Visual acuity testing measures how clearly a person can see detail at a specific distance, usually using letter or symbol charts. It provides a standardised way to record central vision.
Test Methods
Common charts include lines of letters that get progressively smaller, special symbols for children, or automated displays. Each eye is tested separately, often with and without glasses, and results are recorded as a fraction or decimal.
- Conducted at defined distances, such as 6 metres or 4 metres
- Near acuity can be assessed with handheld reading charts
- Testing conditions like lighting and contrast are controlled
- Pinhole testing can help distinguish refractive from other causes of blur
Clinical Role
Visual acuity is a key parameter in eye examinations, monitoring disease progression, and assessing treatment outcomes. It also helps determine fitness for activities such as driving.
- Changes over time can signal new or worsening eye disease
- Acuity is interpreted with reference to age and previous records
- Reduced acuity can arise from optical, retinal, or neurological causes
- Results are combined with other tests to reach a diagnosis
