In this blog post, we’ll explore the principles, types, preoperative examinations, postoperative care, and pros and cons of intraocular lens implantation (ICL)—an alternative to consider when LASIK or LASEK surgery isn’t feasible.
Having worn glasses since elementary school, I understand the inconvenience of glasses better than anyone. My vision was so poor that I could barely distinguish people without my glasses, and I’ve wanted to undergo vision correction surgery since I was young. That’s why I’ve now had LASEK surgery and live without glasses. However, LASIK or LASEK surgery isn’t an option for everyone. This is because laser vision correction may not be suitable depending on the condition of the cornea, visual acuity, or eye structure. In such cases, one alternative to consider is intraocular lens implantation (hereinafter referred to as ICL). For those who are not eligible for LASIK or LASEK, I’d like to explain what intraocular lens implantation is in simple terms.
LASIK and LASEK, as people generally understand them, are surgeries that use lasers to correct the cornea. LASIK involves creating a corneal flap and then using a laser to reshape the corneal stroma, while LASEK involves removing or displacing the corneal epithelium and then using a laser to reshape the cornea. Therefore, if the cornea is excessively thin or has an irregular shape, it may be difficult to undergo laser vision correction surgery. Additionally, depending on one’s occupation, separate criteria regarding the type of vision correction surgery or surgical history may apply; therefore, if you are interested in a specific profession—such as those in the aviation industry—you should verify the latest physical examination standards set by the relevant organization. In particular, laser corneal surgery may not be suitable for individuals with hereditary corneal disorders, such as Abellino corneal dystrophy. A study estimates the prevalence of Abellino corneal dystrophy in South Korea to be approximately 11.5 cases per 10,000 people; if a genetic mutation is confirmed, the decision to undergo laser vision correction should be made with caution, even if corneal thickness is sufficient.
ICL is a surgical procedure that involves inserting a special lens into the eye without using a laser to reshape the cornea. The lens is selected based on the patient’s eye structure and prescription; unlike regular contact lenses, which must be removed daily for cleaning or disinfection, the ICL can be used long-term while remaining inside the eye. Although ICLs can be used to treat high myopia, the correctable range varies depending on the lens type and country-specific approval criteria. Currently, the U.S. approval range for the leading EVO ICL is from -3.00D to -20.00D based on spherical equivalent for myopia; a separate astigmatism correction range applies for cases with astigmatism. Therefore, rather than categorically stating that ICL is a procedure capable of correcting nearly all vision conditions, it is more accurate to understand it as a procedure capable of correcting a wide range of myopia, including high myopia. Additionally, since the ICL procedure does not involve the removal of corneal tissue, it preserves the cornea; furthermore, the implanted lens can be removed or replaced at the discretion of the medical team if necessary. However, it cannot be assumed that removing the lens will always result in a complete return to the pre-operative state, and the procedure carries the risk of complications such as increased intraocular pressure, cataracts, decreased corneal endothelial cell count, inflammation, and lens dislocation.
There are several types of intraocular lenses. These include ICLs made of Collamer material and toric ICLs that correct astigmatism; there are also iris-fixated lenses such as Altis and Altiflex, which differ from ICLs in their placement method. Here, the term “ICL” may refer to the lens implanted inside the eye rather than the surgery itself, depending on the context. Artisan and Artiflex are anterior chamber lenses that are fixed in front of the iris, whereas ICLs are positioned in the posterior chamber behind the iris. In some earlier ICL surgeries, iridotomy was required prior to surgery to ensure unobstructed aqueous humor flow after lens insertion. Iridotomy is a procedure that creates a small opening in the iris to allow aqueous humor to flow freely; however, in some cases, it could lead to inflammation or light-related discomfort. The EVO ICL, featuring a central port, was developed to address these drawbacks. This lens, made of Collamer—a material developed by STAAR Surgical in the United States—is designed with biocompatibility in mind. In particular, because it features a small opening of approximately 360 μm in the center of the lens to ensure aqueous humor flow, iridotomy is generally not required before EVO ICL surgery. Therefore, the “360 m” in the original text should be corrected to “360 μm” for accuracy.
However, ICL surgery is not a procedure that can be performed simply because a patient wants it. Before surgery, a very detailed examination must be conducted to assess the structure and condition of the eye. Typically, an UBM (ultrasound biomicroscopy) examination is used to examine the internal structures of the eye and measure the depth of the anterior chamber, among other things, to evaluate whether there is sufficient space for lens implantation. In particular, if there is insufficient space between the iris and the crystalline lens, the implanted lens may come too close to or come into contact with the crystalline lens, increasing the risk of complications such as cataracts. Additionally, a comprehensive evaluation—including cycloplegic refraction, intraocular pressure and glaucoma screening, and the condition of the cornea and corneal endothelium—is necessary to determine whether the patient’s eyes are suitable for surgery. In the case of the EVO ICL as well, since several conditions must be met—including anterior chamber depth, anterior chamber angle, corneal endothelial cell count, intraocular pressure, and the presence or absence of glaucoma—surgical eligibility cannot be determined based solely on the degree of myopia.
ICL is also one of the procedures for which postoperative care is crucial. After surgery, patients must be careful not to rub their eyes, and activities such as washing the face, showering, exercising, swimming, using the sauna, and drinking alcohol must be resumed only after following the timeframe and guidelines provided by the hospital where the surgery was performed. The original text recommends washing your face with soap starting on the third day at the earliest, showering after 4–5 days, resuming exercise or travel after 2 weeks to 1 month, and avoiding alcohol for about 1 month; however, these timeframes may vary depending on the surgical method, the patient’s condition, and the medical team’s instructions. In fact, post-operative guidelines from medical institutions regarding ICL surgery often specify different restriction periods for light exercise, alcohol consumption, swimming, and saunas; therefore, it is important to follow the instructions of the medical team who performed the surgery rather than applying a one-size-fits-all timeframe.
If not properly managed, ICL surgery can lead to complications such as increased intraocular pressure, problems with aqueous humor outflow, pigment dispersion, inflammation, and cataracts. Although the EVO ICL, which features a central port, has helped reduce the need for iridotomy—a procedure required in traditional methods—this does not mean that all side effects have been eliminated.
Since ICL implantation is an intraocular procedure, it is important to undergo regular ophthalmic examinations after surgery to monitor intraocular pressure, corneal endothelial cell count, and the position of the lens. In particular, anterior chamber ICLs require caution against external impacts, and posterior chamber ICLs also necessitate ongoing monitoring of intraocular pressure and ocular condition. ICL is a procedure with many advantages, primarily because it does not involve cutting the cornea. Since no corneal tissue is removed, it avoids risks associated with laser vision correction, such as corneal flap dislocation or keratectasia, and generally carries a lower risk of dry eye caused by corneal nerve damage compared to LASIK. Another advantage is that vision recovers relatively quickly. However, it cannot be definitively stated that ICL always provides sharper vision than LASIK or LASEK, as results may vary depending on the individual’s eye condition and surgical outcome.
There are various methods of vision correction. Since the structure of the eye and visual condition differ for each individual, the most suitable surgical method may vary. Therefore, it is important to choose a surgical method appropriate for your eyes after thorough consultation with medical professionals. If you choose ICL, it is essential to carefully consider not only the type of lens and its suitability but also the skill and experience of the medical team. While LASIK and LASEK are surgeries that use laser equipment to reshape the cornea, ICL is a procedure in which the precise insertion and positioning of the lens within the eye are critical. Above all, rather than simply viewing ICL as an “alternative surgery” for those who cannot undergo LASIK or LASEK, it is better to understand it as a distinct method of vision correction that preserves the cornea while correcting vision by inserting a lens into the eye.
