Eye prescriptions often contain confusing numbers and abbreviations. These documents record your visual status and guide the creation of corrective lenses. Understanding the terminology is key to knowing what your eyes need. DVA, or Distance Vision Acuity, is a frequently noted term relating to the clarity of your eyesight over long distances.
Defining Distance Vision Acuity (DVA)
DVA stands for Distance Vision Acuity, measuring the sharpness or clarity of your vision at a specific distance. Acuity refers to the eye’s ability to resolve fine detail. This measurement is typically taken without corrective lenses to establish a baseline of natural eyesight.
The primary purpose of DVA is to determine the severity of refractive errors, especially myopia (nearsightedness). Myopia causes distant objects to appear blurry because the eye focuses light in front of the retina. The DVA measurement quantifies this blurriness, allowing the eye doctor to calculate the necessary lens power for correction.
Clear distance vision is necessary for many daily tasks, such as driving, recognizing faces, or viewing a presentation screen. DVA represents a significant metric used to develop a comprehensive vision correction plan.
Interpreting Your DVA Acuity Score
The DVA score is typically presented as a fraction derived from the Snellen eye chart test. This chart measures vision at a standard viewing distance of 20 feet. The resulting fraction compares your vision to the statistical average or norm.
The benchmark for normal distance vision is 20/20. A person with 20/20 vision sees at 20 feet what the average person also sees at 20 feet.
If your DVA is 20/40, you must be 20 feet away to clearly see an object that a person with 20/20 vision sees from 40 feet away. This indicates your distance vision is half as sharp as the standard and suggests a need for corrective lenses. Conversely, a score of 20/15 is better than average, meaning you see at 20 feet what the average person sees clearly at 15 feet.
Scores are recorded for each eye individually, noted as OD (right eye) and OS (left eye). This helps the doctor pinpoint differences between the eyes. The DVA score provides the objective measurement that informs the sphere and cylinder values found in the final prescription.
DVA in Context: Understanding Near Vision Acuity (NVA)
While DVA focuses on distance, Near Vision Acuity (NVA) measures how clearly you see up close. NVA assesses the ability to discern fine details at a close working distance, such as reading or looking at a smartphone screen. This measurement is often taken using a hand-held chart at a distance of 14 to 16 inches.
The distinction between DVA and NVA is relevant when a person develops presbyopia, an age-related loss of focus for close objects. Presbyopia occurs when the eye’s lens hardens and loses the flexibility needed for near focusing. In these cases, a prescription may contain both a distance correction (DVA) and an “ADD” power to correct the near vision (NVA).
The NVA score completes the assessment of your visual system, ensuring the prescription addresses needs like reading small print. Some detailed prescriptions may also include Intermediate Visual Acuity (IVA), which covers ranges like computer screen distance. By comparing DVA, NVA, and IVA, professionals can create multifocal lenses that provide clear vision at every distance.