laser treatment with good safety profile

Selective Laser Trabeculoplasty (SLT)

  • May be offered as first choice treatment for POAG 
  • Similar to ALT but makes use of a laser with a very short duration of discharge
  • Same mechanism of action as ALT but raised IOP is less likely to occur due to less photocoagulative damage to adjacent tissue
  • Same IOP lowering effect as ALT but produces less thermal damage to the TM
  • Shown to have comparable efficacy in reducing IOP with prostaglandin analogues
  • Studies showed SLT is more cost effective than medical therapy usage for 3 years
  • Causes less scarring and less ocular discomfort thus, can be repeated
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