Yes, an eye grade of 400 is considered very bad. This refers to visual acuity, and a 20/400 visual acuity means you see at 20 feet what a person with normal vision (20/20) sees at 400 feet.
Understanding Eye Grades and Visual Acuity
The number "400" in the context of "eye grade" likely refers to a visual acuity measurement. Visual acuity measures how clearly you see at a specific distance. The standard notation is 20/X, where:
- 20: Represents the distance (in feet) at which the test is conducted.
- X: Represents the distance (in feet) at which a person with normal vision can see the same line on the eye chart.
Therefore, 20/400 means you need to be 20 feet away to see what someone with normal vision can see at 400 feet.
Severity of 20/400 Vision
- Severe Vision Loss: Visual acuity between 20/200 and 20/400 is classified as severe vision loss.
- Profound Vision Loss: Anything below 20/400 is considered profound vision loss. This level of vision impairment significantly impacts daily life and often necessitates assistive devices.
- Legal Blindness: In many jurisdictions, 20/200 or worse in the better eye is the definition of legal blindness. 20/400 certainly falls under this criteria.
Different sources mention variations in how the eye grade is numerically represented. However, the visual acuity interpretation remains consistent. A 20/400 result is a severe visual impairment.
The information provided in several references consistently classifies vision below 20/400 as profound vision loss, while vision between 20/200 and 20/400 is considered severe. This clearly indicates that an eye grade of 400, interpreted as 20/400 visual acuity, represents a significant level of vision impairment.
