Near Vision Test

What it measures

Your near visual acuity — how clearly you can read small print at a normal reading distance of about 40 cm (arm's length). It gives an estimate in Jaeger notation (J1, J2, J3 ...) and an equivalent 20/xx value at 40 cm, the same kind of measurement an optometrist takes with a hand-held reading card.

How it works

First you calibrate the screen: drag an on-screen card until it matches the width of a real bank card (85.6 mm), which tells us the true physical size of everything on your display. You set your reading distance, then read a series of short, neutral phrases that shrink line by line. Each line is sized so that the smallest 'normal' line subtends 5 arc-minutes at 40 cm, matching the geometry of standard near-vision charts. You answer 'yes' only while a line is crisp; the smallest line you can read clearly becomes your near-acuity estimate. One eye is tested at a time.

Tips for an accurate result

• 1Test each eye on its own — Cover one eye and read with the other, then re-take for the second eye. A difference between eyes is worth mentioning to an optometrist.
• 2Don't squint or lean in — Squinting and moving closer temporarily sharpens print and hides reduced near vision. Read at your set distance with relaxed eyes.
• 3Blink and rest first — A few blinks and a short rest clear the tear film, so dryness or tiredness doesn't masquerade as blurred near vision.
• 4Re-test if your setup was off — If the card calibration or distance wasn't ideal, the result can shift by a line or two — re-run the calibration and try again.