Blindness

What is Blindness?

Blindness is the inability to see or a significant lack of vision. In severe cases, it means being unable to perceive even light. This condition cannot be corrected with eyeglasses, contact lenses, eye drops, or surgery.

Types of Blindness

• Partial Blindness: Also known as “low vision,” where some vision remains.
• Complete Blindness: The inability to see or detect light, which is quite rare.
• Congenital Blindness: Vision impairment present at birth due to genetic conditions or birth defects.
• Legal Blindness: The WHO defines it as central vision of 20/200 in the best-seeing eye, even with correction. It can also involve a severe reduction in peripheral vision (less than 20 degrees). In India, the criteria have been modified in the NPCB to be: distance visual acuity less than 3/60 (20/400) in the better eye or limitation of field of vision to be less than 10 degree from centre of fixation.
• Nutritional Blindness: Vision loss due to vitamin A deficiency, leading to conditions like xerophthalmia and difficulty seeing in low light.
• Sudden vision loss: This is a medical emergency, and you must contact your doctor immediately.

Common Questions About Blindness

Color Blindness: Often referred to as color deficiency, this condition involves perceiving colors differently. It can be inherited or caused by diseases affecting the retina or optic nerve.

Preventable Blindness: Refers to loss of vision resulting from untreated diseases due to lack of access to healthcare, such as diabetic retinopathy or hypertensive retinopathy.

Prevalence of Blindness

Blindness affects millions worldwide. In the U.S., approximately 1 million people are blind, with numbers expected to double by 2050. Globally, around 43 million people live with blindness.

The most common reasons for low vision include cataract and refractive error. The most important cause of irreversible blindness is glaucoma.

Blindness in India:

• India is home to one of the largest populations of blind people in the world, with an estimated 8 million people living with blindness.
• Approximately 62 million people in India suffer from some form of vision impairment.
• The primary causes of blindness in India include cataracts, glaucoma, and uncorrected refractive errors.
• Cataracts alone account for 62.6% of cases of vision loss in India. This is reversible loss (or decrease) in vision, and may be corrected by cataract surgery.
• The prevalence of blindness in rural areas is significantly higher due to lack of access to quality eye care services.

Causes

• Injuries: Chemical burns, accidents, sports injuries
• Infections: Trachoma, cytomegalovirus, keratitis, syphilis, uveitis
• Non-Infectious Diseases: Retinitis pigmentosa, macular degeneration, diabetic retinopathy, cataracts, glaucoma

Diagnosis and Tests

Eye Exams: Comprehensive tests for each eye, including:

• Snellen Test: Measures central vision through letter charts.
• Visual Field Testing: Assesses peripheral vision.

Treatment Options

Treatment varies based on the cause and extent of damage:

• Medications: For infections and some conditions.
• Surgery: For cataracts, corneal transplants, and retinal repairs.
• Vitamin Supplements: For deficiencies like vitamin A-related xerophthalmia.
• Vision Rehabilitation: Enhances visual functioning through therapy and low-vision devices.

Prevention Tips

• Regular eye exams and following healthcare advice.
• Managing diabetes and high blood pressure.
• Wearing protective gear and sunglasses.
• Maintaining a healthy diet and weight.
• Exercising regularly.
• Knowing family health history and avoiding smoking.
• Practicing good hygiene with contact lenses.

Living with Blindness

Adjusting to low, or no vision involves significant lifestyle changes. Seek support and resources for:

• Education and skills training.
• Emotional health and recreational options.
• Technology training and support groups.

When to See Your Doctor

Seek immediate medical attention if you experience:

• Sudden vision loss
• Eye pain
• Vision-affecting accidents
• New floaters or flashes

Questions to Ask Your Doctor

• Can this type of disease be treated?
• Am I eligible for clinical trials?
• What services will I need if treatment isn’t possible?
• Are there support groups you recommend?