Laser Eye Surgery Guide to PRK/LASEK, LASIK, and SMILE
(Updated for 2025)
Research is supposed to help people feel more informed, but those looking into Laser Eye Surgery are often left more confused. From the endless jargon and acronyms to the daunting list of potential procedures, many people may be put off before they even begin.
But the fact is, you only really need to know about three Laser Eye Surgery procedures: PRK/LASEK, LASIK, and SMILE.
During your research, you’ll likely encounter terms such as UltraLASIK, UltraLASIK plus, Accu-Wave LASIK, Custom LASIK, Wavefront LASIK, and Zyoptix. While this can be confusing, the truth is that each of these names refers to the same treatment, albeit packaged slightly differently. For example, some clinics offer a basic LASIK treatment and charge extra for using additional technology such as Wavefront. At London Vision Clinic, Wavefront-guided LASIK is offered as standard.
We believe all patients should be offered the very best Laser Eye Surgery treatment, free from hidden costs and extras. That’s why our treatment costs cover everything, from your procedure to your aftercare appointments and everything in between.
But let’s get back to those three types of Laser Eye Surgery procedures. What’s the difference between PRK/LASEK, LASIK, and SMILE? In this comprehensive guide to Laser Eye Surgery, we’ll cover everything you need to know.
How Does Laser Eye Surgery Work?
All Laser Eye Surgery procedures are based on the same principle: Using laser technology to reshape the cornea. Removing tissue from the cornea allows us to change the way light is refracted into the eye, correcting the existing refractive error.
Using this principle, Laser Eye Surgeons can correct a full range of errors, including myopia (short-sightedness), hyperopia (long-sightedness), astigmatism, and presbyopia (ageing eyes). Our expert surgeon, Mr Glenn Carp, tells us more in the video below.
This epithelium – surface layer – of the cornea is extremely durable, protecting our eyes from dust, debris, and wind; however, it is also incredibly thin. This means that the cells of the epithelium can completely repopulate in just 7-14 days. As Mr Carp explains, the first step in any Laser Eye Surgery procedure is to remove a layer of the corneal epithelium to allow access to the tissue beneath. The key difference between the three types of Laser Eye Surgery procedures is how this is achieved.
The Main Difference Between SMILE, LASIK, and PRK/LASEK Laser Eye Surgery
PRK/LASEK – The Surface Procedures
PRK – photorefractive keratomileusis – is the oldest and most invasive form of Laser Eye Surgery. It involves the complete removal of a portion of the epithelium. This tissue is discarded and once the treatment is complete, a protective contact lens is placed over the exposed area of the eye. This lens remains in place while the epithelium re-grows.
LASEK is extremely similar to PRK – both are known as “surface procedures” or “surface ablation procedures” – in that a portion of the epithelium is completely removed. However, in LASIK, this tissue is temporarily pushed aside to allow access to the corneal bed beneath. Once the treatment is complete, the surface layer of tissue is put back in place and, again, covered with a protective contact lens to protect the eye while the tissue heals.
LASIK – The Corneal Flap
LASIK is the most common type of Laser Eye Surgery. Unlike PRK and LASEK, it does not involve the complete removal of epithelium. Instead, a high-precision laser is used to create a thin, hinged flap in the surface layer of the cornea. When folded back, the surgeon can use this flap like a door to access and reshape the tissue beneath.
Once the treatment is complete, the corneal flap is simply put back in place where the edges immediately begin fuse to the rest of the epithelium. The rapid healing power of the eye means that LASIK doesn’t require the use of protective contact lenses.
SMILE – The Keyhole Procedure
ReLEx SMILE – also known simply as “SMILE” – is the latest innovation in Laser Eye Surgery. It is the least invasive Laser Eye Surgery procedure, avoiding both the removal of epithelium and the creation of a corneal flap.
Instead, SMILE involves creating a small “keyhole” incision on the surface of the eye. State-of-the-art laser technology is then used to deliver small pulses, creating a tiny connected tunnel from the surface of the eye to the corneal bed. Through this tunnel, the surgeon can remove a pre-determined area of corneal tissue which can then be drawn out of the eye. The minimally invasive nature of the SMILE procedure means that the eye begins to heal almost immediately.
So, now that we’ve covered the basics of PRK/LASEK, LASIK, and ReLEx SMILE, let’s take a look at the pros and cons of each procedure.
ReLEx SMILE: A Revolutionary Laser Eye Surgery Procedure
“Generally speaking, traditional Laser Eye Surgery can only correct prescriptions up to a maximum of between -8 and -10… With ReLEx Laser Eye Surgery treatment at London Vision Clinic, people with thin corneas and those with prescriptions of higher than -10 can be treated, because we do not make a flap from the corneal surface.” — Prof Dan Reinstein
ReLEx SMILE (Refractive Lenticule Extraction/Small Incision Lenticule Extraction) is the latest development in Laser Eye Surgery. SMILE eliminates the need for surface ablation or a corneal flap. As a result, SMILE’s “keyhole” approach makes for a much less invasive procedure than its predecessors.
Co-created by London Vision Clinic founder and expert Laser Eye Surgeon, Professor Dan Reinstein, the Carl Zeiss VisuMax laser makes this groundbreaking procedure possible. In addition to being the only laser in the world with the precision required to perform the SMILE procedure, the state-of-the-art VisuMax laser also limits the amount of pressure in the eye. This means that the patient feels almost nothing during their treatment!
But, how does it work?
The VisuMax laser utilises 3D placement to deliver pulses from the surface of the cornea, creating a series of tiny bubbles (less than 1/1000th the width of a human hair). These bubbles form a small tunnel from the surface right through to the corneal tissue that needs to be removed. Finally, the removed tissue is drawn through this tunnel, leaving the corrected cornea to heal.
While this might sound complex, the procedure can usually be completed in less than four minutes. This makes SMILE the fastest Laser Eye Surgery procedure. In the video below, you can see a ReLEx SMILE procedure performed in real time!
The Pros of ReLEx SMILE
Safety and Comfort: The minimally invasive nature of ReLEx SMILE makes for a faster and more comfortable experience for patients – both during and after the procedure. The keyhole approach helps to retain the strength of the cornea, which can help to significantly reduce the severity and duration of common Laser Eye Surgery side effects such as dry eyes.
Treatment and Recovery Time: Perhaps one of the biggest benefits of this procedure doesn’t become apparent until after the surgery. SMILE offers the fastest recovery time of all Laser EyeSurgery procedures. While the procedure itself is over in minutes, many patients will find that the surface of their eyes is healed in just a matter of days.
Suitability and High Prescriptions: The development of ReLEx SMILE opened up the possibility of Laser Eye Surgery to more people than ever before, including many who may have been previously found unsuitable for treatment. Leaving the surface layer of the cornea intact allows for more demanding prescriptions to be safely treated. Moreover, patients with pre-operative dry eyes or thinner corneas are often also candidates for SMILE.
Each procedure has its benefits, but we evaluate the suitability of each treatment on a patient-by-patient basis. At London Vision Clinic, all three procedures are charged at the same rate and are all discussed openly with our patients. However, as mentioned before, there will always be a reason for me to choose one procedure over another for any particular patient; I do not offer “options” and allow the patient to choose the procedure. It’s all or nothing with only the best option on the table.
The Cons of ReLEx SMILE
Limited Prescriptions: SMILE can often be used to treat higher prescriptions than other kinds of Laser Eye Surgery; however, it is not suitable for everyone. In particular, patients with more severe long-sightedness (hyperopia) may not be candidates for ReLEx SMILE.
Availability: As our founder, Professor Reinstein, helped to develop this innovative treatment, London Vision Clinic was the first Laser Eye Surgery clinic in the UK to offer ReLEx SMILE. But while SMILE was developed over a decade ago, not all Laser Eye Surgery clinics have access to the technology required to perform this revolutionary procedure. In fact, SMILE is still only available at a select few clinics across the UK.
The reality is that even in SMILE’s relative infancy compared to LASIK, the results are impressive. SMILE means that clinics are now able to offer procedures that best suit their patients and add another tool for refractive surgeons to use to help best serve their patients. With over 1.5 million procedures performed to date, this is proving a great option for many patients.
In fact, we have written a textbook on SMILE, which was released in April 2018, with many chapters dedicated to educating Surgeons on the procedure and busting any myths out there.
LASIK: The Staple of the Laser Eye Surgery World
“Aside from the “keyhole” SMILE procedure, there are essentially two groups of Laser Eye Surgery treatments. LASIK involves creating a flap in the cornea, and there are surface treatments, which we know are PRK, LASIK, Epi-LASIK etc. The main difference between the groups is the healing time. The results themselves are pretty much the same three months down the line, but it is how you travel, how your journey is in the interim that makes a big difference, and LASIK offers a rapid healing time.” – Mr Glenn Carp
LASIK (Laser-assisted in situ keratomileusis) was approved for use in refractive surgery in the late 1990s – representing a huge development in the Laser Eye Surgery field. Since then, LASIK has remained the most popular form of the treatment, and as such, one of the most popular elective procedures in the world.
The corneal flap that characterises LASIK helped to significantly reduce recovery times compared with surface procedures (PRK/LASEK). As a result, the vast majority of patients can return to many of their usual activities – including returning to work – within a couple of days of their treatment. In the video below, you can see a LASIK procedure performed in real time!
The Pros of LASIK
Recovery Time: While more significant than the keyhole incision created in SMILE, the corneal flap causes much less disruption to the surface of the eye when compared to surface ablation. This allows for much faster recovery times than those seen with PRK or LASEK.
It Can Treat Wavefront Errors: Wavefront errors are higher-order aberrations that can affect our quality of vision, outside of your refractive error. These errors account for around 5% of our overall vision quality. While glasses and contact lenses can treat refractive errors like long- and short-sightedness, they cannot correct wavefront irregularities. Wavefront-guided LASIK (which is offered, as standard, at London Vision Clinic) can correct many of these errors.
The Cons of LASIK
Treatment Options: As we mentioned earlier, there are many variations on LASIK treatment which have swamped the marketplace, causing confusion for prospective patients. As a result, patients may be uncertain of the treatment they are getting – and whether it is the best option for them. It is therefore important to opt for a reliable clinic with clear and transparent fees, and always prepare some important questions to ask at your consultation.
Safety and Comfort: LASIK is less invasive than its surface ablation predecessors. Nonetheless, it may still be associated with some discomfort during and following treatment. The good news is that this discomfort is usually effectively managed with the help of lubricating eye drops and over-the-counter painkillers.
Minor Side Effects: Laser Eye Surgery, in general, can be associated with a few side effects, including dry eyes and night vision disturbances. Typically, these side effects are mild and easily managed with the aftercare provided by your clinic. However, post-LASIK dry eye symptoms typically last for around 3-6 months.
PRK and LASEK: The Grandparents of Laser Eye Surgery
“With PRK we are able to treat all refractive errors. We can treat the full range of myopia, astigmatism and long-sighted treatments, hyperopia. However, it is less predictable for hyperopia when compared to short-sightedness, myopia and astigmatism.” —Mr Glenn Carp
Photo-Refractive Keratectomy (PRK) is the oldest form of Laser Eye Surgery. It has been used to successfully treat the refractive errors of millions of patients since its introduction in the 1980s. It was the first refractive surgery to apply the excimer laser – an ultra-precise alternative to the microkeratome used in traditional blade-based treatments.
After PRK, LASEK was the next major development in Laser Eye Surgery. This technique removed the need for the epithelium to completely repopulate, instead allowing for the removed epithelial tissue to be put back in place. It was initially expected that this would help to reduce post-operative side effects and speed up recovery; however, scientific studies indicate no significant difference between PRK and LASEK.
PRK and LASEK remain good options for correcting a wide range of refractive errors; however, thanks to the option of more modern techniques, these procedures are usually only offered when LASIK or SMILE is not suitable.
The Pros of PRK/LASEK Laser
Better Option for Some: As mentioned earlier, PRK and LASEK can be used to treat the full range of refractive errors. Furthermore, it is often a good option for patients who are unsuitable for SMILE or LASIK. For example, patients with higher prescriptions who also have thin corneas may be offered PRK/LASEK as their eyes cannot accommodate a corneal flap. Patients with co-existing eye issues such as scars or loose surface epithelium may also benefit from this treatment.
The Cons of PRK/LASEK Laser Eye Surgery
Recovery Time: The surface procedures are the most invasive forms of Laser Eye Surgery. As a result, recovery and healing times can be significantly longer than those of LASIK and SMILE. For example, it can take 7-14 days for the surface of the treatment area to heal sufficiently. This means it can take longer for patients to be able to return to normal activities.
Safety and Comfort: Like all Laser Eye Surgery procedures, PRK/LASEK treatment is generally pain-free; however, as the procedure is more invasive, patients may experience more discomfort in the days after their surgery. Still, this discomfort is usually managed effectively with painkillers and eye drops, which are provided by your clinic.
Summary
It can often seem that there is an endless list of Laser Eye Surgery options, which can make going ahead with treatment more daunting than it needs to be. But, as we have explained in this guide, things are actually much simpler than they first appear.
In reality, there are only really three Laser Eye Surgery treatments you need to be aware of – and what’s more, the vast majority of patients will have either LASIK or ReLEx SMILE! For now, LASIK remains the most popular option; however, the new kid on the block may soon take this crown. As ReLEx SMILE becomes more widely available, a greater number of people may soon benefit from its less invasive nature and faster healing times.
Opting for a higher-quality Laser Eye Surgery clinic will help to make the whole process smoother and less confusing, from your initial consultation to your final aftercare appointment. By choosing London Vision Clinic, you can be sure that an experienced surgeon will always offer you the best option for you with clear and transparent prices.
Do you want to learn more about PRK/LASEK, LASIK, or ReLEx SMILE? One of our friendly clinic coordinators is always on hand to answer any questions. Alternatively, to start your Laser Eye Surgery journey, Book a Consultation today.
