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Peripheral Anterior Synechia Treatment & Management

  • Author: Baseer U Khan, MD; Chief Editor: Hampton Roy, Sr, MD  more...
Updated: Oct 10, 2014

Medical Care

No specific medical management exists pertaining to the treatment of peripheral anterior synechiae (PAS). In general, the treatment of the underlying etiology prevents the formation of peripheral anterior synechiae.

  • The appropriate management of peripheral anterior synechiae depends on the disease process that leads to peripheral anterior synechiae formation. The following drug categories may be considered depending on the primary diagnosis: topical beta-blockers, topical alpha-agonists, topical carbonic anhydrase inhibitors, oral carbonic anhydrase inhibitors, topical prostaglandin analogs, miotics, cycloplegics, and topical corticosteroids.
  • Treat intraocular pressure (IOP) as necessary.
    • Topical alpha-agonists, beta-blockers, carbonic anhydrase inhibitors, and prostaglandin analogs may be useful in lowering intraocular pressure in eyes with peripheral anterior synechiae.
    • Miotics are useful in pupil block due to primary angle closure but may accentuate angle closure in posterior pushing mechanisms.
    • Miotics or prostaglandin analogs likely will not be useful in cases where 360° peripheral anterior synechiae exist.
  • Inflammatory states
    • Topical steroids minimize inflammation and, therefore, peripheral anterior synechiae formation.
    • Cycloplegics should be used to prevent 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 are as follows:

  • If peripheral anterior synechiae are to be successfully surgically treated to increase aqueous outflow, treatment should be undertaken within the first 612 months of formation according to conventional thinking. After this time, significant scarring has occurred in the trabecular meshwork and synechialysis will open the angle, but the trabecular meshwork will not be able to function normally. However, there has been more recent literature to suggest that peripheral anterior synechiae from an appositional etiology may be amenable to treatment even a few years after formation.
  • The intraocular pressure of the contralateral eye will play a role in modifying the threshold for these procedures, ie, if the intraocular pressure is elevated or on the high end of normal, this would lower the threshold because it suggests poor baseline function of the exposed trabecular meshwork. The converse also would be true; with a low intraocular pressure, the threshold would be increased.
  • Anterior chamber compression with Zeiss gonioprism may be successful, although unlikely, in breaking pupil block or early posterior synechiae.
  • Nd:YAG/argon laser iridotomy
    • This treatment is indicated when angle-closure glaucoma is the identified etiology of peripheral anterior synechiae; consider even with nonelevated intraocular pressure.
    • Prophylactic treatment of the other eye should be considered in angle-closure glaucoma.
    • Second eye risk is 50% within 5 years without an iridotomy.
  • Surgical iridectomy
    • Prophylactic iridectomy is recommended in patients who receive anterior chamber intraocular lenses (IOLs) or who are aphakic.
    • Surgical iridectomy is performed in cases where a laser iridotomy is indicated but unable to be performed.
  • Argon laser peripheral iridoplasty
    • When peripheral anterior synechiae continue to form after an iridotomy has been performed, laser iridoplasty is indicated. By creating burns in the peripheral iris causing contraction of the iris, the iris is pulled away from the trabecular meshwork.
    • Argon laser peripheral iridoplasty also may be useful in preventing peripheral anterior synechiae formation in a persistent narrow angle after iridotomy.[4]
    • Argon laser peripheral iridoplasty is useful in posterior pushing mechanisms, such as plateau iris and nanophthalmos.
  • Argon laser pupilloplasty is used to expand/enlarge pupil, which may break acute angle-closure attack and/or posterior synechiae.
  • Nd:YAG peripheral synechialysis can be attempted in early synechial closure but may not be effective if the synechiae are firm. Laser synechialysis should be attempted before surgical goniosynechialysis.
  • Surgical goniosynechialysis[5, 6, 7, 8]
    • Surgical lysis of synechiae has been shown to be an effective surgical modality when the etiology of the peripheral anterior synechiae formation has been secondary to primary angle closure.
    • Using a smooth-tipped irrigating cyclodialysis spatula, the iris can be separated from the TM, rupturing the peripheral anterior synechiae. This is not recommended unless there is 270° or more of synechial closure. This is performed under either direct or indirect visualization of the meshwork intraoperatively.
    • More recently, goniosynechialysis has been described using intraocular microforceps.
    • If significant glaucomatous cupping associated with visual field loss is present, a filtering operation would be performed in addition to goniosynechialysis.
  • Concurrent lens extraction (independent of the presence of a cataract) is strongly recommended when performing goniosynechialysis as removal of the lens helps to further widen the angle, which facilitates intraoperative access as well as removing an etiologic contribution to angle closure.
  • Glaucoma filtering procedures
    • Trabeculectomy,[9] while the criterion standard of glaucoma filtering procedure, has generally had lower success rates in angle closure patients in the case of primary angle closure with higher rates of choroidal effusions, aqueous misdirection, and flat anterior chambers. In secondary angle closures, the etiologic process further reduces the likelihood of success such as in neovascular glaucoma or iridocorneal endothelial (ICE) syndromes.[1]
    • Primary tube shunt surgery is certainly a consideration in primary angle closure patients, and is strongly advised for secondary etiologies.
    • The Mini Express Shunt is a potential alternative to trabeculectomy as well, given its preclusion to an iridectomy and relatively controlled outflow. More research in this area is required to fully evaluate this technology in this context.
  • Goniophotocoagulation/panretinal photocoagulation is used to treat 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.

Contributor Information and Disclosures

Baseer U Khan, MD 

Baseer U Khan, MD is a member of the following medical societies: Canadian Ophthalmological Society

Disclosure: Nothing to disclose.


Iqbal Ike K Ahmed, MD, FRCSC Clinical Assistant Professor, Department of Ophthalmology, University of Utah

Iqbal Ike K Ahmed, MD, FRCSC is a member of the following medical societies: American Academy of Ophthalmology, American Society of Cataract and Refractive Surgery, Canadian Ophthalmological Society, Ontario Medical Association

Disclosure: Nothing to disclose.

Khalid Hasanee, MD Glaucoma and Anterior Segment Fellow, Department of Ophthalmology, University of Toronto

Khalid Hasanee, MD is a member of the following medical societies: Canadian Medical Association, Canadian Ophthalmological Society, Ontario Medical Association

Disclosure: Nothing to disclose.

Specialty Editor Board

Simon K Law, MD, PharmD Clinical Professor of Health Sciences, Department of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, David Geffen School of Medicine

Simon K Law, MD, PharmD is a member of the following medical societies: American Academy of Ophthalmology, Association for Research in Vision and Ophthalmology, American Glaucoma Society

Disclosure: Nothing to disclose.

J James Rowsey, MD Former Director of Corneal Services, St Luke's Cataract and Laser Institute

J James Rowsey, MD is a member of the following medical societies: American Academy of Ophthalmology, American Association for the Advancement of Science, American Medical Association, Association for Research in Vision and Ophthalmology, Florida Medical Association, Sigma Xi, Southern Medical Association, Pan-American Association of Ophthalmology

Disclosure: Nothing to disclose.

Chief Editor

Hampton Roy, Sr, MD Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences

Hampton Roy, Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, Pan-American Association of Ophthalmology

Disclosure: Nothing to disclose.

Additional Contributors

Bradford Shingleton, MD Assistant Clinical Professor of Ophthalmology, Harvard Medical School; Consulting Staff, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary

Bradford Shingleton, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Ophthalmology

Disclosure: Nothing to disclose.

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  4. Lin Z, Liang Y, Wang N, Li S, Mou D, Fan S, et al. Peripheral anterior synechia reduce extent of angle widening after laser peripheral iridotomy in eyes with primary angle closure. J Glaucoma. 2013 Jun-Jul. 22(5):374-9. [Medline].

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  14. Roy FH. Ocular Differential Diagnosis. 6th ed. Baltimore: Lippincott Williams & Wilkins; 1997.

Table 1. Description of PAS on gonioscopy
Description of PASAssociationsPossible Conditions
Broad bands
 PAS to all levels but not to cornea No bridging usually presentAngle-closure glaucoma
 PAS to all levels, sometimes to cornea

Bridging may be present

Posterior pushing mechanism, postoperatively shallow AC, or from iris bombé
 PAS with new vessels, multiple sitesNeovascularization
Scattered, irregular
 PAS tent and form columns up to, but not on, the corneaIridocyclitis with keratic and trabecular precipitates
 Small PAS to scleral spurPost-argon laser trabeculoplasty (ALT)
Table 2. Summary of Important Mechanisms and Causes of Peripheral Anterior Synechiae
Iris Pulled ForwardIris Pushed Forward
Neovascular membrane ICE membrane Posterior polymorphous dystrophy Epithelial/fibrous ingrowth


Pupil block

Inflammatory syndromes


Lens related

Primary angle-closure glaucoma

Posterior synechiae resulting in iris bombé

Pseudophakic or aphakic pupil block


Flat anterior chamberPlateau iris

Posterior pushing



Choroidal effusion

-Posterior uveitis



-Post-pan retinal photocoagulation (PRP) or cryotherapy

Suprachoroidal hemorrhage

Ciliary block (malignant) glaucoma (aqueous misdirection)

Posterior segment tumors


-Choroidal melanoma or metastasis

Iris cyst or tumor

Ciliary body cyst, tumor, or effusion

Contracting retrolental tissue

-Retinopathy of prematurity

-Persistent hyperplastic primary vitreous (PHPV)

Postscleral bucking surgery

Anterior lens subluxation (ectopia lentis)

Lens intumescence (phacomorphic)


Argon laser trabeculoplasty 
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