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Age-Related Causes of Visual Impairment

The leading causes of visual impairment in older Americans are:

 

Age-Related Macular Degeneration (AMD)


Definition

Age-Related Macular Degeneration (AMD) is defined by the AMD Alliance International as “a progressive retinal disease, usually occurring at age 55 or older, with multiple environmental and genetic factors."

Example

simmacular

Source for illustration: www.lighthouse.org/about-low-vision-blindness/vision-disorders/age-related-macular-degeneration-amd/

AMD Alliance International lists two stages of AMD:  Dry and Wet.

Dry AMD

This is the more common form of AMD, accounting for 85% to 90% of all cases.  Dry AMD is characterized by good vision and the presence of drusen, a collection of small, round, white-yellow, fatty deposits found in the central part of the retina, which is the macula.  The macula’s light-sensitive cells start to break down as the eye ages and the macular tissue grows thin.

Symptoms of Dry AMD include needing more light for reading or and other tasks, difficulty seeing detail, and the occurrence of localized areas of vision loss or scotomas, which produce blurred spots, blank spots, blotches, and distortion.

Wet AMD

This form is referred to as late AMD and accounts for 10% to 15% of all cases.  Characterized by loss of central vision, wet AMD increases the risk of severe vision loss.  Wet AMD occurs when abnormal blood vessels begin growing underneath the macula, and later burst, leak and damage the macular tissue.

Symptoms of Wet AMD include seeing objects as wavy or distorted (the straight edge of a building may appear curved) and a sudden and rapid decrease in central vision. If blood vessels break through the surface of the retina and cause leakage of blood (hemorrhage), blind spots may occur.

Diagnosis of Either Type of AMD

For AMD to be detected before symptoms appear, screenings are advised for individuals who meet the following criteria:

  • Age 60 or older;
  • Have hypertension or cardiovascular disease;
  • Smoke cigarettes or other tobacco products;
  • Have a close relative (sibling, parent or child) with AMD or any related vision loss, regardless of age;
  • Have had cataract surgery;
  • Have had significant cumulative light exposure (airline pilots, boaters, farmers).


A comprehensive eye examination also is advised. Such an exam would include Visual Acuity Testing, Ophthalmoscopy followed by slit-lamp examination (to reveal the internal structures of the eye), and Tonometry (measures the pressure of fluids inside the eye in order to rule out glaucoma).

Supplemental testing may include:

  • Amsler Grid: A simple chart with horizontal and vertical black lines on a white background with a black dot at the center.
  • Angiography: Assesses the extent, type, and location of abnormal vessel growth in the eye.
  • Optical Coherence Tomography: Produces high-resolution images of cross-sections of the retina, allowing its thickness to be measured.


Sources:

www.lighthouse.org/about-low-vision-blindness/vision-disorders/age-related-macular-degeneration-amd/

www.amdalliance.org/information_overview_basic_facts.html

www.nlm.nih.gov/medlineplus/maculardegeneration.html

www.everydayhealth.com/vision-center/macular-degeneration.aspx

www.nlm.nih.gov/medlineplus/magazine/issues/winter07/articles/winter07pg18-19.html

ezinearticles.com/?Macular-Degeneration,-Your-Diet-and-Natural-Supplements&id=4899618

www.afb.org/seniorsite.asp?SectionID=63&TopicID=286&DocumentID=3196

www.rpbusa.org/rpb/eye_info/amd/

 

Glaucoma


Definition

According to the AFB Senior Site, glaucoma is “a serious condition that involves an elevation in pressure inside the eye caused by a build-up of excess fluid." Glaucoma is also known as the leading cause of blindness in the United States, and usually occurs in individuals age 40 or older.

Example

simglaucoma

 
Source for illustration:
www.lighthouse.org/about-low-vision-blindness/vision-disorders/glaucoma/

Lighthouse International enumerates the following types of glaucoma:

Types of Glaucoma

  • Open-Angle Glaucoma – The decrease in peripheral (side) vision caused when fluid doesn’t flow out easily, which leads to vision loss. In the early stages of the disease, the affected person experiences no pain or changes in vision.
  • Normal-Tension Glaucoma – Also called Low-Tension Glaucoma, this type occurs when there is damage to the optic nerve of a person’s eye even with normal eye pressure. Risk factors for this type include a family history of any type of glaucoma or a history of cardiovascular disease.
  • Angle-Closure Glaucoma – Also called Closed Angle Glaucoma, this is a rare type, which occurs when the iris blocks the eye fluid from flowing, creating pressure that leads to vision loss.  (Note: This type of glaucoma is characterized by the following symptoms: Sudden onset of severe eye pain, nausea or vomiting, blurry vision, halos around bright lights, headaches, and redness of the eye.)
  • Congenital Glaucoma – Another rare type, sometimes inherited, which is present at birth.
  • Secondary Glaucoma – Said to be secondary because it is caused by another disease or can develop because of an eye injury, eye surgery, inflammation, certain eye tumors or advanced cataracts.


Symptoms of Glaucoma

Except as noted above with Angle-Closure Glaucoma, generally, glaucoma symptoms are not noticeable until the disease has progressed. Adults who have risk factors (see below) need to be screened every two years, regardless of age. Generally, people age 65 or older should see an eye doctor every one or two years to be tested for glaucoma and other eye diseases because risk increases with age.

According to Everyday Health, the risk factors are:

  • Being 65 years of age or older;
  • Having a family history of glaucoma;
  • Being of African, Asian or Spanish descent;
  • Being nearsighted or farsighted;
  • Having had a past eye injury.


Source:  Lighthouse International.


Diagnosis of Glaucoma

An eye exam to diagnose glaucoma includes:

  • Contact Tonometry – A pressure gauge makes contact with the eye after numbing drops are instilled in the eyes.
  • Dilated Eye Examination – Also referred to as ophthalmoscopy, in this test the pupils are dilated in order to view the interior structures of the eye, including the optic nerve.
  • Visual Field Test  – Also known as Perimetry, a visual field test maps the response to a series of lights flashed in the central and peripheral vision indicating which areas he/she can and cannot see, based on which lights he/she responds to.
  • Pachymetry – Using a pachymeter to scan and measure the corneas, the thickness or thinness of the cornea is used to interpret eye pressure reading.
  • Gonioscopy – A painless test that measures the angle at which fluid drains from the person’s eye.

 
Sources:

www.nlm.nih.gov/medlineplus/glaucoma.html

www.lighthouse.org/about-low-vision-blindness/vision-disorders/glaucoma/

www.everydayhealth.com/vision-center/the-eye-exam/get-an-eye-exam-to-guard-against-glaucoma.aspx

www.afb.org/seniorsite.asp?SectionID=63&TopicID=286&DocumentID=3198

www.rpbusa.org/rpb/eye_info/glaucoma/


Cataract


Definition

Cataract, according to the AFB Senior Site, is “a clouding of the lens in the eye." As people age, cataracts grow progressively darker and more dense, preventing light from easily passing through the lens. This results in vision loss.

Example

simcataract

Source for illustration: www.lighthouse.org/about-low-vision-blindness/vision-disorders/cataract/

Symptoms of Cataract

The following symptoms are from the National Eye Institute:

  • Blurry vision
  • Colors that seem faded
  • Glare
  • Not being able to see well at night
  • Double vision
  • Frequent prescription changes in eyewear


Diagnosis

An eye exam to diagnose cataract would include:

  • Visual Acuity Testing;
  • Opthalmoscopy followed by slit-lamp examination to reveal the internal structures of the eye;
  • Tonometry to measure the pressure of fluids inside the eye;
  • Keratometry and A-Testing to measure the curvature of the cornea and the length of the eye.  
  •  

    Other specialized tests to determine if cataract is present include:

    • Contrast Testing which assesses the eye’s ability to detect subtle shade variations.
    • Glare Sensitivity Testing to test the eye’s opacity stage.
    • Corneal Endothelium Testing to examine the layer of tissue that lines the posterior surface of the cornea.
    • Potential Acuity Testing to estimate how well a person can expect to see after surgical removal of the cataract.
    • Wavefront Mapping which uses computer analysis of a laser beam to track the distortion of light as it passes through the eye.


    Sources:

    www.nlm.nih.gov/medlineplus/cataract.html

    www.lighthouse.org/about-low-vision-blindness/vision-disorders/cataract/

    www.everydayhealth.com/vision-center/when-cataracts-cloud-your-vision.aspx

    www.afb.org/seniorsite.asp?SectionID=63&TopicID=286&DocumentID=3197

    www.rpbusa.org/rpb/eye_info/cataract/

    Diabetic Retinopathy


    Definition

    According to the AFB Senior Site, diabetic retinopathy is “the eye condition that results from diabetes, Type I insulin dependent, and Type II, typically non-insulin dependent. It occurs when blood vessels stop feeding the retina properly. In its early stages, the blood vessels may leak fluid in the retina, which can affect the macula, the entire retina, or the vitreous gel (a clear substance that fills the interior of the eye). In the later stages of the condition, new vessels may grow and send blood into the center of the eye, causing serious vision loss that can lead to blindness. Approximately 40% of people with diabetes have at least mild retinopathy. The incidence increases with the condition’s duration and when blood glucose cannot be controlled.”

    Example

    simdiabetic


    Source for illustration: www.lighthouse.org/about-low-vision-blindness/vision-disorders/diabetic-retinopathy/diabetic-retinopathy-overview/

    According to Lighthouse International, the symptoms for diabetic retinopathy are:

    Symptoms

    • Blurry or double vision
    • Halos or flashing lights
    • Double vision
    • Dark spots or floaters
    • Pain or sensation of pressure in one or both eyes
    • Diminished peripheral (side) vision
    • Poor night vision


    Diagnosis

    All adults and children aged 10 and older who have diabetes should have a comprehensive dilated eye examination every year even if no symptoms are identified. An immediate eye examination is highly recommended for the scenarios below:

      • Type 1 diabetes for a year or more and no eye exam in over a year or more;
      • Type 2 diabetes and no eye exam in over a year or more;
      • Child with diabetes who has reached puberty;
      • Pregnant woman with diabetes or a woman who plans to get pregnant and has diabetes.


    Sources:

    www.nlm.nih.gov/medlineplus/diabeticeyeproblems.html

    www.lighthouse.org/about-low-vision-blindness/vision-disorders/diabetic-retinopathy/

    www.afb.org/seniorsite.asp?SectionID=63&TopicID=286&DocumentID=3199

    www.rpbusa.org/rpb/eye_info/diabetic_retinopathy


    Additional Age-Related Vision Impairments

    Two additional age-related conditions are worth mentioning here:

    • Hemianopsia:  A vision loss condition (usually permanent) caused by stroke or other brain injury. It affects either the right, left, upper or lower side of the visual field, making it extremely difficult to perform everyday tasks.
    • Charles Bonnet Syndrome:  This may cause a person to see a wide range of images such as animals, buildings and shapes that are not real. Such visual disturbances usually affect people who have experienced visual impairment or sight loss later in life.


    Source: www.afb.org/seniorsite.asp?SectionID=63&TopicID=286&DocumentID=3200