Astigmatism, a refractive error affecting around 40% of people worldwide, occurs when the eye's cornea or lens is irregularly shaped, leading to blurred or distorted vision. Instead of being round like a football, the cornea may be oval, causing light to scatter across the retina rather than focusing sharply.
The condition is broadly classified into two types: regular and irregular. Regular astigmatism, the more common form, arises from an oval-shaped cornea and is partly genetic. Irregular astigmatism is rarer and results from corneal scarring, growths, or conditions like keratoconus, where the cornea becomes cone-shaped over time.
Symptoms include blurry vision, reduced contrast sensitivity, shadows or double vision, and increased sensitivity to bright lights. Mild cases may go unnoticed, but higher levels can cause eye strain and fatigue. Children with significant astigmatism may experience impacts on learning and development.
Historically, Sir Isaac Newton first described the physics of irregular surfaces affecting light focus in 1727. Thomas Young, who had astigmatism, detailed its effects in 1800. Sir George Airy pioneered cylindrical lenses for correction in 1825, and William Whewell coined the term 'astigmatism' in 1846, from Greek meaning 'without a point'.
Optometrists detect regular astigmatism during refraction tests, while irregular astigmatism requires corneal topography for a 3D map of the cornea. Correction options include cylindrical lenses in glasses or contact lenses, orthokeratology (overnight hard lenses that reshape the cornea), and, for irregular cases, hard contact lenses or surgery such as corneal transplants.
Astigmatism can develop at any age and may change over time. Regular eye exams are recommended to monitor and manage the condition, ensuring clear vision and reducing associated discomfort.
