The complete guide to ReLEx SMILE in Singapore

ReLEx SMILE is one of 3 laser vision correction procedures available in Singapore today that corrects common eye conditions such as short-sightedness and astigmatism; the other 2 being LASIK and Advanced Surface Ablation (comprising PRK, Epi-LASIK, LASEK, TransPRK).

ReLEx SMILE which stands for Refractive Lenticule Extraction – Small Incision Lenticule Extraction, is minimally invasive, flapless, FDA-approved, and ideal for people with active lifestyles and occupations. It is an out-patient procedure that takes about 30 minutes for both eyes.

ReLEx SMILE may be a viable surgical option if you want to do away with the inconvenience from lugging around your spectacles, contact lens cases and cleaning kits; no more eye infections from contaminated lens solutions; no more putting up with spectacles when you have decreased tolerance for them; and no more having to put on contact lenses because of the nature of your profession or hobby.

transprk vs lasik

Isn’t ReLEx SMILE a LASIK procedure?

As mentioned previously, ReLEx SMILE is a laser vision correction procedure just as LASIK is also a laser vision correction procedure. Therefore, ReLEx SMILE is not a LASIK procedure. The misperception arose when people started to use the term LASIK interchangeably with laser vision correction, probably as a result of LASIK being the more commonly performed laser vision correction procedure. To avoid confusion, the terms laser vision correction and LASIK are not used interchangeably throughout this article. The only exception is in the last section – Frequently Asked Questions – where LASIK is used as the umbrella term for all the 3 procedures.

The Complete Guide

There has never been a Complete Guide to ReLEx SMILE in Singapore…until now. In this 2,500-word guide, everything you need to know about this laser vision correction procedure and how it compares to LASIK and Advanced Surface Ablation, can be found here:

laser eye surgery singapore
laser eye surgery singapore
laser eye surgery singapore
Advanced Surface Ablation (PRK, Epi-LASIK, LASEK, TransPRK)

History and Development

The beginning of ReLEx SMILE can be traced back to the introduction of the ZEISS VisuMax femtosecond laser in 2006. It is a laser system that ensures reproducibility and predictability, making it an ideal platform for numerous corneal surgery applications including ReLEx SMILE.

The first ReLEx SMILE procedure was performed by award-winning ophthalmologist Walter Sekundo in 2007. With its speed and gentle treatment, the procedure was commercially launched 4 years later globally. In the US, ReLEx SMILE was launched in 2017, after the FDA – with its strict regulations and safety standards – granted it approval.


 Extent Of Correction

The ReLEx SMILE procedure is recommended for correcting:

  • Myopia (short-sightedness) in the range of 100 to 1,000 degrees
  • Astigmatism of up to 350 degrees


Although ReLEx SMILE is a great solution for individuals desiring independence from spectacles and contact lenses, not everyone is suitable. Here are some of the main reasons why some individuals are not suited for the procedure:

  • Below 18 years old as the eye prescription has not stabilised (also, parental consent is required if you are below 21 years old)
  • Eye prescription that is well out of the treatment ranges stated previously
  • Eye prescription that is not stable during the past 12 months
  • Eye conditions such as cataracts and glaucoma
  • Poor health
  • Those who have long-sightedness or purely suffer from astigmatism (absence of short-sightedness)
  • Women who are pregnant or breastfeeding
  • Corneas that are very thin, are of irregular shape, or are steep (keratoconus)
  • Severe case of dry eye syndrome (see next section)
relex smile post surgery

Dry Eye Syndrome

For most individuals with dry eye syndrome, their condition is mild enough for them to undergo ReLEx SMILE. When assessing patients with dry eye syndrome, we look at how severe it is as well as whether the condition is reversible.

Compared to LASIK, undergoing ReLEx SMILE results in a lower incidence of dry eye syndrome. There may be a temporary increase in dryness, but for most patients, the dryness will taper down within 3 months of the procedure. However, a small number of people may experience increased dryness up to 6 months, while an even smaller proportion of patients (less than 1%) will continue to experience it up to 12 months or more.

It is highly recommended that if you have dry eye, you should have it diagnosed and treated promptly before undergoing ReLEx SMILE. Faithfully keeping up with your treatment will prevent the symptoms from reappearing even if you do not feel that you need to apply the prescribed eyedrops regularly. If you do not keep to your treatment, the symptoms may reappear, and you will have a relapse.

Key Features of ReLEx SMILE

1. Minimally Invasive Surgery

With LASIK, a flap measuring 22mm across the circumference is created on the surface of the cornea. With ReLEx SMILE however, no flap is created. Instead, a small incision of 2 to 4 mm is made, making the procedure minimally invasive.

The procedure starts off with a laser creating a lenticule (a disc-shaped piece of corneal tissue) beneath the cornea surface. The same laser then creates the aforementioned small incision, to allow for the lenticule to be removed. Once it is removed, the cornea will be reshaped, thus correcting your vision.

2. Predictable Outcomes

The ReLEx SMILE procedure utilises the VisuMax femtosecond laser from ZEISS, which gives results with predictability.

The laser creates a pre-determined lenticule (a disc-shaped piece of corneal tissue) and incision, coming very close to the target refraction. Due to the accuracy of the laser, the ReLEx SMILE procedure is valid across a wide range of correction; from low to high degrees of short-sightedness and astigmatism.

3. Single Laser

Whereas LASIK employs 2 different lasers and requires the patient to be moved from 1 laser station to the other, ReLEx SMILE employs a single laser.

4. Maintaining The Integrity Of The Upper Corneal Layers

With ReLEx SMILE, most of the upper corneal layers remain intact which preserves the biomechanical stability of the eye. When making the small incision, the lamellar deflection (the deviation of the incision towards a plane parallel to the layers of collagen fibrils in the cornea) is minimal, thus keeping the refractive correction at the desired level.

lasik surgery
lasik surgery

5. The Benefits Of Going Flapless

As no flap is created, the ReLEx SMILE procedure leaves the anterior part of the cornea almost untouched which reduces the possibility of nerves being transected (cut). The procedure has proven results in maintaining corneal sensitivity, speedy reinnervation (restoration of nerves), and low incidence of transient (temporal) dry eye syndrome.

As there is no risk of flap dislodgement, ReLEx SMILE may be a suitable procedure if you engage in contact sports or if your occupation entails some risk of head or eye trauma.

6. Easier Post-Procedure Management

Due to the predictability of the refractive outcome, there is only a very small percentage of re-treatment/enhancement being required. In addition, the ReLEx SMILE procedure reduces the incidence of infections and epithelial ingrowth, hence resulting in rapid healing.

7. Limitations of ReLEx SMILE

Do take note that ReLEx SMILE cannot correct for long-sightedness or for those with astigmatism only. In addition, any re-treatment/enhancement to finetune the prescription, requires conversion to either LASIK or PRK.

LASIK and Advanced Surface Ablation (ASA)

Besides ReLEx SMILE, the other 2 laser vision correction procedures are Advanced Surface Ablation (ASA) and LASIK.

Advanced Surface Ablation (ASA) is a ‘no-flap, no incision, surface-based’ procedure, developed in the 1980s. It includes PRK, Epi-LASIK, LASEK and TransPRK.

ASA may be recommended if you have low refractive errors, thinner corneas or if you have an active lifestyle or occupation (no flap is made). It is also recommended if one is concerned about procedure-induced dry eyes, and flap-related issues arising from LASIK; flap dislodgement and Corneal Ectasia (see section on Collagen Cross-Linking in Frequently Asked Questions).

The ASA procedure starts with the removal of a thin layer of cells on the corneal surface. A laser then sculpts the corneal tissue to correct the refractive errors. Finally, a protective contact lens is placed over the eye to allow the cells to regrow over several days.

You will be prescribed eyedrops for several weeks to up to a few months. Note that there is a relatively longer downtime of 5 to 7 days; before you can resume work. Compared to LASIK and ReLEx SMILE, your vision will also typically need a longer duration to fully stabilise.

LASIK – Laser-Assisted In Situ Keratomileusis – is the more commonly performed laser vision correction procedure worldwide and here in Singapore.

LASIK is effective especially for higher levels of myopia, takes minutes to perform, and the recovery is comfortable and quick.

LASIK improves upon ASA in the areas of discomfort and recovery time. Although it involves creating a corneal flap during surgery, it is rare that complications arise from it.

LASIK involves the creation of a 22mm circumferential flap on the surface of the cornea by a femtosecond laser. The flap is then folded back allowing for a second laser (excimer laser) to sculpt the corneal tissue thus correcting the refractive errors. The flap is then repositioned for it to stay in place over the cornea till it is fully healed.

As there is a flap involved, it may get dislodged due to trauma, although the occurrence of this is rare. There is also a rare possibility of Corneal Ectasia occurring (see section on Collagen Cross-Linking in Frequently Asked Questions).

Pre-laser Evaluation

Sign up for a pre-laser evaluation if you are keen to have ReLEx SMILE done. This 3-hour evaluation consists of a comprehensive list of eye tests, which typically includes dilation of the pupils and consultation with your eye doctor (ophthalmologist).

You are required to stop wearing soft contact lenses at least 3 days prior to the evaluation, or at least 14 days prior to it if you are wearing hard contact lenses. The tests conducted will determine your corneal thickness and shape, intraocular pressure, visual acuity, manifest refraction etc.

To dilate the pupils, eyedrops will be administered. Do note that after pupil dilation, far vision remains unaffected. However, you will need to remove your glasses to see near, while others may be sensitive to bright lights. The effects of dilation will typically wear off after 4 to 6 hours. So, it may be a good idea to bring along your sunglasses on the day of your evaluation.

Is ReLEx SMILE My Best Option?

After you have completed your pre-laser evaluation, your eye surgeon will share with you the results and discuss with you if ReLEx SMILE is the best option for you. Its suitability for your eye condition, occupation and lifestyle will depend on:

  • Corneal thickness and shape – ASA is preferred if the cornea is thinner
  • Myopia – ASA is recommended if your degree is low
  • Astigmatism – ReLEx SMILE is able to correct astigmatism up to 350 degrees with the presence of short-sightedness
  • Occupation and lifestyle – ReLEx SMILE is suitable if there is risk of head/eye trauma in your job or sporting activity

Take this opportunity to ask your eye surgeon questions and clear any doubts that you may have. Together with your eye doctor (ophthalmologist), you will arrive at the surgical option that is most suited for your eyes.

Lasik Consultation

Side Effects

Following your ReLEx SMILE procedure, you may experience some temporary side effects which may persist over several days/weeks:

  • Glares
  • Haloes
  • Dry eyes
  • Mild fluctuation of vision
  • Infections and complications – very rare with today’s laser technology

In the event of over or under-correction occurring in the range of +/-0.75 or more (less than 2 to 5% of cases), you may undergo an enhancement 3 months after the procedure or when the refractive error has become stable.

Comparative Benefits

The following is a summary of the benefits of the 3 laser vision correction procedures:


  • Minimally invasive and no risk of flap complications as it is flapless
  • Less chances of infection due to the small incision
  • Recovery that is quick and comfortable
  • Lower incidence of dry eye syndrome when compared to LASIK
  • Suitable if your profession or sporting activity entails a risk of head/eye trauma
  • Flexible in treating a wide range of eye prescriptions


  • Quick recovery time
  • Comfortable post-surgery recovery
  • Early enhancements relatively easier to do
  • Flexible in treating a wide range of eye prescriptions

Advanced Surface Ablation (PRK, epi-LASIK, LASEK, TransPRK)

  • No risk of flap complications (flapless)
  • Lower incidence of dry eye syndrome post-surgery
  • Suitable if you have an active lifestyle, e.g., if you do contact sports
  • Ideal if you have thinner corneas
  • Flexible in treating a wide range of eye prescriptions (though not as wide as ReLEx SMILE or LASIK), including very low ones
  • Lower risk of Corneal Ectasia (see section on Collagen Cross-Linking in Frequently Asked Questions)

Relative Disadvantages

The following is a summary of the comparative drawbacks of the 3 Laser Vision Correction procedures:


  • Not suitable for very low myopia
  • Not recommended for those with a purely astigmatic refractive error
  • Cannot treat long-sightedness (hyperopia)


  • Rare possibility of flap-related complications
  • Higher incidence of dry eye post-procedure

Advanced Surface Ablation (PRK, epi-LASIK, LASEK, TransPRK)

  • Longest recovery time
  • Higher levels of discomfort

Cost of ReLEx SMILE in Singapore

As there are many variables involved, it can be quite challenging to make direct comparisons between the various packages that clinics and hospitals offer for ReLEx SMILE. The difference in the cost of the packages can usually be attributed to the following:

  • Pre-surgery evaluation including the suitability screening, consultation etc
  • Post-surgery follow-ups/reviews and enhancements

To avoid being faced with hidden costs or paying for unnecessary additions, pay careful attention to what is being offered. If you prefer, you can approach different clinics and hospitals to get a comparative estimate of the costs.

For having ReLEx SMILE done on both eyes, the estimated fee that you can expect at both hospitals and private clinics is between $5,300 and $8,000 (ASA is between $3,600 and $6,000 while LASIK is between $3,500 and $6,000).

ReLex Surgery

Medisave & Insurance

Laser vision correction procedures are considered as optional/elective procedures. Because of this, you are unable to use your Medisave for ReLEx SMILE. There is an exception however; you can use your Medisave when you have a difference in prescription of at least 300 degrees between your eyes AND if you are intolerant to glasses and contact lenses.

Insurance policies on the other hand, usually do not cover laser vision correction procedures. However, there are some policies with higher premiums that allow for it. In addition, there are some companies that include it under their corporate benefits. Please check with your provider/company beforehand to see if you are covered.

Frequently Asked Questions

When LASIK was first introduced, patients had to undergo surgery 1 eye at a time. This was because of:

  1. The risk of infection to both eyes – by having 1 eye treated at a time, the risk would only be limited to 1 eye.
  2. The accuracy of lasers being not as precise as what they are today – having the procedure done for the second eye at a later time, would allow for the second procedure to take into account any inaccuracies in the first eye and make the adjustments accordingly.

As these are no longer concerns today, the majority of LASIK procedures are done on both eyes in the same sitting, minimising your downtime after surgery.

However, if you prefer to stagger the procedures, surgeons are usually happy to oblige your request.

Collagen Cross-Linking (CXL) is a top-up procedure in addition to LASIK procedures, done at the same session, that aims to strengthen the cornea to:

  • Reduce the risk of Corneal Ectasia, a rare complication where the cornea loses its ability to keep its shape, thus degrading vision.
  • Extend the longevity of the laser results.
  • Minimise the possibility of an enhancement after the first procedure.

The process consists of applying drops of Vitamin B2 to your eye during the laser treatment. UV light is then shone on your eye for about 1 minute which activates the collagen fibres in your eye to cross-link, thereby strengthening your cornea. The whole process adds merely another 5 minutes to the procedure time.

The need to have CXL done can’t be directly answered, as it is difficult to predict if your eyes are prone to having poor vision returning. However, studies have indicated that generally, people with high power have a greater tendency to suffer a regression in eye power. If you have CXL done, it can reduce the chance of this happening, as well as reduce the risk of Corneal Ectasia which may occur over time; many years after LASIK surgery.

Likewise, with how you would prepare yourself for a pre-LASIK evaluation, stop using soft contact lenses at least 3 days before the surgery, and at least 14 days for hard lenses.

If you want to have Collagen Cross-Linking on top of your procedure, do not consume large amounts Vitamin C 1 week before the surgery. Having small pieces of fruits and vegetables containing Vitamin C is fine.

You can expect to spend a total of about 2 hours in the hospital/clinic, with the procedure itself taking about 30 minutes for 2 eyes.

You will experience blurry vision during the first 6 hours, so it will be nice to have someone accompany you home after the procedure. Otherwise, you are still able to make your own way home in a cab.

Do follow all medical instructions strictly. You will also be provided with eye shields to be used while sleeping during the first week to prevent the accidental rubbing of your eyes.

You will be required to return for reviews after the surgery. The general timeline is as follows:

LASIK/ReLEx SMILE: 1 day, 1 week and 1 month post-surgery. Depending on your recovery, your eye surgeon may want to review you again 3 months, 6 months and 1 year post-surgery.

ASA: 1 day, 3 days, 1 week and 1 month post-surgery. Depending on your recovery, your eye surgeon may want to review you again 3 months, 6 months and 1 year post-surgery.

Of the 3 procedures, LASIK and ReLEx SMILE have faster recovery time, followed by ASA.

The majority of LASIK and ReLEx SMILE patients can resume work/school after resting for 3 days though some do return to work to work/school the next day. For ASA patients, this usually takes 5 to 7 days.

Do follow these precautions after the surgery to ensure the best outcomes:

  • 3 days: Avoid prolonged reading, computer work or watching TV
  • 24 hours: Do not drive vehicles or operate heavy machinery
  • 1 week: Do not use eye makeup
  • 1 week: Avoid smoky and dusty places
  • 1 week: Avoid getting water into your eyes when washing your face/bathing
  • 1 month: Avoid swimming, jacuzzi, sauna, hot tubs and hot yoga
  • 1 month: Avoid contact sports, and prevent sweat from entering your eyes by using a headband

Studies have shown that more than 95% of patients continue to enjoy good vision many years after having their procedure done. However, some patients (up to 6%) may require an enhancement procedure for short-sightedness, long-sightedness or astigmatism within 10 years of having the surgery.

If you develop Cataracts, Glaucoma and Macular Degeneration (eye diseases that typically occur due to ageing), you can still go for surgery to correct them.

If you like putting on cosmetic and coloured contact lenses for aesthetic reasons, you may do so, but only 1 to 3 months after your surgery. However, due to the altered shape of your cornea post-procedure, your contact lenses may not fit as well as before, and they may also tend to fall out, especially if you have dry eye.

To prevent this from occurring, you should have an optometrist prescribe contact lenses that are shaped for a better fit with your cornea.

When deciding who you should go to for your surgery, keep in mind the following considerations:

  • The ability of the surgeon to listen to your needs and provide an unbiased consultation
  • Transparency in the pricing with neither hidden costs nor hard-selling/upselling
  • The credentials and experience of the eye surgeon and eye centre
  • The percentage of patients who require an enhancement after surgery
  • The laser technology adopted by the eye centre
  • The availability of the full spectrum of treatment choices to enable a customised approach
  • The level of service provided by the eye centre

Ultimately, you should choose the eye surgeon/centre you feel the most comfortable with.

Your sight is precious, and you should do all you can to ensure a positive outcome for your health and well-being.

Senior Consultant Eye Surgeon
Medical Director
MB ChB (UK), M Med, FAMS,
MRCS (Edin), FRCS (Edin)

Dr David Chan is the Medical Director and Senior Consultant Eye Surgeon at Atlas Eye Specialist Centre. As an ophthalmologist (eye doctor), he specialises in complex cataract surgery, anterior segment surgery and refractive surgery. His treatments include high-risk cataract surgery, lens replacement or exchange, lens capsular bag support, iris repair, laser vision correction (ReLEx SMILE/LASIK), collagen cross-linking, implantable contact lens and refractive lens exchange.