Why the arguments for laser surgery to correct myopia are compellingby Nicky Pellegrino
However, laser surgery is not for everyone.
More short-sighted people means more contact-lens wearers, and scientists are now saying this may be contributing to the pollution of waterways.
Contact lenses are disposable – some are designed to be worn for only one day – and the obvious way to get rid of them is to flush them down a sink or toilet. A team from Arizona State University has estimated that six to 10 tonnes of plastic lenses end up in wastewater in the US each year. And, as these lenses are broken down into smaller particles, there is a risk that aquatic organisms will mistake them for food. The researchers suggest wearers dispose of used contact lenses in the bin with the rest of their solid waste.
Another option is to do away with the need for contact lenses altogether by having a corrective procedure. The most common technique for this is Lasik (laser-assisted in situ keratomileusis), which uses a laser to reshape the front surface of the eye to correct focusing problems. This cures both short- and long-sightedness, but it doesn’t negate the need for reading glasses as we age, as this has a different cause – a stiffening of the lens of the eye.
Dr Mo Ziaei, a lecturer at the University of Auckland and a specialist at Re:Vision sight-correction centre, says there are misconceptions about laser surgery.
“People worry that it’s a painful operation, but it’s painless,” he says. “We use anaesthetic drops in the eye, it takes 10 to 15 minutes, then off you go.”
Lasik has been available since the 1990s, so there is no shortage of data to show it is safe and effective. Recently in Singapore, an 18-year study of more than 50,000 eyes found 99% of patients achieved driving-standard 20/40 vision after the surgery, and the complication rate was low.
Over time you are more likely to have an infection related to contact-lens wear than issues stemming from laser surgery, according to a meta-analysis of research by the University of Tennessee.
Although contact lens-related infections are rare, when they do happen they can be serious, says Ziaei, who also works in the eye department at Greenlane Clinical Centre. “Occasionally, people go on to need corneal transplants, and it’s not unknown for patients to lose an eye.”
One particular parasitic infection, Acanthamoeba keratitis, is on the rise and it predominantly affects contact-lens users. This cyst-forming organism causes the cornea to become sore and inflamed. In some cases, poor contact-lens hygiene may be to blame, but a major risk factor is exposure to water. So, that means no rinsing lenses under the tap and no swimming, showering, using hot tubs or face washing while wearing them.
“The Acanthamoeba bug is incredibly difficult to get rid of,” says Ziaei.
Contact-lens wearers also experience side effects ranging from dry and irritated eyes to the more serious overgrowth of blood vessels caused by over-wear. Moreover, being myopic is a risk factor for developing sight-threatening complications, such as retinal detachment, later in life.
If this is swinging the pendulum towards laser surgery, then first you need to check whether you are a good candidate.
“There isn’t a cap on age, but one in five patients aren’t suitable, for various reasons,” says Ziaei.
For those with a large amount of astigmatism, very thin or weak corneas, or a very high prescription strength, it isn’t an option. Some of these patients may find intraocular contact lenses – tiny, permanent contact lenses placed inside the eye rather than on top of it – are a better solution.
The technology for vision correction is improving all the time – Ziaei describes advances as “breathtaking” – so be aware that clinics offering cheap Lasik surgery may be using dated equipment.
Cost tends to be a barrier for treatment, although Ziaei says that at between $5000 and $6500, Lasik is competitively priced.
“Plus, if you have the procedure when you are younger, there is the potential of saving thousands of dollars on glasses, contact lenses and cleaning solution.”
This article was first published in the March 16, 2019 issue of the New Zealand Listener.
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