Tuesday, October 8, 2013
Judy Torres, BFA, JD, NREMT-P
Decision-making by paramedics in the field has the potential to become a challenging situation. The decision of whether to transport has to be made quickly and efficiently. It often becomes a collaborative effort among the responding unit, the patient and their family members or friends. Insufficient information related to the actual complaint and limited access to the patient’s past medical history can also contribute to on-scene confusion. Balancing the patient’s care, safety and patient choice can sometimes be overwhelming.
When confronted with a patient who has one or more complaints that range from blurred vision and seeing halos around lights to severe eye pain and vomiting, time is of the essence.
This article discusses the classic signs and symptoms of acute angle closure glaucoma and will help you make critical transport decisions and understand available treatment options when faced with making a choice that could save someone’s vision.
What Is It?
Acute angle closure glaucoma (AACG), sometimes called acute narrow angle glaucoma or acute closed angle glaucoma, is a true medical emergency. Rapid and immediate treatment is necessary to prevent optic nerve damage and permanent loss of vision, which can occur within hours without prompt and appropriate treatment.
AACG is caused by a rapid or sudden increase in pressure inside the eye or intraocular pressure (IOP). This typically happens when the iris is pushed against the trabecular meshwork (the spongy tissue located near the cornea where the aqueous humor flows out of the eye) or drainage channels, and the fluid or aqueous humor (the watery fluid that nourishes the interior of your eye) that normally drains out of the eye is blocked. This creates the increase in IOP. (See Figure 2, p. 44.)
Keep in mind that there are four main types of glaucoma: open angle or chronic glaucoma, AACG, congenital glaucoma and secondary glaucoma. Secondary glaucoma can be open or closed. The disease is considered acute and requires immediate care if the angle closes suddenly rather than gradually or intermittently.
Treatment for AACG includes laser trabeculoplasty, which is a modification of the trabecular meshwork, and iridotomy, which is the making of small holes through the iris without the removal of tissue.
An iridectomy, which involves the actual removal of iris tissue, can be done with a laser or by surgical means. A laser beam (either an argon laser or neodymium-doped yttrium aluminum garnet [Nd:YAG] laser) creates a hole in the iris to relieve the pressure so the aqueous humor can drain from the posterior chamber of the eye to the anterior chamber. The Nd:YAG allows for a newer technique that can actually target specific cells in the trabecular meshwork and can cause less damage than the argon laser.
Signs, Symptoms & Treatment
The signs and symptoms of AACG can be dramatic. Field providers may be presented with a distressed patient complaining of severe pain around the eyes with blurred vision. They may be seeing colored haloes around lights, have profuse tearing and redness, nausea and vomiting, abdominal discomfort, and a headache and/or brow ache.
Taking time to examine your patient’s pupils may reveal moderately dilated and nonreactive pupils. The patient may also have nerve damage. These signs and symptoms will usually be sudden or acute and constant in nature. Many times only one eye is affected (uniocular) but AACG can affect both eyes.1
The recommended immediate treatment is to reduce the intraocular pressure as soon as possible. Your objective would be to get the patient to the ED as soon as possible, providing supportive measures (e.g., IV, O2, monitor, position of comfort, and rapid transport) en route to the hospital.
These patients should be transported to the nearest appropriate ED. It’s also important to know which hospital in your area has an ophthalmologist on call or on staff since the vision loss can occur within a day of its onset.
Knowing the risk factors can help you if you suspect if a patient with the above signs and symptoms might have AACG. The following risk factors can increase the incidence of AACG:1–4
Dim lighting, eye drops administered by the eye practitioner during the course of a routine eye exam, antihistamines/decongestant drops or cold medications. Anything that causes dilation of the pupil and anything that can block the drainage chamber of the eye.
Hyperopia (farsightedness). Farsighted people are at an increased risk because their anterior chambers are shallow and their angles are narrow.
Race. Some races are more prone to narrow angles and are more likely to develop AACG. Notable are: Asians, people of African descent, and Eskimos or Inuits.
Gender. In Caucasians, AACG is three times more likely in females than in males.
Family history. In general, glaucoma tends to run in families. Be sure to inquire about a patient's family history when performing your assessment.
Diabetes, hypertension and heart disease. These three conditions can be contributing factors.
Tumors behind the iris and physical injuries to the eye. Both cause internal damage that can contribute to an increased risk towards AACG. Ask the patient if they have experienced any recent trauma to their head, eye or eyes.
Inflammation. Eye infections causing inflammation inside the eye increase the risk of developing AACG.
Age. As we age the lens of our eye tends to enlarge and push our iris forward also increasing the risk for AACG.
Pupillary block. If the back of the iris (the colored part of the eye) adheres to the lens inside the eye the channel becomes blocked and fluid builds up behind the iris pushing it forward causing it to close the drainage of fluid in the anterior chamber of the eye.
Studies have shown occurrences of the disease rise with the intentional dilation of the eye during a routine eye examination.5,6 One study indicated that three in 10,000 patients were likely to develop AACG after diagnostic mydriasis (intentional prolonged dilatation of the pupil of the eye) even though the exams were followed by miotic drops (which constrict the pupil and increase the flow of aqueous humor).5
Decision-making in the field when a patient has signs and symptoms consistent with AACG can be aided by being familiar with the condition. Early recognition along with correct transport and treatment decisions can help give these patients the best chance for a positive outcome. Always being sensitive to your patient’s complaints and concerns is key to providing the best possible care. Your knowledge of this condition and its signs and symptoms can be the deciding factor in someone living with future blindness or not.
1. American Optometric Assocation. (n.d.) Glaucoma. Retrieved on Aug. 26, 2013, from www.aoa.org/patients-and-public/eye-and-vision-problems/glossary-of-eye-and-vision-conditions/glaucoma.
2. Glaucoma Research Foundation. (Jan. 11, 2011.) Are you at risk for glaucoma? Retrieved on Aug. 26, 2013, from www.glaucoma.org/glaucoma/are-you-at-risk-for-glaucoma.php.
3. Heiting G. (April 2010.) Narrow-angle glaucoma. All About Vision. Retrieved on Aug. 26, 2013, from www.allaboutvision.com/conditions/narrow-angle-glaucoma.htm.
4. BrightFocus Foundation. (Apr. 28, 2013.) Glaucoma facts & statistics. Retrieved on Aug. 26, 2013, from www.brightfocus.org/glaucoma/about/understanding/facts.html.
5. Liew G, Mitchell P, Wang JJ, et al. Fundoscopy: To dilate or not to dilate? BMJ. 2006;332(7532):3.
6. Dahl AA. Acute angle-closure glaucoma. eMedicineHealth. Retrieved on Aug. 26, 2013, from www.emedicinehealth.com/script/main/hp.asp.
Aqueous humor: The watery fluid that bathes and nourishes the anterior part of the eye.
Ciliary body: The part of the eye above the lens that produces aqueous humor.
Cornea: The outer transparent structure that covers and protects the iris and pupil.
Choroid: A layer of the eye behind the retina that contains the blood vessels that supply the retina.
Iris: The colored tissue behind the cornea that regulates the light entering your eye by changing the size of the pupil.
Lens: The clear part of the eye which is suspended behind the iris.
Optic nerve: A bundle of nerves located in the posterior eye that carries messages from the retina to the brain.
Trabecular meshwork: The spongy tissue near the cornea. This is where the aqueous humor flows out of your eye.