Myopia has become a worldwide problem, and with the popularity of myopia surgery, more and more people want to have myopia surgery.
Many people have many concerns before having myopia surgery:
Is there any sequelae after myopia surgery?
Will I be blind or myopia will rebound?
Is myopia surgery just a knife on the eye? What if I do something wrong?
…
These are the questions almost everyone asks about myopia surgery, and we’ll address them all at once.
Our vision is mainly related to the 3 structures in the eye – the cornea, the lens and the axis of the eye.
Most nearsightedness is the long axial length of the eye, which causes the light entering your eye to be imaged before the retina, making it difficult to see [1].
(close-up note)
The axis of an adult’s eye is almost fixed, and only two other structures can be changed – the cornea and the lens.
This is also where myopia surgery is performed. Myopia surgery involves changing the curvature of the cornea or lens to refocus light on the retina [2].
The three most common types of myopia surgery today are refractive surgery:
LASIK surgery;
Full Laser Surgery (T-PRK Surgery);
Full Femtosecond Laser Surgery (SMILE Surgery).
These three types of surgery are all “shaving” the cornea – using a laser knife to “shave” the cornea to thin the cornea to correct vision.
There is another type of nearsightedness surgery that is becoming more common: Intraocular Lens Implantation (ICL) – an intraocular lens (the equivalent of an invisible lens) is inserted into the eye glasses) to correct vision.
Next, we’ll talk about one by one.
We compare the cornea to a piece of watermelon, let’s see how the myopia surgery “shaves” the cornea step by step [3]:
1. LASIK surgery: corneal flap needs to be made
The surgical procedure can generally be divided into 3 steps:
1. Make a corneal flap (watermelon rind).
The corneal refractive surgery is mainly done in the corneal stroma, so the first step is to lift the corneal surface, and this process is to make the corneal flap.
You can understand that: cut a circular cover on the surface of the watermelon, not cut it completely, connect it through the rind, and then lift up the cut area.
Operations can be divided into two types depending on the flap technique:
Microkeratome + excimer laser surgery, commonly known as excimer laser surgery;
Femtosecond laser flap making combined with excimer laser, commonly known as half-femtosecond surgery (FS-LASIK surgery). FS-LASIK surgery uses femtosecond laser to make corneal flaps, which are thinner, more precise and smoother, and safer. Therefore, there are fewer complications related to corneal flaps after FS-LASIK surgery, and the corneal flaps heal after surgery. faster.
2. Grinding the corneal stroma (watermelon pulp)
Use an excimer laser to polish the corneal stroma, which is the watermelon flesh inside.
3. Reposition corneal flap (watermelon peel)
Flip the corneal flap back and cover it in place, that is, put the watermelon rind back.
LASIK surgery is currently the most widely performed myopia surgery in the world. There is generally no obvious eye discomfort after surgery, and vision recovery is fast.
At this time, some people will ask, will grinding the corneal stromal layer damage it?
Don’t worry about this. Research and practice have shown that the incision of the fine lamella in the corneal stroma will not lead to intrastromal opacity [4].
Second, all laser surgery (T-PRK surgery): “no knife/no incision/flap”
T-PRK surgery mainly operates on the superficial layer of the cornea and is a superficial surgery.
Compared with the above FS-LASIK surgery, T-PRK surgery does not need to make a corneal flap, and all operations can be done in one step, so “no knife”, “no incision”, “no flap” .
The specific procedure of the surgery is as follows:
1. Excimer laser ablation of epithelial tissue
2. Scan the matrix layer (watermelon flesh) based on excimer laser to correct myopia
T-PRK surgery only needs one step to remove the corneal epithelium and stroma, no corneal flap is required, no incision or skin flap will be formed on the cornea, so there will be no corneal flap after the operation related complications, the safety is higher [5].
Studies suggest that T-PRK surgery is one of the safest and most suitable options for myopic patients with thin corneas.
However, this operation also has limitations, and is generally suitable for myopia below 800 degrees [5].
3. Full femtosecond laser surgery (SMILE): no need to make corneal flaps, “fighting the tiger”
Full femtosecond laser surgery, also known as smile surgery, does not require a corneal flap.
The lens that needs to be removed is made directly in the corneal stroma by femtosecond laser, just like fighting a tiger across a mountain.
Compared to FS-LASIK, because no corneal flap is required, the procedure becomes a two-step procedure:
Cut: Fighting tigers across mountains. A microlens is made with a femtosecond laser, and an incision is made with the femtosecond laser (usually at the periphery of the cornea, 2-4 mm in size);
Extract: Take out the excised corneal stroma.
In the whole process, each person’s different degrees are input into the computer, and the computer automatically controls the thickness of the microlens to maintain the accuracy of the operation.
This benefit is:
There is no need to make a corneal flap, which can avoid surgical complications caused by making a corneal flap;
Avoid corneal flap displacement due to trauma, etc.
The risks are:
There may be a risk of incomplete lens extraction intraoperatively.
Full femtosecond laser surgery has less risk of corneal flap than FS-LASIK surgery, but full femtosecond surgery may be less effective in patients with larger pupils.
4. Intraocular Lens Implantation (ICL)
Intraocular lens implantation (ICL)Your natural lens is implanted with an intraocular lens (equivalent to a contact lens) for clear vision.
This procedure does not require cutting the cornea, and some people find that the cornea is not thick enough after examination to be suitable for corneal refractive surgery, which may be performed after a doctor’s evaluation.
The benefits of this procedure are:
Reversibility, which means the intraocular lens can be removed at any time after surgery.
The risks are:
The risk of intraocular infection is higher due to the operation into the eye;
The risk of complications such as cataracts, glaucoma, and uveitis is relatively high because of the implanted intraocular lens in the eye.
Myopia surgery is a very clinically mature surgery, with little trauma, quick recovery, and overall safety.
But not the most expensive is the best, and the one that suits you is the best. You can choose according to your actual situation and the advice of your doctor.
From LASIK surgery, T-RPK surgery to full femtosecond laser surgery, intraocular lens implantation, the changing trend is:
More and more automation;
The wound on the eye is getting smaller and smaller;
More and more expensive;
In general, it’s getting safer.
To summarize, the pros and cons of these procedures are:
In general, the general requirements for myopia surgery are [6]:
Age 18+;
The degree of myopia is basically stable within 2 years (the increase of myopia degree does not exceed 50 degrees per year);
Myopia ≤1200 degrees; Astigmatism ≤600 degrees; Hyperopia ≤600 degrees.
Persons with these conditions cannot have nearsighted surgery:
Active inflammation and infection in the eye;
Insufficient corneal thickness;
Severe dry eye;
cataracts, which have progressed to affect vision;
…
However, whether each person can do it, and what kind of myopia surgery is suitable, it is still necessary to go to a regular hospital, check the various indicators of the eye, and make a decision together with the doctor.
Myopia surgery is a mature surgery because the risk of side effects is low and manageable.
However, all surgeries carry risks, and myopia surgery is no exception.
Different people and different surgeries may have different side effects [7].
Take full femtosecond laser surgery (SMILE) as an example, the possible complications are [7,8]:
(1) Dry Eye Syndrome
This is the most common complication because surgery destabilizes the tear film.
This side effect is usually temporary and can be relieved with artificial tears.
(2) Diffuse interlayer keratitis
The postoperative incidence rate ranges from 0.04% to 1.6%, and symptoms such as photophobia and vision loss may occur.
(3) Night glare, halo
Some people experience nighttime glare, halos, etc. after myopia surgery. It usually resolves on its own after a few months.
It can be seen from the above that the complications after myopia surgery are relatively minor, and the doctors have rich experience in dealing with them, which will basically not cause too much impact on life.
Here, as an extra, many people say that retinal detachment occurs after myopia surgery.
Here’s a rumor! Myopia surgery itself does not increase or decrease the risk of retinal detachment, but high myopia itself is one of the high risk factors for retinal detachment.
Most myopia is axial myopia, which means that the eye axis becomes longer and the retina is elongated, and the higher the degree, the more prone to peripheral retinal detachment [9].
Laser corneal refractive surgery has been carried out in China for nearly 30 years – from the earliest hundreds of patients per year, to 500,000 per year in 2003, and 100 per year in 2018 about 10,000 cases [10].
Not only military personnel and public officials, but many medical personnel and relatives have undergone myopia surgery.
Image source: Zhanku Hailuo
In 2008, NASA approved corneal refractive surgery for astronauts and space crews [11], and four years later published a paper saying: after myopia surgery, astronauts The eyes are not affected, this operation is a safe and effective alternative to contact lenses and spectacles [12].
After years of development, the effectiveness of myopia surgery has also been verified——
American Ophthalmology Technology Evaluation Committee 2000~2001 Refractive Surgery Group[13] reviewed 160 papers from 1968 to 2001, and screened 47 papers with sufficient clinical significance for evaluation, covering Nine high-quality randomized controlled trials found:
For myopia with low to moderate degree of myopia (≤600 degrees), good uncorrected vision can be obtained after excimer laser surgery.
Rarely.
Adults over the age of 18 with moderate to low myopia less than 500 degrees, as long as the degree does not increase by more than 100 degrees within 2 years before surgery, generally rarely rebound after surgery.
However, after myopia correction surgery, it is still possible to deepen the degree of myopia, because myopia surgery only corrects your previous degree of myopia:
Keratoplasty is equivalent to “shaving” off the degree of myopia;
IOL implantation is simply the addition of a contact lens to the eye.
If you still have unhygienic eye habits (such as excessive eye use, etc.) after surgery, myopia may continue to develop.
However, most patients undergoing excimer laser surgery and semi-femtosecond laser surgery can undergo enhanced surgery after the degree is stable.
The other is presbyopia. As with normal eyes, you will still be presbyopic after nearsighted surgery.
This is because: after the age of 45, aging may occur, which is related to the aging of the lens. Laser surgery for myopia by itself does not make presbyopia worse than in the non-surgical population [14].
Image source: Zhanku Hailuo
Have the patience to see here…
I must have seriously considered myopia surgery…
However, myopia surgery involves so many questions, we’ve chosen the main ones to answer.
Do you have any other questions about myopia surgery? Welcome to leave a comment in the comment area~
Reviewers:
Hu Liang
Deputy Chief Physician of Ophthalmology Hospital Affiliated to Wenzhou Medical University
Xianmei Zhang
Deputy Director, Department of Ophthalmology, Affiliated Hospital of Hangzhou Normal University
Guo Chungang
Director, Chief Physician, Department of Ophthalmology, Beijing You’an Hospital Affiliated to Capital Medical University
References
[1] Ophthalmology. Human Health Ninth Edition
[2] Keratology Group of Ophthalmology Branch of Chinese Medical Association. Expert consensus on clinical diagnosis and treatment of laser corneal refractive surgery (2015). Chinese Journal of Ophthalmology. 2016.51(04): 249-254.
[3]Refractive Surgery. Eighth Edition
[4]The state of the cornea after laser cutting
[5] Hu Liang, Wang Qinmei. Three technical points and prospects of all-laser corneal refractive surgery [J]. Chinese VisionJournal of Optics and Vision Science, 2016, 18(4): 193-198.
[6] National Health Commission. Guidelines for the Prevention and Treatment of Myopia.
[7]Chan C, Lawless M, Sutton G, et al. Small incision lenticule extraction (SMILE) in 2015. Clin Exp Optom. 2016;99(3):204-212.
[8]Kim TI, Alió Del Barrio JL, Wilkins M, et al. Refractive surgery. Lancet. 2019, 393(10185):2085-2098.
[9]Williams K, Hammond C. High myopia and its risks. Community Eye Health. 2019;32(105):5-6.
[10]Wang Yan, Shi Weiyun, Li Ying. Rapid development and changes of corneal refractive surgery in my country [J] . Chinese Journal of Ophthalmology, 2020,56 (02): 81-85.
[11]Gibson CR. Effect of Microgravity on the Cornea of a Refractive Surgery Subject (Visual_Acuity). nasa.gov. 2008.
[12]Gibson CR, Mader TH, Schallhorn SC, et al. Visual stability of laser vision correction in an astronaut on a Soyuz mission to the International Space Station. Journal of Cataract and Refractive Surgery . 2012. August: 38(8):1486-1491.
[13]Sugar A, Rapuano CJ, Culbertson WW, et al. Laser in situ keratomileusis for myopia and astigmatism: safety and efficacy: a report by the American Academy of Ophthalmology. Ophthalmology. 2002 , 109(1):175-187.
[14]https:https://americanrefractivesurgerycouncil.org/how-long-does-lasik-last/
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