Blindness is the inability to see or a lack of vision i.e., it is complete or partial loss of vision. In the most severe cases, there’s an inability to see even light. It also means that you can’t correct your vision with eyeglasses, contact lenses, eye drops or other medical therapy, or surgery.
Blindness is a significant public health problem in India. Nationally representative RAAB surveys (Rapid Assessment of Avoidable Blindness) are being conducted periodically in the country to know the current status of blindness in the country. The current study describes the findings from the RAAB survey conducted during 2015–19 in India.
The results of the survey demonstrate that currently more than one fourth of persons aged 50 years and above are visually impaired (PVA<6/12 in better eye) in India. The prevalence of blindness among them is 1.99%, and older age and illiteracy are significantly associated with blindness.
Major causes of blindness included:
- cataract (66.2%),
- corneal opacity (CO) (8.2%),
- cataract surgical complications (7.2%),
- posterior segment disorders (5.9%) and
- glaucoma (5.5%).
The proportion of blindness and visual impairment that is due to avoidable causes include 92.9% and 97.4% respectively.
TYPES OF BLINDNESS
- Partial blindness: You still have some vision. People often call this "low vision."
- Complete blindness: You can't see or detect light. This condition is very rare.
- Congenital blindness: This refers to poor vision that you are born with. The causes include inherited eye and retinal conditions and non-inherited birth defects.
- Legal blindness: This is when the central vision is 20/200 in your best-seeing eye even when corrected with glass or contact lenses. Having 20/200 vision means that you have to be 10x closer or an object has to be 10x larger in order to see compared to a person with 20/20 vision. In addition, you can be legally blind if your field of vision or peripheral vision is severely reduced (less than 20 degrees).
- Nutritional blindness: This term describes vision loss from vitamin A deficiency. If the vitamin A deficiency continues, damage to the front surface of the eye (xerophthalmia) This type of blindness can also make it more difficult to see at night or in dim light due to retinal cells not functioning as well.
With complete blindness there is a lack of vision and the inability of the eye to detect light.
Symptoms that you may have while vision loss develops include:
- Blurry vision.
- Eye pain.
- Floaters and flashers.
- Sensitivity to light (photophobia).
- Sudden loss of vision, or the sudden appearance of black spots in your vision.
DIAGNOSIS AND TESTS
Each eye is tested for sight, thorough eye exam. It’s possible for blindness to affect only one eye.
Tests may include:
- The Snellen test: You’re probably familiar with this test. A provider asks you to read lines of letters that get smaller as they go down the page. This test of visual acuity measures what you can see in front of you (central vision).
- Visual field testing: The visual field means more than central vision. It’s what you can see to either side or above and below without moving your eye.
There are many causes of blindness, including injuries, infections and medical conditions.
Eye injuries and blindness
Eye injuries, or ocular trauma, can happen in many ways. It usually affects only one eye. Damage can result from:
- Chemical burns.
- Exposure to toxins
- Industrial accidents, including falls.
- Motor vehicle crashes.
Infections and blindness
Many infectious diseases can lead to vision loss and sometimes blindness. These include:
- This is the leading cause of preventable blindness in the world.
- Keratitis, including acanthamoeba keratitis.
NON-INFECTIOUS DISEASES AND BLINDNESS
Many non-infectious diseases can cause blindness, but some in only the most severe stages of the disease. These include:
- Retinitis pigmentosa: This term refers to a group of conditions that affect your retina, the part of your eye that has special cells that react to light. As the condition progresses, the retinal cells break down. This leads first to problems seeing at night and then subsequent loss of your peripheral vision.
- Age-related macular degeneration: This condition affects the macula, the part of your retina that controls central vision. When substantial central vision loss occurs, tasks like reading or recognizing people’s faces become very difficult, but your peripheral vision often remains intact.
- Retinopathy of prematurity: This retinal condition happens to some premature babies. Blood vessels grow into parts of their eye where they don’t belong. Scar tissue forms and can damage their retina, leading to significant vision loss and blindness.
- Cataracts: Cataracts cause vision loss by clouding the lenses of your eyes, leading a blurring of the vision and loss of contrast. Without access to surgical care, advanced cataracts can lead to blindness.
- Diabetes-related retinopathy: This condition may happen when you have diabetes and the blood vessels in the eye are damaged. The vision loss may be mild at first, but with progression or lack of treatment, blindness can occur.
- Glaucoma: With this condition, you have optic nerve damage. The vision loss often starts in the periphery but can lead to blindness in advanced stages of the disease.
- Leber hereditary optic neuropathy: This term refers to an inherited type of gradual vision loss. For unknown reasons, it affects males more than females.
- Anophthalmia: This disease happens when you’re born without one or both eyes.
- Microphthalmos: This disease happens when you’re born with very small eyes. Sometimes these smaller eyes don’t work as well as they should, or at all.
- Stroke: You can lose your eyesight from a stroke that occurs in an area of the brain that is involved in seeing, like the occipital lobe or along the visual tract. The stroke reduces or blocks blood flow to your brain.
- Cancer: Cancers, like retinoblastoma or orbital tumors, can cause eyes to become blind.
- Nutritional deficiencies: A poor diet can cause vision loss. Vitamin A deficiency is one cause, but you also need B vitamins and other minerals and vitamins for healthy vision.
Blindness is preventable in many cases.
Some governments and societies are working to stop blindness caused by preventable diseases, like trachoma. They’re making medicines more available in large areas of the world.
On a personal level, there are things you can do to reduce your risk of partial or total blindness. These include:
- Have regularly scheduled eye exams. Follow the advice of healthcare providers on how often you should go for exams. Always contact an eye care provider when you have a change in vision or something wrong with your eyes. Wear your prescription glasses and contact lenses when necessary.
- Keep blood sugar levels stable if you’re a person with diabetes and manage your blood pressure if you have high blood pressure.
- Wear protective gear when you’re working, riding a motorcycle or participating in contact sports. Don’t forget to wear sunglasses.
- Eat foods that make up a healthy, well-rounded diet.
- Get enough exercise. Ask your provider about an exercise plan that’s healthy for you.
- Achieve a healthy weight for you.
- Know about health issues in your family.
- Quit smoking, or never start.
- Avoid infections in your eye by always washing your hands when you put your contacts in and following instructions about how often to change them.
A healthy diet can help in prevention of blindness. If you tips which everyone must follow to keep their eyes healthy are:
ü Vitamin A: Vitamin A deficiency may lead to night blindness and dry eyes. Vitamin A is only found in animal-derived foods, but your body can convert certain plant-based carotenoids into vitamin A.
ü 2–3. Lutein and Zeaxanthin: A high intake of lutein and zeaxanthin may reduce your risk of eye diseases, such as macular degeneration and cataracts. Lutein and zeaxanthin usually occur together in foods. Spinach, swiss chard, kale, parsley, pistachios, and green peas are among the best sources. Other sources are egg yolks, sweet corn, and red grapes may also be high in lutein and zeaxanthin . In fact, egg yolks are considered one of the best sources due to their high fat content
ü Omega-3 Fatty Acids: Getting adequate amounts of the long-chain omega-3 fatty acids EPA and DHA from oily fish or supplements may reduce your risk of several eye diseases — especially dry eyes.
ü Gamma-Linolenic Acid: GLA, which is found in high amounts in evening primrose oil, may reduce symptoms of dry eye disease.
ü Vitamin C: Vitamin C is necessary for your eye health, and getting enough of this antioxidant may protect against cataracts. High amounts of vitamin C are found in many fruits and vegetables, including bell peppers, citrus fruits, guavas, kale, and broccoli.
ü Vitamin E: Vitamin E deficiency may lead to visual degeneration and blindness. For those who aren’t deficient, supplements probably won’t provide an added benefit. The best dietary sources of vitamin E include almonds, sunflower seeds, and vegetable oils like flaxseed oil.
ü Zinc: Zinc plays an important role in eye function. One study suggests that supplements may slow the early development of macular degeneration in older adults. Natural dietary sources of zinc include oysters, meat, pumpkin seeds, and peanuts.
Few of the homoeopathic listed below are helpful to prevent blindness or to treat blindness with favourable result, if taken according to the totality of symptoms. They are:
Osmium: Glaucoma; with iridescent vision. Violent supra and infra-orbital neuralgia; violent pains and lachrymation. Green colors surround candle-light. Conjunctivitis. Increase in intra-ocular tension, dim sight, photophobia.
Comocladia: Ciliary neuralgia with eyes feeling large and protruded, especially right. Worse, near warm stove; feels as if pressed outward. Sees only glimmer of light with left eye. Glaucoma, sense of fullness; eyeball feels too large. Motion of eyes aggravates.
Cineraria maritama: used with great success incases of cataract as an external application. Indicated in Traumatic cataract, senile cataract and in corneal opacities.
Phosphorus: Cataract. Sensation as if everything were covered with a mist or veil, or dust, or something pulled tightly over eyes. Black points seem to float before the eyes. Patient sees better by shading eyes with hand. Fatigue of eyes and head even without much use of eyes. Green halo about the candlelight (Osmium). Letters appear red. Atrophy of optic nerve. Œdema of lids and about eyes. Pearly white conjunctiva and long curved lashes. Partial loss of vision from abuse of tobacco. Pain in orbital bones. Paresis of extrinsic muscles. Diplopia, due to deviation of the visual axis. Amaurosis from sexual excess. Glaucoma. Thrombosis of retinal vessels and degenerative changes in retinal cells. Degenerative changes where soreness and curved lines are seen in old people.
Causticum: Causticum is rich in eye symptoms. Very often the patient says that the eyelids feel so heavy that he can hardly hold them up. This gradually increases until it becomes an actual paralysis. Sometimes there is the appearance of a veil before the eyes; foggy vision. Flickering before the eyes. Air seems full of little black insects. Then, again, large black or green spots are seen. After looking at the light a green spot appears and remains in the field of vision for a long time. Diplopia. And the vision gradually grows weaker until it is lost. Paralysis of the optic nerve. Lachrymation, tears acrid, burning; ulceration, copious discharges from the eyes, agglutination of the lids, paralysis of the eye muscles.
Physostigma: Night-blindness; photophobia; contraction of pupils; twitching of ocular muscles. Lagophthalmus. Muscæ volitantes; flashes of light; partial blindness. Glaucoma; paresis of accommodation; astigmatism. Profuse lachrymation. Spasm of ciliary muscles, with irritability after using eyes. Increasing myopia. Post-diphtheritic paralysis of eye and accommodation muscles.
Gelsemium: Double vision. Disturbed muscular apparatus. Corrects blurring and discomfort in eyes even after accurately adjusted glasses. Vision blurred, smoky. Dim-sighted; pupils dilated and insensible to light. Orbital neuralgia, with contraction and twitching of muscles. Bruised pain back of the orbits. One pupil dilated, the other contracted. Deep inflammations, with haziness of vitreous. Serous inflammations. Albuminuric retinitis. Detached retina, glaucoma and descemetitis. Hysterical amblyopia.