Primary Angle Closure Glaucoma (PACG)

Primary Angle Closure Glaucoma (PACG)
SYMPTOMS May be asymptomatic, especially in cases of primary angle closure suspects
In the later or more advanced stages of primary angle closure glaucoma, patients may report visual field loss such as scotomas or tunnel vision. If left untreated, complete blindness can occur
If IOP is too high (considered > 40mmHg), patient may experience Ocular pain, Pressure around the eye, Cloudy vision, Nausea, Vomiting, Headache, and Browache (these symptoms are typically exacerbated in dark environments)
SIGNS Primary angle closure suspect (PACS): Shallow anterior chamber, Bowed iris, Narrow angles on Van Herick
Primary angle closure (PAC): Shallow anterior chamber, Bowed iris, Narrow angles on Van Herick, Fixed and mid-dilated pupil, Peripheral anterior synechiae, Circumlimbal injection, Corneal edema, Mild uveitis, Iris atrophy
Primary angle closure glaucoma(PACG): Shallow anterior chamber, Bowed iris, Narrow angles on Van Herick, Fixed and mid-dilated pupil, Peripheral anterior synechiae, Circumlimbal injection, Corneal edema, Mild uveitis, Iris atrophy, Glaucomatous optic nerve damage (notching, rim tissue thinning, cupping, vessel shelving, vessel bearing, vessel bayonetting), RNFL thinning, Drance hemes, Peripapillary atrophy
With advanced glaucomatous optic nerve damage, Optic nerve pallor will be present
WORK-UP Pupils (fixed, mid-dilated pupil/can present with a decrease in light response if glaucoma is advanced or an APD if glaucoma is asymmetric), Color vision (typically normal), Slit lamp examination, IOP with GAT or ORA (typically between 40-80 mmHg), Optic nerve evaluation (dilation is typically contraindicated), Post-dilated IOP with GAT or ORA, Fundus photos, Visual field with Humphrey 24-2/30-2/24-2C threshold or 10-2 threshold in more advanced glaucoma (nasal step, arcuate defect, paracentral scotoma, tunnel vision with temporal crescent sparing if glaucoma present), OCT analysis of the optic nerve/RNFL/GCL (RNFL and GCL thinning with GCL loss typically preceding RNFL loss if glaucoma is present), OCT-Angiography (decrease in density of the radial peripapillary capillary plexus and superficial capillary plexus if glaucoma is present), Anterior segment OCT (narrow/occluded angles with a shallow anterior chamber and possible areas of peripheral anterior synechiae), Gonioscopy (narrow/occluded angles with possible areas of peripheral anterior synechiae), Pachymetry (thin corneas carry a higher risk of glaucoma), Corneal hysteresis (low hysteresis carries a higher risk of glaucoma), VEP/Pattern ERG (decrease in ganglion cell function if glaucoma is present), Ultrasound biomicroscopy (narrow/occluded angles with a shallow anterior chamber and possible areas of peripheral anterior synechiae)
TREATMENT Primary angle closure suspect (PACS): Refer patient to ophthalmology for laser peripheral iridotomy (LPI) or cataract surgery
Primary angle closure with or without glaucoma: The goal is to lower the IOP as quickly as possible in office
Combigan (may use a separate topical beta blocker and topical alpha-2-agonist)
Cosopt (may use a separate topical beta blocker and topical carbonic anhydrase inhibitor)
Apraclonidine 1%
Pred Forte
Pilocarpine 1-2% (should not use in cases of secondary angle closure such as neovascular glaucoma as this will cause exacerbation. Not effective if IOPs are > 40mmHg)
Diamox 250mg (2 tablets given in one dose)
Always keep in mind the contraindications and side effects before prescribing any glaucoma medications
Prostaglandins should be avoided
Dynamic gonioscopy can also be attempted in order to break a primary angle closure (gonioscopy lens with a flange would not work well for this procedure)
IOP should be checked every 15 minutes for 1 hour while treating in-office
Once IOP is in better control, refer to ophthalmology ASAP for further evaluation and treatment which usually includes a laser peripheral iridotomy (a laser peripheral iridoplasty is typically done in patients with a plateau iris)
FOLLOW-UP Primary angle closure suspect (PACS): Monitor every 6-12 months. Patient education on angle closure should be given
Primary angle closure (PAC): After seeing and being treated by ophthalmologist, monitor every 6 months. The patient may need to continue topical glaucoma drops
Primary angle closure glaucoma (PACG): After seeing and being treated by ophthalmologist, monitor every 3-4 months. The patient will need to continue topical glaucoma drops
ADDITIONAL LAB | TESTS None
ETIOLOGY Increase in IOP due to closure of the anterior chamber angle (typically due to pupillary block)
DIFFERENTIAL DX Primary open angle glaucoma, Secondary angle closure glaucoma, Pigment dispersion glaucoma, Pseudoexfoliative glaucoma
NOTES Stages of angle closure: Primary angle closure suspect (the presence of anatomically narrow angles with no evidence of peripheral anterior synechiae, optic nerve damage, visual field loss, and elevated IOP), Primary angle closure (evidence of angle closure is present such as peripheral anterior synechiae and elevated IOP but the optic nerve and visual field are normal), Primary angle closure glaucoma (evidence of angle closure is present such as peripheral anterior synechiae and elevated IOP with glaucomatous optic nerve damage)
Risk factors for angle closure include hyperopia, family history of angle closure, older age, being female, Asian and Inuit descent, shallow anterior chamber, and developing a cataract
Plateau iris should be considered if there is continued evidence of angle closure along with elevated IOPs in the presence of a patent laser peripheral iridotomy. Patients with plateau iris will also typically have a deep anterior chamber but narrow angles on Van Herick
Secondary angle closure due to such etiologies as pseudoexfoliation syndrome, Topamax, etc. will typically require a different treatment protocol than primary angle closure
Secondary angle closure due to such etiologies as pseudoexfoliation syndrome, Topamax, etc. will typically require a different treatment protocol than primary angle closure
Positive transillumination of an LPI is not always an indication of patency especially in the presence of continued evidence of angle closure and elevated IOPs. An anterior segment OCT or ultrasound biomicroscopy should be used to confirm the patency of the LPI
If posterior trabecular meshwork is only seen in less than 90-180 degrees of the angle when performing gonioscopy, the angle would be considered occludable and there should be strong consideration to avoid dilation and refer the patient to ophthalmology for an LPI
If worried about closing an angle when dilating a patient, Tropicamide should only be used because if post-dilated IOPs and post-dilated gonioscopy appear normal after 60 minutes, it is highly unlikely that the angle will close. However, when using phenylephrine, the angle has a potential to close at the 60 minute mark and 4 hour mark.
IOP should always be measured before gonioscopy
When performing gonioscopy, the light of the slit lamp should not get into the pupil as this can show a falsely open angle
If more structures are able to be visualized when rocking, pushing, or tilting the gonioscopy lens, the closure is more likely to be appositional as opposed to synechial (if this is the case, dynamic gonioscopy is more likely to break the closure)
Primary Angle Closure Glaucoma (PACG): Gonioscopy image showing primary angle closure with peripheral anterior synechiae https://www.asuo.org.uy/mailing/boletin/n18-06-2016/descargas/Gu%C3%ADa%20terap%C3%A9utica%20del%20glaucoma%20cr%C3%B3nico%20por%20cierre%20angular%20primario.pdf

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