PRK, Epi-LASIK, LASIK, and Intra-LASIK in Calgary: how to they compare?
There are a variety of options available to anyone considering laser vision correction in Calgary. In order to make a good choice it is important to understand the similarities and differences between procedures.
Similarities Between PRK, Epi-LASIK, LASIK, and Intra-LASIK
The following things are the same regardless of the type of laser vision correction procedure you choose:
– You will have to undergo an assessment to determine if you qualify for laser vision correction.
– There is some risk to any of the laser vision correction procedures – no technique is risk free.
– The most common side effects of all of the laser vision correction techniques are dry eye and rarely glare or halo with night vision
– The goal of all laser vision correction procedures is to reduce your dependence on glasses – none of the techniques will result in better vision than you have with your most up to date glasses or contact lenses.
– If you are 40 to 45 years old or older you will need reading glasses for close work unless you choose monovision.
– PRK, Epi-LASIK, LASIK, and Intra-LASIK all have excellent long term results. To date there have been no large scale studies to prove that the visual outcomes are better with any one of these laser vision correction techniques.
– Custom Wavefront or other types of customized laser vision correction can be done with any of these techniques.
Differences: Flap (LASIK and Intra-LASIK) Versus No-FLAP (PRK and Epi-LASIK)
As mentioned above, the long term outcomes of any of these procedures are equally good. The main difference between a flap based procedure and a no-flap surface treatment is that creating a flap carries a higher level of risk and gives more rapid recovery of vision in the first few days following surgery.
The risk of complications with flap creation is low, but it is possible that irregularities in the flap such as a buttonhole or partial flap may occur at the time of surgery. With no-flap techniques there is no flap to become involved in that type of intra-operative complication so the risk is lower. The flap may also be damaged or shifted months or years after surgery. This is very uncommon and in most cases the flap can be replaced and smoothed back into position with additional surgery.
There are a number of additional possible complications that are uncommon but can occur following a flap based procedure. I have co-authored the book “LASIK Complications” which has been translated into Spanish and Japanese and has gone into three editions – there is not a book called PRK Complications. While the risk of the no-flap procedures is not zero, it is lower because there is no flap that can become involved in these types of complications.
The reason the flap based procedures are so much more popular is due to the more rapid recovery of vision and earlier return to work. Most people are back to work within one to two days, although the night vision may take longer to recover. With no-flap procedures approximately one week is required to recover useful vision and the vision may sharpen up over a few weeks to a month following surgery. Most people undergoing laser vision correction with a no-flap technique will plan to take about a week off of work and may need assistance with young children or other duties for the first 3 days following surgery.
The other reason that flap based procedures became quickly popular when introduced in the 1990’s has to do with the older excimer laser technology and the past tendency for the formation of scarring and haze with PRK. Due to advancements in laser technology, medications, and surgical techniques the risk of visually significant haze is very low now.
The most feared complication of the flap based procedures is corneal instability called ectasia. Ectasia has been reported following PRK but is much more common with LASIK. Intra-LASIK and newer SBK (sub-Bowmans keratomeleusis) microkeratomes create very thin flaps which are thought to reduce the risk of ectasia. Thin flap techniques are very new and the prevalence of ectasia with thin flaps may not be known for several years as this condition can develop any time from immediately post-operatively to several years following surgery.
There is a significant amount of discussion recently about the risk factors for ectasia and the corneal biomechanics of creating a corneal flap. Some risk factors have been identified but there are some cases of ectasia in which no risk factors were apparent. Risk factors may include corneal mapping abnormalities, thin corneas, and family history of keratoconus.
Ectasia can not be corrected by further laser vision correction and requires treatment with customized contact lenses or in severe cases with corneal transplant. There are some surgeons who will only perform no-flap procedures due to this risk of ectasia, some are turning to thin flap procedures to reduce the risk, and others feel the risk of ectasia is so low that it is reasonable to give people a choice of procedures.
Differences Between Surgeries
PRK & Epi-LASIK: no flap treatment with laser applied to corneal surface after surface epithelial cells are removed
LASIK & Intra-LASIK: flap is created and the laser is applied to the interior corneal bed under the flap
PRK: surface epithelial cells are removed using a brush or by using a dilute alcohol solution to soften the cells followed by manual removal
Epi-LASIK: surface cells are removed using an epi-keratome device with an epithelial separator which uses a suction ring to stabilize the eye
LASIK: the flap is made using a microkeratome device with an oscillating blade; a suction ring is used to stabilize the eye.
Intra-LASIK: a femtosecond laser is used to create a corneal flap; a suction ring is used to stabilize the eye
Qualifying: some people may not qualify for flap procedures due to thin corneas or other factors
Risk: PRK is the lowest risk followed by Epi-LASIK; flap procedures have a mildly higher risk with Intra-LASIK felt to be safer than LASIK
Outcomes: depending on the study there have been some differences discussed between procedures but there are no large scale studies to show that one type of surgery is better than another over the long term
LASER: each center will have a particular type of laser which may have the capacity to do customized treatments; the laser application will be essentially the same regardless of the procedure type.
When given a choice between a low risk flap based procedure with a return to work within a few days and a lower risk no-flap procedure many people will choose the more rapid return to work and others will choose the lower risk treatment and accept the longer recovery. What it comes down to is each individual’s choice.
If you would like more information or to book a free assessment, contact Western Laser Eye Associates today.