A newer technique and surgery procedure, ReLEx SMILE has been developed for correction of refractive errors for better vision, with no need for creation of the flap, since that laser vision correction is performed with the Lasik. The procedure needs only a small incision at one side by an experienced and trained surgeon. The ReLEx SMILE eye surgery can leave the cornea anterior lamellae intact, by removing the refractive lenticule. This procedure needs no excimer laser for correction of vision. The ReLEx Small Incision Lenticule Extraction or SMILE is a new generation method of laser correction for vision, where the procedure is performed with a femtosecond laser. The procedure is performed by making two cuts at the layer of cornea, for separation of lenticule and removal of the same. This technology is made available only through Visumax machine by Carl Ziess, currently.

The technique of ReLEx SMILE Laser eye surgery stands as one of the most innovative approaches for correction of vision and it is purely blade free procedure and so pain free and flap free treatment. The procedure has shifted the correction of vision to the next level, as it offers best precision, comfort and maximum safety.

The surgery for ReLEx laser eye procedure is done by Carl Ziess with the Visumax machine and performed with two small side incisions over the cornea, measuring to the length lesser than 4 mm. here, vision correction is achieved by creating a disc shaped or lenticule shaped cornea tissue. Then a side incision is made to remove the lenticule. And finally, the lenticule that caused the changes in the cornea will be removed towards correction of the refractive error.


SMILE Technology – Advantages

  • More appropriate choice for more refractive error values for the patients
  • Being a flapless procedure, concerns of traumatic flap dislodgement or displacement eliminated
  • Very minimal procedure, hence minimized possibility of tissue ingrowth or infections
  • Because of small incision made, increased corneal nerves preserved from the procedure, resulting minimal discomfort of dry eye
  • Much better choice for higher refractive error values, for patients
  • Faster cornea healing, however, needs more time for visual recovery than the Lasik Surgery

Complications Possible

Similar to any other technology, the ReLEx SMILE technology also is not free from post operation complications. Some of the possible complications associated with this technology are the following.

  • During the lamellar cuts, there is a possibility of most being lot, because of the suction. In such cases, the procedure would just be aborted, so that the vision of the patient would not be disturbed, postponing the procedure to the later date. Another alternative is to switch to either PRK or Lasik.
  • Incomplete removal of lenticule is possible sometimes. The solution is the re-procedure and sometimes the surgeons recommend shifting to standard or conventional Lasik that may be difficult in some cases.
  • Possibility of not reaching the refraction targeted and may need enhancement procedure. The possible options can be ideally Thin Flap Lasik or sometimes PRK also. Thin Flap Lasik is better feasible, as long as,
  • There is an enough space is left for a new flap along with space for ablation, when the previous ReLEx SMILE procedure was performed with a cap that is thick enough.
  • Before new flap is made, the maximum epithelial thickness is confirmed, so that buttonhole is avoided.
  • The thickness of the residual stroma, present below the lenticule is beyond the safety limits of the standard Lasik, and it may not be necessary for the procedure of the primary ReLEx SMILE.

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ReLEx SMILE is the beginning of a new era in laser refractive eye surgery, on patient’s comfort grounds, as its significant advantage. An innovative treatment technique, ReLEx SMILE is designed and developed by Carl Zeiss, in Germany for treatment of precise and sensitive defects of vision. First time in the history of refractive laser eye surgery, correction is enabled to perform without flap cut. So far it is the first and only flapless, bladeless and minimally invasive 3D procedure.

What is SMILE?

ReLEx SMILE is the beginning of a new era in laser refractive eye surgery, on patient’s comfort grounds, as its significant advantage. An innovative treatment technique, ReLEx SMILE is designed and developed by Carl Zeiss, in Germany for treatment of precise and sensitive defects of vision. First time in the history of refractive laser eye surgery, correction is enabled to perform without flap cut. So far it is the first and only flapless, bladeless and minimally invasive 3D procedure.

What is SMILE?

SMILE (SMall Incision Lenticule Extraction) was introduced in the year 2012. It is a very minimal invasive procedure, which is also performed as a blade-free procedure.

ReLEx SMILE Surgery

ReLEx (Refractive Lenticule Extraction SMall Incision Lenticule Extraction) is a newer technology surgery procedure developed for refractive error correction to achieve improved vision and most importantly, there is no necessity for flap creation, because the correction of vision gets achieved from LASIK procedure. The surgery is performed as a bladeless, minimally invasive laser eye surgery. So, the procedure stands as one of the most vision correction approaches and it completely flap free and pain free, as it is blade free. It offers the best comfort, precision and maximum safety. This procedure is better compared to the PRK procedure.

Eligibility For SMILE

SMILE procedure is the best suitable procedure for the following refractive error conditions.

  • Myopia is the condition, which can be very well treated with excellent results.
  • Myopia, within the range of -8.0 D and cylinder value reaching till -0.5D can be corrected.
  • It is a well opted procedure to treat short-sightedness and also short-sightedness combined with astigmatism.
  • Eye patients with drier eyes get benefited from this procedure.
  • Higher prescription gets good benefit from this procedure.
  • People with contact lens intolerance can be relieved well from this procedure.
  • Patients with thinner cornea can prefer this procedure, as they are not eligible for LASIK.



ReLEx SMILE is better than traditional LASIK and PRK and it combines the benefits of both these procedures. Some of eye patients are not cannot be candidates for LASIK procedure, but they can be for SMILE. On the other hand, PRK procedure needs more time for recovery, however, SMILE procedure does not take much time. Small problems associated with these two procedures can be solved with the ReLEx SMILE procedure and stands as the best alternative.

Exclusive Features

SMILE is different from the other standard LASIK procedures, because of the following special features.

  1. Minimally Invasive

Incision through ReLEx SMILE is 80% smaller than standard LASIK procedure. The incision needed is from 2 to 4mm, instead of 20 mm incision required for the LASIK procedure.

  1. Preserving Upper Structure of Cornea

Since no corneal flap is necessary to create, the upper structure of the cornea is left untouched, practically. So, the stability of cornea structure is unaffected, largely.

  1. No Flap Like LASIK

As the flap is not needed to create, flap related complications, such as dislodgment and displacement are nullified or ruled out.

  1. Lesser Post Surgery Discomfort of Dry-Eye

Post-operative discomfort, in terms of dry eyes is reduced to a greater extent, since most of the upper structure of the cornea is untouched, during the procedure.

  1. Night Vision

Optical aberrations induction is very lesser as corneal flap is not created.

Pre SMILE Procedure

The selection of ReLEx SMILE procedure is done by eye surgeon, by considering the following parameters.

  • Refractive correction required
  • Thickness of the cap
  • Diameter of lenticule or optical zone
  • Side cut angle of lenticule
  • Diameter of the cap
  • Side cut angle of the cap
  • Minimum thickness of the lenticule

All these parameters are considered and when they exist in the required range of measurement, SMILE procedure is chosen finally.

The Procedure

The procedure starts with anaesthizing process, by applying eye drops. Then a speculum is positioned carefully over the lids to ensure prevention of blinking of the eye and keeping the eye open. A precise lenticule is created by using femtosecond technology.

The procedure of ReLEx SMILE involves two small incisions made at both the sides of the cornea with lesser than 4 mm length. Correction of vision in this procedure is achieved through lenticule or disc shaped cornea tissue creation. The surgery removes the refractive lenticule and cornea anterior lamellae are left intact. Correction vision in this case does not demand any excimer laser. It is because this new incision lenticule extraction procedure makes use of femtosecond laser for this new generation laser correction method. The procedure is conducted though two cuts at the cornea layer for lenticule sepration and its removal as well.

After correction is complete, the small incision made is closed itself. Hence no stitches are required and it demands no complex and too careful post-operative precautions. Unlike LASIK surgery procedure, patient does not need to change the positions in between instruments. Hence it gives lesser time and greater comfort for the entire procedure. On an overall, the procedure is completed with low suction and so gently.

The procedure is painless. However, mild discomfort is possible, while the procedure is performed, because of light and pressure imposed to the eyes, though it is minimal. The entire procedure takes 10 to 15 minutes, though laser is used only for a few seconds. The procedure is simple to perform, though very advanced technology is involved in it and so patients can visit the hospital on an outpatient basis.

ReLEx SMILE procedure is performed with low suction and gentle process and the result is preserving the vision with no ‘black out’ phenomenon, which is varied from other procedures of laser refractive surgeries.


Compare to the other LASIK procedures, SMILE procedure takes longer time. Recovery from this procedure is quite comfortable. Eye patch is not needed after the surgery, however, use of sunglasses, both indoor and outdoor are recommended for a few days after the surgery. You need to wait for a few days before you resume driving your two or four wheeler. When it comes to recovery, 80% of vision can be recovered immediately and more than 90% in a few days. Recovery from this surgery is comfortable, just like LASIK and recovery is quicker comparatively.

Vision immediately after the surgery is hazy, but enough navigational after going for a short nap. However, it is safe enough to go for driving and working with the computer after three days of recovery post surgery. Recovery is as quick as LASIK surgery and much quicker compared to LASEK and PRK procedures.


ReLEx SMILE procedure is safe enough and it is approved by the FDA.

Candidates for the Procedure

Basically, most of the patients, who are eligible for the general LASIK surgery are also eligible for SMILE surgery. The following are the criteria to undergo this surgery procedure.

  • Patients, who are in the range of 18 to 40 years of age, are eligible. However, preferred lower age limit is usually 22, by most of the surgeons.
  • Prescription conditions are similar to the LASIK patients, but include thin flap patients also.
  • Patients have astigmatism or nearsightedness.


ReLEx SMILE surgery is not very costly procedure. However, major contribution for this surgery includes the consumables spent for patient interface. This surgery usually costs about 1,00,000 INR in New Delhi.


SMILE is an advanced technology and possesses various benefits.

  • Patients with more refractive error are more appropriate to undergo this procedure.
  • SMILE uses Femtolaser to carve out an accurate corneal lenticule to make 2 lamellar planes.
  • The procedure is very minimal and eventually possibility of infections or ingrowth of tissue is minimized.
  • The concern of flap dramatic displacement or dislodgment is totally eliminated, since it is a flapless procedure.
  • Corneal nerves are preserved better, since the incision made is very small.
  • Minimal discomfort is felt by the patient, because of very small incision made.
  • The best choice or option for the patients, who have very high refractive error values.
  • Cornea healing is faster, though visual recovery takes considerably more time.
  • The procedure is safer as it is minimally invasive and not much part of the cornea is touched.
  • It is a bladeless procedure and so complications are minimized.
  • The procedure is faster and painless making patient less discomfort.
  • It is a customized process and any level of refractive error and prescription can be treated.
  • Vision quality would be quick and excellent post the surgery.
  • The procedure is totally odour and noise free.
  • The natural strength of the cornea is well retained.

Possible Complications

Though incision made is very small, the technical complications are possible after ReLEx SMILE surgery. The complications possible are the following.

  • While lamellar is being cut, more than required part may be cut because of the process of suction. However, the procedure gets immediately aborted to ensure that the vision is retained undisturbed. Further solution is either to go for LASIK or LASIK or postponing the same surgery later date.
  • A few times, the targeted refraction may not be reached and it may end up the need for enhancement procedure. other alternatives are PRK or Thin Flap LASIK and the later is the most preferred by the surgeon.
  • Sometimes, removal of lenticule may be incomplete. It may require re-procedure and sometimes shifting to conventional or standard LASIK may also be recommended, though it becomes a bit complicated a few times.
  • In cases of going for second ReLEx SMILE procedure, there can be adequate space could be left for one flap more, while enough space is provided for ablation. It is possible in certain cases, like the previous procedure is performed with a thick enough cap.
  • Maximum epithelial thickness needs to be conformed, before making a new flap as it is need to avoid buttonohole.
  • Residual stroma thickness, which is beyond the standard LASIK safety limits, may not be the same for the primary ReLEx SMILE procedure.

However, these complications are quite infrequent, since it is safer procedure.


Though risks are very few, these are technically possible. These risks can be any of the followings.

  • Small tears are possible at the site of incision.
  • Sometimes epithelial abrasions are also possible.
  • In a few cases perforated caps become risky factor.
  • Suction loss is comparatively frequently occurring risk, because of the low-pressure system implemented and longer suction time. This risk is prominent for the patients with smaller palpebral fissures and deeper set eyes or uncooperative patients.
  • Black spots are possible because of air bubbles or debris entrapped in between cornea and contact lens. This risk is possible when the ocular surface is not maintained cleanly.
  • Side cut tears and cap tears are possible, in cases of excessive surgical manipulation, extraction, dissection and forceful lenticule.
  • Epithelial defects are possible, usually resulting from frequent topical anaesthesia installation and surgical trauma.
  • Opaque bubble layer may be formed in case the laser energy settings are set too low or too high. It may delay visual recovery.

SMILE is a minimally invasive procedure and incision is so minimal that it may have the need for another treatment post the ReLEx surgery, since most of the cornea is left intact. So, though the incision is so small, the actual correction over the cornea must be performed completely, without the need for re-procedure.

ReLEx Versus LASIK

Both SMILE and LASIK procedures are quite similar with a very smaller difference. In LASIK procedure, excimer laser is used for reshaping underlying cornea and it needs larger opening, approximately 20mm, whereas SMILE procedure is concerned, only a very small opening of approximately, 4mm, is sufficient.

ReLEx is much advanced than LASIK and it prevents the need of passing from one instruction to another instrument, unlike in LASIK. ReLEx procedure is much shorter than this LASIK. The best part is that the patients, who are not eligible for LASIK procedure are eligible for ReLEx. And ReLEx SMILE procedure makes use of only one laser, unlike two lasers in LASIK. Most importantly, ReLEx does not create flap, complications related to flap are less likely than LASIK. The most probable post-surgery symptom, dry eye is less likely with ReLEx, unlike LASIK, because very fewer corneal nerves get severed.

Best Suitable Conditions to Undergo ReLEx

There are multiple laser refractive eye surgeries available in the medical industry, each with its own pros and cons, though ReLEx stands as one of the most advanced procedures to correct refractive errors. The following are the best suitable conditions to prefer ReLEx procedure, rather than the other procedures.

  • Refractive error eye patient with significant myopia or astigmatism are the best suitable and can go for ReLEx SMILE procedure.
  • If the patient has severe dry eye symptom before the surgery, then ReLEx SMILE procedure is the best option and optimal choice, since post-surgery dry eye symptoms are very less likely.
  • Patients with thin cornea can go for ReLEx, as they are not eligible for LASIK. Though they are also eligible for LASEK or PRK, they can prefer ReLEx, as it is less complicated and recovery is quicker.
  • If patient is expecting very active lifestyle with regular physical exercises and contact sports, surgeons may prefer ReLEx, as it can eliminate flap related complications, unlike LASIK and faster recovery time is possible compared to LASEK or PRK.
  • When the budget is low ReLEx can still be a better choice, as it is cost effective procedure, since it makes use of only one laser.
  • Patients, who look for the best alternative to femto-LASIK or ASA can prefer ReLEx.


Retreatment and Enhancement

Re-treatment is sometimes required because of abandoned primary procedure, resulting from difficult dissection and suction loss. Sometimes enhancement may become necessary after the surgery, usually needed because of regression, overcorrection or overcorrection. And this percentage is lesser than 4%. Sometimes enhancement may also be needed because of irregular astigmatism, usually resulting from difficult lenticule dissection, partially retained lenticule fragments or decentered ablation.

Usually repeat SMILE is not recommended or advised, because of multiple dissection planes creation. But sub-cap lenticule extraction feasibility is evaluated in cases, which demand enhancement or post-SMILE procedure.

Future Advances

The applications of SMILE have been evolving consistently for including high astigmatism and hyperopia.

More than everything, seeing is living and it should not be disturbed or obstructed by glasses or contact lenses. ReLEx can be the best choice to get rid of contact lenses and eye glasses and continue quality vision and quality life.