World Blindness Week  (1st - 7th April)

 

Blindness is a lack of vision or, the inability to see anything, including light.

Blindness may be partial or complete. If you’re partially blind, you have limited vision. For example, you may have blurry vision or the inability to distinguish the shapes of objects. Complete blindness means you can’t see at all.

The majority of individuals who use the term "blindness" imply total blindness, which is not the case. The National Federation of the Blind takes a much broader view. They encourage people to consider themselves as blind if their sight is bad enough—even with corrective lenses—that they must use alternative methods to engage in any activity that people with normal vision would do using their eyes.

 

Prevalence Worldwide

1.   According to WHO;

Globally, at least 2.2 billion people have a near or distance vision impairment. In at least 1 billion – or almost half – of these cases, vision impairment could have been prevented or has yet to be addressed

The majority of people with vision impairment and blindness are over the age of 50 years; however, vision loss can affect people of all ages.

2.   The estimated number of blind persons increased (by 42.8%) from 34.4 million in 1990 to 49.1 million in 2020 yet global all-age age-standardized prevalence of blindness decreased between 1990 (0.85%; 95% UI:0.68%-1.1%) and 2019 (0.60%; 95% UI:0.48%-0.75%).

3.   2021 has seen the official launch of the International Agency for the Prevention of Blindness's Vision Atlas – a compilation of the very latest eye health data. The report reveals that globally there are 43 million people living with blindness and 295 million people living with moderate-to-severe visual impairment.

 

What are some of the signs and symptoms of blindness?

You can't see anything if you're completely blind. You might have the following symptoms if you're partially blind:

• cloudy vision

• an inability to see shapes

• seeing only shadows

• poor night vision

• tunnel vision

 

Infants' signs and symptoms of blindness

The visual system of your child develops in the womb. It doesn't fully develop until around the age of two.

Your infant should be able to fix their sight on an object and follow its movement by the age of 6 to 8 weeks. By 4 months of age, their eyes should be properly aligned and not turned inward or outward.

Visual impairment in young children can manifest itself in a variety of ways, including:

• constant eye rubbing

• extreme sensitivity to light

• poor focusing

• chronic eye redness

• chronic tearing from their eyes

• a white instead of black pupil

• poor visual tracking, or trouble following an object with their eyes

• abnormal eye alignment or movement after 6 months of age.

 

What causes blindness?

The following eye diseases and conditions can cause blindness:

• Glaucoma refers to different eye conditions that can damage your optic nerve, which carries visual information from your eyes to your brain.

• Macular degeneration destroys the part of your eye that enables you to see details. It usually affects older adults.

• Cataracts cause cloudy vision. They’re more common in older people. 

• A lazy eye can make it difficult to see details. It may lead to vision loss.

• Optic neuritis is inflammation that can cause temporary or permanent vision loss.

• Retinitis Pigmentosa refers to damage to the retina. It leads to blindness only in rare cases.

• Tumors that affect the retina or optic nerve can also cause blindness.

Blindness is a potential complication if you have diabetes or have a stroke. Other common causes of blindness include:

• birth defects

• eye injuries

• complications from eye surgery

 

Causes of blindness in infants

The following conditions can impair vision or cause blindness in infants:

• infections, such as pink eye/ conjunctivitis (inflammation/ infection of the transparent membrane that lines your eyelid and eyeball)

• blocked tear ducts (a condition in which your tears can't drain normally, leaving you with a watery, irritated eye)

• cataracts (lens of the eye become progressively opaque, resulting in blurred vision)

• strabismus (crossed eyes) – a condition in which the eyes do not line up with one another.

• amblyopia (lazy eye) – reduced vision in one eye caused by abnormal visual development early in life.

• ptosis (droopy eyelid) – also called blepharoptosis is a condition where the upper eyelid droops.

• congenital glaucoma (inherited condition, caused by incorrect development of the eye’s drainage system before birth)

• retinopathy of prematurity (ROP), which occurs in premature babies when the blood vessels that supply their retina aren’t fully developed

• visual inattention, or delayed development of your child’s visual system

 

Risk Factors

Blindness is a threat to the following groups of people:

• people with eye diseases, such as macular degeneration (also known as age-related macular degeneration, which is a medical condition that may result in blurred or no vision in the center of the visual field) and glaucoma

• people with diabetes or stroke

• people undergoing eye surgery

• people who work with or near sharp objects or toxic chemicals

• premature babies

 

Diagnosis

The diagnosis of blindness is made by examination of all parts of the eye by an ophthalmologist.

Your eye doctor will administer a series of tests that measure:

• the clarity of your vision

• the function of your eye muscles

• how your pupils react to light

They’ll examine the general health of your eyes using a slit lamp. It’s a low-power microscope paired with a high-intensity light.

There are two main areas that are looked at when someone’s vision is measured;

 

A. Visual Field Testing

During visual field testing, one will be taught to look straight ahead at a device while lights in their peripheral vision flash on and off. When people see a light, they will be instructed to click a button. This reveals any blind spots in his vision.               

 

B. Test for Visual Acuity

A Snellen chart is used to measure visual acuity. It involves reading letters off a chart on which the letters become progressively smaller. This chart is used during a routine eye test. After the test, a score made up of two numbers is given. The first number represents how far away from the chart were able to successfully read the letters on the chart. The second number represents how far away a person with healthy vision should be able to read the chart.

So, if your visual acuity score is 6/60, you can only read 6 meters away what a person with normal eyesight can see 60 meters away. The normal eyesight is 6/6.

               

Management

The treatment of blindness depends on the cause of blindness;

• Blindness due to nutritional deficiency: It can be addressed by dietary changes.

•  Visual impairment due to refractive error: It can be addressed by doing refraction and providing appropriate spectacles.

•  Inflammatory and infectious causes of blindness can be treated with medication in the form of drops or pills.

•  Most people are blind due to cataracts: In these patients, cataract surgery would, in most cases, restore their sight. Usually, an intraocular lens (IOL) is implanted in the eye after the removal of the opaque natural lens.

 

How can blindness be prevented?

Your eyes are an important part of your health. You can do many things to keep them healthy and make sure you’re seeing your best.  Some tips to prevent vision loss include;

•  Have a comprehensive dilated eye exam: To detect eye diseases and help prevent vision loss, get regular eye examinations. If you receive a diagnosis of certain eye conditions, such as glaucoma, treatment with medication can help prevent blindness.

• Maintain your blood sugar levels: as 90% of blindness caused by diabetes is preventable, your health care team to set and reach goals to manage your blood sugar including blood pressure and cholesterol.

• Know your family’s eye health history: It is important to know if anyone in the family has been diagnosed with an eye disease or condition since many are hereditary.

• Eat right to protect your sight: Carrots, a diet rich in fruits and vegetables- particularly dark leafy greens, such as spinach. Research has also shown there are eye health benefits from eating fish high in omega-3 fatty acids, such as salmon, tuna, and halibut.

• Maintain a healthy weight: Being overweight or obese increases your risk of developing diabetes and other conditions, which can lead to vision loss.

• Wear protective eyewear: Wear protective eyewear when playing sports or doing activities around the home. Protective eyewear includes safety glasses and goggles, and safety shields.

• Quit smoking or never start: Smoking increases the risk of developing age-related macular degeneration, cataract, and optic nerve damage.

•  Be cool and wear your shades: Sunglasses protects your eyes from the sun's ultraviolet rays.

•  Give your eyes a rest: If you spend a lot of time at the computer or focusing on any one thing, you sometimes forget to blink and your eyes can get fatigued.

•  Clean your hands and contact lenses (if used) properly: To avoid the risk of infection, always wash your hands thoroughly before putting in or taking out your contact lenses.

• Practice workplace eye safety: Employers are required to provide a safe work environment in order to prevent eye injury.

 

By RN Sujata Khatri

Danphe Care