If you’ve ever had an eye exam, you’ve probably heard the term astigmatism. For some, especially those with high astigmatism, it’s a familiar concept. In fact, almost everyone has some degree of astigmatism — the severity just varies from person to person. But what exactly is astigmatism, and how does it present itself? Let’s break it down.

Patients with high astigmatism often squint, frown, or even pull on their eyelids to see distant objects more clearly. This creates a “pinhole” or slit-like effect, which reduces the visual distortion caused by astigmatism and improves clarity.

When both eyes have astigmatism — especially if the degree or axis differs between them — a person may tilt their head to one side to achieve clearer vision. This can lead to strabismus (crossed eyes), head tilt, or neck misalignment. Proper correction usually resolves these issues.

Symptoms can include tearing, nausea, vomiting, eye pressure, and headaches. Astigmatism produces two focal points instead of one, causing constant strain on the eye muscles as they attempt to adjust. This is especially pronounced in those with farsighted astigmatism. Interestingly, people with high astigmatism may experience less noticeable fatigue since they can’t improve clarity through effort alone.

In high astigmatism, the optic disc often appears oval. The vertical edge may be clear while the horizontal edge is blurred, or vice versa. The shape of the optic disc can give clues about the astigmatism’s axis.

Astigmatism can cause blurred or double vision at both near and far distances. The degree of impairment depends on the type, severity, and axis of astigmatism. Mild astigmatism within the normal range may have no impact on vision, while high astigmatism often leads to significant vision loss and difficulty achieving full correction — especially if accompanied by amblyopia (lazy eye) or other issues.