ReLEx SMILE surgery embarks a paradigm shift in ophthalmic surgery. Small incision lenticule extraction or SMILE has been adapted from refractive lenticule extraction or ReLEx and it is regarded as a state-of-the-art corneal refraction correction technique. ReLEx uses a single laser for the correction of refractive errors which was further modified as SMILE that requires no retractable flap further reducing patient inconvenience and surgical time. Higher order aberrations in myopia with or without astigmatism are preferably treated by SMILE that leads to better quality of vision. It is a minimally invasive procedure wherein a lenticule is created in the cornea using femtosecond laser and extracted via a keyhole incision in the cornea.
What happens during the procedure?
- Preoperative preparation: Contact lenses are to be removed at least 3-4 days prior to the surgery. The patient is educated regarding the procedure and an informed consent is duly obtained. Antibiotics and anesthesia are topically administered in both the eyes.
- Docking: The patient is placed in a supine position and covered via a sterile drape. Local anesthesia is injected and a speculum is inserted such that the patient’s eye is centered along the VisuMax femtosecond laser delivery system. The patient is asked to fix his/her gaze on the green internal fixation light. The bed of the patient is moved up, and a contact is established between the corneal surface of the patient’s eyes and the machine’s contact lens. This contact leads to the formation of a meniscus tear film and subsequently the fixation light becomes apparent. The beam is focused according to the patient’s refractive power. After the centering is confirmed, the suction is fixed and the laser is activated for photo-dissection. The patient is supposed to look directly at the green light. This phase of docking is based on the coaxially sighted corneal light reflex (CSCLR), which causes the green light to reflect on the cornea. Infrared light can be used for the confirmation of docking.
- Femtosecond laser application: A femtosecond laser is used systematically to create a lenticule. The parameters are adjusted depending on the patient’s condition and surgeon’s preference. Optical zones are set separately for the correction of spherical errors and astigmatism, while the cap diameter and pulse energy are also accordingly adjusted. Using the femtosecond laser, an intrastromal lenticule is formed by selective cutting.
- Lenticule dissection: A uniform bubble layer is created in the cornea as a result of the femtosecond laser delivery. Two rings are formed which correspond to the diameter of the lenticule which guide the dissection process. Consequently, the lenticule is dissected according to the set parameters.
- Extraction: Using micro forceps the dissected lenticule is extracted in a circumferential manner. Following which it is analyzed to confirm that it has been removed in entirety. The interface is flushed using a balanced salt solution and the cap is smoothed over the cornea using blunt instruments. Finally, the apposition of the cap is evaluated using the VisuMax laser system.
What to expect post-procedure?
The ReLEx SMILE surgical procedure may take 15-20 minutes or even less. The patient experiences an improvement in the vision within a few hours post-surgery. Initially the vision might be foggy but it will become clear gradually within a couple of days or weeks. He/she needs to stay indoors for the first 24 hours. As the vision starts becoming clear then the patient can continue with the daily activities. Light sensitivity may persist for some time during which the patient is instructed to take rest. It is advised not to wash the eyes with water, rather use a salt balanced eye drop as water can irritate the eyes. This is to be done till the sensitivity is lost. Hair wash can be done after two days.
How soon does normal life resume?
It may take a day or two to adapt to the corrected vision. The patient might experience glare and halos for a couple of weeks postoperatively, which will gradually subside. Patients with presbyopia i.e. age related hardening of the lens leading to refractive errors, will require wearing their glasses or contact lenses. Contact lenses are to be worn only after consulting and as directed by the surgeon, which is mostly allowed after a month or so. Anti Glare glasses are recommended for use when working on computers to provide better shielding.
Who performs it?
The ReLEx SMILE surgery is performed by skilled and experienced eye surgeon.
Are you a good candidate?
Patients with higher order aberrations in myopia with or without astigmatism are treated by SMILE. The myopia values ranging between -0.5D and -10D can be corrected via SMILE while astigmatism or cylindrical refractive errors up to -5D are suitably treated by this procedure. The patient should be otherwise healthy with a stable refractive error since a year. Patients between 18-40 years of age are preferred as it can only correct nearsightedness and the errors in distant vision related to age which is termed as presbyopia cannot be treated via this procedure. In patients with higher power a thick lenticule is removed.
How to prepare for surgery?
Patient is advised to stop wearing contact lenses at least 3-4 days prior to the ReLEx SMILE surgery. Avoid wearing cologne or perfume and hairspray. Alcohol containing beauty products are also to be avoided. Eye makeup needs to be thoroughly removed prior to the surgery. It is mandatory to avoid alcohol consumption at least a day before and after the operative procedure as alcohol has strong dehydrating properties that can lead to dry eyes. Wear comfortable clothing. It is advised to be accompanied by a family member, friend or relative and also arrange transportation accordingly beforehand. The surgery is performed as a day care procedure but the patient might be required to stay in the hospital or at home till he vision is clear which might take a day or two so leave should be planned accordingly.
Are there risks or potential side effects?
- Suction loss: It is an intraoperative complication seen in 0.8 to 4.4 % of cases. Following the docking of the patient at the laser interface, the patient needs to maintain that position. If there is mobility it may lead to ocular movement resulting in the loss of docking. In such situations either the procedure needs to be stopped or docking needs to be done again.
- Black spots: Presence of liquid droplets, dust particles or even air between the laser and the ocular surface result in an untreated part of the lenticule which further makes extraction difficult. In patients with a thick cornea and thin lenticule, opaque bubbles are formed.
Are there alternatives to this procedure?
- LASIK (laser in-situ keratomileusis): A flap is created in the epithelial layer of the cornea through which the defected part is extracted. This reshaping of the cornea focuses light into the eye and reaches the retina. It can be performed in subjects with nearsighted, farsighted, or astigmatism.
- PRK (photorefractive keratectomy): It only reshapes the epithelial layer of the cornea via a laser. It is preferred in mild to moderate nearsightedness, farsightedness, or astigmatism.
- EpiLasik: Similar to PRK, the cornea is reshaped or removed and a soft contact lens is placed over it to protect it during the healing phase.
- LASEK (laser epithelial keratomileusis): In this procedure a flap is created by dissolving the intercellular substance using an alcoholic solution. Following this a laser is used to reshape the cornea. The flap is repositioned and the healing occurs below it. It can correct nearsightedness, farsightedness, and astigmatism.
- ALK (automated lamellar keratoplasty): This procedure does not use laser. A flap is created via an incision and the cornea is reshaped. It is used in patients with severe nearsightedness and few levels of farsightedness.
- AK (astigmatic keratotomy): One or two incisions are made in the cornea that enable it to assume a more round shape and relaxed position. It is preferred for the correction of astigmatism.
- PRELEX (presbyopic lens exchange): In this procedure a multifocal lens is implanted to correct refractive errors and restore focus.
- Intacs or intracorneal ring segments (ICR): A small incision is made in the cornea through which two crescent-shaped plastic rings are inserted and the cornea is flattened.