Astigmatism is the term used to describe visual distortion caused by the cornea (front surface of the eye) or the lens inside the eye, having a rugby ball shape rather than a spherical shape. Astigmatism usually occurs very early in life, and affects approximately 25% of the population.
Irregular astigmatism can result from corneal injury, corneal disease such as keratoconus or pellucid marginal degeneration or secondary to eye surgery.
What problems does astigmatism cause?
If astigmatism goes unnoticed in early childhood, it can lead to amblyopia (permanently impaired vision) so it is extremely important for children to have regular eye examinations from birth to ensure normal visual development. Astigmatism can present with myopia (short sightedness) or hyperopia (long sightedness). Symptoms of uncorrected astigmatism include headaches, eye strain, glare and visual distortion and are often increased at night.
How to correct astigmatism?
Spectacles and soft contact lenses can provide good stable vision with regular astigmatism, however rigid gas permeable or specialist contact lenses usually provide much better visual correction than spectacles for irregular astigmatism, by providing a new front surface masking any corneal irregularity.