The Complete Guide to PRK, EpiLASIK and TransPRK Laser Vision Correction in Singapore – BY DR TONY HO

Modern Laser Vision Correction as Alternative to Contact Lens Wear

Nowadays, most of us are aware that the burden of wearing glasses and contacts to see clearly no longer has to be a “life sentence”! Indeed modern medical advancements in laser vision correction have now made it a safer choice than wearing contact lenses daily for a prolonged period of time. But most of us are still confused as to which laser vision correction procedure to choose. In the past, LASIK was correctly regarded as the de-facto procedure of choice. But recent developments in laser vision correction have made it such that there are now other equally viable alternatives out there. This article is focused on three popular methods of laser vision correction, namely PRK, EpiLASIK and TransPRK – surface-based methods that do not involve the cutting of the cornea. Therefore, they have the advantage of having no risk of corneal flap complications and the least risk of procedure-induced dry eyes complications.  

Understanding Surface-Based Laser Vision Correction Procedures

It may come as a surprise to most that LASIK is not the first FDA-approved laser vision procedure! The first laser vision correction procedure was actually PRK, a surface-based laser procedure. The first PRK was first performed in 1988. However, it did not take off back then as the excimer lasers used back then were first generation lasers that caused uneven ablation. Also, oxygen-permeable bandage contact lenses and the eye drops used today to prevent eye pain, swelling and cornea scarring were not available then.

What is PRK?

PRK was the first laser vision correction procedure to come into the market. The results were accurate and safe enough to gain USA FDA approval in 1995. PRK was performed using an ultra-violet light laser called the excimer laser. The procedure is done with the patient lying down and using only numbing eyedrops. The concept is simple – after removing the surface cornea epithelium cells using a mechanical scraping device, the excimer laser beam is applied onto the exposed underlying cornea stroma tissue to re-shape its curvature, so that light rays entering the eye will be bent into a new focus point to correct the refractive error. With advances in medical technology, modern PRK surgery is now called Advanced PRK and is vastly different from early PRK. Firstly, medications are now used to prevent corneal haze that may occur in some patients. NSAID analgesic eyedrops are now used to eliminate post-op discomfort. The excimer laser sculpting process is now performed with accurate eye tracking systems, and uneven ablation issues are no more due to “flying-spot” laser sculpting technology. High oxygen permeability contact lenses can now be placed over the treated cornea surface to greatly speed up the healing process so that patients can see well enough to go back to work and even resume sport activities in one week.

What is EpiLASIK?

EpiLASIK is different from PRK as the surface cornea epithelium cells that are removed prior to the sculpting process by mechanical scraping with the PRK procedure are now removed in a gentler manner. This is achieved by applying a suction ring device to hold the eyeball securely in place and under pressure, then using a plastic epithelium tissue separator vibrating extremely fast at close to ultrasonic speed, to separate the epithelium from the underlying cornea stroma tissue in preparation for the excimer laser sculpting. This translates to a faster and more comfortable healing process.

How EpiLASIK is done

Suction ring & epithelium separator used in EpiLASIK procedure  

What is TransPRK?

Unlike PRK, EpiLASIK or any of the other laser vision correction procedures, TransPRK has the benefits of having no surgical instruments touching the cornea – there is no suction ring used and no cornea cutting. This makes the procedure less scary and more comfortable for the patient. To the eye surgeon, there is no worry about the loss of suction ring pressure or incidence of procedure-induced flap complications, because there is no cornea flap being cut. Here, the surface epithelium cells are removed using the excimer laser itself – no more mechanical scrapping or suction rings. As with PRK and EpiLASIK, TransPRK also carries the least worry of post-procedure dry eyes.

How TransPRK is done

TransPRK is a simple and elegant procedure that involves the following steps: 1. All you have to do is simply lie down and look ahead at a blinking fixation green light. There is no suction ring nor surgical instrument touching the eye. 2. The epithelium cells will be removed by the “cool” (not hot) ultraviolet pulses emitted by the excimer laser. 3. The same excimer laser will go on to reshape the cornea curvature to correct the refractive power in one seamless step. 4. A transparent, high-oxygen permeability content soft contact lens is then placed over the cornea to act as an artificial cornea flap to protect the treated surface while the epithelium cells regenerate. 5. The epithelium cells will take around 1 week to regenerate and heal. It is important to use the eye drops medications prescribed and stay away from strong sunlight to ensure a good recovery. The high-oxygen permeability contact lens is removed after 1 week.

Summary of Benefits of PRK, EpiLASIK and TransPRK:

1. No cutting of a cornea flap or lenticule A major advantage that you gain by opting for surface-based procedures (PRK, EpiLASIK and TransPRK) is that your cornea will not be cut. This may come as a relief to you if you have a fear of cutting your cornea or the possible cornea flap or lenticule complications that are associated with other laser vision correction procedures. 2. Least worry of procedure-induced dry eye If you are someone who worries about having uncomfortable dry eyes, you should consider undergoing surface-based procedures as there is no cutting of the cornea nerve endings. PRK, EpiLASIK and TransPRK are associated with the least complaints of post-procedure induced dry eyes and lowest likelihood of permanent procedure-induced dry eyes. 3. Suitable for More People There is hope yet if you have been rejected from other laser vision correction procedures because of dry eyes, high myopia and/or thin corneas! As laser sculpting begins at the surface, even if you have been unsuitable for LASIK or ReLEx SMILE, you may be pleasantly surprised to find yourself a suitable candidate for PRK, EpiLASIK or TransPRK.  4. You are into contact sports or in active military service As the cornea is not cut, there is no fear of cornea flap dislodgement from a finger poke injury or blunt facial trauma when participating in contact sports such as boxing or wrestling or carrying out active military duties. Thus, you may go ahead and participate in vigorous activities without worry!

How do I know if I am suitable for the laser vision correction procedures?

If you are considering getting rid of those glasses for good, you may be a suitable candidate for the procedures if you are at least 18 years old and above and your eye power has been stable for the past two years. This can only be determined through a detailed pre-laser treatment eye evaluation. The eye evaluation would include a series of eye tests to comprehensively evaluate your refractive error, cornea parameters and eye health. If suitable, you will be examined by and have a consultation with the eye surgeon. You should take this opportunity to address any concerns that you may have with the doctor. However, if you are pregnant or breastfeeding, suffering from major systemic disease causing dry eyes or eye inflammation, have thin corneas or irregularly shaped corneas, you may not be suitable for PRK, EpiLASIK and TransPRK procedures. Therefore it is essential that you first schedule yourself for a pre-surgery eye evaluation to determine your suitability for the various laser vision correction methods.

How do I prepare for the pre-laser treatment check?

As most clinics work by appointment-only basis, it would be wise to book an eye evaluation appointment with your preferred clinic or eye surgeon before going down to the clinic. Contact lenses may alter the shape of your cornea that will in turn affect the accuracy of the pre-laser treatment measurements. Therefore, if you are a soft contact lens wearer, you will first have to stop wearing them for at least three days before your eye evaluation appointment date. If you are wearing hard lenses or overnight Ortho-K contact lenses that have greater effect on the cornea curvature, you should stop wearing them for at least ten days.  

Are there any preparations that I will have to make before my PRK, EpiLASIK or TransPRK surgery appointment?

Similar to your eye evaluation, you will also have to cease the wearing of your soft lens for at least 3 days (or at least 10 days for hard lens) in preparation for the surgery appointment. A few other things that you would have to take note for the procedure are:

• You will have to stop wearing your make-up a day before and on the surgery day itself.
• Good hygiene is important so you should have a good full shower before coming for the surgery.
• Please do not wear any perfumes, deodorants, colognes or aftershave on the surgery day.
• You will be able to see well enough after the procedure to go home without an escort but you should not drive yourself.
• If you are to undergo the additional cornea cross-linking treatment at the same time to strengthen the cornea, you will then have to stop consuming your Vitamin C supplements a week before.

Also, you will need to take some time off to recover after the surgery – expect to set aside one week from your work and exercise schedule to rest at home.

What are some of the things that I will have to take note of post-operatively?

It takes around one week for the surface cornea epithelium cells to heal, during which your vision will be pretty hazy. Hence, you should stay at home to rest and apply the antibiotic eyedrops according to the prescribed schedule. To minimise the risk of infection, you should not be wearing any eye make-up until the bandage lens is removed after one week. In addition, do maintain good eye hygiene such avoiding dust and dirt, wash your hands before applying the eyedrops, and avoid touching your eyelids with your hands. Fortunately, serious infection is rarely encountered if good hygiene is observed. Once the bandage contact lenses are removed (typically on the fifth day), you can resume your normal activities including computer work and light sports. However, you must be diligent to continue to apply the prescribed anti-cornea haze steroid eyedrops and wear sunglasses whenever you go outdoors in the sun for the next month or so.

How long will it take for my vision to recover?

You will be pleasantly surprised to learn that your vision will be pretty clear immediately after the procedure. However, it is not advisable to drive for the first week. Almost all patients recover well enough to go back to work after one week of rest. You can also fly without worry. You can use your phone and computer after the procedure, but usage will be limited and discouraged as your vision will be fuzzy for the first week while the surface epithelium cells heal. There is a healing curve that depends on the refractive power being corrected. Full vision recovery is usually achieved within two – three months. However, those with high myopia or astigmatism may take three or more months to achieve full vision recovery. Most patients are discharged from follow-up reviews after the third month. Additional things that you will have to take note of:

• You should remember to wear sunglasses when you are outdoors in the day for the first 1 month post-op to minimise exposure to the sun’s ultraviolet rays

• Please apply the eyedrops prescribed diligently for a smooth recovery process

• Keep your scheduled follow-up appointments with your eye doctor

Can My Degree Come Back after the Procedure? Can I Undergo the Procedure Again?

This is very unlikely to happen with modern laser vision correction. If it does happen, it is generally limited to low powers of less than 1 dioptre (or 100 “degrees”).  Enhancement surgery can then be considered but only after a waiting period of at least six months to allow for full and complete eye healing. All enhancement surgeries are also subjected to the pre-condition that the residual cornea thickness is thick enough to allow it.

Can I do the procedure if I have both myopia and “lao hua” i.e. presbyopia or middle-aged onset far-sightedness?

Yes, you can! “Lao hua” or presbyopia is a middle age-related condition that usually affects people above the age of 40 years old due to age-related weakness of the eye focusing muscles and loss of the crystalline lens elasticity. For these patients, a strategy known as “mono-vision treatment“ or “blended vision treatment” is employed to allow clear vision for both distance and near. The principle is to correct your dominant eye to see clearly for the distance and to leave a small amount of myopia in the other eye to compensate for the presbyopia.

Can I still wear cosmetic contact lenses?

Yes, cosmetic contact lenses may be safely worn after your PRK, EpiLASIK and TransPRK procedure after a month of recovery.

What about Future Cataracts and Other Eye Diseases?

Laser vision correction corrects the eye pre-existing refractive error only and will not cause cataracts or increase the risk of cataracts or other eye diseases. If you do develop cataracts when you are older, you can still go for cataract surgery with no fear of increased risks. The only difference is the dioptric power of the lens implant to be implanted but this is calculated using computers during the pre-cataract evaluation.

What is Cross Linking (CXL) Treatment? Can I Still Undergo the Correction If I Have Thin Corneas and/or High Myopia or Astigmatism?

If you have thin corneas and/or high degree of refractive error, your eye doctor may advise you to do Cross-Linking (CXL) treatment at the same time as the laser vision correction to strengthen the cornea to prevent future problems or cornea weakening. Cross-Linking (CXL) treatment is a cornea strengthening procedure using Vitamin B2 solution dripped onto the cornea followed by an ultraviolet A (UVA) light shone onto the cornea for a set duration. This makes the collagen fibres in the cornea sticky and strong, thus greatly reducing the risk of future cornea weakening that may lead to regression of the treated power, and also a medical condition known as cornea ectasia where the cornea curvature becomes progressively irregular.

How is CXL Done?

CXL done during laser vision correction is a simple two-minute procedure that involves 2 steps:

1. Riboflavin (Vitamin B2) eye drops are applied to the cornea and left to soak into the cornea for 1 minute.

2. The riboflavin-soaked cornea is then illuminated with ultra-violet A (UVA) light for 1 minute. This cause the collagen fibres within the cornea to cross-link with each other thus strengthening the cornea.

How much does PRK, epiLASIK and TransPRK Procedures Cost in Singapore?

Depending on your doctor or clinic of choice, the cost of the laser vision correction procedures could differ greatly. Generally, the cost of the pre-laser eye evaluation in Singapore ranges anywhere from $10 and up to $300. The surgery pricing for PRK, EpiLASIK and TransPRK typically ranges from $3,500 to $7,000 for both eyes. We would advise you to clarify the procedure cost before booking an appointment. You should also clarify if the surgery price include the initial post-op medications and first few follow-up reviews.

Can I claim from my Medisave, Medishield or insurance?

Laser vision correction falls into the category of “cosmetic” procedures, therefore you will not be able to claim from your Medisave or Medishield to defray the surgery costs. It is usually also not insurance claimable. However, there is an exception to this rule for Medisave claims. If you have a refractive error difference between the eyes of more than three dioptres (three hundred degrees) and complain of spectacles intolerance, you may submit an application to claim from your Medisave account. However, this is subject to approval on a case-by-case basis. Also do not that some clinics offer 6 or 12 months 0% interest instalment plans using credit cards from certain banks. Do check out with the clinic directly if you are considering this financing option!

Key Takeaways

In summary, by opting for surface-based laser vision procedures such as PRK, EpiLASIK and TransPRK, you will be able to eliminate flap-related complications. You will also have the least fear of dry eyes after the procedure and can take part in active contact sports with no fear of sustaining cornea flap injuries. If you are considering undertaking this journey to clear vision, you should certainly carry out careful research to find out which laser vision correction procedure best suits you. Remember that each procedure has its own set of pros and cons. Therefore, it pays to put in the effort to be an informed patient – and I hope that this article has contributed to that process!