Astigmatism

Astigmatism is a refractive error (eye does not refract/focus light properly) whereas light enters the eye and focuses in two different areas, at least one of which focuses in front of or behind the retina (light sensitive tissue of rods and cones in the back of the eye) instead of on the retina. Astigmatism is often described as having an eye that is shaped like an egg or a football versus a perfect sphere. This causes issues with seeing clearly both far away and up close.

There are 2 types of astigmatism: corneal astigmatism (cornea is not spherical) and lenticular astigmatism (lens is not spherical). Astigmatism can occur in conjunction with myopia (nearsightedness) or hyperopia (farsightedness).¹

The symptoms of Astigmatism include:

• Blurry vision, both far away and up close
• Squinting, both far away and up close
• Shadowing of images
• Headaches
• Eyestrain¹

Astigmatism is usually genetic, whereas one or both parents also has astigmatism.¹

Astigmatism is diagnosed by an eye doctor with retinoscopy and/or manifest refraction. Retinoscopy is an objective test performed with a retinoscope, whereas an eye doctor shines a light into the eye and uses lenses to determine a glasses prescription by how the light moves within the pupil. Manifest refraction is a subjective measure of determining a patient’s prescription by giving a patient choices between different lenses, whereas the patient chooses based on clarity.

Astigmatism can also be diagnosed with a keratometer, which measures the curvature of the front of the eye (cornea).¹

Glasses and contact lenses: refocus light rays entering the eye, so that they focus on the retina.²

Refractive surgery: most commonly LASIK or PRK, used to reshape the cornea.^{1, 2}

Irregular astigmatism can occur as a result of corneal irregularities like corneal scarring, keratoconus (steepening of the cornea in a cone shape), corneal dystrophies, and corneal infection.³ It is important to have eye exams as recommended by one’s eye care provider to assess ocular health and progression of astigmatism.

1. https://www.aao.org/eye-health/diseases/what-is-astigmatism
2. https://www.aao.org/eye-health/diseases/myopia-nearsightedness-treatment
3. https://www.reviewofcontactlenses.com/article/pathologic-causes-of-irregular-astigmatism