Laser eye surgery was first performed in the 1980s with a technique known as photorefractive keratectomy. Since then, hundreds of thousands of eyes have benefitted from this medical procedure.
Glasses and contact lenses, while both amazing optical inventions in themselves, can be a significant inconvenience to a busy, active lifestyle. If you wear glasses, you know that they break, get lost, fog up, and need constant cleaning. If you’re a contact lens wearer you’d be well aware of the ongoing cost of replacing disposable lenses, not to mention that reusable contacts need frequent cleaning and maintenance as well.
The idea of undergoing any sort of surgical procedure to the eyes can leave some feeling queasy. However, laser eye surgery has come a long way in the last four decades and is now considered a very safe eye operation with high rates of success and low rates of complications. So, exactly how does laser eye surgery work?
The Problem: Refractive Error
Before delving into more than you’d ever want to know about how laser eye surgery works, it helps to first understand what refractive error is.
Refractive error is the medical term for what we commonly think of as the power or prescription of our glasses or contacts. In other words, it’s a state of the eye where the optics are imperfect, leading to blurry vision. Refractive error includes myopia (short-sightedness), hyperopia (long-sightedness), and astigmatism.
There are two major components that control the refractive state of the eye – the cornea (including the layer of tears that cover it) and the crystalline lens inside the eye. These two anatomical structures are responsible for bending incoming light so that it focuses to a sharp point on the retina at the back of the eyeball. When this happens, our vision is clear and crisp. But when the refracting
power of the eye is mismatched with the length of the eyeball, the result is a refractive error.
● Myopia occurs when the eyeball is too long for the power of the eye and light comes to a focus in front of the retina
● Hyperopia occurs when the eyeball is too short; light focuses behind the retina
● Astigmatism occurs when incoming light is focused at two different points; one or neither of these points may fall on the retina
How Does Laser Eye Surgery Work?
Laser eye surgery is a type of refractive surgery which aims to reduce or eliminate your dependence on glasses or contact lenses for clear vision.
While laser eye surgery is the most well-known type of refractive procedure, not all refractive surgeries involve the use of a laser, such as implantable Collamer lenses (ICL) or refractive lens exchange (RLE).
So, how does laser eye surgery work to correct your vision?
All laser eye surgery procedures focus on the cornea, the clear dome of tissue at the front of your eye. As explained earlier, the cornea is one of the structures of the eye responsible for bending light. Laser eye surgery utilises a high precision medical laser to reshape the corneal tissue in a process known as photoablation, guided by a computer algorithm. The sculpting of the cornea modifies the way light bends through it such that incoming light will end up focusing accurately on the retina, resulting in sharp vision without the need for optical aids like glasses.
There are several different techniques of laser eye surgery; some are variations of other techniques. Here’s a brief summary of the most popular procedures for those who are wondering about how does laser eye surgery work in each case.
LASIK: This is potentially one of the most well-known laser eye surgery techniques. Short for laser-assisted in situ keratomileusis, LASIK involves the creation of a flap of superficial corneal tissue which is then flipped out of the way to expose the underlying layers. This flap can be made either using a conventional handheld instrument or with a laser, known as a femtosecond laser. Once the flap is moved to the side, a second laser, an excimer laser, can perform photoablation to reshape the cornea. The flap is then repositioned.
PRK: PRK, or photorefractive keratectomy, is similar to LASIK in the way that the superficial corneal layers are removed to allow the excimer laser to reshape the deeper corneal tissues. However, during PRK the superficial cells are entirely removed, either using a chemical solution or a manual instrument. These cells then regenerate over the following weeks.
SMILE: SMILE surgery is one of the more modern techniques of laser eye surgery. It stands for small incision lenticule extraction and carries several advantages due to its minimally invasive nature. A femtosecond laser is used to create a precisely shaped disc of tissue from the deeper layers of the cornea with minimal disturbance to the outer tissues. This disc is then removed from the cornea through a keyhole incision, reshaping the cornea from the inside. Benefits of SMILE laser eye surgery include retaining the stability of the cornea and a lower risk of postoperative dry eye.
Many of these procedures have a wide prescription range that can be treated, even into the double digits of myopia. However, your suitability for any laser eye surgery technique will also depend on factors other than your prescription, such as your corneal thickness or the presence of any eye diseases, including dry eye. Your eye specialist is the best person to assess your eligibility for laser eye surgery and decide which would be the most appropriate technique for your eyes. If laser eye surgery is considered to be an unsafe option for you, your eye specialist may guide you towards another refractive surgery technique, such as ICL or RLE.
If you’re ready for the freedom of clear vision without glasses or contact lenses, book your appointment with Dr Anton van Heerden today. Call us now on 03 9000 0389.
Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.