GLAUCOMA

GLAUCOMA – Etiology and Risk Factors, Pathophysiology, Types, Signs and Symptoms, Diagnostic Evaluation and Management

Glaucoma is a disease of the major nerve of vision, called the optic nerve. Glaucoma is characterized by a particular pattern of progressive damage to the optic nerve that generally begins with a subtle loss of side vision.

ETIOLOGY AND RISK FACTORS

The most important risk factors include:

• Age
• Elevated eye pressure
• Thin cornea
• Family history of glaucoma
• Nearsightedness
• Past injuries to the eyes
• Steroid use
• A history of severe anemia or shock

PATHOPHYSIOLOGY

Ocular perfusion, metabolic demand, ocular blood flow, intraocular pressure —- vulnerability to change —- autoregulation dysfunction —- retinal ganglion cell death —- glaucoma

TYPES

• Open-angle glaucoma (chronic): chronic open-angle glaucoma is the most common form of glaucoma. The ‘open’ drainage angle of the eye can become blocked leading to gradual increased eye pressure. If this increased pressure results in optic nerve damage, it is known as chronic open-angle glaucoma. The optic nerve damage and vision loss usually occurs so gradually and painlessly
• Angle-closure glaucoma: angle-closure glaucoma results when the drainage angle of the eye narrows and becomes completely blocked. In the eye, the iris may close off the drainage angle and cause a dangerously high eye pressure. When the drainage angle of the eye suddenly becomes completely blocked, pressure builds up rapidly, and this is called acute angle-closure glaucoma
• Exfoliation syndrome: exfoliation syndrome is a common form of a open-angle glaucoma that results when there is a buildup of abnormal, whitish material on the lens and drainage angle of the eye. This material and pigment from the back of the iris can clog the drainage system of the eye, causing increased eye pressure.
• Pigmentary glaucoma: pigmentary glaucoma is characterized by the iris bowing backwards, and coming into contact with the support structures that hold the lens in place. This position disrupts the cells lining the back surface of the iris containing pigment, and results in a release of pigment particles into the drainage system of the eye. This pigment can clog the drain and can lead to an increase in eye pressure. 
• Low-tension glaucoma: this is another form that experts do not fully understand. Even though eye pressure is normal, optic nerve damage still occurs. Perhaps the optic nerve is over-sensitive or there is atherosclerosis in the blood vessel that supplies the optic nerve.

SIGNS AND SYMPTOMS

The signs and symptoms of primary open angle glaucoma and acute angle-closure glaucoma are quite different.

Signs and Symptoms of Primary Open-angle Glaucoma

• Peripheral vision is gradually lost. This nearly always affects both eyes
• In advanced stages, the patient has tunnel vision

Signs and Symptoms of Closed Angle Glaucoma

• Eye pain, usually severe
• Blurred vision
• Eye pain is often accompanied by nausea and sometimes vomiting
• Light appears to have extra halo-like glows around them
• Red eyes
• Sudden, unexpected vision problems, especially when lighting is poor.

Common Symptoms are:

• Unusual trouble adjusting to dark rooms
• Difficulty focusing on near or distant objects
• Squinting or blinking due to unusual sensitivity to light or glare
• Change in color of iris
• Red-rimmed, encrusted or swollen lids
• Recurrent pain in or around eyes
• Double vision
• Dark spot at the center of viewing
• Lines and edges appear distorted or wavy
• Excess tearing or ‘watery eyes’
• Dry eyes with itching or burning
• Sudden loss of vision in one eye
• Sudden hazy or blurred vision
• Flashes of light or black spots
• Halos or rainbows around light

DIAGNOSTIC EVALUATION

• Eye-pressure test: Tonometer, a device which measures intraocular pressure. Some anesthetic and a dye are placed in the cornea, and a blue light is held against the eye to measure pressure. This test can diagnose ocular hypertension; a risk factor for open-angle glaucoma.

Gonioscopy: this examines the area where the fluid drains out of the eye. It helps determine whether the angle between the cornea and the iris is open or blocked (closed)

Perimetry test: also known as a visual field test. It determines which area of the patient’s vision is missing. The patient is shown a sequence of light spots and asked to identify them. Some of the dots are located where the person’s peripheral vision is; the part of vision that is initially affected by glaucoma. If the patient cannot see those peripheral dots, it means that some vision damage has already occurred.

Optic nerve damage: the ophthalmologist uses instruments to look at the back of the eye, which can reveal any slight changes which may also point towards glaucoma onset

Visual acuity test: this eye chart test measures how well you see at various distances

Visual field test: this test measures peripheral (side vision)

Dilated eye exam: in this exam, drops are placed in eyes to widen, or dilate, the pupils. Eye care professional uses a special magnifying lens to examine retina and optic nerve for signs of damage and other eye problems.

MANAGEMENT

Medical Management

• Prostaglandin analogues: these medications have prostaglandin-like compounds as their active ingredient. They increase the outflow of the fluid inside the eye. Examples include Xalatan and Lumigan. (Beta blockers: these medications reduce the amount of fluid the eye produces. Some patients may experience breathing problems, hair loss, fatigue, depression, memory loss, a drop in blood pressure. Examples of such medications include timolol, betaxolol and metipranolol). (Carbonic anhydrase inhibitors: these also reduce fluid production in the eye. Side effects may include nausea, eye irritation, and dry mouth, frequent urination, tingling in the fingers or toes, and a strange taste in the mouth. Examples include brinzolamide and dorzolamide). (cholinergic agents: also known as miotic agents).

SURGERY

• Trabeculoplasty: a high-energy laser beam is used to unblock clogged drainage canals, making it easier for the fluid inside the eye to drain out. This procedure nearly always reduces inner eye pressure. However, the problem may come back.
• Filtering surgery (viscocanalostomy): if eyedrops and laser surgery are not effective in controlling eye pressure, trabeculectomy is required. This procedure is performed in a hospital or an outpatient surgery center. Patient receives a medication to help relax and usually an injection of anesthetic to numb eye. Using small instruments under an operating microscope, an opening is created in the sclera and removes a small piece of eye tissue at the base of cornea through which fluid drains from eye (the trabecular meshwork). The fluid in eye can now freely leave the eye through this opening. As a result, eye pressure will be lowered.
• Drainage implant (aqueous shunt implant): this option is sometimes used for children or those with secondary glaucoma. A small silicone tube is inserted into the eye to help it drain out fluids better.
• Laser cycloablation (ciliary body destruction, cyclophotocoagulation or cyclocryopexy) is another form of laser treatment generally reserved for patient with severe forms of glaucoma with poor visual potential. This procedure involves applying laser burns or freezing to the part of the eye that makes the aqueous fluid. This therapy destroys the cells that make the fluid, thereby reducing the eye pressure
• Aqueous shunt devices: they are artificial drainage devices used to lower the eye pressure. They are essentially plastic microscopic tubes attached to a plastic reservoir. The reservoir is placed beneath the conjunctival tissue. The actual tube is placed inside the eye to create a new pathway for fluid to exit the eye. This fluid collects within the reservoir beneath the conjunctiva creating a filtering bleb. This procedure maybe performed as an alternative to trabeculectomy in patients with certain types of glaucoma.

NURSING MANAGEMENT

Nursing Assessment

• Evaluate the patient for any of the clinical manifestations
• Assess patient’s level of anxiety and knowledge base
• Assess the patient’s knowledge of disease process

Nursing Diagnosis

• Pain related to increased to increased IOP
• Fear related to pain and potential loss of vision
• Self-care deficit related to visual deficit
• Anxiety related to lack of knowledge about the surgical and postoperative experience
• Risk for injury related to blurred vision
• Risk for infection related to trauma to incision
• Acute pain related to trauma to incision

Intervention

Relieving Pain

• Notify health care provider immediately
• Administer medications as directed
• Explain to patient that the goal of treatment is to reduce IOP as quickly as possible
• Explain procedures to patient
• Reassure patient that with reduction in IOP, pain and other signs and symptoms should subside

Relieving Fear

• Provide reassurance and calm presence to reduce anxiety and fear
• Prepare patient for surgery, if necessary

Relieving Anxiety

• Assess the degree and duration of visual impairment
• Orient the patient to new environment
• Explain the perioperative routines
• Push to perform daily living habits when able
• Encourage the participation of family

Prevention of Injury

• Provided a comfortable position to the patient
• Help the patient to set the environment
• Orient the patient in a room
• Discuss the need for use of goggles when instructed
• Do not put pressure over the affected eye trauma
• Used the proper procedures when providing eye drugs

Promoting Self-Care

• Cleared the all doubts of patient regarding the disease condition
• Maintained good IPR with the patient
• Provided calm cool environment to the patient
• Music therapy and pet therapy given to patient
• Relaxation therapy also provided to relieve the anxiety of patient

Improving Knowledge

• Provided adequate knowledge about a disease condition
• Provided the sunglasses to patient during exposure to sunlight
• Provided medications to patient on proper time
• Advised the patient to talk with doctor

COMPLICATIONS

If left untreated, glaucoma will cause progressive vision loss, normally in these stages:

• Blind spots in peripheral vision
• Tunnel vision
• Total blindness