Many articles about Singaporean health today begin with the country’s unofficial title as the “Myopia Capital of the World”. This reflects the high prevalence of myopia locally, including cases of high myopia, which is typically defined as a prescription of -6.00 dioptres or higher.
One question many people ask today is whether high myopia disqualifies them from lasik eye surgery. And more importantly, can modern laser eye correction effectively treat hgh myopia?
What Causes High Myopia?
To answer the question, it is helpful for us to understand what leads to high myopia in the first place.
High myopia typically occurs when:
- The eyeball is too long, or
- The cornea is too steeply curved
The result in either case is that light entering the eye focuses in front of the retina instead of directly on it. The retina is the light-sensitive tissue at the back of the eye that converts the light into signals and visual data for the brain.
When light is focused in front of the retina instead of on it, this results in blurry distance vision, which is characteristic of myopia.
Can Laser Eye Surgery Help?
Laser eye correction procedures work by reshaping the cornea. The cornea is the clear front surface of the eye that plays a key role in focusing light onto the retina.
In cases where high myopia is largely due to increased corneal curvature, laser eye surgery may be a suitable option. The laser reshapes the cornea to allow light to focus more accurately on the retina.
Even when the chief cause of the high myopia is an elongated eyeball, laser eye surgery may still provide correction. In such cases, the surgery will aim to reshape the cornea in a way that compensates for the eyeball’s length in the way it focuses light to the back of the eye.
When Laser Eye Surgery May Not Help
There are situations where laser correction procedures may not produce optimal results.
For example, patients with very thin corneas are generally not suitable for procedures like LASIK. This is because LASIK involves creating a corneal flap and removing tissue, which may compromise corneal stability if the cornea is already thin.
This can increase the risk of complications such as corneal ectasia, where the cornea becomes weakened and bulges outward.
There may still be alternative laser procedures to consider, such as PRK (photorefractive keratectomy), which does not involve creating a corneal flap.
However, even with PRK, patients with very high prescriptions (for example, beyond -10.00 dioptres) may not achieve optimal outcomes. There are limits to how much the cornea can be safely reshaped.
When Lasers Aren’t Enough
For higher degrees of myopia, you may be advised to consider Implantable Collamer Lens (ICL) surgery instead.
ICLs function similarly to contact lenses, but instead of sitting on the surface of the eye, they are implanted inside the eye, typically behind the iris.
These lenses can provide a higher degree of correction and are often considered when laser eye surgery is not suitable or sufficient for severe myopia.
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