PRK is the process of removing the surface epithelial cells from the cornea and using an excimer laser to reshape the cornea so light is focused naturally on the retina. PRK was the first procedure to use the excimer laser to treat many types of refractive errors and is still the procedure of choice for many patients. During PRK, the excimer laser uses a cool ultraviolet light beam to precisely remove tissue from the surface of the cornea in order to reshape it. Once the cornea is reshaped, it works better to focus light through the eye and onto the retina, providing clearer vision than before. PRK differs from LASIK (Laser in Situ Keratomeleusis) and IntraLase (using the femtosecond laser to create a corneal flap) by avoiding the need to cut a flap of tissue into the corneal surface.
The term “custom” refers to the pattern of laser energy which uses an optical map that is generated from your own eye using the Wavescan mapping unit – like an optical fingerprint.
Custom PRK Advantages
- PRK sculpts the outside of your cornea using an individualized laser pattern, instead of the inside.
- No incision
- No corneal flap
- Many surgeons feel the custom laser pattern is more effective if a LASIK or Intralase corneal flap does not cover it.
This makes Custom PRK available to patients who are ineligible for LASIK surgery due to:
- Thin corneas
- Corneal scars
- Corneal dystrophy
- Recurrent corneal erosion
- Lifestyle choices (such as contact sports)
Since PRK does not involve creating a corneal flap there are no flap complications during or after surgery – the most common problem encountered with LASIK procedures.
Custom PRK Procedure
PRK is same-day surgery, and you will not need general anesthesia. We use numbing eye drops so that you do not have discomfort during surgery. We can give you an oral sedative if you are nervous.
- A speculum holds your eye open so that you do not blink
- The excimer laser precisely removes tissue, reshaping your cornea
- A bandage contact lens is placed on your eye
Custom PRK is a safer procedure for most patients but will require a longer recovery than LASIK. If you have Custom PRK on both eyes you will need about 1 week to 10 days recovery before returning to usual activities such as work and driving.
Custom Laser Treatment
Wavefront-guided Custom PRK is a precise, customized form of refractive surgery that can correct vision problems beyond nearsightedness (myopia), farsightedness (hyperopia), and astigmatism as well as higher order aberrations. Wavefront guided treatments offer superior results compared to standard laser correction.
Established Technology Applied in a New Way
Wavefront is an established technology that has only in recent years been applied to human vision. Wavefront has been used for years by astronomers who need to adjust the optics of their telescopes. A reflecting mirror within the telescope that can be deformed is adjusted using wavefront data to eliminate aberrations induced by the Earth’s atmosphere. With wavefrontcustom PRK the excimer laser uses wavefront information to change the shape of the cornea by precisely removing corneal tissue.
Wavefront is actually used in two separate steps before and during surgery. First, the wavefrontaberrometer is used to measure existing aberrations. The second time wavefront is used is using what is to create a unique wavefront-guided laser ablation profile for custom PRK. This treatment is customized to each individual cornea.
With wavefront-guided mapping, light is sent into your eye and measured as it passes through the visual system. A 3-D map is created that shows all of the distortions of light that occur in your eye, pinpointing aberrations. It is accurate up to one hundredths of a diopter. This map is used to guide the laser during your surgery giving you a precise, customized procedure.
High Order Aberrations
Higher order aberrations are not measured by eye chart tests. Even if you have 20/20 vision, they can cause visual problems including:
- Double vision
- Poor night vision
- Decreased contrast
Iris Recognition and Cyclotorsion (Rotational) Adjustment
The Visx S4 IR laser has the ability to recognize unique iris landmarks in order to adjust positioning for each eye treated. In addition to vertical and horizontal eye tracking, the Visx S4 IR laser makes a rotational adjustment for improved accuracy. In many people the eye may rotate up to 10 degrees between sitting upright and laying down on your back. In addition, a small tilt of the head to the right or left while laying on your back can introduce rotational errors as compared to the measurements which are made while sitting upright. Iris landmarking allows for fine adjustments in the laser application pattern in order to match up the optical wavescan mapping precisely during Custom PRK.
Advantages of Wavefront (Custom PRK)
Traditional refractive procedures can make higher order aberrations worse than they already are.
The precision of Wavefront prevents the creation of higher order aberrations and/or worsening of those that you may already have. With Wavefront-guided Custom PRK you are:
- Less likely to lose best-corrected vision
- Less likely to lose vision quality
- More likely to achieve 20/20 vision or better
Is Wavefront-guided Custom PRK for me?
Wavefront-guided refractive surgery will offer superior results for most people. Most people can benefit from the precision of this technique; however, there are some who may not qualify due to very small or very large pupils. Dr. Anderson Penno will conduct a thorough examination of your eyes during your Custom PRK evaluation to determine if Wavefront-guided Custom PRK is the right solution for you. If not, she will recommend your best option.
Learn more by reading Am I a candidate?
Did You Know?
Since PRK does not involve creating a corneal flap, there are no flap complications during or after surgery – the most common problem encountered with LASIK procedures.
Dr. Anderson Penno has been practicing refractive surgery since 1996 and and has performed thousands of surgeries.
The first step in achieving your best vision is choosing the right surgeon.
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