What is Blindness?
Blindness is defined as a state of being sightless or visionless. In this state, an individual is unable to see and the loss of vision cannot be corrected with glasses or contact lenses. In medical term, it is a visual impairment in which a blind person may have a completely dark sight. The term blindness is usually used to describe severe sight decline in one or both eyes.
Complete blindness means that an individual cannot see anything or do not see light (total darkness). Partial blindness is a state in which the eyesight is limited. Vision impairment, or low vision, means that even with eyeglasses, contact lenses, medicine, or surgery, someone doesn’t see well.
Vision impairment can range from mild to severe. People with a vision that is worse than 20/200 with glasses or contact lenses are considered legally blind. What a person with healthy eyes can see from 200 feet away, a legally blind person can see only from 20 feet away. The World Health Organisation (WHO) defines blindness as visual sharpness of less than 3/60. Whereas, the National Programme for Control of Blindness (NPCB) in India, defines blindness as a vision of 6/60.
How common is Blindness?
Globally there are 39 million blind people and 12 million of them are from India, which means India is now home to the world’s largest number of blind people.
Worldwide, between 300 million to 400 million people are visually impaired due to various causes. Of this group, approximately 50 million people are totally blind. Approximately 80% of blindness occurs in people over 50 years of age.
What are the causes of Blindness in the elderly?
- Age-Related Macular Degeneration: Legal blindness can be caused by age-related macular degeneration (AMD) because this disease affects the central vision provided by the macula (the specialized central part of the retina). Patients with severely damaged maculas in both eyes have visual acuity measured on an eye chart of 20/200 or worse. However, their peripheral, or side vision is usually intact, so they can see shapes and movement, and read large letters with the help of magnification and bright lights.
- Diabetic Retinopathy: Another retinal disease that can cause legal blindness is diabetic retinopathy. Patients with diabetes can lose vision from swelling or bleeding in the retina, or from retinal detachment. A person suffering from diabetes can decrease the risk of legal blindness with good blood sugar and blood pressure control and annual eye examination from an expert of the retina.
- Glaucoma: Legal blindness can also be caused by glaucoma. It is a disease in which the eyeball pressure increases, leading to death of retinal neurons that send the signal from the eye to the brain. This disease most often progresses gradually over time, with patients losing part of their visual field and/or visual acuity. If the visual field diminishes to 20 degrees or less, then the patient is legally blind. The normal binocular visual field (using both eyes) in the horizontal plane is about 180 degrees. Progression of visual field loss can usually be slowed or stopped by lowering the eye pressure with medications and/or surgery.
- Cataract: Severe cataract (clouding of the lens) can cause visual acuity to drop to 20/200 or less because the cataract does not permit enough light to reach the retina in the back of the eye. Fortunately, cataracts can be surgically removed and the cloudy lens can be replaced with a clear artificial one, usually resulting in significantly improved vision if treated on time.
- Childhood Blindness: About 1.4 million children are blind and 12 million are visually impaired due to causes like uncorrected refractive errors, Vitamin A deficiency, cataract or injury.
What are the symptoms of Blindness?
- Sudden loss of vision: Sudden vision loss could signal a number of eye diseases and conditions. One is macular degeneration, also known as age-related macular degeneration or AMD, which is a leading cause of vision loss in people of age 65 and above. Vision loss caused by AMD can be gradual, but in some cases it can be sudden — when blood vessels in the eye leak fluid or blood under the retina, which is made up of nerve cells that allow you to see.
- Eye injury: Any significant injury to the eye should be evaluated by a doctor, particularly if there is redness or pain that lasts for more than 15 to 20 minutes.
- Persistent discomfort: Experiencing any discomfort in your eye after doing an activity in which a small particle could have entered your eye, such as hammering or working under a car, don’t ignore it. Have your eyes examined by a doctor to make sure that you don’t have a foreign particle in the eye, which can cause an infection.
- Red eye: Redness in both eyes may be a sign of cold, conjunctivitis or minor infections that are self-healing. However, redness in one eye may be due to deeper inflammation, such as scleritis or uveitis.
- Blurred vision: Blurred vision may be a sign of multiple eye problems. Losing vision in one eye may be an early symptom of stroke.
- Eye surgery: After an eye surgery, if you experience any redness, eye pain or blurred vision, it is recommended to visit your doctor immediately. Follow up after an eye surgery should be considered.
How is Blindness diagnosed?
Ophthalmologists are the specialists who have the knowledge and tools to diagnose the cause of blindness and to provide treatment.
Blindness is diagnosed by testing each eye individually and by measuring the visual acuity and the visual field, or peripheral vision. People may have blindness in one (unilateral blindness) or both eyes (bilateral blindness). Past or family history regarding the blindness can be helpful in diagnosing the cause of blindness. Poor vision that is sudden in onset differs in potential causes than blindness that is progressive or chronic. Temporary blindness differs in cause from permanent blindness. The cause of blindness is made by a thorough examination by an ophthalmologist.
The earlier the diagnosis and treatment, the better, to preserve your sight.
How can Blindness be treated?
The treatment of blindness altogether depends on the cause. Blindness has multiple types, such as night blindness, colour blindness, etc. Hence, treatment of blindness varies and depending upon the severity, prolonged medical attention may be required.
- Refractive surgery encompasses a variety of technologies and procedures for correcting several common eye conditions such as myopia (near-sightedness) and hypermetropia (farsightedness).
- There are many types of glaucoma surgery, and variations or combinations of those types help in lowering the intraocular pressure.
- Blindness or vision impairment due to cataract (cloudiness of the eye lens) is the most common and successfully corrected surgically if done at an appropriate time.
- Diabetic or hypertensive retinopathy if tackled early, can prevent blindness. There are various surgeries for retinal detachment and retinopathies.
- Other therapies: A gene therapy works by providing a functional copy of a gene that is missing or mutated. Gene therapy is particularly suited to treat blindness due to genetic causes and other eye diseases.
What lifestyle changes are required to cope with Blindness?
Visual impairment has the ability to create consequences for health and well-being. Visual impairment is increasing especially among older people. It is recognized that those individuals with visual impairment are likely to have limited access to information and healthcare facilities, and may not receive the best care possible, because not all health care professionals are aware of specific needs related to vision.
- A prerequisite of an effective health care system is a trained staff that is aware of the fact that people may have problems with vision and is aware of the available treatment modalities.
- Communication and different ways of being able to communicate with visually impaired clients must be tailored to individual needs and available at all times.
- Learning braille can be useful, as it will ease the communication difficulties and improves the interactions between the patient and caregiver.
- Also, improving lights and organizing the house, to keep the living space clear of obstacle and hazard will be helpful for visually impaired. Assistive devices like magnifiers, penlights, audio products and telephone will be useful for people with visual impairment.
- Most people with vision loss do find that their confidence about living with reduced eyesight increases over time. By participating in rehabilitation training and trying the techniques taught there, your loved ones will likely begin to trust their new skills and feel better about the future
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