Approach Considerations
The refractive surgery planning sheet information is transferred to the VisuMax® planning software.
Topical ocular anesthetic is given to the patient, who is placed on a slit lamp biomicroscope, and the corneal limbus is marked with a surgical marker at 0° and 180°. It is important that the head of the patient be aligned properly to avoid tilt and erroneous marking. The patient is then seated and given a facial povidone iodine facial and eyelid scrub, followed by perioperative antibiotic ophthalmic solutions.
A sterile Carl Zeiss curved contact glass is opened and attached to the VisuMax® at two points. The distal end (curved contact glass) is attached to a suction device, with the proximal end attached to the laser head, and will be in contact with the corneal surface. Centration is achieved with the patient looking at the center of the cone and focusing at a blinking green light. Once 90% contact between the curved cornea glass cone and the corneal surface is achieved, suction is initiated.
The centration is tested with an infrared light. Once centration is acceptable, it is possible to proceed with firing of the femtosecond laser.
Femtosecond laser shots create bubbles applied side by side, creating a cleavage plane, initially creating a posterior surface of the lenticule, followed by the lenticule border, then the anterior surface of the lenticule, and, finally, the side-cut incision, which creates an entrance to the pocket to access the lenticule. A thin spatula is inserted via the side-cut incision to bluntly dissect the intrastromal lenticule using windshield wiper–like side-to-side motion based on a fulcrum (the pocket entrance).
This lenticule is then extracted from the cornea using a pair of thin reverse-action forceps. The corneal pocket is lightly hydrated with balanced salt solution. The corneal epithelial surface is squeegeed with a moistened microsponge toward the direction of the side-cut incision. Topical antibiotic steroids and lubricants are applied. An eye patch is applied. The fellow eye undergoes the same procedure.
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SMILE treatment steps in comparison to LASIK and PRK. Courtesy of ZEISS (http://www.zeiss.com/corporate/en_us/home.html).
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SMILE animation. Courtesy of ZEISS (http://www.zeiss.com/corporate/en_us/home.html).
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Carl Zeiss VisuMax Femtosecond Laser. Published with permission from St Luke's Medical Center Global City Tan Eng Gee Eye Institute.
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The VisuMax Femtosecond Laser, used in performing ReLEx SMILE, is part of the Carl Zeiss VisuMax MEL80 (or MEL90) Refractive Laser Surgery Suite. Published with permission from St Luke's Medical Center Global City Tan Eng Gee Eye Institute.
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SMall-Incision Lenticule Extraction (ReLEx SMILE).
