Overview
Refractive surgery, laser eye surgery, laser vision correction, and LASIK are some of the terms that are used to describe surgical procedures that correct common eye conditions such as myopia (short-sightedness), hyperopia (long-sightedness), astigmatism, and presbyopia (‘lao hua’).
In fact, refractive surgery refers to implantable contact lens (ICL) and laser-assisted surgeries, the latter of which is also known as laser eye surgery or laser vision correction. For more information on ICL surgery, please read here.
LASIK, on the other hand, is one of several types of laser-assisted surgeries. Due to its widespread adoption and popularity, many people have used it as a blanket term for all laser-assisted surgeries.
Today, we can classify the various types of laser-assisted surgeries under 3 main categories:
Advanced Surface Ablation
LASIK
Laser In Situ Keratomileusis
ReLEx SMILE/SMILE Pro
Refractive Lenticule Extraction – Small Incision Lenticule Extraction
HOW IS EACH TYPE OF SURGERY PERFORMED?
Epi-LASIK/LASEK*
Step 1:
Alcohol is applied onto the cornea (transparent part of the eye that covers the front portion of the eye)
Step 2:
The epithelium (outermost layer of the cornea) is removed
Step 3:
An excimer laser removes corneal tissue to reshape the eye
Step 4:
A bandaged contact lens is applied and will stay in the eye for 3 to 4 days to help with epithelialisation (healing)
LASIK*
Step 1:
An femtosecond laser is used to create a corneal flap which is then folded backwards
Step 2:
An excimer laser removes corneal tissue to reshape the cornea
Step 3:
The flap is repositioned and will heal on its own
ReLEx SMILE/SMILE Pro
Step 1:
An excimer laser creates a lenticule (corneal tissue) beneath the cornea
Step 2:
The excimer laser then creates an incision on the cornea
Step 3:
An instrument is used to manually remove the lenticule which reshapes the cornea
FEATURES OF EACH TYPE OF LASER SURGERY
|
Epi-LASIK/LASEK
with the VISX excimer laser technology
|
LASIK
with the VISX excimer laser technology
|
ReLEx SMILE/SMILE Pro |
|---|---|---|
| Epi-LASIK uses a motorised blunt dissector while LASEK uses alcohol to remove the surface epithelium. A central cornea wound is created on the surface and the laser treatment is performed on the surface (surface ablation). | A corneal flap is created and the laser treatment is beneath the flap. | A corneal lenticule is created without a flap. The lenticule is then manually dissected free from the surrounding cornea tissue and manually removed through a small incision. |
| Surgery takes 10 to 12 minutes surgery for 2 eyes. | Surgery takes 10 to 12 minutes surgery for 2 eyes. | Surgery takes 20 to 30 minute surgery for 2 eyes – longest procedure as the corneal lenticule is manually removed. |
| Slow visual recovery which may take more than a month to become more stable. | Fast visual recovery. | Fast visual recovery though LASIK’s visual recovery is faster. |
| More uncomfortable in the first 4 to 5 days because of the large cornea wound. Most can return to work 4 to 5 days after surgery. | Very comfortable the next day. Most can return to work 1 day after surgery. |
Very comfortable the next day. Most can return to work 1 to 3 days after surgery. |
| Initially more sensitivity to light, tearing and more haloes and starbursts. | Minimal sensitivity to light or tearing. | Minimal sensitivity to light or tearing. |
| Option of a customised Wavefront-guided treatment. Apart from removing degrees, it also removes imperfections unique to each eye aiming to provider sharper vision with lesser haloes and glares at night. | Option of a customised Wavefront-guided treatment. Apart from removing degrees, it also remove imperfections unique to each eye aiming to provider sharper vision with lesser haloes and glares at night. | No option of a customised Wavefront-guided treatment. |
| High predictability, especially for myopia of less than 600 degrees. Limited by the lower power it can safely correct as more tissue removal can increase the risk of haze, scarring and loss of best corrected vision. | High predictability for high myopia and high astigmatism using the Wavefront-guided treatment and iris registration. | Fairly high predictability. Less accurate for low myopia. Less accurate for astigmatic correction and corrects lower levels of astigmatism compared to LASIK, Epi-LASIK and LASEK. |
| Suitable for those with thinner corneas as it removes the least corneal tissue. | Requires thicker cornea to accommodate the creation of the cornea flap. More tissue saving than ReLEx SMILE/SMILE Pro. | Requires thicker cornea to accommodate the creation of the cornea lenticule and its removal. Removes the most cornea tissue hence suitability criteria can be more limited. |
| May have less dry eye compared to LASIK as a surface procedure. | May have more dry eye initially but will usually improve or resolve with time and is not usually significant in the long-term. | May have less dry eye compared to LASIK as a flapless procedure. |
| Enhancement surgery can be performed as a repeat surface ablation procedure with high predictability. However, removing more tissue through the surface may increase the risk of haze, scarring and loss of best corrected vision. | Enhancement surgery can be performed by lifting up the pre-existing LASIK flap and treating beneath the flap with high predictability as there is no scarring or haze. LASIK enhancement may be performed multiple times without the risk of scarring. | Enhancement surgery cannot be performed as a repeat ReLEx SMILE/SMILE Pro. If enhancement is needed, it is performed via other forms of laser treatment, e.g. Epi-LASIK or LASIK. As different treatments are used, results can be unpredictable. |
| Flapless surgery; can engage in contact sports. | The LASIK flap is stable and dislodgement after a month is rare; can engage in contact sports. | Flapless surgery; can engage in contact sports. |
| Ideally less than 600 degrees, as greater tissue removal may be associated with haze, scarring and loss of best corrected vision. | Large range of treatment as there is no scarring associated with LASIK as the treatment is beneath the Bowman’s membrane. As long as there is sufficient corneal tissue, it can correct up to 1,200 degrees of myopia, 800 degress of hyperopia and 800 degrees of astigmatism. | Can correct 250 to 800 degress of myopia and up to 250 to 350 degrees of astigmatism. Unable to correct astigmatic eyes if one has no myopia. |
| Able to correct hyperopia. | Able to correct hyperopia. | Unable to correct hyperopia. |
| Able to correct presbyopia. | Able to correct presbyopia. | Able to correct presbyopia. |
| Risk of infection and inflammation because of the large wound (rare). | Flap complication with IntraLase bladeless technology (rare). | Tearing or incomplete removal of the lenticule (rare). |
Epi-LASIK uses a motorised blunt dissector while LASEK uses alcohol to remove the surface epithelium. A central cornea wound is created on the surface and the laser treatment is performed on the surface (surface ablation).
Surgery takes 10 to 12 minutes surgery for 2 eyes.
Slow visual recovery which may take more than a month to become more stable.
More uncomfortable in the first 4 to 5 days because of the large cornea wound. Most can return to work 4 to 5 days after surgery.
Initially more sensitivity to light, tearing and more haloes and starbursts.
Option of a customised Wavefront-guided treatment. Apart from removing degrees, it also removes imperfections unique to each eye aiming to provider sharper vision with lesser haloes and glares at night.
High predictability, especially for myopia of less than 600 degrees. Limited by the lower power it can safely correct as more tissue removal can increase the risk of haze, scarring and loss of best corrected vision.
Suitable for those with thinner corneas as it removes the least corneal tissue.
May have less dry eye compared to LASIK as a surface procedure.
Enhancement surgery can be performed as a repeat surface ablation procedure with high predictability. However, removing more tissue through the surface may increase the risk of haze, scarring and loss of best corrected vision.
Flapless surgery; can engage in contact sports.
Ideally less than 600 degrees, as greater tissue removal may be associated with haze, scarring and loss of best corrected vision
Able to correct hyperopia.
Able to correct presbyopia.
Risk of infection and inflammation because of the large wound (rare).
A corneal flap is created and the laser treatment is beneath the flap.
Surgery takes 10 to 12 minutes surgery for 2 eyes.
Fast visual recovery.
Very comfortable the next day. Most can return to work 1 day after surgery.
Minimal sensitivity to light or tearing.
Option of a customised Wavefront-guided treatment. Apart from removing degrees, it also remove imperfections unique to each eye aiming to provider sharper vision with lesser haloes and glares at night.
High predictability for high myopia and high astigmatism using the Wavefront-guided treatment and iris registration.
Requires thicker cornea to accommodate the creation of the cornea flap. More tissue saving than ReLEx SMILE/SMILE Pro.
May have more dry eye initially but will usually improve or resolve with time and is not usually significant in the long-term.
Enhancement surgery can be performed by lifting up the pre-existing LASIK flap and treating beneath the flap with high predictability as there is no scarring or haze. LASIK enhancement may be performed multiple times without the risk of scarring.
The LASIK flap is stable and dislodgement after a month is rare; can engage in contact sports.
Large range of treatment as there is no scarring associated with LASIK as the treatment is beneath the Bowman’s membrane. As long as there is sufficient corneal tissue, it can correct up to 1,200 degrees of myopia, 800 degress of hyperopia and 800 degrees of astigmatism.
Able to correct hyperopia.
Able to correct presbyopia.
Flap complication with IntraLase bladeless technology (rare).
ReLEx SMILE/SMILE Pro
A corneal lenticule is created without a flap. The lenticule is then manually dissected free from the surrounding cornea tissue and manually removed through a small incision.
Surgery takes 20 to 30 minute surgery for 2 eyes – longest procedure as the corneal lenticule is manually removed.
Fast visual recovery though LASIK’s visual recovery is faster.
Very comfortable the next day. Most can return to work 1 to 3 days after surgery.
Minimal sensitivity to light or tearing.
No option of a customised Wavefront-guided treatment.
Fairly high predictability. Less accurate for low myopia. Less accurate for astigmatic correction and corrects lower levels of astigmatism compared to LASIK, Epi-LASIK and LASEK.
Requires thicker cornea to accommodate the creation of the cornea lenticule and its removal. Removes the most cornea tissue hence suitability criteria can be more limited.
May have less dry eye compared to LASIK as a flapless procedure.
Enhancement surgery cannot be performed as a repeat ReLEx SMILE/SMILE Pro. If enhancement is needed, it is performed via other forms of laser treatment, e.g. Epi-LASIK or LASIK. As different treatments are used, results can be unpredictable.
Flapless surgery; can engage in contact sports.
Can correct 250 to 800 degress of myopia and up to 250 to 350 degrees of astigmatism. Unable to correct astigmatic eyes if one has no myopia.
Unable to correct hyperopia.
Able to correct presbyopia.
Tearing or incomplete removal of the lenticule (rare).
Speak to us today to arrange for a comprehensive LASIK evaluation to find out which procedure is suitable for your eyes and lifestyle.
