LASIK eye surgery is a type of refractive surgery. Refractive surgeries are a group of procedures that surgically correct the prescription of the eye. This can either be done by changing the shape of the cornea at the front of the eye, as in LASIK surgery or through certain implants. If you’ve done any research on laser vision correction, you’ve probably come across LASIK eye surgery. So, how does LASIK work to correct your sight?
How Does LASIK Work: The Basics
LASIK surgery is one of the better-known refractive procedures. It’s based on the idea of reshaping the cornea to change the way that light bends through this surface. Light entering the eye must focus on a sharp point by the time it reaches the retina at the back of the eyeball. If the focal point falls in front or behind the retina, your sight will be blurry. This is a condition known as refractive error. Refractive error encompasses long-sightedness (hyperopia), short-sightedness (myopia), and astigmatism.
People pursuing LASIK, or any other refractive surgery, typically do so in order to reduce their dependency on glasses or contact lenses.
LASIK eye surgery is performed as a day procedure by an ophthalmologist with interest and further training in refractive surgery. Before being booked in at the operating theatre, your ophthalmologist and clinical team will do a thorough assessment of your eyes and your vision before concluding that LASIK surgery is the most appropriate method for you. They will look into factors such as:
- Is your prescription within range for LASIK eye surgery?
- Are your corneas thick enough to withstand the LASIK procedure safely?
- Are there any other eye diseases that might limit your vision even after undergoing successful LASIK?
- Do you have any eye or general medical conditions that may increase your risk of a complication?
You will also have a thorough discussion with your ophthalmologist about what you’re expecting from the LASIK surgery procedure.
Of course, you’re hoping to no longer need your glasses or contact lenses.
However, it’s important to realise that LASIK eye surgery is not typically able to improve your sight beyond what you could achieve with your glasses.
This means if you are also suffering from another eye condition such as amblyopia (lazy eye) or macular degeneration, LASIK will not restore the sight lost from these diseases.
In most cases, LASIK eye surgery targets distance vision. Therefore, patients undergoing LASIK in early adulthood will still eventually require near vision glasses as they enter their mid-40s. This is because presbyopia, the age-related deterioration of our near focus, tends to begin around this age.
Once your ophthalmologist has determined that you are a suitable candidate for LASIK eye surgery, your surgery date can be organised.
How Does LASIK Work: Pre-Operation
Leading up to your LASIK eye surgery, you may be advised to stay out of your contact lenses. This is because contact lenses reduce how much oxygen can get to your cornea, no matter how advanced the lens material is. Lowered oxygen can cause swelling of the cornea, which will interfere with the biometry measurements taken before your operation. These measurements will guide the laser equipment in reshaping your cornea, so it’s important that they’re as accurate as possible.
The other effect of contact lens wear is that it can disrupt the tear film, which covers the cornea. As the dry eye is a potential complication after LASIK, you want to ensure this tear film is as robust as possible before your operation.
If you’re wearing soft contacts, your surgeon may ask you to avoid wearing them for at least 2 weeks before your LASIK operation. If you’re in hard lenses (rigid gas permeable contacts), you may need to wear your glasses for at least 3 weeks pre-op.
For people with a condition known as blepharitis (eyelid inflammation), this may need to be treated in the weeks leading up to your LASIK procedure. Bacteria, debris, and inflammation around the eyelids may increase your risk of a complication during LASIK, such as an infection or post-op dry eye.
How Does LASIK Work: The Operation
Your eyes will be made comfortable using a topical anaesthetic, which may be reapplied during the procedure if needed. To hold your eyelids out of the way, your ophthalmologist may use a tool called a lid retractor or speculum.
You’ll then have a suction ring placed on your eye, which can cause the feeling of some slight pressure. However, this is not considered to be painful. A flap will be created out of the top layers of your cornea. Depending on what technique your surgeon uses, this can either be done with a femtosecond laser or with a handheld instrument. Once the corneal flap has been moved to the side, an excimer laser tool will be guided by a computer to vaporise selected areas of your cornea. This step is what alters your corneal shape and curvature to redirect the light that passes into your eye.
In the end, the flap of the cornea will be put back in place; this flap will self-seal. A protective shield is placed over the eye.
How Does LASIK Work: Post-Operation
Immediately after LASIK, you can expect your sight to be slightly blurry, and your eye may feel gritty and sore. Your ophthalmologist will give you some instructions to optimise your healing post-LASIK, so it’s important to follow these guidelines. It can take a couple of months for your eye to heal fully, though you will be able to see well before then. If anything seems not right, make sure you contact your ophthalmologist.
Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.
References
When Should I Stop Wearing Contact Lenses Before LASIK?
https://www.allaboutvision.com/visionsurgery/faq-stop-cls.htm
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