National Eye Donation Fortnight 2019: What Causes Blindness, Its Types, Symptoms And Treatment

National Eye Donation Fortnight is celebrated every year from 25 August to 8 September. The 12 days will be used to spread awareness of the importance of eye donation. According to several reports, one in five blind people of the world is from India, that is, at least 46 lakhs of Indians are suffering from blindness.

On this National Eye Donation Fortnight, read on to know about blindness and how it can affect anyone and everyone.

This type of visual impairment cannot be corrected by glasses or contact lenses. Any individual can become blind, it is not specific to any group, however, cataracts and macular degeneration are increasingly linked with ageing ^[1] .

If you are partially blind, you will have a blurry vision; complete blindness is when you are not able to see anything at all and legal blindness is the when the vision is highly compromised. That is, what an individual with healthy vision can see from 200 feet away, can only be seen 20 feet away for a legally blind person ^{[1] [2]} .

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A large number of the population suffer from one form or other of blindness and in comparison to 10 years ago, the numbers have hiked predominantly (0.4 per cent to 6.% per cent) and this can be accorded to the new-age lifestyle and other physical demands ^[3] .

Types Of Blindness

The state of being sightless can vary depending on the levels of vision disability ^[4] . The different types of blindness are as follows:

Complete blindness: It is the total and complete loss of vision. Also termed as legal blindness, a person suffering from legal blindness has a vision as equal or worse than 20/200. It is increasingly found in individuals aged above 60 years.

Colour blindness: Also called as dyschromatopsia, colour blindness causes a person to lack the ability to distinguish certain colours. It is common in men and red-green colour blindness is the most common type of colour blindness. In most people, it is congenital ^[5] .

Night blindness: It is the type of vision impairment that occurs when there is low light, basically at night. Night blindness does not cause a complete lack of vision but impairs vision.

Causes Of Blindness

Various conditions and eye diseases can cause blindness and the most common ones are listed below ^[6] :

Cataracts: This is a common cause of blindness in the elderly.

Macular degeneration: This occurs mostly at the age of 60 years and above. Macular degeneration disease damages the central vision and affects the ability to read, write and drive.

Glaucoma: One of the major causes of blindness, glaucoma affects the optic nerve and leads to blindness. It occurs when the fluid pressure slowly increases inside the eye, thus damaging the optic nerve.

Diabetic retinopathy: Caused by diabetes, the condition affects the retina and results in blindness among adults. It can cause vision loss in people diagnosed with diabetes at the age of 18 years or more ^[7] .

Rubella: This disease can pass from a mother to an unborn child and hence preventive measures must be taken to prevent German measles.

Ophthalmia neonatorum: This disease refers to the inflammation in the eyes of a newborn. It is found in infants and is caused when the bacteria from the birth canal of the mother moves into the eyes of the baby.

Optic nerve hypoplasia: The condition develops after birth and is mostly inherited. It occurs due to loss of blood supply to the optic nerve ^[8] .

Optic nerve atrophy: This condition develops when there is a deficiency of optic nerve fibres, as well any defects or disabilities in the eye.

Myopia: A refractive error, myopia is also defined as near-sightedness. For individuals suffering from this condition, close objects will look clear and distant objects appear blurred. Myopia can be fixed by wearing corrective glasses ^[9] .

Eye injuries: The protective glands of the eye will be worn out in the case of eye injuries and burns and hence this increases the risk of vision loss or blindness and is one of the major causes of blindness.

Retinal breaks: Due to the ageing process or genetics, people may have breaks in their retina, and this may lead to blindness. This condition occurs as a result of the degeneration of the retina.

Some of the specific causes that affect an infant's vision and cause blindness are ^[10] :

• amblyopia, or a lazy eye,
• infections, such as pinkeye,
• visual inattention, or delayed development of your child's visual system,
• blocked tear ducts,
• cataracts,
• strabismus, or crossed eyes,
• retinopathy of prematurity,
• ptosis, or a droopy eyelid and
• congenital glaucoma.

Symptoms Of Blindness

A person who is legally blind will not be able to see anything. If the condition is one that develops with time, the person will suffer from sudden blurriness and can go in and out of clear vision; which will gradually turn into complete darkness ^[11] .

The other symptoms are:

• tunnel vision,
• poor night vision,
• an inability to see shapes,
• seeing only shadows and
• cloudy vision.

The symptoms of blindness in infants are ^[12] :

• a white pupil instead of black,
• constant eye rubbing,
• abnormal eye alignment or movement after 6 months of age,
• extreme sensitivity to light,
• chronic eye redness,
• poor focusing,
• poor visual tracking, or trouble following an object with their eyes and
• chronic tearing from their eyes.

Risks Of Blindness

Certain individuals are at the risk of developing blindness and they are ^[13] :

• diabetic individuals,
• people with eye diseases, such as macular degeneration and glaucoma,
• eye surgery patients,
• people who have had a stroke,
• individuals who work with toxic chemicals and
• premature babies.

Diagnosis Of Blindness

The optometrist will carry out an eye examination which will help determine the cause behind the condition.

There will be a variety of tests that will be carried out to check aspects such as to measure the clarity of your vision, the function of your eye muscles, and how your pupils react to light ^[14] .

Then, using a slit lamp (a low-power microscope paired with a high-intensity light), the general health of your eyes will be examined.

For diagnosing blindness in infants the method will vary. The initial check-up will be conducted at the time of birth. 6 months later, the infant's eyes will be checked for visual acuity, focus, and eye alignment ^[15] .

Treatment For Blindness

The most common treatment measures adopted for blindness are ^[16] :

• eyeglasses,
• medication,
• surgery and
• contact lenses.

These above-mentioned are prescribed for minor problems or blindness that are not extremely severe. If the person is suffering from partial blindness, he or she will be directed to make use of magnifying glasses or use bigger text sizes ^[17] .

For an individual who is completely blind, life has to be redone. That is, they need to be taught of approaching life in a new manner. A person who is completely blind has to take up the following elements, such as ^[18] :

• Learn Braille
• Organise their home in a manner that is easy to find and locate things
• Fold money in distinct ways
• Memorise the keypad on your phone
• Take help through the use of a guide dog etc.