Angle Closure Glaucoma

Angle Closure Glaucoma

Glaucoma is a composed of several ocular diseases that is characterized by an increased pressure within the eye or intraocular pressure.  Angle closure glaucoma is type of glaucoma wherein there is an obstruction in the anterior chamber angle of the eye, causing the fluid to back up, leading to damage in the optic nerve and the symptoms related to glaucoma.

Pathophysiology

Angle closure glaucoma can be a primary disease, or a secondary to another condition.  Primary angle closure glaucoma predominantly affects Asians, advanced age, and those with a family history of this condition.  In those with narrow angles, there is a narrow distance from the papillary iris and the lens of the eye.  During the times when the iris dilates, the iris and lens come into contact with each other, preventing the aqueous humor (fluid within the eye) to pass into the anterior chamber.  Outflow becomes blocked, thereby causing elevation of the intraocular pressure (IOP).  If this occurs rapidly over several hours and becomes severe (more than 40 mmHg), it may be termed as acute and is an ophthalmic emergency, requiring immediate treatment to prevent damage to the optic nerve and loss of vision.  Intermittent angle closure glaucoma may also occur when the blockage resolves spontaneously after several hours, which could happen after sleeping supine.  Chronic angle closure glaucoma occurs when the development of the narrowing is slow; therefore the increase in the IOP is also slow.

Another type is the secondary angle closure glaucoma, which is related to another coexisting condition (ie, proliferative diabetic retinopathy, uveitis, or ischemic central vein occlusion).

Cause

Angle closure glaucoma is primarily caused by factors that push the iris toward the angle such as with shallower anterior chambers and shorter axial length of the eye, and blockage of the drainage of the aqueous humor.  Medications may also precipitate this condition, like sympathomimetics, anticholinergics, antidepressants, cocaine, and botulinum toxin. 

Epidemiology

Angle closure glaucoma is more common among certain races like Asians and Eskimos.  This is also more common among women the anterior chamber tends to be shallower.  Elderly individuals (ie, those in their 60s-70s) are also more at risk, because of the tendency of the lens to enlarge and push the iris forward with age. 

Clinical Features

Typically, patients with angle closure glaucoma present with eye pain, blurred vision and seeing haloes around objects, profuse tearing, nausea and vomiting, and headache.  This may occur on only one eye, especially in cases of acute angle closure glaucoma. 

Patients may also experience intermittent episodes of elevation in the IOP.  These patients may have subacute angle closure glaucoma.  Symptoms may or may not be present, or may be mild.

During physical examination, patients with blurring of vision may only be able to detect hand movements.  The cornea and the sclera (whites of the eye) may appear red and edematous.  There may be pain on eye movement and the pupil may be slightly dilated and nonreactive.  Examination using a slitlamp would reveal corneal edema or an irregular shape of the pupil. 

Diagnosis

Several tests may be performed during physical examination for angle closure glaucoma.  One test that may be performed is gonioscopy, wherein a special contact lens is placed on the eye to determine whether the angles are open, closed, or narrowed.  However, this may be difficult to perform because the involved eye may have clouded cornea.  Tonometry is performed to measure the intraocular pressure.  Normally, the pressure in the eye range from 10-21 mmHg.  In episodes of acute angle closure glaucoma, the IOP may go as high as 40-80 mmHg.  Ophthalmoscopy is a procedure to visualize the optic nerve for any abnormality or damage.

Management

In cases of acute angle closure glaucoma, the patient must be brought to the emergency department immediately to have the IOP reduced.  He or she is maintained on the supine position and given medications like Acetazolamide and a beta blocker which could decrease the IOP.  Topical steroids are also given to reduce the inflammatory reaction and the optic nerve damage. 

Definitive treatment may be performed 24 to 48 hours after the IOP has stabilized and controlled.  In laser peripheral iridotomy, a laser beam is used to make burns in the peripheral iris, thus making a hole and allowing the aqueous pass from the posterior to the anterior chamber.  An alternative is an iridectomy, wherein incisions are surgically done in the iris.  Laser gonioplasty may be performed prior to laser iridotomy, wherein laser beams are also used to create burns in the iris, causing it to flatten, resulting in a deeper angle of the anterior chamber and opening it up.

Prognosis

Prognosis is good with early diagnosis and prompt treatment, since loss of vision or a decrease in visual acuity may occur if the condition had not been managed immediately.  Other complications include a repeat episode, involvement of the other eye, and central retinal artery or vein occlusion.

Efficacy of Alternative and Other Treatments According to GRADE* Ranking:

Cannabis (Marijuana, weed, hemp) [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]:

Please note, this management does NOT treat the condition itself. It may mildly help with some of the symptoms, and even then has insufficient evidence to back up this claim at present.

Recommendation: Strongly in favor (Evidence shows that smoking or ingesting cannabis may help in relieving symptoms of occular hypertension in glaucoma)

Grade of Evidence: moderate quality of evidence

* www.gradeworkinggroup.org

Summary References

Treatments:

1. Ades T, Alteri R, Gansler T, Yeargin P, "Complete Guide to Complimentary & Alternative Cancer Therapies", American Cancer Society, Atlanta USA, 2009

2. http://www.nlm.nih.gov/medlineplus/marijuana.html

3. http://nccam.nih.gov/research/extramural/awards/2004/

4. http://www.cancer.org/Treatment/TreatmentsandSideEffects/ComplementaryandAlternativeMedicine/HerbsVitaminsandMinerals/marijuana

5. http://www.nationalmssociety.org/about-multiple-sclerosis/what-we-know-about-ms/treatments/complementary--alternative-medicine/marijuana/index.aspx

6. http://www.ncbi.nlm.nih.gov/pubmed/16957511

7. http://www.ncbi.nlm.nih.gov/pubmed/12965981

8. http://www.ncbi.nlm.nih.gov/pubmed/17589370

9. http://mct.aacrjournals.org/content/6/11/2921.long

10. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2562334/?tool=pmcentrez 

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