Can PRK Surgery Correct Astigmatism?

PRK (photorefractive keratectomy) is a type of laser surgery used to correct refractive errors such as farsightedness (hyperopia), nearsightedness (myopia), and astigmatism. PRK was the first type of laser eye surgery for vision correction. LASIK was introduced after PRK and became more popular than PRK. PRK has several advantages over LASIK for some patients but it takes longer to recover from PRK than LASIK.

The cornea and natural lens of the eye bend and focus light on the retina and create images on the retina for vision. This bending and focusing of light are also known as refraction. Refraction is affected in refractive errors, causing blurred or distorted vision. Similar to LASIK and other types of laser eye surgery, PRK also uses an excimer laser for reshaping the cornea, causing the light entering the eye to bend properly and focus onto the retina for clear vision. PRK replaces the need to use eyeglasses or contact lenses.

In LASIK, a thin flap is created on the cornea using a small surgical knife or a laser.  The flap is then lifted, exposing the underlying corneal tissue. Small amounts of corneal tissue are removed and the cornea is reshaped. The flap is repositioned and allowed to heal, without using stitches.

In PRK, the thin outer layer of the cornea is removed using an excimer layer. No flap is created. The cornea repairs itself and heals within a few days after surgery.

During the procedure:

The procedure is done under local anesthesia using anesthetic eye drops and a mild sedative may be administered. The procedure is short and takes around 15 minutes for both eyes. The surgeon uses a programmed excimer laser beam over the eye.  Using laser energy, small microscopic amounts of tissue from the top layers of the cornea is ablated (removed) and the cornea is reshaped. There is no pain or discomfort during the procedure except a feeling of pressure in the eye. The treated cornea is covered with a bandage contact lens for a few days till the cornea heals. 

After the procedure:

• Patients can go home soon after the procedure but should not drive. 
• The patients should rest their eyes at home. 
• Antibiotic and anti-inflammatory eye drops are prescribed.
• Pain killers may be prescribed. 
• It may take a few weeks for the eye to heal completely and to achieve satisfactory visual acuity. 
• Most patients can resume work and most activities like driving, one to three weeks after surgery.
• It can take up to three months for the vision to be completely clear, sharp, and stable. Most patients achieve 20/20 vision.
• Regular follow-up with the surgeon is advised.

PRK is a relatively safe procedure but some possible complications (many of which are temporary or treatable) that may occur are:

• Infection 
• Bleeding
• Redness of the eyes
• Dryness of eye
• Decreased vision or loss of vision 
• Glares (difficulty in seeing in the presence of bright light), halos (bright circles that surround a light source), starbursts, and double vision (diplopia)
• Increased sensitivity to light 
• Under correction or overcorrection of the error of vision
• Increased intraocular pressure

The following are the basic eligibility criteria for laser surgery to correct refractive errors:

• Age over 18 years (ideally over 21 years)
• No significant change in vision over the past year
• Possibility of improvement of vision to at least 20/40
• Myopic prescription is between -1.00 and -12.00 diopters
• Not pregnant, breastfeeding, or on hormonal therapy at the time of surgery
• The average pupil size is about 6 millimeters in the dark