Understanding the Real Risks of Laser Eye Surgery
Laser Eye Surgery has been around for almost four decades and has been successfully used to treat tens of millions of people around the world. And yet, despite its widespread availability, understanding the true risks and complications of this common elective procedure can prove challenging.
But that isn’t necessarily because the truth is particularly complicated; it isn’t even because there aren’t enough studies or data to draw from. Laser Eye Surgery can be a tricky topic because of the many opinions, agendas, and sensationalist stories out there.
At London Vision Clinic, we have always strived to be a transparent and reliable voice in the Laser Eye Surgery field. As part of this mission, we want to make understanding the potential risks of Laser Eye Surgery as easy as possible. So, with that in mind, let’s take a deep dive into everything you need to know about Laser Eye Surgery risks.
What are the Risks of Laser Eye Surgery?
Every surgical procedure, no matter how big or small, carries some risk – and Laser Eye Surgery is no exception. For example, the procedure does carry an extremely small risk of compromising your vision so that neither glasses nor contact lenses can correct it to its pre-surgery level. This is a fact.
However, it is also important to note that many Laser Eye Surgery risks are greatly variable. That is, they can differ significantly depending on a range of factors – even to a point that the risk barely exists. For this reason, understanding the risks of Laser Eye Surgery is a matter of the following:
- Talking to an expert surgeon who has experience in minimising risks and handling both foreseen and unforeseen complications and side effects, both during and after Laser Eye Surgery;
- Understanding how different clinics and surgeons manage risk;
- Assessing the possibilities of complications during and after treatment;
- Putting long-term outcomes into context;
- Learning more about specific risks and their relative chances of occurring.
So, let’s go through a few of these points in more detail. Hopefully, by the end of this page, the risks of Laser Eye Surgery will be much clearer.
The Best Way to Reduce Laser Eye Surgery Risks
While these days it might seem like having Laser Eye Surgery is as straightforward as going to the dentist, this isn’t really the case. The unfortunate fact is that the Laser Eye Surgery industry is still largely unregulated.
This can mean that standards vary significantly from clinic to clinic. Thanks to the Royal College of Ophthalmologists, there are recommended guidelines; however, not all clinics will follow these guidelines to the same standard.
Unsurprisingly, this can make the Laser Eye Surgery landscape more difficult to navigate. However, with the right tools at your disposal, you can find a high-quality clinic and feel sure that you are in the best hands.
All surgery has an element of risk
All kinds of surgical procedures come with some degree of risk, and while the vast majority of procedures are successful and complication-free, Laser Eye Surgery is no different. Neither your surgeon, optometrist, nor any clinic staff can guarantee that the procedure will be 100% effective or free from complications – and this should be made clear to you from the get-go.
The doctor conducting your initial pre-operative examination should advise you as to your proposed outcome (e.g. the chances of you seeing well without glasses or contact lenses after surgery) based on the level of your particular refractive error. They should also ensure you fully understand all risks associated with your treatment.
The safety level of laser eye clinics
One of the most important factors in managing risk is the rigorous application of safety protocols. At London Vision Clinic, our safety protocols hark back to our founder and expert surgeon, Professor Dan Reinstein‘s earlier work in the US, where he was responsible for training and controlling the quality of 58 surgeons across 28 clinics – all operating under standardised protocols defined by his research.
By studying the outcomes of these surgeons, Professor Reinstein was able to determine factors that led to better outcomes. This knowledge is now applied to our practices across our treatments.
The possibility of complications
There is a very small risk that Laser Eye Surgery – or a complication arising from the procedure – will cause visual issues that cannot be corrected with glasses or contact lenses. This may include blurriness, distortion, double vision, and glare. However, the likelihood of such complications is highly related to the thoroughness of preoperative testing, the expertise and skill of the surgeon, the equipment used and the degree of follow-up care.
London Vision Clinic has an exceedingly low complication rate. In many cases, complications that do arise can be managed immediately. However, in the event that more action is needed, your surgeon will discuss your options for further treatment. This may include medications or additional surgery.
A complication rate that’s as low as it gets
London Vision Clinic has never discharged a patient from our care with unresolved issues related to their treatment. Our safety and treatment protocols ensure that all our expert surgeons can handle any possible complications promptly and effectively.
Furthermore, our comprehensive aftercare ensures that, should any issues or concerns arise in the future, there will always be someone on hand to help. Patients of London Vision Clinic are considered patients for life. Even if you should require specialised ophthalmic care unrelated to your Laser Eye Surgery, we can refer you to the appropriate specialist.
The long-term outcomes of Laser Eye Surgery
As Laser Eye Surgery is still a relatively new procedure, there are, as yet, no very long-term publications on the procedure’s outcomes. However, around 30 million procedures have been performed successfully to date worldwide.
Professor Reinstein was one of the key contributors to the National Institute of Health and Clinical Excellence (NICE) Guidance Document on LASIK (2006), which determined that the “current evidence suggests that photorefractive (laser) surgery for the correction of refractive errors is safe and efficacious for use in appropriately selected patients.”
Since then, more studies have assessed the long-term safety and outcomes of the procedure. A literature review published in 2021 concluded that “long-term studies with follow-up periods of at least 10 years have shown that PRK and LASIK treatment carried out in the early days of medical excimer lasers have a very high level of safety and late complications occurred only rarely.”
Laser Eye Surgery Risks Described
It may not be possible to list every potential risk of complication related to Laser Eye Surgery; however, you can get a good idea of them from the tables below. While it may seem like there are many risks to be worried about, the chance of them occurring today is often exceedingly small, especially if you find a highly trained, competent surgeon.
Risks and complications that can occur during surgery
| Condition | Probability of Occurrence | Solution |
|---|---|---|
| Under-correction or over-correction | More common with higher prescriptions | Mitigated by planned 2-stage treatments; correctable with an enhancement |
| Corneal flap complications | Rare in expert hands (1 in 1000) | Mitigated by expert use of equipment; correctable with an enhancement |
| Debris under the corneal flap | Rare in expert hands and will likely not affect visual result | Mitigated by stringent adherence to superior safety protocols; correctable with an enhancement |
| Diffuse Lamellar Keratitis, or “Sands of the Sahara” | Rare in expert hands (1 in 500) | Mitigated by stringent adherence to superior safety protocols; correctable with an enhancement |
| Equipment malfunction | Extremely rare in expert hands | Mitigated by stringent adherence to superior safety protocols; correctable with an enhancement |
| Vascular occlusion | 1 in 1 million |
Risks and complications that can develop after surgery
| Condition | Probability of Occurrence | Solution |
|---|---|---|
| Dry Eyes | Common, but generally temporary | Can be mitigated with dry eye testing prior in assessment; managed with lubricating drops |
| Regression | More common in higher prescriptions | Correctable with an enhancement |
| Night vision – glare, starbursts and halos | Extremely rare, mostly temporary | Can be avoided through the use of newer lasers and high resolution wavefront aberrometers; correctable with an enhancement |
| Light sensitivity, fluctuating vision | Very rare, mostly temporary | Will decrease in time |
| Infection | Very, very rare (1 in 5,000), extremely low chance of affecting visual result | Can be avoided through stringent safety protocols; can be managed with antibiotics |
| Excessive corneal haze | Part of the healing process in surface procedures ( PRK / LASEK); higher risk in higher prescriptions | Dependent on smoothness of the surface created by the laser; will often disappear; correctable with an enhancement |
| Fragility on impact | Part of the healing process 3 months after LASIK | Can be mitigated by following aftercare instructions |
| Corneal ectasia | Extremely rare | Can be mitigated by screening for keratoconus or unusually thin corneas using Artemis Insight 100 |
| Epithelial erosion | Rare (1 in 500), more in older patients | Can be identified before surgery; can be managed by a bandaged contact lens |
| Epithelial ingrowth | Rare (1 in 100) | Can be corrected with an enhancement |
| Other extremely rare complications | Extremely rare (1 in 50,000) | Dependent on complication |
A Closer Look at Laser Eye Surgery Risks and Complications
Under-Correction or Over-Correction
While often classed as such, technically speaking, under- or over-correction of your prescription is not really a complication. That’s because distortion resulting from under- or over-correction can be corrected with glasses or contact lenses to the level before surgery.
Such cases can arise despite all precautions and can be related to the healing response of the eye post-surgery. This can lead to slight inaccuracies in the final correction. However, the risk of under- or over-correction increases with the use of older lasers or lasers with less strict maintenance schedules. Clinics that do not employ a digital statistical system for fine-tuning the treatment parameters may risk having more complications.
The good news is that this issue can generally be resolved with a routine enhancement procedure; however, in a small number of cases, patients may not have sufficient remaining corneal tissue to undergo this second treatment. If we think you would benefit from an enhancement procedure, your surgeon will discuss your options with you. Enhancement procedures are offered free of charge at London Vision Clinic.
Corneal Flap Complications
Several complications can occur during the creation of the corneal flap. The flap may be too thin, too thick, uneven, or too short, or it may wrinkle, become displaced, or have problems healing. In some cases, the surgeon may recommend postponing your LASIK treatment until a new corneal flap can be created safely.
Quoted corneal flap complication rates in the medical literature range from 0.3 percent to 1.0 percent. In contrast, London Vision Clinic’s corneal flap complication rate is closer to 0.1 percent.
Debris Under the Corneal Flap
A small amount of debris or tissue can become trapped under the cornal flap after the LASIK procedure. This may be debris from the surgical instruments, oil from the tear film, or other floating material.
Your surgeon may opt to perform an irrigation to remove this debris in the immediate post-operative period. However, in most cases, debris under the corneal flap does not affect the patient’s visual results and can be left in place and monitored without further surgical intervention.
Furthermore, thanks to the advancement of Laser Eye Surgery technology, this complication is exceptionally rare at the right clinics.
Diffuse Lamellar Keratitis or “Sands of the Sahara”
Around one in every 500 patients experiences a temporary inflammatory reaction beneath the corneal flap after LASIK. This is known as Sporadic Diffuse Lamellar Keratitis (Sporadic DLK). It may also be called “Sands of the Sahara”.
Patients with DLK may experience blurred vision and tearing, which can last from several days to a number of weeks. In some cases, this can delay the eye’s healing process. However, other patients with DLK may not present with any symptoms.
DLK can usually be managed with the use of supplemental topical steroid eye drops with no longer-term effects. In some cases, significant levels of DLK may reduce the accuracy of vision correction, increasing the likelihood that an enhancement procedure will be required.
Equipment Malfunction
As its name implies, Laser Eye Surgery is a high-tech procedure that requires high-quality equipment. But more than this, all instruments and equipment used in the process should be well maintained to manufacturer specifications. This can help to safeguard against equipment malfunction.
However, in rare cases, malfunction can occur, potentially resulting in damage to the patient’s vision or eye. Of course such occurrences are extremely rare and malfunctions are likely to be spotted before the commencement of treatments. In such cases, the procedure will likely be rescheduled. Thankfully, the use of more modern equipment, such as that used at London Vision Clinic, can minimise this risk even further.
Vascular Occlusion
The process of creating a corneal flap in LASIK involves placing a suction ring over the eye. This temporarily increases the pressure in the eye, and many patients will notice that their vision will dim or fade completely. This is usually nothing to worry about, and vision is restored once the suction ring is removed.
However, there is a very small risk that this temporary disruption of blood flow in the eye can cause permanent damage to the retina. This can technically result in permanent loss of vision. This possible occurrence has a theoretical probability of less than 1 in 1,000,000, which is again reduced even further according to the technology and surgeon.
Dry Eyes
Dry eye is a very common side effect of Laser Eye Surgery. It occurs due to disruption to the tear film during treatment. However, this condition is generally temporary and can be managed with the help of lubricating eye drops that are provided as part of your routine aftercare package.
In some cases, further treatment may be required, usually in the form of punctal plugs. These temporary inserts prevent the normal drainage of tears into the nose, helping to keep the eyes lubricated.
Dry eye almost always improves within a few months after treatment, but in rare instances, it can continue for longer periods of time and may require long-term use of lubricant drops and permanent plugs. Patients who have dry eyes before LASIK or PRK/LASEK treatment are more likely to experience more severe dry eye symptoms after the procedure. Conducting a thorough screening is important in limiting this risk.
Regression
LASIK involves removing tissue from the stroma – the thickest, middle layer of the cornea – to reshape the cornea. Once this process is complete and the corneal flap is put back in place, the surface epithelium can thicken to compensate for this change. This can happen to a varying degree among patients.
For some patients, this thickening can be negligible, leading to a stable and immediate result. However, in some cases, this can result in the regression of vision. This is more likely to occur in patients with higher prescriptions. In most cases, this can be addressed with further treatment; however, this will depend on the safety parameters set out by your surgeon.
Glare, Starbursts, and Halos
Laser Eye Surgery triggers the eyes’ inflammatory response, which can cause swelling. This swelling can be associated with glare around light sources, particularly at night or in low-light conditions. The most common optical glare effects are called “halos” and “starbursts”.
These nighttime side effects typically last between two weeks and three months, easing off as the swelling in the eyes begins to settle. However, in rare cases, glare symptoms can be longer-lasting and even permanent.
This is more common with treatments performed with older lasers that do not have the most sophisticated software (known as aspheric profiles). More severe halos and starbursts are also more common in patients with high prescriptions and those with larger pupils.
Zeiss incorporates many of Professor Reinstein’s findings in the Carl Zeiss Meditec MEL90 excimer laser system in use at the clinic today. It is, therefore, extremely rare for patients in our practice to end up with severe night vision disturbances.
Light Sensitivity and Fluctuating Vision
Some patients may experience increased sensitivity to light or fluctuations in their visual acuity for a period following their treatment. These symptoms are usually temporary and will resolve themselves as the eye heals. This typically takes a few weeks to a few months. However, in some rare instances, light sensitivity and fluctuating vision can persist for longer.
Infection
Even relative to other complications on this list, infections in Laser Eye Surgery are extremely rare. The rate of infections is generally quoted at approximately 1 in 5,000 cases. Of course, the risk can be higher or lower depending on several factors, including the technique used, the surgeon, and the clinic’s safety protocols.
Close monitoring in the days and weeks after your treatment ensures that signs of infection are spotted early. In most cases, this can be managed with antibiotics with a low risk of any detriment to the final visual outcomes.
Excessive Corneal Haze
Corneal haze is commonly seen following surface procedures such as PRK and LASEK. In these settings, this symptom is considered a normal part of the healing process and typically subsides with little to no lasting effects on the patient’s vision. In some cases, corneal haze may require additional treatment with medications or further surgical intervention.
However, corneal haze is extremely unusual following LASIK and is even rarer in newer treatments. The risk of haze in PRK/LASEK increases with the severity of the prescription to be treated. Other factors that can play a role include the smoothness of the surface created by the laser and the protocols for postoperative management of the cornea.
Fragility on Impact
The corneal flap begins to fuse to the rest of the corneal epithelium almost immediately after LASIK. However, it will remain somewhat sensitive to direct trauma – such as being hit in the eye – for around three months.
After the first month, as the eye begins to regain much of its previous strength, the impact required to dislodge the flap would be rather severe. Nonetheless, it is important to avoid contact sports, such as rugby or martial arts, during this period. Any other activities that could potentially lead to contact with the eye should also be avoided.
Corneal Ectasia
A certain amount of corneal tissue must be left untouched during Laser Eye Surgery treatment. This helps to ensure the long-term stability of the cornea. In very rare cases, less tissue may remain than intended.
This can result in the forward bulging or progressive deformity of the cornea. This progressive deformation is known as ectasia.
Corneal ectasia can be treated with corneal collagen cross-linking (CXL) treatment, by suturing the flap to the underlying corneal tissue or, in rare cases, with a corneal transplant. The probability of progressive ectasia at the time of writing, given our protocols and technology, is estimated to be 1 in 20,000.
Epithelial Erosion
The corneal epithelium is the surface layer of cells that protects the stromal layer beneath. If this layer is removed, it typically grows back within a matter of days. This is the case in PRK/LASEK surgery.
In LASIK, a corneal flap is cut through the epithelium and the stroma. In some patients, there may be less attachment between the epithelium and the underlying stroma, which can increase the risk of epithelial scratching or epithelial “sliding”. This is more likely in older patients as they are more likely to have areas of weakened surface epithelium.
We can often identify patients at risk of this complication; however, in some cases, there may not be any obvious pre-operative clues that this is the case. This is estimated to be the case for around 1 in 500 patients.
When this complication occurs, the surgeon will place a bandage contact lens over the cornea. This assists in the healing process and helps to reduce any discomfort. However, patients who experience an epithelial slide, abrasion, or erosion may experience a longer recovery period and may be at risk of further complications, including infection, inflammation, recurrent erosions, corneal flap wrinkles, or epithelial ingrowth.
In the event of a severe epithelial scratch, your surgeon will still typically be able to perform laser treatment. However, they may recommend delaying the LASIK procedure on the second eye until the vision has improved in the first eye. The risk of such corneal complications is all but eradicated with the minimally-invasive ReLEx SMILE procedure.
Epithelial Ingrowth
Epithelial ingrowth occurs when cells from the surface of the cornea begin to grow under the edge of the corneal flap. In most cases, the vast majority of these cells regress on their own; however, if the cells continue to grow, they can affect the underlying tissue.
This can have several effects, including the development of astigmatism, corneal flap edge thinning, and reduction in quality of vision. A surgeon will generally observe the progression of epithelial ingrowth and provide medication. In some cases, further surgery may be required to remove the epithelial cells. This complication occurs in less than 1 percent of LASIK cases.
Other Extremely Rare Complications
Several further potential complications of Laser Eye Surgery have been either documented or proposed; however, these are extremely rare. They include intraocular haemorrhage, permanent corneal swelling, retinal detachment, venous or arterial blockage, and drug reactions.
Furthermore, there is technically an exceedingly small risk of blindness when undergoing Laser Eye Surgery. However, this risk is lower than the risk of blindness associated with wearing monthly contact lenses for one year.
If you’d like to learn more about the potential risks and complications associated with Laser Eye Surgery, get in touch with one of our friendly clinic coordinators. Alternatively, to learn more about your suitability for treatment, Book a Consultation today.
