Laser eye surgery has come a long way since its inception in 1989. This form of permanent vision correction uses laser technology to modify the shape of the cornea, which is the transparent dome of tissue at the front surface of your eyeball. Amongst the various options for laser vision correction is LASIK eye surgery. So, what is LASIK, and how exactly does it correct your sight?
What is LASIK For?
The aim of LASIK eye surgery is to permanently correct your prescription. This means you become much less dependent on glasses and contact lenses. In many cases, for at least a period of time, you may be able to get rid of your glasses or contacts entirely.
Refractive errors – short-sightedness (myopia), long-sightedness (hyperopia), and astigmatism – occur because the light isn’t properly focused onto the retina. Vision correction, including glasses, contacts, and laser eye surgery, aims to bring the focal point of light sharply onto the retina. This is what provides clear sight.
What is LASIK: Pre-Operation
Prior to undergoing LASIK eye surgery, your eye surgeon will ensure you’re suitable for this form of refractive surgery. Eligibility criteria are based on a number of factors, including:
- Age. Surgeons typically will advise waiting until at least 18 years old as this reduces the likelihood that your prescription will continue changing. Additionally, those over the age of 50 will be experiencing age-related changes to their near sight, known as presbyopia. This may make another procedure more appropriate, such as refractive lens exchange.
- Prescription. The range of treatable prescriptions with LASIK eye surgery is quite extensive. As a general rule of thumb, LASIK can manage prescriptions between -1.00 to -10.00D of short-sightedness, up to +5.00D of long-sightedness, and up to -5.00D of astigmatism.
- Corneal thickness. Although LASIK is able to treat a wide range of prescriptions, as mentioned above, your central corneal thickness will be the determining factor for how high a script LASIK is able to manage in your specific eyes.
- Overall eye health. If your sight is limited by other conditions such as amblyopia or retinal damage, LASIK may not be worthwhile as it won’t be able to provide a significant improvement to your sight.
Pregnant and breastfeeding women are advised to wait as hormonal changes during these periods can affect accurate measurements of the eye. Those who participate in activities with a risk of head trauma are also typically advised against LASIK, as a hit to the head or eye has the potential to cause complications specific to LASIK.
Once you’re deemed suitable for LASIK eye surgery, your surgeon will discuss with you the costs and potential risks of this procedure. You will also have biometric measurements taken of your eyes to inform the computer-guided laser during the operation itself.
What is LASIK: the Procedure
LASIK eye surgery is also known as laser-assisted in situ keratomileusis. As with other forms of laser eye surgery, it uses a laser to change the shape of your cornea. However, one of the main steps that makes it unique is the creation of a corneal flap.
During LASIK eye surgery, your eye surgeon will use either a bladed instrument known as a microkeratome or a femtosecond laser to create a flap of corneal tissue. This flap is comprised of the upper layers of the cornea and remains attached to the eyeball by a hinge. It is because of this flap that the minimal corneal thickness requirement for LASIK is higher than other laser procedures, such as PRK.
Earlier LASIK eye surgery procedures were performed using the microkeratome before the femtosecond laser was approved for use in refractive surgery. This is often described as blade versus bladeless LASIK. Your eye surgeon will use whichever procedure he or she finds produces the best results for his or her patients. Ultimately, studies show that both blade and bladeless LASIK eye surgery result in the same visual outcome and recovery. LASIK performed with the femtosecond laser has some advantages over that with the microkeratome in terms of predictability of the flap thickness and lower likelihood of dry eye. However, bladed LASIK eye surgery is typically much cheaper.
Once the corneal flap has been formed and opened to one side, your eye surgeon will be able to apply an excimer laser to the deeper layers. The excimer laser is used to perform photoablation. Photoablation involves the vaporisation of precise areas of tissue, with the laser-guided by a computer. The result is the cornea is reshaped to adjust the way light enters the eye.
After photoablation is complete, the surgeon replaces the corneal flap. This flap typically self-seals without requiring stitches. Because of the flap, LASIK is subject to unique risks of complications. One of these is the flap becoming displaced or dislodged. This is why people who participate in activities such as contact sports or who are in the military with a risk of head accidents are recommended against LASIK.
After your operation, your surgeon will provide you with medicated eyedrops to support recovery, as well as some post-op guidelines. Recovery after LASIK is typically uneventful. However, if you ever feel that your sight is deteriorating or your eye is becoming increasingly red and painful, it’s important to see your surgeon immediately or call us 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.
References
A Brief History of LASIK Eye Surgery.
https://www.webmd.com/connect-to-care/lasik/brief-history-of-lasik-eye-surgery
Comparison of the femtosecond laser and mechanical microkeratome for flap cutting in LASIK.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4539628/
Does My Eyeglass Prescription Qualify for LASIK?
https://www.allaboutvision.com/visionsurgery/faq-prescription.htm
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