macular degeneration
Photodynamic Therapy Wet Macular Degeneration
(wet macular) This is a specialized laser treatment for macular degeneration that uses the stimulation/activation of a photosensitive dye by exposure to a light (laser) of a known wavelength that results in the closure of new vessels. -->The treatment takes about 20 minutes to complete and can be performed in the provider's office. This therapy slows the rate of vision loss, but it does not stop vision loss or restore vision that has already been lost by macular degeneration. -->The treatment results are often temporary and may require the patient to undergo successive treatments.
Anti-Vascular Endothelial Growth Factor Therapy
(wet macular) Vascular endothelial growth factor (VEGF) is secreted by oxygen-deprived cells, causing stimulation of the growth of abnormal blood vessels. Anti-VEGF therapy uses injections directly into the eye and is used to treat wet macular degeneration. This medication blocks the effects of the growth factor. The patient will need multiple injections that may be given monthly and that usually involve local anesthesia to the eye. This medication helps slow the progression of vision loss from macular degeneration and in some cases even improves sight.
Clinical manifestations of macular degeneration include
straight lines that appear distorted; absent or distorted central vision; dark, blurry areas or whiteout on center vision; and diminished or changed color perception. The clinical presentation of macular degeneration is also related to the specific underlying pathophysiology.
The examination often also includes the use of an
Amsler grid. -->This examination is done by asking the patient to look at a grid that resembles a checkerboard. The patient covers one eye and stares at a black dot in the center of the grid. While staring at the dot, patients with macular degeneration may notice that the straight lines appear wavy or may interpret that some of the lines are missing. -->A fluorescein angiogram may also be performed for confirmation of wet macular degeneration. This test requires that a special dye is injected intravenously, and images are taken as the dye passes through the vessels within the retina, identifying leaking blood vessels.
Dry Macular Degeneration
Dry macular degeneration, the most common form of macular degeneration, occurs when the light-sensitive cells in the macula slowly start to break down. -->The dry form of macular degeneration can turn into wet macular degeneration. ---->All people who have wet macular degeneration initially had dry macular degeneration. -->One of the most common early indications of dry macular degeneration is drusen bodies, which are yellow deposits that are located under the retina and are usually found in people over age 60. -->Eye examinations that include a comprehensive dilation evaluation usually detect drusen bodies.
Surgical Management
Laser surgery uses a light beam to destroy the fragile, leaky blood vessels that are accumulating behind the macula. -->This high-energy beam of light aimed directly at the new blood vessels destroys them, therefore preventing further loss of vision. -->Only a small percentage of patients with wet macular degeneration can be treated with this surgery, and there is also concern that laser treatment may destroy healthy tissue as well as impact visual acuity. -->Surgery is most often performed in the provider's office or eye clinic, and the risk of developing new blood vessels after laser treatment is high. Vision loss may progress despite repeated treatment in some patients.
Evaluating Care Outcomes
Macular degeneration has no complete cure; the goal of therapy is the preservation of vision. Clinical manifestations of macular degeneration start with a decline in visual acuity along with blurring or distortion of vision. Some of the manifestations may be slow to develop and therefore not initially obvious to the patient. Medical and surgical treatments are available depending on the specific condition.
• Safety precautions
Maintain a safe environment related to increased risk of physical injury secondary to impaired vision
• Physical assessment/examination
On physical examination with an ophthalmoscope, yellow spots (drusen bodies) form on the retina. The presence of abnormal vessel leaking is also sometimes seen on ophthalmoscopic examination.
• Education regarding diagnosis
Provide detailed and understandable information regarding patient diagnosis so that patients are able to participate in care and meet expectations for treatment.
• Community resource referrals
Referral to community services as patient circumstances dictate to help ensure that patient has access to care (i.e., Macular Disease Society, Prevent Blindness America)
• Provider follow-up
Routine scheduled follow-up appointments with provider to evaluate for any changes in visual acuity or the presence of other internal changes
Medical Management
The three most common treatments for macular degeneration are laser surgery, photodynamic therapy, and injections directly into the eye. --There is no cure for macular degeneration, and despite treatment, the disease and vision loss may continue to progress.
• Vital signs
There is no direct effect on vital signs, although a risk factor for the development of macular degeneration is elevated blood pressure.
There are three phases of dry macular degeneration:
early dry macular degeneration, intermediate dry macular degeneration, and advanced dry macular degeneration.
• Visual acuity
Visual changes develop as abnormal blood vessels located behind the retina start to grow under the macula. These new networks of blood vessels are usually fragile and often leak blood or fluid, resulting in a loss of sharp, central vision. The onset may be insidious.
Patients with advanced dry macular degeneration have
a breakdown of the light-sensitive cells and supporting tissue in the central retinal area. The presence of drusen bodies is also noted on examination. The breakdown can cause a blurred spot in the center of vision that will gradually get bigger and darker, taking up much of the central vision.
Dry macular degeneration causes
a gradual blurring of the central vision, and the patient may have difficulty recognizing faces. As the condition worsens, a blurred spot may be seen in the center of the visual field; this leads to gradual loss of central vision in the affected eye. Wet macular degeneration usually causes a quick loss of central vision and is also known as advanced macular degeneration. One of the earliest symptoms of this disease is that straight lines begin to appear wavy.
Macular degeneration is most commonly
age related and is a disease that gradually destroys sharp, central vision. -->Affecting the macula (the part of the eye that is responsible for central vision and allows for vision in fine detail), it causes no pain. -->Macular degeneration is slow to develop in some patients, often causing the patient to be unaware of any changes in vision. --->In others, it develops at a much faster pace. Patients who have advanced macular degeneration in one eye are at high risk for developing the same condition in the other eye.
Due to the chances of progressive decrease in visual acuity, assessment for
macular degeneration is important. -->The clinical manifestations of macular degeneration are insidious and result in the loss of sharp, central vision.
Patients with intermediate dry macular degeneration present with
medium-sized drusen bodies, or one or more large drusen bodies are present on examination. --Some patients see a blurred spot in the center of their visual field. --The patient may require more light for reading and other tasks.
Dry Macular Degeneration-Once dry macular degeneration reaches the advanced stage,
no form of treatment can prevent vision loss. -The NEI's Age Related Eye Disease (ARED) study has found that having patients take a specific high-dose formulation of antioxidant and zinc significantly reduces the risk of vision loss. --Nutritional recommendations are made when treating a patient with macular degeneration. Recent research provides some foundation that using an ARED formula (vitamin C, vitamin E, beta-carotene, zinc, and copper) can slow the progression of intermediate macular degeneration to the advanced stage. Lutein and zeaxanthin supplements may also produce protective effects.
In early dry macular degeneration,
patients present with a few small to medium-sized drusen bodies. -There are no other clinical manifestations, and no vision loss occurs.
Photodynamic therapy (Wet Macular Degeneration) uses a medication called
verteporfin (Visudyne), a light-activated medication, which is injected directly into the patient's arm. In the presence of oxygen, highly reactive short-lived reactive oxygen radicals are generated. -->Light activation of this medication results in local damage to the endothelium and therefore results in vessel occlusion. The medication travels through the body and eventually to the blood vessels in the patient's eye and sticks to the surface of new blood vessels. -->A light is then shined into the patient's eye for about 90 seconds to activate the medication. The activated medication then destroys the new blood vessels, therefore slowing the rate of vision decline. -->It is important to instruct the patient to avoid exposing skin/eyes to direct sunlight or bright indoor light for 5 days after treatment because the medication is activated by light.
Nonmodifiable risk factors include:
• Age (patients over age 60 are at greatest risk) • Family history of macular degeneration • Gender (women are more likely than men) • Race (more common in Caucasians)
Nursing Diagnoses
• Disturbed visual sensory perception related to degeneration of the macula • Anxiety related to loss of vision • Risk for injury related to visual loss
Modifiable risk factors include:
• High blood pressure • High cholesterol • Obesity • Smoking • Decrease in zinc blood levels
Epidemiology
The greatest risk factor for macular degeneration is related to advancing age. --According to the study by the NEI at the NIH, middle-aged people have about a 2% risk of developing macular degeneration, but the risk increases to nearly 30% in those patients over age 75. -There are also modifiable and nonmodifiable risk factors for this disorder.
Pathophysiology
The macula is a structure in the eye that is located in the center of the retina. The retina converts light and images instantly into electrical impulses and then sends these impulses or nerve signals to the brain via the optic nerve. There are two primary types of macular degeneration: dry macular degeneration and wet macular degeneration
Wet Macular Degeneration
Wet macular degeneration occurs when abnormal blood vessels located behind the retina start to grow under the macula (Fig. 46.11). These new networks of blood vessels are known to be very fragile and often leak blood and fluid. The blood and fluid raise the macula from its usual position at the back of the eye, and damage to the macula occurs rapidly.
Changes in central vision (straight-ahead vision), along with advanced age, may
raise suspicion with the patient's healthcare provider that the patient has macular degeneration. To assess for possible signs of macular degeneration, the provider completes a comprehensive eye examination, including dilation of the pupils for a better assessment of the back portion of the eye. Tonometry examination may also be done to measure the pressure inside the eye.
