Approach Considerations
The appropriate management of peripheral anterior synechiae (PAS) depends on the disease process that has led to the formation of the PAS.
Laboratory Studies
Perform an inflammatory and/or infectious workup as required.
Imaging Studies
Ultrasound biomicroscopy [6] or anterior segment imaging (eg, optical coherence tomography [7] )
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Useful in evaluating the angle in angle-closure glaucoma
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Can delineate PAS and determine the extent
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May reveal a small space between the PAS and the trabecular meshwork suggesting that the trabecular meshwork may still be functional
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May be useful in documenting supraciliary fluid
Corneal specular microscopy - useful in identifying iridocorneal endothelial or posterior polymorphous dystrophy cells
Other Tests
Provocative testing - measures intraocular pressure while dilating or constricting the pupil to differentiate angle-closure glaucoma from open-angle glaucoma with narrow angles. However, it correctly identifies only 50%-70% of patients with true angle-closure glaucoma.
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Dark room: Increase in intraocular pressure with mydriasis implies pupil block.
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Pharmacologic mydriatic test: Increase in intraocular pressure with mydriasis implies pupil block.
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Thymoxamine and dapiprazole (α-adrenergic antagonists)
- Block iris dilator muscles, resulting in miosis with no effect on outflow facility.
- Decrease intraocular pressure, which implies that miosis has reduced pupil block.
Procedures
A paracentesis with injection of viscoelastic into the anterior chamber done in an attempt to deepen a narrow angle can be used to differentiate appositional closure from synechial closure. By deepening the angle, a better view of the angle can be obtained to determine the presence of PAS. Sometimes, this procedure can be both diagnostic and therapeutic.
Histologic Findings
Histologic findings depend on the causative agent; they can be fibrovascular, epithelial, endothelial, or inflammatory in nature.
Tables
General Appearance |
Detailed Appearance |
Possible Causes |
Broad bands |
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PAS to all levels but not to cornea. Bridging usually not present. |
Angle-closure glaucoma |
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PAS to all levels, sometimes to cornea. Bridging may be present. |
Posterior pushing mechanism, post-operative shallow anterior chamber, or iris bombé |
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PAS with new vessels, multiple sites |
Neovascularization |
Scattered, irregular |
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PAS tent and form columns up to, but not on, the cornea |
Iridocyclitis with keratic and trabecular precipitates |
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Small PAS to scleral spur |
Post-argon laser trabeculoplasty |
Iris Pulled Forward |
Iris Pushed Forward |
Neovascular membrane Iridocorneal endothelial membrane Posterior polymorphous dystrophy Epithelial/fibrous ingrowth Uveitis Trauma Inflammatory syndromes Infection Flat anterior chamber Post-surgical Trauma Post-laser trabeculoplasty |
Pupil block Primary angle-closure glaucoma Posterior synechiae resulting in iris bombé Pseudophakic or aphakic pupil block Iridoschisis Plateau iris Choroidal or supraciliary effusion - Posterior uveitis - Central retinal vein occlusion - Nanophthalmos - Post-panretinal photocoagulation or cryotherapy Suprachoroidal hemorrhage Aqueous misdirection syndrome Posterior segment tumors - Retinoblastoma - Choroidal melanoma - Metastasis Iris cyst or tumor Ciliary body cyst or tumor Contracting retrolental tissue - Retinopathy of prematurity - Persistent hyperplastic primary vitreous Post-scleral bucking surgery Anterior lens subluxation (ectopia lentis) Lens intumescence (phacomorphic glaucoma) Neurofibromatosis |
