Classification of Lasers
Currently, there are two main types of lasers used in refractive surgery, the excimer laser and the femtosecond laser.
What is an Excimer laser?
Excimer laser is an ultraviolet light wave with a wavelength of 193 nm that precisely ablates the expected cut tissue without damaging the surrounding tissue or other tissues. In medicine, it is mainly used for the treatment of refractive errors. For example, LASIK and LASEK are used for the treatment of refractive errors. It is the most common, safe, fast, effective and stable treatment for refractive errors in clinical practice.
What is femtosecond laser?
Femtosecond (Femtosecond Laser), a laser with a pulse of 10 to the minus 15 power, is a cutting-edge technology in the field of ophthalmology, which can focus to a spatial area much smaller than the diameter of a hair for microfine work. In the last two years, it has been used as an ultra-precise surgical scalpel and applied to laser myopia correction surgery.
What is “all laser”?
Also known as “semi-femtosecond”, it refers to the application of a femtosecond laser instead of a mechanical laminar knife to create a corneal stromal flap that is then cut using excimer laser surgery. Because the femtosecond laser allows for more precise flap creation, the procedure is safer and more individualized.
What is “Full Femtosecond”?
It refers to the refractive surgery field of FLEX and SMILE, or Femtosecond Small Incision Stromal Lens Excision. It is a combination of laser flap making and corneal stromal lens removal performed by the same femtosecond laser. The all-femtosecond laser is one of the most advanced keratomileusis surgical modalities in the world, and it brings the safety and accuracy of myopia correction to a new level. Due to high development costs and difficult technical bottlenecks, only the Zeiss “full femtosecond” laser can be used in “full femtosecond” myopia correction surgery.
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, and they do not work in the same way.
Femtosecond laser
Femtosecond lasers can be used not only to simply create the flap needed for excimer laser lamellar surgery, but also to perform refractive correction. It combines flap making and laser cutting into one.
Excimer laser
is generally used to correct the refraction only, not to create a flap. If flap creation is required, a microkeratome or femtosecond laser is used.
Different surgical approaches
At present, laser keratomileusis surgery is developing rapidly internationally and many different surgical procedures have been developed.
What is LASIK surgery?
LASIK is called Laser-in Situ Keratomileusis (LISIK). It is performed by creating a corneal flap with an automated microkeratome and making excimer laser cuts underneath the flap. The flap is finally repositioned. This procedure is suitable for a wide range of patients, especially those with moderate to high myopia and those who wish to restore their vision in a short period of time.
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, with the laser cutting closer to the surface of the eye, resulting in faster recovery of corneal sensation and a reduced incidence of dry eye. Patients who were unable to undergo traditional LASIK surgery in the past due to thin corneas and high degrees SBK surgery is available as an option. Thus the indications for the surgery are largely expanded.
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 thickness-saving than LASIK and is one of the safer 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 LASEK?
LASEK, or Laser Epithellial Keratomileusis (EK), is a procedure that uses a special concentration of alcohol to loosen the corneal epithelium to form a complete epithelial flap, which is then cut with an excimer laser.
What is excimer laser corneal 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 many advantages such as higher accuracy, wide range of treatment, no scalpel required for the procedure, better night vision, and better post-operative vision.
What is Full Femtosecond Laser Keratomileusis?
The “Full Femtosecond” laser is used to treat myopia without the need for an excimer laser. The flap and laser cutting are combined into one procedure, which brings the safety and accuracy of myopia correction to a new level.
What is wavefront-guided excimer laser surgery?
Excimer lasers are 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 high-order aberrations, improving the clarity of vision and the quality of post-operative vision, resulting in better post-operative results.
What is Q-value guided excimer laser myopia surgery?
”Q-value” is a geometric physical optics term that reflects the aspheric properties of the cornea in the human eye. The introduction of Q-values allows the post-operative corneal shape to be more in line with the standard state of the human eye, allowing the patient to reshape the aspheric personality of the cornea, resulting in better post-operative visual quality than with previous laser myopia surgery.
How to choose the procedure
How to choose femtosecond laser, LASIK, SBK, Epi-LASIK, LASEK and other surgical procedures?
The choice of surgical procedure should be based on objective eye examination results. Each of these procedures has its own indications and should be decided after professional discussion with the surgeon based on the examination results and individual requirements.
Surgical procedures
Principle of surgery
Applicable groups
1.All-laser (femtosecond excimer laser) surgery
Femtosecond laser is used to create a more precise and perfect corneal flap, under which excimer laser cutting is performed, compared to traditional mechanical knife flap making. The procedure has higher safety and accuracy than traditional mechanical flap making.
Patients with all kinds of myopia, hyperopia and astigmatism.
2.Full femtosecond laser keratomileusis
The laser flap making and corneal stromal lens removal are done by the same femtosecond laser. It brings the safety and accuracy of myopia correction to a new level.
Patients with less than 1000 degrees of myopia.
3.Standard LASIK (IK for short)
Has a history of nearly more than 10 years. Standard LASIK (abbreviated as IK), is to use a microkeratome to cut a 130-160μm thick flap, and then use the excimer laser to cut.
Patients with 100-1200 degrees of myopia.
4.Standard LASEK (abbreviated as EK)
Alcohol relaxes the cornea to form a complete epithelial flap, and then the laser is used to cut, breaking the “no-go” zone for laser correction.
Patients with relatively thin corneas, small eyes and deep sockets.
5.Epi-LASIK (Corneal Epithelial Knife – LASIK)
It is the application of a specially designed corneal epithelial knife that is finer than the blade used in ordinary LASIK surgery to cut and separate the patient’s cornea, saving about 30um of corneal thickness compared to ordinary LASIK surgery. Compared to E K surgery, Epi-LASIK is more precise and does not use alcohol, and post-operative visual quality, etc., can be significantly improved.
Patients with thin corneas and those who are willing to save corneal tissue.
6.Ultra-thin LASlK
Use the latest French Moria-90u m disposable ultra-thin corneal lamellar knife. Studies have shown that the thickness of the cornea remaining after cutting plays a very important role in preventing the occurrence of cone corneas after surgery and maintaining the normal anatomy and physiological function of the cornea. The thickness of the flap cut with ultrathin LASIK is typically 90um (compared to the traditional 130um), resulting in significant savings in corneal tissue and contributing to safer postoperative vision.
It is very suitable for myopic patients with high degrees and thin corneas.
7.SBK
Compared to common LASIK surgery, SBK produces a thinner flap and the laser cutting site is closer to the eye surface. Patients who were unable to undergo traditional LASIK orthoptic surgery in the past due to thin corneas and high diopters can save corneal tissue by using SBK to produce a flap.
It is very suitable for myopic patients with high diopters and thin corneas.
8.Q-guided excimer laser surgery
”Q-value” guided laser myopia surgery is based on the aspheric characteristics of individual corneas for individualized corneal cutting, as if “tailor-made” for each person, and the postoperative visual quality is more perfect.
For patients with high visual quality requirements and secondary enhancement surgery.
9.Anterior chamber type/posterior chamber type lens implantation
By implanting an IOL with a certain degree of refractive correction on the basis of the original lens, it not only maintains the adjustment ability of the original lens, but also has reversibility, and the postoperative visual acuity can reach or exceed the predicted visual acuity, and the field of vision is increased and the visual function is more perfect.
It is suitable for patients with ultra-high myopia of 1200 degrees or more.
About Wavefront Guided Individualized Surgery
Individualized wavefront-guided surgery is suitable for
Those who seek high visual quality, such as pilots, shooters, and frequent night drivers.
Patients with large pupil diameters at night (because the wavefront technique maximizes nighttime glare and improves night vision).
Those with high astigmatism (because the technique improves the accuracy of astigmatic axis positioning and makes laser treatment more accurate)
Those with large higher-order aberrations by wavefront aberration examination.
What are the advantages of wavefront-guided excimer laser surgery?
Wavefront aberration-guided laser treatment not only corrects low-order aberrations, but also high-order aberrations, improving visual clarity and post-operative visual quality for better post-operative results.
The rotational movements of the eye during surgery can be accurately tracked. It makes laser treatment more accurate. Enables patients with astigmatism and large higher order aberrations to be treated more precisely.
Personalized cutting pattern and plan according to the patient’s wavefront aberration characteristics, making the surgery more personalized.
About Femtosecond Laser
Femtosecond laser is a cutting-edge technology in the field of ophthalmic lasers that can be used not only to create uniform and consistent flaps, but also to correct refractive errors using all-femtosecond laser technology.
Who is a candidate for the femtosecond laser?
Usually, patients who are suitable for conventional myopia surgery can undergo the procedure.
What are the advantages of femtosecond laser flap creation?
The risk of surgery is greatly reduced.
It is highly accurate and produces flaps of uniform thickness and shape.
No scalpel is required for the entire procedure.
Embedded flap for more accurate repositioning.
A wider range of correction, regardless of corneal curvature.
Relatively avoid medical infection.
Better post-operative visual quality.
What is the difference between femtosecond laser flap and conventional LASIK?
Traditional LASIK uses a microkeratome (mechanical lamellar knife) to create a corneal flap, which is then cut with an excimer laser. To correct myopia. Femtosecond LASIK is the application of a femtosecond laser system instead of a mechanical laminotome to create the flap. Under the precise control of the computer program, it can cut the cornea at any depth and shape. Femtosecond laser can not only produce ultra-thin flap, but also pre-set the thickness, diameter, position of the corneal tip and the angle of the edge incision according to the surgeon’s requirements, so as to achieve the effect of personalized cutting according to different patients’ conditions.
Femtosecond laser flap making
Conventional LASIK
Device used
Femtosecond laser
Mechanical lamellar knife
Advanced
More advanced
General
Accuracy
Adjustment of corneal flap thickness, diameter, and position of the corneal tip can be made according to individual patient conditions.
Fixed parameters
Safety
High
With some risk
Comfortable
Comfortable
Slight discomfort
Adaptation range
0.75D to 13.00D
0.75D to 13.00D
Similarities
Excimer laser is required for diopter cutting after flap creation
In the process of creating a flap with a microkeratome (mechanical lamellar knife), the flap may not be created satisfactorily due to patient tension, small lid fissures, etc. This does not happen in femtosecond laser surgery. It can be said that the application of femtosecond laser has realized the bladelessness of refractive surgery and greatly improved the safety of the surgery.
What is the difference between all-femtosecond and normal femtosecond (or “all-laser” surgery)?
Although both have the word “all” in them, the two are very different. Most of the femtosecond lasers currently used in LASIK are only capable of creating a corneal flap and must be combined with an excimer to achieve the treatment. It is also called “all laser” or “semi-femtosecond”.
Full Femtosecond is a newer concept that refers to the application of a femtosecond laser system throughout the entire treatment process. The Femtosecond laser performs two separate scans at different depths in the corneal lamina, completing a complete lenticular cut to correct myopia. The surgeon uses special instruments to separate and remove the lenticular corneal tissue from the Femtosecond shaped corneal tissue along the micro-incision, without involving the process of flap making and flap lifting, which greatly reduces the risk of flap complications.
Full Femtosecond
General Femtosecond
English Name
FLEX/SMILE
Femtosecond Laser
Equipment used
The entire process is performed by a single femtosecond laser
Femtosecond laser combined with excimer laser
Advanced
The most advanced
More advanced
Accuracy
More precise
More accurate
Safe
Safer
Safer
Comfortable
Very comfortable
More comfortable
Range of refraction treated
Myopia-10D or less, Astigmatism-5D
Myopia – 0.75 – up to 13.0D, Astigmatism – 5D
Currently available devices
Zeiss Femtosecond VisuMax only
Various brands of femtosecond lasers
Most of the femtosecond lasers cannot perform full femtosecond treatment, and only the Zeiss VisuMax full femtosecond laser system is currently the pioneer in this field. Among them, SMILE (Micro Incision Total Femtosecond Refractive Surgery) is the most advanced procedure in this field.
Frequently Asked Questions
Is the surgery safe?
Excimer laser treatment for myopia is an external eye surgery and is relatively safe. The procedure has been performed overseas for more than 20 years, and our hospital was one of the first units in China to perform excimer laser treatment for myopia. The U.S. National Food and Drug Administration (FDA) has approved excimer laser correction after a long and rigorous review, and confirmed that the procedure is safe and effective. Current studies have concluded that the laser itself has no side effects on the internal tissues of the eye and there is no reason for sequelae to occur after several years of treatment.
What are the results of laser treatment? Are the results stable?
To date. The results of the treatment are satisfactory, both domestically and internationally, and the removal of myopic glasses can basically be achieved. The naked eye vision after treatment is generally at or close to the corrected vision with glasses before treatment. Many years of theory and practice have proven that if the myopia is stable before treatment and the anterior and posterior diameters of the eyes do not get longer, myopia will not reappear after treatment, so the treatment effect is basically stable and long-lasting.
Can all myopic patients undergo excimer laser refractive surgery?
Not all myopic patients can undergo excimer laser refractive surgery, and strict preoperative examination and screening are required. Active inflammatory disease in the eye must be cured before surgery can be performed. Patients with immune disorders, allergic diseases, severe mental illnesses, diagnosed cone corneas and thin corneas are not suitable for this surgery.
Are there any age and prescription restrictions?
The most suitable age is above 18 years old and below 45 years old. Usually myopia between 50 and 1200 degrees, astigmatism under 600 degrees and hyperopia under 600 degrees are eligible for excimer laser surgery.
Why is there an age limit and can I still be treated in my 50s?
Myopia is unstable under the age of 18, and all aspects of the body are still developing. If you are older, your physical condition is declining and your eye adjustment ability is declining, so you will most likely have to wear glasses after surgery. Therefore, this type of surgery is not suitable.
Do contact lenses affect the examination and surgery?
The first examination can be done after the contact lenses are removed, and a review and surgery should be considered 2-4 weeks after the contact lenses are removed (hard contact lenses or OK lenses should be done 1-3 months after removal).
What kind of anesthesia is used during the surgery? Will the surgery be painful?
Only eye drops are needed for surface anesthesia, and the procedure is painless.
What is the cost of the examination and the cost of the surgery?
The examination fee is $200 (special examinations are paid separately), and the surgery fee for both eyes varies depending on the procedure, with prices ranging from $6,600 to $19,800 for both eyes.
For example, the current pricing is.
Regular LASIK $2200/both eyes; SBK $5500/both eyes; Personalized SBK $6500/both eyes
Epi-L_ASIK $5,500/eye; personalized Epi-LASIK $6,500/eye
Femtosecond laser flap Fetosecond-LASIK (FS-LASIK) RMB 12,500/eye; personalized FS-LASIK RMB 14,500/eye
Full Femtosecond LASIK SMILE $16,000/both eyes.
Monocular surgery is half the cost of the above procedures.
Is it reimbursable?
No, excimer laser treatment for myopia is a non-medical insurance item.
How can I shorten the time of medical treatment for out-of-town patients?
In order to shorten the time for out-of-town patients to seek medical treatment. Reduce the cost burden. You can prepare the following before you come.
Stop wearing contact lenses for at least 2 weeks.
If you have conjunctivitis or keratitis, you must first treat the inflammation and wait for more than two weeks for a follow-up visit after the symptoms have subsided.
With active systemic lesions, please treat them first and come back to the clinic after a period of stabilization.
For female patients, please avoid menstruation, pregnancy and breastfeeding.
Patients should not drive themselves to the clinic.
A family member should accompany you on the day of surgery.
Why do fees vary from hospital to hospital?
Charges are generally determined by a combination of many factors, such as the level of technology, examination items, and the type of equipment used. In addition. The strict use of various types of disposable surgical consumables is also an important factor in the different prices of surgery.
How do I choose a hospital and surgeon to ensure a safe surgery?
Patients should keep a clear mind. Surgery is not a commercial practice and medical safety is of utmost importance. You should choose a doctor and specialist hospital with more advanced professional equipment, more surgical cases and more experience, and listen to more objective presentations from professional doctors, but ultimately you need to make a careful decision in the light of your own situation.
Why does the price of femtosecond laser vary?
Femtosecond lasers have evolved rapidly. It has undergone several updates in a short period of time. The difference in the level of digitization and the value of the intellectual property of different femtosecond technologies makes the price of the equipment vary from several million to tens of millions of dollars, and the quality of the disposable consumables used varies, which results in different charges for different types of femtosecond laser surgery.
Procedure
What are the procedures I need to go through to get laser surgery?
Two pre-operative eye exams (about 1-2 hours each), the first exam requires dilated pupils (to avoid driving yourself), an appointment for surgery after the exam, and antibiotic eye medication 1-3 days before surgery.
Questions to note about the surgery
How many types of surgery are there? Which one should I have?
This type of surgery is currently developing rapidly internationally and there are many different surgical procedures. Tianjin Eye Hospital has now performed more than ten different surgical procedures. After a series of pre-operative examinations, the surgeon will recommend which procedure to perform based on your own situation, so as to “tailor the procedure”.
What should I pay attention to before surgery?
Take care to follow your doctor’s prescription, sleep well, keep your eyes clean, no makeup, no perfume, eat a good breakfast, relax and eliminate tension, and have a family member with you on the day of surgery.
How long does the surgery take?
The procedure takes about ten minutes for all types of refractive surgery.
What are the possible reactions after the treatment?
After LASIK/SBK and femtosecond laser treatment, you may experience mild foreign body sensation, tearing, photophobia, etc., which usually last 3-4 hours. After LASEK/Epi-LASIK, you may experience pain, foreign body sensation, tearing, photophobia and other discomforts. The discomfort is especially pronounced within 24 hours and will decrease later. It lasts about 2-3 days.
Do I need to change my medication after surgery?
Usually, LASIK/SBK and Femtosecond laser procedures require a checkup at the hospital on the next day to open the eye patch without changing the medication. Other procedures (LASEK, Epi-LASIK) require a checkup at the hospital for 3 consecutive days after surgery.
How long after surgery can I work normally?
Currently we carry out the technology, the recovery speed after surgery varies for each modality, generally speaking: LASIK/SBK, femtosecond laser. The recovery is the fastest, most people can use their eyes normally the day after surgery and basically achieve the best vision, individual people vary depending on individual differences. Others (Epi-LASIK, LASEK) require a break of about three days. And the recovery of vision is gradual.
How can I protect my eyes after surgery?
The following needs to be noted.
No makeup on the eyes for one month and no hard rubbing of the eyes.
Do not swim for six months.
Use eye drops according to your doctor’s instructions.
Review your eyes regularly as instructed.
Eat properly and refrain from smoking and alcohol.