Test d'astigmatisme

Ce que ça mesure

Signs of astigmatism — an irregular curvature of the cornea or lens that makes lines in some orientations appear darker, sharper or more blurred than others. The fan (sunburst) chart reveals this directional difference in focus.

Comment ça marche

You look at a radial fan of evenly spaced lines, one eye at a time with the other covered. With a refractive eye, every line looks equally crisp and dark. If some orientations stand out as bolder or blurrier, you tap the direction that differs; that orientation hints at the axis of a possible astigmatism.

Conseils pour un résultat fiable

• 1Compare opposite directions — Astigmatism makes one pair of opposite lines (e.g. vertical) stand out against the rest — look for that contrast.
• 2Mild differences are common — Small amounts of astigmatism are very common and often need no treatment at all.
• 3Check both eyes — Each eye can have a different axis and amount, so always complete the test on both sides.
• 4Persistent blur should be checked — Astigmatism is easily corrected with glasses, contacts or surgery — an optometrist can measure it precisely.