As mentioned in our previous blog posts, the two main types of refractive surgery available today include keratoconus and crystalline refractive surgery. In the previous lecture, we mainly reviewed the corneal refractive surgery with you, and today, we will review about the crystalline refractive surgery with you. The most widely used type of crystalline refractive surgery is the ICL crystalline lens implantation. The principle of the surgery is very easy to understand, it is equivalent to putting a contact lens inside the eye. Nowadays, there are several different brands of IOLs, but comparatively speaking, the one with the best overall evaluation in all aspects is the ICL lens. Li Haiyan, Department of Ophthalmology, Shanghai Xinhua Hospital ICL belongs to the posterior chamber type of IOL, that is to say, ICL is placed in the posterior chamber, that is, between the iris and the person’s own lens. See the picture below for the exact location. Of course, the fact that the lens is transparent and has no color, the green part in front indicates the iris, and the red part behind indicates the person’s own natural lens. One of the important features of the ICL compared to other IOLs is that the material used to make it is very special. The crystal material is Collamer’s high-tech patented material, which is a collagen-like material that has no rejection in the human body. the ICL is manufactured by STAAR, and the factory where the ICL is made is in Switzerland. Currently the production cycle of this ICL lens is quite long, so it is possible that patients may have to wait some time after booking before the surgery. Especially for lenses with astigmatism, which are usually not stocked in China and need to be ordered from Switzerland, the waiting time will be longer. The ICL lens, in its true form, is a very thin lens that is soft and can be placed in the eye through only a very small incision. Unlike corneal refractive surgery, the main feature of ICL implantation is the “additive principle”, which means that the operating room “adds” something to the eye, whereas corneal surgery is the “subtractive principle”. Corneal surgery is “subtractive”, that is, it “subtracts” tissue from the eye. This makes it clear why lens implantation is safe. Theoretically, the “additive principle” of surgery is reversible, and what is put in can be taken out, while the “subtractive principle” of surgery is irreversible, and what is subtracted from the eye is impossible to restore. Of course, this does not mean that corneal surgery is unsafe. For lower myopia, the tissue ablated by the laser in corneal surgery is also very small, and the thickness of the cornea is still retained within a safe range after the surgery, so there will be no safety issues. However, for high myopia, more corneal tissue is cut if corrected by laser surgery. The surgery is designed not to go beyond the safe range. Therefore, for very high myopia, in corneal laser surgery, sometimes the diameter of the optical zone needs to be reduced in order to minimize the degree of myopia, in which case the pupil becomes bigger and the quality of vision decreases when the light is dimmer after the surgery, for example, when driving a car in the evening, the viewing of the light may be glare, thus affecting the safety of driving. The results achieved through ICL implantation surgery, on the other hand, are much better. Because the ICL lens is placed directly behind the pupil, the actual quality of vision achieved is superior to that of an optical area of the same size cornea. The following chart from the website provides a visual comparison between ICL and corneal surgery. On STAAR’s website, they also summarize some of the advantages of ICL surgery, which are summarized as the “Six Advantages”, and we list them as follows: Safety ICL does not remove or destroy corneal tissue, and is becoming the fastest growing trend in the world due to its superior results that cannot be matched by laser surgery. Reversible Unlike contact lenses, ICL lenses can be permanently implanted in the eye. If a myopic patient needs other eye surgery, the ICL can be removed without causing any structural changes in the eye or cornea. High Definition Restore your eyes to a superior high definition quality of vision, with corrected visual acuity that meets or exceeds pre-corrected corrected visual acuity. Rigorous Exhaustive pre-operative testing and preparation, customized lenses made by Swiss precision craftsmen, and a team of international VISIAN ICL-certified surgeons. Protection The ICL material contains UV-blocking genes, which can organize the entry of harmful UV rays into the eye, thus effectively curbing the eye diseases caused by UV rays. Comfort The stable position of the ICL in the eye ensures that it works in harmony with your eye. Once the lens is implanted in the eye, not only can you not see or feel the presence of the lens. The Range of Myopia the ICL Can Correct Many people are concerned about how many degrees of myopia the ICL can correct. The recommendation of STAAR is 200 degrees to 2000 degrees of myopia. However, in actual clinical work, there will be some factors to consider: 1. For lower myopia, such as myopia of 600 degrees or less, and sufficient corneal thickness, the ideal visual quality can also be achieved through corneal refractive surgery. Most doctors in China will prefer laser corneal refractive surgery. On the one hand, the cost of this type of surgery will be significantly lower than ICL implantation surgery. On the other hand, corneal surgery does not require any special preoperative preparation, and you can even have the surgery the next day after having the examination on the previous day, whereas ICL requires a longer waiting time before the surgery, and the requirement of postoperative review is higher than that of keratoconus laser surgery. 2. If you have astigmatism, the correction of myopia by ICL will not be able to reach 2000 degrees. Due to the limitation of the production process of the intraocular lens itself, it is not possible to increase the number of corrected degrees indefinitely. For example, an eye with 2000 diopters of myopia and 500 diopters of astigmatism. If you choose lenses with astigmatism, your myopia may only be corrected by 1500 degrees. Of course, this is only a rough calculation, specific to each eye, the number of degrees of correction will be somewhat different. 3, then, myopia more than 2000 degrees, is it not possible to operate? In fact, it is also possible to operate, you can consider undercorrection. For myopia of more than 2,000 diopters, which may also be accompanied by astigmatism, we can actually correct most of the myopia through ICL, leaving some diopters. The remaining degrees of myopia and astigmatism can be corrected with glasses or through laser corneal surgery. What are the requirements to consider ICL surgery? 1. Be at least 18 years old and under 50 years old. The optimal age for correction recommended by STAAR is 21-45 years old, but in practice, the decision is made on a patient-by-patient basis. I do my own surgery patients, the maximum age of 55 years old, is myopia is very high, its own intraocular conditions are relatively good, there is no crystal clouding and fundus disease, the patient itself wants to improve the quality of life through surgery. 2. Myopia is generally recommended -2.0D to -20D, astigmatism ≤5D; hyperopia +2D ~ +10D. No history of internal eye surgery and intraocular pigment membrane, retina and glaucoma and other pathologies, good corrected vision. 3. Routine examination of the cornea has not become, the structure of the atrial angle is not abnormal, the intraocular pressure is normal. 4. Depth of anterior chamber ≥2.8mm. 5. Corneal endothelial cell count >2500/mO. 6. Complementary correction of high refractive errors involved in various laser surgeries. 7.No mental illness, with a reasonable desire for lens removal and appropriate postoperative expectations of the mind. Which cases are not recommended to do ICL implantation surgery? 1.Patients with unstable myopia. 2, Age less than 18 years old or more than 50 years old 3, Those with anterior chamber depth ACD<2.8mm (distance from corneal endothelium to anterior surface of lens) 4, Low corneal endothelial cell counts, corneal degeneration or corneal endothelial cell counts <2500/m 5, Patients with insulin-dependent diabetes mellitus. 6, Either eye is glaucoma or cataract or diagnosed with high intraocular pressure. 7, The patient has systemic collagen sensitivity or autoimmune disease. 8, Active inflammation or tumor of the eye and ocular appendages. 9.Psychological abnormalities without the permission of psychological or psychiatric doctors for surgery. 10.Female pregnancy, breastfeeding. What do I need to do before ICL surgery? The first thing you need to do is a comprehensive pre-operative examination. Usually an appointment is made to come to the hospital for the examination, and it is recommended to stop wearing contact lenses for 1 week before coming to the hospital for the examination. There are many checkup items, including optometry, corneal topography, corneal endothelial count, funduscopic examination, anterior chamber depth measurement and so on. The examination usually takes at least 2 hours. Due to the dilated pupil examination, you cannot drive on the day of your appointment. After a thorough examination to make sure that your eyes are suitable for ICL surgery, you will also have to come to the hospital at least once for preoperative preparation. Another optometry will be needed to determine the refractive error of the eye and to book the crystalline lens. In addition, there is a special pre-operative treatment called YAG laser iris perforation. This is where a small hole is cut through the iris of the eye by laser. This is to prevent an increase in intraocular pressure. After the iris punch, your eyes will be blurry, especially within an hour after the laser has just been applied. You will also not be able to drive or wear contact lenses that day. The waiting period after ordering lenses usually takes from 1 week to 6 weeks. In the case of lenses without astigmatism, they usually arrive within 1 week (they are stocked domestically). In the case of lenses with astigmatism, the waiting time may take 3-6 weeks and need to be customized from Switzerland. What to Expect After Surgery The ICL implant surgery itself is a very short procedure, usually done within 10 minutes. A few hours after surgery, the eyes will be able to see. However, just because the recovery from the surgery is quick, it does not mean that you can take it lightly after the surgery. Postoperative follow-up is very important. Generally, the first day, one week, one month, three months, six months, and one year after surgery. In the future, yearly checkups are also recommended. High myopia itself may cause some problems such as fundopathy, so the review is not only for the ICL surgery itself, but also for the overall condition of the eye.