The term glaucoma is used to refer to a group of ocular conditions characterized by optic nerve damage. Most cases are asymptomatic until extensive and irreversible damage has occurred. Glaucoma affects people of all ages but is more prevalent with increasing age (older than 40 years). Others at risk are patients with diabetes, African Americans, those individuals with a family history of glaucoma, and people with previous eye trauma or surgery or those who have had long-term steroid treatment. There is no cure for glaucoma, but the disease can be controlled. Glaucoma is the second leading cause of blindness among adults in the United States.
Classification of Glaucomas
There are several types of glaucoma. Current clinical forms of glaucoma are identified as open-angle glaucoma, angle-closure glaucoma (also called pupillary block), congenital glaucoma, and glaucoma associated with other conditions. Glaucoma can be primary or secondary, depending on whether associated factors contribute to the rise in IOP. The two common clinical forms of glaucoma encountered in adults are primary open-angle glaucoma (POAG) and angle-closure glaucoma, which are differentiated by the mechanisms that cause impaired aqueous outflow.
Aqueous humor flows between the iris and the lens, nourishing the cornea and lens. Intraocular pressure (IOP) is determined by the rate of aqueous production, the resistance encountered by the aqueous humor as it flows out of the passages, and the venous pressure of the episcleral veins that drain into the anterior ciliary vein. When aqueous fluid is inhibited from flowing out, pressure builds up within the eye. Increased IOP damages the optic nerve and nerve fiber layer, but the degree of harm is highly variable. The degree of damage to the optic nerve is related to the elevations in IOP caused by the congestion of aqueous humor in the eye.
The aim of all glaucoma treatment is prevention of optic nerve damage. Lifelong therapy is almost always necessary because glaucoma cannot be cured. Treatment focuses on pharmacologic therapy, laser procedures, surgery, or a combination of these approaches, all of which have potential complications and side effects. The objective is to achieve the greatest benefit at the least risk, cost, and inconvenience to the patient. Although treatment cannot reverse optic nerve damage, further damage can be controlled. The goal is to maintain an IOP within a range unlikely to cause further damage. Periodic follow-up examinations are essential to monitor IOP, the appearance of the optic nerve, the visual fields, and side effects of medications. Therapy takes into account the patient's health and stage of glaucoma.
Pharmacologic Therapy
Medical management of glaucoma relies on systemic and topical ocular medications that lower IOP.
- Patient is usually started on the lowest dose of topical medication and then advanced to increased concentrations until the desired IOP level is reached and maintained.
- One eye is treated first, with the other eye used as a control in determining the efficacy of the medication. If the IOP is elevated in both eyes, both are treated.
- Several types of ocular medications are used to treat glaucoma, including miotic agents (medications that cause pupillary constriction), adrenergic agonists (i.e., sympathomimetic agents), beta-blockers (preferred initial topical medications), alpha2-agonists (i.e., adrenergic agents), carbonic anhydrase inhibitors (decreases aqueous humor production), and prostaglandins (increases aqueous humor outflow).
Surgical Management
- Laser trabeculoplasty or iridotomy is indicated when IOP is inadequately controlled by medications.
- Filtering procedures create an opening or a fistula in the trabecular meshwork; trabeculectomy is standard technique.
- Drainage implant or shunt surgery may be performed.
- Trabectome surgery is reserved for patients in whom pharmacologic treatment and/or laser trabeculoplasty do not control the IOP sufficiently.
Outline
Promoting Home, Community-Based, and Transitional Care
Educating Patients About Self-Care
- Educate patient regarding the nature of the disease and the importance of strict adherence to the medication regimen to help ensure compliance.
- Review the patient's medication program including administration techniques for eye drops, particularly the interactions of glaucoma control medications with other medications.
- Explain effects of glaucoma control medications on vision (e.g., miotic drugs and sympathomimetic agents result in altered focus; therefore, patients need to be cautious in navigating their surroundings).
Continuing and Transitional Care
Refer patient to services that assist in performing activities of daily living, if needed.
- Refer patients with impaired mobility for low vision and rehabilitation services; patients who meet the criteria for legal blindness should be offered referrals to agencies that can assist them in obtaining federal assistance.
- Provide reassurance and emotional support.
- Integrate patient's family into the plan of care and, because the disease has a familial tendency, encourage family members to undergo examinations at least once every 2 years to detect glaucoma early.
For more information, see Chapter 63 in Hinkle, J. L., & Cheever, K. H. (2018). Brunner and Suddarth's textbook of medical-surgical nursing (14th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.