Is ReLEx® SMILE® the best option for dry eyes? Or can I still do LASIK?

Suitability for Lasik / Refractive Surgery is a common concern of patients with dry eyes.

It is well established that post-Lasik, patients experience longer periods of reduced cornea sensitivity and symptomatic dry eyes.

This is thought to be related to the cornea nerves being severed at the nasal and temporal limbus during creation of the flap.

However dry eyes per se doesn’t automatically disqualify you from having Lasik performed.

This is because most patients with symptomatic dry eyes can be optimised before surgery so that they may get better results after surgery. A complete pre-surgical examination with your Ophthalmologist is recommended.

SmILE / ReLEx is a great option for patients considering Lasik, especially if they have symptomatic dry eyes.

It is postulated that the all-femtosecond procedure cleaves the lenticule within the intrastromal bed of the cornea, and hence spares a significant quantity of corneal nerves as it does not require the creation of the corneal flap.

Several case-series studies have demonstrated that:

1. Corneal sensation returns more rapidly after SmILE

2. There have been anecdotal reports of less problems with dry eyes.

As SmILE is a relatively young procedure, there are no truly objective (direct head-to-head controlled, blinded-observer) studies that have evaluated these reports.

So, to summarise that super-long answer:

1. Dry eyes does not disqualify you from having Lasik.

2. I would suggest a thorough evaluation by your Ophthalmologist as he may be further able to optimise your condition prior to having any surgery.

3. If you do choose to have Lasik surgery performed, SmILE is a great option for dry eyes as it theoretically and on several objective parameters seems to perform better for patients with dry eyes (including more rapid return of corneal sensation, and normalisation of Schirmer tear break-up times).

Hope this is helpful!

Current options available for laser vision correction include LASIK and ReLEx SMILE that are cornea flap-based procedures, and also no flap Advanced Surface Ablation methods like TransPRK.

During LASIK, the doctor will have to cut your cornea to create an external flap. This will result in cut corneal nerve endings, increasing the risk of dry eyes.

In ReLEx SMILE, the cut made to your cornea is smaller than in LASIK and thus, the incidence of dry eyes is lower as compared to LASIK.

However, TransPRK is a surface-based, no cut no flap procedure that has been shown in scientific studies to have a lower incidence of dry eye complications.

If you have dry eyes, it is best not to opt for a procedure that involves cutting a corneal flap. Instead, you may want to opt for a surface-based procedure like TransPRK.

In any case, do see your ophthalmologist to do a thorough evaluation of your eyes before deciding on any procedure 🙂

Let’s take a step back first, and see if we can answer this question:

Why do people get dry eyes after LASIK?

Most eyes do get somewhat drier after any kind of laser corneal refractive surgery, whether it is LASIK, PRK/epiLASIK, or SMILE.

This induction of dryness is related to several factors, such as:

1. Disturbance of corneal surface innervation

2. Alteration of corneal surface shape

3. Effects of various anaesthetic/antibiotic/anti-inflammatory eyedrops during and after surgery.

Possibly the more significant difference between these methods is how corneal surface innervation is affected.

This is important since reduced corneal sensation is thought to reduce dryness feedback and contribute to reduced tear secretion.

How much disturbance to corneal surface innervation is there for the various surgical procedures (LASIK/SMILE/PRK/epiLASIK)?

In LASIK, most of the corneal nerve ends to the flap are ‘disconnected’, except at the hinge area of the flap.

However, since the flap is very thin, the distance which the nerves need to grow back into the flap is also very short.

(Remember, these are just nerve branches that are affected, not the cell bodies, so there is regrowth and reinnervation of the LASIK corneal flap with time.)

In SMILE, there is also a reduction of corneal cap innervation. This is because there is a wound through which the lenticule is accessed and removed, and also because removal of the lenticule disconnects nerve branches that come up from deeper parts of the cornea.

However, because there is no circumferential flap cut, there is less disturbance compared with LASIK.

In PRK/epiLASIK, there is no flap and no lenticule, so corneal innervation is disturbed the least and would be expected to recover fastest among the 3 methods.

Is there any laser procedure that does not cause dry eyes?

Anecdotally, most patients regardless which method was performed, experienced increased eye dryness in the early period after surgery.

There is a meta-analysis of studies comparing LASIK and SMILE and I quote the abstract conclusion for simplicity:

“Dry eye after both SMILE and FS-LASIK usually occurs transiently. SMILE does not show obvious superiority over FS-LASIK by exhibiting similar and acceptable objective parameters, and SMILE may have milder subjective symptoms.”

Certain parameters like tear film break up time were better with SMILE than LASIK, but when questionnaires regarding dry eye related symptoms and quality of life issues were given to patients in a blinded fashion, there was no significant difference in the answers.

If you have dry eyes, what do you need to consider?

If a patient with dry eyes is considering refractive surgery, the most important factor is its severity.

The following helps your doctor determine the severity of your dryness:

1. Are there a lot of dry spots (punctate erosions) on the cornea?

2. How often must you use artificial tears to maintain function?

3. Also, are there underlying problems like the use of isotretinoin for treating acne, which could make your eyes very dry?

How do I manage patients with dry eyes?

Generally, if the dry eye problem is mild, or is associated with contact lens wear, then there is usually no problem with any of the methods above including LASIK.

Yes, the eyes can get drier in the early period after surgery, but even with LASIK, recovery usually occurs by 6 months and often earlier.

There may be somewhat earlier recovery with SMILE, but even this also causes an increase in dryness post-operatively.

Patients who are taking isotretinoin should stop taking it before surgery, and ideally wait for several months after stopping before considering LASIK.

For people with a lot of dry spots, I would generally postpone surgery and treat the dryness aggressively with frequent artificial tear drops and perhaps punctal plugging.

Would SMILE be better than LASIK for patients with dry eyes?

Perhaps, bearing in mind that surface ablation like PRK/epiLASIK might be an even better option if the patient can put up with the delayed visual recovery.

What about patients with severe dry eyes?

For severe dry eyes, generally I would advise against any kind of laser corneal refractive surgery.

The induced dryness, regardless of method, may affect healing, and cause prolonged blurring of vision.

To sum up:

I personally don’t think there is a huge difference in terms of dryness induction following LASIK or SMILE.

Both methods cause some temporary increase in dryness, which might be milder in SMILE. This is not clearly shown in large studies.

If I thought someone’s eyes were too dry for LASIK, I would hesitate to recommend SMILE too.

The main advantage of SMILE over LASIK is that there is no flap.

The main advantage of SMILE overPRK/epiLASIK is better comfort and faster visual recovery.

The advantages with LASIK over SMILE include:

1. Custom wavefront guided treatments with LASIK

2. Flexibility to treat all kinds of spectacle power (SMILE is restricted to moderate to high myopia, and low astigmatism only to about 150 degrees; LASIK is OK to treat up to around 400 degrees of astigmatism).

3. Ease of enhancing in case of remaining power after surgery – with LASIK the flap is simply lifted and the eye retreated, while with SMILE an enhancement requires conversion to either LASIK or PRK/epiLASIK.

These factors, in my mind, should be the main arbiter of the final chosen method.

Dryness is a consideration, but a minor one only.

To give a quick answer to your question – Yes, you may definitely still consider LASIK despite your dry eyes.

My advice would be the following:

1. Address your pre-existing dry eyes until you have reached a stage of minimal to no symptoms.

2. Recognise that any one of these refractive procedures may exacerbate your dry eye symptoms, hopefully temporarily.

3. After your chosen refractive surgery, treat your dry eyes aggressively immediately after the procedure to prevent symptoms from appearing. Don’t wait for symptoms to appear before starting to treat them!

4. Be compliant to your treatment, ie. use your eyedrops frequently and regularly, even if you don’t feel you need them.

Recently, I listed a few methods to treat dry eyes effectively. You may want to try out some of these methods before and after your refractive procedure.

To conclude, dry eyes (especially if mild) can be treated and managed properly, hence it is definitely not an exclusion criteria for refractive procedures like LASIK.

I hope that was helpful to you.

The incidence of dry eye indeed has been reported to be lower in ReLEx SMILE than LASIK. A large part of this difference has been attributed to the fact that ReLEx SMILE is a flapless procedure requiring just 2 to 4mm sidecut as compared to LASIK which needs a 22mm sidecut. Hence, ReLEx SMILE has often been described as a minimally invasive form of laser vision correction.

Now whether ReLEx SMILE is “the best option” for you is largely dependent on many factors that have to be taken into account when trying to determine which type of laser option best suits your eye.

Broadly speaking, there are now 3 different types of laser treatments available. LASIK has been the most common and popular form of laser treatment for the past 20 years, due in part to its excellent accuracy especially at higher levels of refractive errors, swift recovery and high level of comfort. However, in some cases LASIK, due to the creation of a flap, poses potential complications relating to dry eye, corneal ectasia (corneal weakening and warpage) and traumatic flap dislodgement.

Prior to the introduction of ReLEx SMILE, the only alternative to LASIK was Advanced Surface Ablation (e.g. PRK, TransPRK, Epi-LASIK & LASEK). Despite its many different names, Advanced Surface Ablation (ASA) has been around for over 30 years. It preceded LASIK and became less popular than LASIK primarily due to its longer healing & downtime (ASA – 1 week vs LASIK – 3 days), higher levels of discomfort or pain and inflammation and poorer accuracy at higher levels of refractive errors. However, ASA has some advantages over LASIK, which include lower risks of ectasia and dry eye as well as negating any flap dislodgement issues as no flap is ever created in the first place. ASA is an excellent choice for people who have low refractive errors or are involved in contact sports.

Though some may consider ReLEx SMILE to be a relatively newer technique, it has by now been in practice for over 10 years and is approved by both the US FDA and CE. More appropriately, one should view ReLEx SMILE as a refinement of previous generations of laser techniques whereby its goal is to draw benefits from both ASA and LASIK without some of their less desirable traits. ReLEx SMILE by nature of its techniques has similar recovery rate and comfort as LASIK with the advantage of not creating a flap as is the case in ASA (e.g. less dry eyes) without ASA’s pain and slow healing time. Does this make ReLEx SMILE the “perfect” choice? The answer is no. There is no perfect option. ReLEx SMILE in its current form has some limitations. For example, ReLEx SMILE cannot correct far-sightedness (hyperopia).

So the decision on whether any technique is suitable for your eyes has to be dependent on working closely with your eye surgeon. Factors to be considered include the level of refractive error, speed of recovery, comfort level, accuracy of results and risks from flap-related complications like dry eye, corneal ectasia and flap dislodgement. Key to navigating your way successfully through the various choices is to ensure your surgeon is willing and able to discuss, offer and perform all the available modalities of laser techniques and hence give you an unbiased recommendation of the technique that best suits your eyes.

Read more about ReLEX SMILE surgery in this guide I've written.