An astigmatism is a common refractive error of the eye, where one or sometimes more of the eye’s surfaces aren’t perfectly smooth or round.
If you’ve ever been to the optician and they’ve mentioned your peepers are more football-shaped, you might just be one of many who are unwittingly living with an eye ‘blunder’.
Astigmatism is a widespread refractive error in the eye, characterised by one or more of the eye’s surfaces being less than perfectly smooth or spherical, falling into two types – regular and irregular.
It appears that a whopping 40% of folks may have this particular variation in their eyes, which can bring along some pesky symptoms.
How to manage astigmatism
Specialists at the Centre for Eye Research Australia and an honorary fellow at the University of Melbourne suggest that minor astigmatism might not interfere with your sight, reports the Express.
However, as astigmatism becomes more pronounced, you could notice a dip in vision quality, alongside eye strain and tiredness. Correcting astigmatism for sharper vision is possible, aiming to balance out the cornea’s uneven curves and ensuring light entering the eye focuses more precisely on the retina.
One way to achieve this is through cylindrical lenses, available as either spectacles or contact lenses, or for a longer-lasting fix, laser eye surgery. The boffins in their study noted: “Orthokeratology can also be used.
“This involves wearing specialised hard contact lenses overnight. These hard contact lenses temporarily reshape the cornea, allowing the wearer to be glasses-free during the day.
“To manage irregular astigmatism, it is important to treat the underlying condition causing astigmatism as well. But often, hard contact lenses are needed for clear vision during the day, as they can sit on the surface of the eye to compensate for local uneven patches in a way that glasses or soft contact lenses cannot.”
Regular vs. Irregular Astigmatism
The most prevalent type is regular astigmatism, which typically stems from alterations in the cornea’s shape – the transparent outer layer positioned at the front of your eye. In contrast to normal eyes, it takes on a more oval appearance, resembling a rugby ball or an egg, and whilst the exact cause remains unclear, it’s believed to be linked to fundamental genetics.
A less common variant is irregular astigmatism, which develops when sections of the cornea lose their smoothness, generally due to scarring or growths on the cornea, or when its structure becomes unevenly distorted. Eye disorders like keratoconus, where the cornea progressively weakens and adopts a cone-shaped form, typically trigger irregular astigmatism.
When a cornea loses its smoothness or round shape, incoming light scatters across the retina, often resulting in distorted vision. This can also lead to reduced sensitivity to high contrasts and shadows, potential double vision, and heightened sensitivity to bright lights.
Understanding astigmatism
A fitting comparison to illustrate how our eyes function is to liken it to a camera’s inner workings. The eye captures light through the front surface, the cornea, and focuses it on the ‘film’ at the back, known as the retina.
For the clearest images, the eyeball and all its layers must adhere to specific size and shape requirements. Without this, vision can become blurred or out-of-focus, much like an unfocused camera.
This knowledge isn’t new; indeed, as early as 1727, Sir Isaac Newton was the first to explain the fundamental physics of how an irregular surface can influence the focus of light passing through it. Not long after, in 1800, Thomas Young confirmed that he himself had astigmatism and provided a detailed description of how it impacted his vision.