Classification of Lasers
Currently, there are two main types of lasers used in keratoconus surgery, the excimer laser and the femtosecond laser.
What is an Excimer laser?
Excimer laser is a wavelength of 193 nm excimer laser ultraviolet light wave that can precisely ablate the expected cut tissue without damaging the surrounding tissues and other tissues and organs. In medicine, it is mainly used for the treatment of refractive errors. For example, LASIK, LASEK and other methods of refractive error treatment, is currently a more common, safe, fast, effective and stable clinical application of refractive error treatment.
What is femtosecond laser?
Femtosecond (Femtosecond Laser) is an infrared laser that operates in pulses. 1 femtosecond is equal to 10-15 seconds, and is capable of producing extremely high instantaneous power at the focus point, which is the current cutting-edge technology in the field of ophthalmology. In recent years, it has been used medically as an ultra-precise surgical scalpel and applied to laser myopia correction surgery.
What is all-laser?
In the field of corneal refractive surgery, it refers to excimer laser surgery using a femtosecond laser instead of a mechanical laminate flap, which makes the surgery safer and more personalized because the femtosecond laser can create the flap more precisely.
What is a “full femtosecond” laser?
This refractive field refers specifically to FLEX and SMILE femtosecond small incision corneal stromal lens removal. The laser flap creation and corneal stromal lens removal are performed by the same femtosecond laser. The all-femtosecond laser is one of the most advanced modes of corneal refractive surgery in the world. It takes myopia correction to a new level of safety and precision.
Are femtosecond and excimer lasers the same thing? What is the difference?
They are not the same thing, they are two different types of lasers. They do not work in the same way. Femtosecond lasers can be used not only to simply create the corneal flap needed for excimer laser lamellar surgery, but also to perform refractive correction, combining flap making and laser cutting into one. The role of the excimer laser is generally to correct the refraction only, not to create the flap. If a flap is needed, a corneal lamellar knife or femtosecond laser is required.
Different surgical approaches
Refractive surgery has evolved rapidly and many different surgical procedures have been developed. More than ten different surgical procedures have been performed to choose the right one for each patient’s specific situation, making it truly “customized”.
What is LASIK?
LASIK is known as Laser in Situ Keratomileusis (LISIK). The method is to create a corneal flap with an automated microkeratome, perform excimer laser cutting under the flap, and finally reset the flap. It is suitable for a wide range of patients with moderate to high myopia and for those who wish to restore their vision in a short period of time.
What is LASEK?
LASEK is called Laser Epithelial Keratomileusis (EK for short) and is performed by loosening the corneal epithelium with a special concentration of alcohol to form a complete epithelial flap, which is then cut with an excimer laser, especially for low to moderate myopic patients with thin corneas, large curvatures and corneal opacities.
What is Epi-LASIK?
Epi-LASIK is known as Epipolis Laser in Situ Keratomileusis (Epi-LASIK). This procedure uses a miniature corneal epithelial knife to create an epithelial flap, which is more economical than LASIK in terms of corneal thickness and is one of the most advanced and safest surgical procedures available today. It is widely popular in Europe and the United States, and is especially suitable for low and moderate myopic patients with thin corneas.
What is SBK?
SBK is known as Sub-Bowman’s Keratomileusis (Sub-Elastic Excimer Keratomileusis). Compared to traditional LASIK surgery, SBK produces a thinner flap and the laser cutting site is closer to the surface of the eye, resulting in a faster recovery of corneal sensation and a lower incidence of dry eye. Patients who were unable to undergo traditional LASIK in the past due to thin corneas and high degrees can choose SBK surgery, thus largely expanding the indications for the procedure.
What is excimer laser surgery with femtosecond laser flap making?
Also known as all-laser surgery, it is the use of a femtosecond laser to precisely create a more uniform and perfect corneal flap under which excimer laser cutting is performed. Femtosecond laser is a new high point. Femtosecond laser flap making has higher accuracy, a wide range of treatments and a scalpel-less procedure. This procedure has now become a mainstream international procedure.
What is a full femtosecond laser keratomileusis?
”Full Femtosecond laser” surgery is a procedure that uses the Femtosecond laser system exclusively, without the need for excimer involvement. By combining flap making and laser cutting into one, it takes myopia correction to a new level of safety and accuracy. The all-femtosecond laser cuts an interface of a specific diameter and curvature at the relatively deep level of the cornea, and then cuts an interface of a specific curvature with a slightly larger diameter at the relatively shallow level of the cornea, where the two interfaces intersect peripherally to form a thin layer of corneal tissue in the shape of a convex lens in the interlayer, and removes the created interlayer tissue with a special tool, which is equivalent to applying the principle of excimer laser cutting.
What is wavefront-guided excimer laser surgery?
The excimer laser is generally used only to correct low order aberrations such as myopia, hyperopia and astigmatism. Wavefront aberration-guided laser treatment can correct not only low order aberrations but also higher order aberrations, improving visual clarity and quality of vision after surgery, resulting in better postoperative outcomes.
Why use iris-positioned wavefront-guided excimer laser for surgery (IR wavefront-guided LASIK)?
The use of iris positioning ensures the accuracy of surgical treatment and improves the overall quality of vision. It allows the eye position during the sitting and standing examination to exactly match the eye position during treatment in the horizontal position, and also allows accurate tracking of the rotational movements of the operated eye, making the laser treatment more precise and enabling more accurate treatment for patients with astigmatism and large high-order phase differences.
What is corneal topography-guided excimer laser surgery?
Using corneal topography to link with the excimer laser mainframe, we can do more optimized corneal personalized cutting based on the corneal topography features to save corneal tissue, which can make the cutting surface smoother, reduce post-operative glare and dazzle, and increase post-operative comfort.