Vision impairment severity varies greatly. Legally blind is defined as 20/200 vision or worse in the better eye, or a field of vision less than 20 degrees. [Source: Sharpe Vision Blog, AllAboutVision.com] This means someone with 20/200 vision needs to be 20 feet away to see what a person with normal vision (20/20) sees at 200 feet.
However, "bad vision" isn't solely determined by legal blindness. Many levels of impairment exist before reaching that threshold. These levels often depend on the specific eye condition and how it impacts daily life.
Defining Levels of Vision Impairment
Here's a breakdown of vision levels, noting that these are broad generalizations and individual experiences can vary:
- Mild Vision Loss (Near-Normal): 20/30 to 20/60. This typically requires minimal correction and doesn't significantly affect daily activities. [Source: AOA]
- Moderate Visual Impairment: 20/70 to 20/160. This level of impairment may necessitate stronger corrective lenses and could impact some daily tasks. [Source: AOA]
- Severe Visual Impairment: 20/160 to 20/400. Significant visual impairment requiring assistive devices and impacting most daily tasks. [Source: AOA - inferred from ranges]
- Legal Blindness: 20/200 or worse in the better eye, or less than 20° visual field. This signifies a significant loss of vision impacting almost all aspects of daily life. [Source: Sharpe Vision Blog, AllAboutVision.com]
Myopia (Nearsightedness): The severity of nearsightedness is also graded: Mild (-0.25 to -2.00), Moderate (-2.25 to -5.00), and High (-5.00 and above). [Source: AllAboutVision.com] Higher numbers indicate more significant nearsightedness.
Other factors: Conditions like astigmatism, diabetic retinopathy, and computer vision syndrome can further affect visual acuity and comfort, independent of the numerical measures above. [Sources: Optical Masters, WebMD, AOA, Cleveland Clinic]. These conditions may cause blurry vision, eye strain, headaches, and night vision problems. Temporary blurry vision can also result from high blood sugar levels in individuals with diabetes. [Source: WebMD, NIDDK]
Low vision is defined as vision impairment that cannot be fully corrected with glasses or surgery and significantly impacts daily life activities. [Source: Cleveland Clinic]
