An astigmatism test checks whether the cornea or lens has an irregular curve that causes blurred or distorted vision. Astigmatism is very common and can occur alongside short‑sightedness or long‑sightedness.
Common methods
Optometrists use a mix of charts and instruments.
- Refraction with a phoropter to find the best lens correction
- Special charts with radiating lines to see if some look clearer or darker
- Corneal topography or keratometry to measure the corneal shape
- Autorefractors to provide an initial estimate of astigmatic power and axis
Why it is important
Correcting astigmatism can greatly sharpen vision.
- Reduces eyestrain, headaches, and ghosting of images
- Guides the choice of glasses, contact lenses, or laser vision correction
- Helps detect irregular astigmatism from keratoconus or previous surgery
- Should be checked regularly, especially if prescriptions are changing
