It’s widely known that nearsightedness, or myopia, is a growing epidemic around the world. The condition results when the eye grows too long, causing light to focus in front of the retina instead of directly on it, resulting in blurred distance vision. Myopia usually starts in childhood or adolescence and its prevalence has grown considerably in recent decades. Although glasses correct the distorted vision caused by myopia, they can’t stop the eye from continuing to grow. Enter contact lenses. Wearing soft contact lenses instead of glasses has been shown to slow the progression of myopia.

Let’s start with the science of how contact lenses can arrest the progression of myopia, how effective they are compared to other treatments, and what your options are for using contact lenses to control your myopia.

The Myopia Epidemic

The prevalence of myopia is growing at a staggering rate. It’s projected that, by 2050, around half the world’s population could be myopic. Basically, the more your eyes grow, the more your eyes get stretched and weakened with eventual breakdown These estimates are built on a rising tide of myopia. Significant lifestyle changes – too much time spent staring at screens, not enough time outside, almost constant work up close with reading and use of digital devices – can all be risk factors. ‘Basically, the more your eyes grow, the more your eyes get stretched and weakened with eventual breakdown,’ says Prakash Chauhan, a consultant ophthalmologist with Saifee Hospital in Mumbai who focuses on myopia. Severe myopia can lead to more serious complications including retinal detachment, glaucoma and macular degeneration later in life.

As a result, stopping myopia worsening, and especially in children, is now an important focus in optometry. Various approaches have been suggested, and soft contact lenses are leading the way.

How Contact Lenses Control Myopia Progression

Unlike conventional glasses or standard soft contact lenses that merely help to see blurry objects clearly, myopia control lenses shift the focus of the eye, reducing the stimulus for eye growth. Two types of contact lenses are currently used in myopia control: orthokeratology lenses (Ortho-K) and soft multifocal lenses.

Orthokeratology (Ortho-K) Lenses

These lenses are orthokeratology or ‘ortho-K’ lenses, which are rigid gas-permeable lenses that are placed on the eye overnight. While asleep, the cornea is ‘refractored’ or reshaped, which helps to correct myopia temporarily during the day, without the use of either glasses or contact lenses. In addition to working to correct myopia, the temporary, overnight reshaping of the cornea alters the way light is focused on the retina, especially in the peripheral areas of the eye. This reduction of the stimulus for further eye growth appears to have a positive effect on slowing the progression of myopia.

Several clinical studies have revealed that Ortho-K can reduce the rate of myopia progression by up to 45-50%. The advantage of wearing Ortho-K lenses is that they affect myopia control by flattening the central cornea, which allows the peripheral image to come in sharper focus thus reducing the focus error that results in continued eye elongation. The effects of Ortho-K lenses are transient and have to be worn regularly to maintain the outcome.

Soft Multifocal Contact Lenses

The soft multifocal contact lenses also take a different approach to myopia control, since they form multiple concentric zones of different focusing power, resulting in a pattern of focused and defocused light falling on the retinal surface; the central zone focuses light spectacle-free for distance, while the peripheral zones focus in front of the retina (this is the so-called ‘peripheral defocus’ that is thought to slow eye elongation – the mechanism responsible for myopia progression).

Comparing Contact Lenses to Other Myopia Control Methods

Contact lenses have also been shown to be an effective treatment for slowing the progression of myopia, but there are other treatments as well. Myopia control glasses (including multifocal or progressive addition lenses) can also be used to lower the speed at which myopia progresses but they’re only a third as effective as contact lenses, slowing myopia by 15-30%.

The other is atropine eye drops, which have been used in low concentrations to slow myopia progression by relaxing the eye muscles that control focusing for short periods of time. Atropine drops have been shown to reduce progression by as much as 60%, on a par with soft multifocal lenses. But they can also cause symptoms such as glare and difficulty reading up close, so contact lenses are typically more appealing to kids.

The Science Behind Slowing Eye Growth

To follow how contact lenses slow down myopia, we have to consider how they alter how light is absorbed by the retina. In normal eyes, light is focused on the retina, giving us clear distance vision. When the eye grows too long, light is focused in front of the retina, causing blurry distance vision.

Myopia control lenses achieve this by refocusing the light rays coming into the eye in the peripheral regions, so that they land in front of the retina rather than behind it. In this way, the eye is signaled to slow down its elongation. Standard lenses, on the other hand, will correct only central vision, so peripheral light rays still stimulate the eye to continue to elongate and cause it to continue to get worse.

The Benefits of Contact Lenses for Myopia Control

Effectiveness

As noted, however, use of orthokeratology (Ortho-K) or soft multifocal lenses can reduce myopia progression by between 45-59 per cent, making this option one of the most effective for the control of childhood myopia.

Non-invasive

Unlike surgical procedures, contact lenses are reversible and non-invasive. If a child grows to dislike the lenses, or can’t adapt to them, he or she can simply stop wearing them with no long-term effects.

Convenience

Ortho-K lenses can be worn only overnight, giving clear vision during the day without the need for glasses or contacts.

Long-term Vision Health

Just slowing the progression of myopia during childhood can dramatically reduce the risk of eye disease associated with high myopia later in life, including glaucoma, cataracts and retinal detachment.

Challenges and Considerations

While there are obvious benefits to myopia-control contact lens use, there are also potential issues:

Cost

Myopia control contact lenses are more expensive than normal lenses or glasses and the price can be a limiting factor for some families; however, over the long term, it might be worth the investment.

Lens Care

Contact lenses need to be properly maintained and cleaned, particularly in children. Ortho-K lenses worn at night need special care throughout the night to avoid infection.

Adaptation

While some children can easily wear contacts, others might not adapt well, especially if they are wearing contacts for the first time. They might experience some discomfort, and soft lenses need to be worn for the majority of the day for myopia control to work.

A Promising Solution

Contact lenses are the best alternative to manage the progression of myopia and to improve overall eye health. These lenses affect how the retina interacts with the light. If used correctly, contact lenses can drastically reduce the rate of eye elongation in children by changing the interaction between the retina and the light. If we consider the high price of surgery and the potential irreversibility of eye damage, the risk for eye problems in adulthood makes lenses a good option for myopia management. Obstacles such as the cost of contact lenses and the labor needed to take care of them pose a challenge.

Children with myopia should consult with an optometrist to see what the best course of action will be for their child’s myopia management, as treatment during childhood might have lifelong implications for their eye health.