Laser Vision Correction

Epi-LASIK: How Does It Work?

By September 18, 2020 No Comments

Author: Dr Val Phua MBBS, MMed (Ophth), FRCOphth, FAMS

Photo by: Matt Collamer

Epi-LASIK surgery is one of the options for laser vision correction. While many have heard of LASIK as an option to achieve glasses and contact lens freedom, not as many have heard of Epi-LASIK. What is Epi-LASIK surgery and how does it work? 

LASIK stands for Laser-Assisted In-Situ Keratomileusis. It is a form of laser vision correction which requires the creation of a corneal flap. The addition of the prefix “epi” here points to the modified way of performing LASIK. Instead of creating a corneal flap, the superficial layer of the cornea (Epithelium) is removed. This exposes the underlying corneal tissues onto which the excimer laser is applied to correct the refractive error. 

Before going for Epi-LASIK surgery, a detailed eye examination with specialised investigations are done to determine how suitable you are as a candidate for Epi-LASIK surgery. This includes checking the amount of refractive error in the eye as well as corneal scans to see how healthy your corneas are. Patients with specific conditions like irregular astigmatism or corneal ectasia are not suitable for Epi-LASIK surgery. Once it has been determined that you are a suitable candidate for Epi-LASIK surgery what happens next?

On the day of surgery, your eye is cleaned and made numb with topical anesthetic eye drops. This ensures that surgery proceeds painlessly. Your eyes are held open with a small clip while an instrument is used to remove the epithelial layer of the cornea. Once this is done, your eye is now ready for the corrective laser. You will be shown a blinking light for you to keep your focus on. This ensures that your eyes are well aligned and the laser is applied accurately. The application of the excimer laser is quick and the duration depends on the degree correction that needs to take place. For an individual with about 500 degrees of myopia, the laser takes less than 10 seconds to complete. 

After the surgery, antibiotic and steroid eye drops are given to prevent infection and to aid healing. Your doctor will usually review how your eye is healing at several time points. Typically at 1 day after the surgery, 1 week after the surgery and 1 month after the surgery. One of the benefits of Epi-LASIK surgery is that there is no corneal flap created, hence during the recovery period, eye rubbing (while not encouraged) will not result in complications like corneal flap dislodgement. 

Epi-LASIK surgery takes place after removing the superficial layer of the cornea and hence vision recovery is expected to take slightly longer compared with LASIK surgery. In the first 3-5 days, there is slightly more discomfort while the epithelial layer of the corneal heals. Vision is not expected to be sharp during this early recovery period but does slowly improve and stabilise over about 3 months. It is well summed up by the line “short term pain, long term gain”

As with all other forms of surgery, Epi-LASIK surgery has potential side effects as well. This includes dry eyes, glare and halos, under and over correction of the refractive error and infection.Not all laser corrections are spot on in every case. Should there be any residual refractive error, an enhancement (retreatment) can be done to address this. 

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