Epi LASIK
If you have been researching LASIK eye surgery you might have come across something called Epipolis Laser In Situ Keratomileusis (Epi-LASIK). This is a version of LASIK eye surgery more commonly associated with (PRK). Epi-LASIK is a recently adopted type of LASIK eye surgery and like LASIK it is performed to correct nearsightedness, farsightedness, and astigmatism. Epi-LASIK combines advantages from both PRK and traditional LASIK into one single procedure.
Epi-LASIK Eye Surgery
Epi-LASIK involves cutting a very thin flap of tissue from the epithelium that covers the front of the eye's surface (also called the cornea). Epi-LASIK differs from conventional LASIK eye surgery mostly because of the type of flap created. The flap cut is so thin that it does not penetrate the actual cornea, whereas LASIK actually penetrates into the cornea.
With Epi-LASIK the surgeon uses epithelial separator to separate the sheet from the eye. After the epithelial separator has created this ultra thin flap the flap is lifted and carefully folded back. The next step involves using an excimer laser as is used in conventional LASIK. The laser treatment then reshapes the surface of the eye. The epithelial flap is gently repositioned back on the eye and a contact lens bandage may be required after the surgery to assist with the healing process.
After Epi-LASIK, like regular LASIK eye surgery a patient typically enters the post-operative period where close attention is needed. Most Epi-LASIK patients are not as comfortable in this initial post-operative period as they are with LASIK. Traditional LASIK still offers better initial improvement and a WOW factor! In about 2 weeks the vision after Epi-LASIK is comparable to that of LASIK.
Are There Advantages Over Traditional LASIK?
The most significant advantage of Epi-LASIK over traditional LASIK is that the flap is so thin it does not completely penetrate the cornea. Therefore the flap complication rate is better than that of LASIK; however, there is not much evidence of this since Epi-LASIK is a newer procedure. Epi-LASIK has a better healing process than artificial flaps made in LASIK eye surgery or a traditional PRK procedure.
Epi-LASIK could be the best vision correction treatment option for you if you have relatively thin corneas, as patients with thin corneas in the past have been rejected from traditional LASIK. If you have been told in the past you have thin corneas and therefore are a candidate for LASIK, Epi-LASIK may present a new option for you!
Is 20/20 vision guaranteed with PRK, LASEK and Epi-LASIK?
Excimer laser surgery is an extremely advanced technology for surgical vision correction. The excimer laser is one of the most precise instruments available for use in modern medicine, and it can be programmed to match exactly the refractive correction your eye requires. As such, the vast majority of people undergoing excimer laser surgery are very happy with their post-procedure vision. In fact, a person's happiness with their vision after the procedure is a far more important measure of success than the somewhat arbitrary "20/20" measurement done in a dark room of a doctor's office.
Several factors may lead to a person still requiring additional help from glasses or contact lenses post-surgery. First, the excimer laser is precise enough to inscribe letters on a grain of sand and could correct an inert object, such as a piece of plastic, exactly as predicted; however, in PRK, LASEK and Epi-LASIK surgery, the laser not being applied to something inert, but rather, a living tissue. Because of this, and the individual healing response of each patient, there are some variables of patient response to the treatment. Additionally, it is harder to hit an exact refractive outcome target for individuals with higher levels of refractive error.
What are the risks of Epi-LASIK surgery?
The risks of these surgeries fall into two main categories: Vision Loss Risks, and Nuisance Risks.
Vision Loss Risks
It is very rare to lose vision after laser refractive surgery causing Epi-LASIK to have a very good safety profile. Two other ways may exist in which vision could be lost to a more severe degree.
- Infection: Since cuts are made on the eye, it is possible that bacteria could gain access to the corneal tissue and start an infection. Scarring from such an infection could lead to vision loss. This is very uncommon as powerful antibiotics are used after surgery to prevent infection. The risk of severe infection is less than 1 in 500.
- Progressive Corneal Warpage (Ectasia): In this condition, the cornea begins to warp in odd directions, leading to loss of vision. Occasionally, a corneal transplant is required. Ectasia, however, is typically only seen in patients with abnormal corneal shapes, or corneal dystrophies such as keratoconus; its likely these conditions exist even before the surgery is done. Your surgeon will screen your corneas to help identify any preexisting corneal shape irregularity. The risk of Ectasia is less than 1 in 3500.
Nuisance Risks
Most of the other risks associated with PRK, LASEK and Epi-LASIK surgery don't usually cause a significant loss of vision. Rather, they can cause nuisance problems with the eyes that may not have been present before the surgery.
- Epithelial Healing:In most cases, the scratches made on the surface of the cornea for PRK, LASEK and Epi-LASIK heal within 5-7 days. A bandage contact lens is left in the eye during this time to promote healing. Eye drops are also given to help healing. Occasionally, though, it can take up to several weeks for the surface cells to heal, during which time the vision can be blurry.
- Dry Eye: Almost everyone undergoing laser refractive surgery has some mild dryness, in which the eyes feel scratchy. Typically, these symptoms resolve after a few months; however a small percentage of people have chronically worse dry eyes after surgery requiring continuous treatment with drops or dry eye medications.
- Night Vision Symptoms: Some patients notice their night vision after laser refractive surgery is different than before. Usually, this occurs in the form of halos
around streetlights, added glare from oncoming traffic, or increased difficulty seeing dimly light shapes in the dark. Typically, these symptoms improve with time. Data from several studies has shown that if 100 patients had such symptoms at 1 month after surgery, only 20 to 30 will still have symptoms by 1 year.
Some surgeons believe that a larger pupil size may put a patient at increased risk for night vision problems. However, such complaints can still happen in people with small pupil sizes. Most people with night vision complaints find them only mildly annoying. However, a few individuals may feel that they are unable to function well in low light settings. Medications can be used to change the size of the pupil in low light or nighttime settings, which can help reduce night vision symptoms if they occur.
- Corneal Haze: Occasionally after surface ablation laser surgery, a mild haze forms in the front of the cornea during the healing process. This haze may cause mildly decreased vision. Haze is uncommon with current surgical techniques because of a medication called Mitomycin-c that is used during the procedure to help reduce the risk of haze formation. If it does occur, it typically improves over several months with steroid treatment.
- Enhancements: Even though the excimer laser is extremely precise, the fact that the eye is a living tissue and that individual healing response can vary means that sometimes laser refractive surgery over or under corrects the refractive error of the eye. If this happens, an enhancement procedure can be done several months later to correct the remaining refractive error. Enhancement procedures carry a small risk of all of the above complications, as does the original procedure. In general, about 5-10% of patients undergoing laser refractive surgery will need an enhancement procedure to obtain their vision goals.
What Will I Experience during the PRK, LASEK or Epi-LASIK procedure?
On the morning of your procedure, your surgeon will ask you not to wear any makeup (which may stain the cornea) or perfume or cologne (which may damage the laser). At the laser surgery center, you will usually be given a Valium pill to help you feel calm during the procedure. You lie on a special bed under the laser, and the procedure itself usually takes less than 10 minutes an eye. A blinking red light serves as your target to focus on during the procedure. A lid holder is used to hold your eyelids open, and numbing drops are placed on the eye.
The doctor then removes the surface cells from the eye. In LASEK and PRK, this typically involves some cool fluids and brushing on the cornea, during which you feel nothing but see blurry shapes. In Epi-LASIK, the epikeratome is placed on the eye with a suction ring, during which you will feel some squeezing and pressure lasting approximately 10 to 20 seconds. Once the surface cells are removed your vision will be blurry.
The laser is then activated, and it typically takes less than a minute to change the shape of the cornea. The laser tracks the eye, so if small eye movements occur it will follow and still apply the laser to the right position. Large eye movements will cause the laser to stop treatment, ensuring that only the correct treatment is performed. A bandage contact lens and eye drops are placed on the eye.
After the procedure is done, your surgeon may examine your eye, or simply have you go home and take a long nap. Your eyes will start to burn and feel irritated about half an hour after the surgery as the numbing medicine wears off. The nap, plus the eye drops your surgeon will give you helps make your eyes feel more comfortable.
Your doctor will see you the next day, at which point the eyes feel more comfortable. You typically see your doctor again in about a week to assess the healing of the surface cells and remove the contact lens. You will continue using eye drops for several weeks after the surgery, and then see your doctor again in about a month for a vision check. If all is well, as it typically is, your doctor will usually see you again in 6 months to a year for another vision check. During the few months after the surgery, artificial tears should be used regularly to help limit dryness of the eyes while they heal.
