The Laser in situ keratomileusis (LASIK) procedure is considered as the standard procedure for the surgical correction of refractive errors especially myopia or nearsightedness. The introduction of femtosecond laser technology to LASIK surgery has revolutionized modern corneal surgery. New femtosecond lasers have evolved over the last few years which has made femtosecond LASIK more common. These femtosecond lasers produce short duration light pulses that cause disruption of the damaged corneal tissues. The procedure provides increased safety, precision and reproducibility of flap, predictability of healing, faster recovery, minimal discomfort to the patient and better biomechanical outcomes.
What happens during the procedure?
- Preoperative preparation: The patient is educated regarding the procedure and an informed consent is duly obtained. Antibiotics and anesthesia are topically administered in both the eyes.
- Suction: The suction ring is adjusted so that it is centered above the pupil and activated after verification. The intraocular pressure is raised.
- Docking: Keeping the eye parallel to the suction ring the docking procedure is started using an applanating glass contact lens. It functions to stabilize the globe and keeps the cornea flat thus avoiding complications.
- Femtosecond laser application: Following confirmation of docking by the laser’s computer, the femtosecond laser is initiated which produces free electrons and ionizes molecules. This results in the formation of minuscule gas bubbles that eventually dissipate into surrounding tissue. Thus multiple pulses are generated which are applied in succession to form a cleavage plane and consequently a LASIK flap is created. The femtosecond laser is beneficial in producing a smaller flap which is adequately positioned over the optical zone along the central line.
- Excimer laser aplication: Folding of the flap exposes the underlying stroma of the cornea. Subsequently the suction is released. A spatula is used to carefully pass across the flap to lift it like a hinge for the induction of excimer laser. The patient is instructed to look and fix his/her gaze at the green fixation light and the laser system is accordingly focused over the patient’s pupil following which the ablation is performed.
- Flap closure: After complete ablation, the flap is repositioned on the stromal bed. In case of a significant epithelial defect, a bandage contact lens will be placed. Therapeutic soft contact lenses are preferred as it promotes re-epithelialization, reduces pain, and increases mobility. An antibiotic solution and steroids are applied over the eye at the end of the procedure and covered via a clear shield.
What to expect post-procedure?
The corneal flap is optionally rechecked by slip lamp technique, an hour postoperatively in order to confirm the proper alignment. The therapeutic lenses are to be maintained until complete re-epithelialization is complete. Mild pain or discomfort is anticipated which will gradually wear off. Topical antibiotics and steroids are prophylactically given which are to be continued four times a day for approximately 4 to 10 days. Preservative-free lubricating eye drops are advised during the first postoperative month. Care should be taken to not overuse these drops hence they are to be taken only as and when instructed. It is strictly advised not to rub the eyes and avoid swimming during the first month as it can lead to corneal flap displacement or infectious keratitis. Patient might experience some glare or haloes with resolves as the vision stabilizes. It might take up to 3-6 months for complete vision stabilization.
How soon does normal life resume?
If the postoperative evaluations are normal then the patient can continue with his/her daily activities. Patient is advised to appear for postoperative evaluation at 1 day, 1 week, 1 month and after that at 3 months, 6 months and lastly at 12 months. Refractive stabilization may take up to 3 months in patients with myopia and it usually takes a longer time for hyperopia. An enhancement or repeat surgery can be performed after the stabilization of the refraction i.e. at least after a month but preferably after 3 months. Wearing contact lenses is prohibited for at least 2 weeks post-surgery.
Who performs it?
The femtosecond LASIK surgery is performed by skilled and experienced eye surgeon.
Are you a good candidate?
Patients who are equal to or above 18 years of age with a stable refraction in the eyes persisting for at least a year are suitable for Femtosecond LASIK. The myopic error falling within -12 diopters and hyper myopic error +6 diopters are best suited for this procedure. It can also be performed for astigmatism correction of 5 diopters or less. The patient should be otherwise healthy with absence of other ocular diseases such as keratoconus, herpetic keratitis, corneal degeneration, cataract and glaucoma. Systemic conditions such as diabetes mellitus, keloids, autoimmune diseases and also pregnancy are contraindications. Pupil size are also imperative in LASIK procedures as large pupils tend to increase the risk of corneal aberrations leading to reduced visual acuity, and vice versa for small pupils.
How to prepare for surgery?
Wearing rigid contact lenses is to be discontinued at least three weeks prior to all the corneal investigations while soft lenses should be discontinued approximately a week preoperatively. Avoid wearing cologne or perfume and even 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 confortable clothing. It is advised to be accompanied by a family member, friend or relative and also arrange transportation accordingly beforehand.
Are there risks or potential side effects?
- Pupillary constriction: After docking, opaque bubbles formed in the anterior chamber of the eye might release minor amounts of free radicals that lead to pupillary constriction. A non-steroidal anti-inflammatory might be beneficial in such cases.
- Transient light sensitivity syndrome: The patient might develop extreme photophobia days or weeks following the femtosecond LASIK procedure with no clinical findings. Patient might also experience rainbow glare or colored bands.
Are there alternatives to this procedure?
- ReLEX SMILE: 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.
- 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 near- and farsightedness along with 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 lower stages of farsightedness.
- AK (astigmatic keratonomy): One or two incisions are made in the cornea that enables it to assume a more round shape and relaxed position. It is preferred for the correction of astigmatism.