blind

Blindness refers to a lack of functional vision, ranging from significant vision loss to complete absence of light perception. In medical and legal contexts, “legally blind” often denotes a corrected visual acuity of 20/200 or worse in the better eye or a visual field of 20 degrees or less. Some people have no usable sight (absolute blindness), while others have low vision, meaning they retain some usable sight but it is insufficient for daily tasks.

Causes of blindness are varied and can be congenital or acquired. Common age-related causes include cataracts, glaucoma, age-related macular degeneration, and diabetic retinopathy. Other etiologies include optic neuropathies, retinal diseases, infections, injuries, and genetic disorders. Conditions and treatments affecting vision can progress or improve, depending on underlying causes and access to care.

Impact and accessibility are central considerations. Blindness affects many daily activities, education, and employment. Assistive technologies and strategies—such as braille, screen readers, audio formats, tactile graphics, and orientation and mobility training—help independence. Mobility aids like long canes and guide dogs support navigation. Accessible design, including tactile signage, high-contrast interfaces, and compatible software, benefits people who are blind or have low vision.

Rehabilitation and research aim to maximize independence and quality of life. Programs offer skill development, adaptive technology instruction, and support for families. Scientific advances continue in areas such as retinal implants, gene therapy, and stem cell research, alongside improvements in early detection and preventive eye care.