Peripheral Anterior Synechia Treatment & Management

Updated: Mar 19, 2021
  • Author: Maria Hannah Pia U de Guzman, MD, DPBO, FPAO; Chief Editor: Hampton Roy, Sr, MD  more...
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Approach Considerations

The appropriate management of peripheral anterior synechiae (PAS) depends on the disease process that leads to the formation of the PAS. 


Medical Care

The following drug categories may be considered, depending on the primary diagnosis: topical β-blockers, topical α-agonists, topical carbonic anhydrase inhibitors, oral carbonic anhydrase inhibitors, topical prostaglandin agonists, miotics, cycloplegics, and topical corticosteroids.

Treat elevated intraocular pressure, as necessary.

  • Topical α-agonists, β-blockers, carbonic anhydrase inhibitors, and prostaglandin agonists may be useful in lowering intraocular pressure in eyes with PAS.
  • Miotics are useful in the treatment of pupil block due to primary angle-closure but may exacerbate angle closure due to posterior pushing mechanisms.
  • Miotics or prostaglandin analogs are unlikely to be useful in cases in which the PAS extent is 360 degrees.

Treat inflammation, as necessary.

  • Topical steroids minimize inflammation and, therefore, PAS formation.
  • Cycloplegics should be used to prevent formation of posterior synechiae.
  • Miotics and epinephrine should be avoided because they can increase inflammation.

Surgical Care

General principles in the surgical treatment of peripheral anterior synechiae (PAS) are as follows:

  • As much as possible, the pathologic process causing PAS formation should be addressed. Various laser and surgical procedures may be indicated, depending on the etiology.
  • If PAS have already formed, surgical treatment to restore aqueous outflow through the trabecular meshwork should be undertaken within the first 6 months of formation. [8] After this time, significant trabecular meshwork (TM) scarring has already occurred, and the TM may no longer function normally, despite an anatomically successful synechialysis. [9]  
  • It is possible, although unlikely, to break a pupil block or early PAS by performing anterior chamber compression using a gonioprism such as a Zeiss goniolens.
  • Neodymium-yttrium-aluminum garnet (Nd:YAG) or argon laser iridotomy
    • Indicated when pupil block is the cause of or contributes to the formation of PAS. Consider performing this even when the intraocular pressure is not yet elevated.
    • Prophylactic treatment of the other eye should be considered in patients with primary angle-closure glaucoma.
    • The fellow eye's angle closure risk is 50% within 5 years without an iridotomy in patients with primary angle-closure glaucoma.
  • Surgical iridectomy
    • Prophylactic iridectomy is recommended for patients who receive anterior chamber intraocular lenses or who have aphakia.
    • Surgical iridectomy can be performed when a laser iridotomy is indicated but cannot be performed.
  • Argon laser peripheral iridoplasty
    • Indicated when PAS continue to form or the angle fails to widen after a patent iridotomy. Creating burns in the peripheral iris causes the iris to contract and pull away from the TM.
    • Useful when posterior pushing mechanisms, such as plateau iris and nanophthalmos, are involved.[RK1] 
    • Has limited usefulness in anterior pulling mechanisms such as uveitis.
  • Argon laser pupilloplasty is used to expand or enlarge the pupil, which may break an acute angle-closure attack and/or posterior synechiae.
  • Lens extraction is needed if the lens size, shape, or position is significantly contributing to PAS formation.
  • Surgical goniosynechialysis [8, 10, 11, 12]  is an effective surgical modality when the etiology of the PAS formation is primary angle closure. 

    See the list below:

    • A spatula or microforceps can be used to pull the iris away from the TM to break the PAS. This is not recommended unless synechial closure is 270 degrees or greater. This can be performed under either direct or indirect visualization of the meshwork. Continuous irrigation or a viscoelastic is used to maintain the anterior chamber during the procedure.
    • If significant glaucomatous cupping and visual field loss are present, a filtering operation may be required in addition to goniosynechialysis.
    • Concurrent lens extraction (independent of the presence of a cataract) is strongly recommended when goniosynechialysis is performed because removal of the lens helps to further widen the angle, which facilitates intraoperative access and eliminates a potential contributing etiology of the angle closure.
  • Glaucoma filtering procedures
    • Trabeculectomy, [13]  despite being the gold standard glaucoma-filtering procedure, has a generally lower rat of success in patients with primary angle-closure glaucoma and higher rates of choroidal effusion, aqueous misdirection, and flat anterior chamber. In some patients with secondary angle-closure glaucoma, the pathologic process reduces the likelihood of trabeculectomy success; expamples include neovascular glaucoma and iridocorneal endothelial syndromes. [2]
    • Primary tube shunt surgery can be considered for patients with primary angle-closure glaucoma and is the first-choice procedure for certain secondary etiologies.
    • Insertion of the Ex-PRESS Mini Shunt is a potential alternative to trabeculectomy. More research in this area is required to fully evaluate this technology in this context.
  • Goniophotocoagulation can be used to treat the open stage of neovascular glaucoma. 
  • Choroidal tap is used to treat choroidal effusions or hemorrhage.


A rheumatologic consultation should be considered in patients with a sterile uveitis of unknown origin.


Long-Term Monitoring

Long-term monitoring depends on the etiology of the peripheral anterior synechiae and the severity or stage of the condition.