Astigmatic Keratotomy: Eye Surgery for Astigmatism Correction

Astigmatism is a common eye ailment that is easily corrected by one of three surgeries, including astigmatic keratotomy (AK). Eye doctors have performed AK, also known as accurate keratotomy, for more than a century. Today they achieve better results by using a femtosecond laser to scale back on the excess curvature of the cornea.

About Astigmatic Keratotomy

Astigmatic Keratotomy, or AK, is an eye surgery that treats astigmatism, a condition in which the cornea has an oval (egg) shape instead of a normal spherical curvature (like a golf ball).

The misshapen cornea means that one end of its curvature is flatter, while the other is steeper. This affects the way light retracts to your retina. As a result, you have a blurry vision, which may occur in several directions, horizontally, vertically or diagonally.

AK is a popular choice for resolving different kinds of astigmatism, including:

• Congenital astigmatism
• Residual corneal astigmatism
• Post-traumatic astigmatism
• Astigmatism after corneal transplantation

AK is one of the most effective surgical procedures for astigmatism, achieving this through incisions in the steeper end of the cornea, flattening it and allowing it to take a spherical shape. 

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Who Is a Candidate for AK Surgery?

You are a candidate for AK surgery if:

• You wish to eliminate or reduce your dependence on contact lenses and eyeglasses.
• You are 18 years and above.
• You have low to moderate astigmatism.
• You are in good general health: connective tissue conditions and diabetes could affect your recovery process.
• You have no eye conditions like acutely dry eyes, which may affect your healing. 
• You have had a stable prescription for eyeglasses for one year or more

How Does an Astigmatic Keratotomy Work?

The astigmatic keratotomy procedure works by getting the cornea assume its normal rounded shape. To achieve this, the ophthalmologist makes microscopic incisions at the steepest curvature of the cornea. The incisions make the cornea flatten and relax, allowing it to take a more rounded shape, leading to improved vision.

Before performing AK surgery, ophthalmologists consider three things: optical zone diameter, AK depth and arc length. All three elements need to be within specific ranges before the doctor will engage.

The Procedure

Astigmatic keratotomy is an outpatient procedure that takes less than an hour. The surgery itself takes only five minutes or so, but preoperative procedures may push the time commitment to almost an hour.

You get to the ophthalmologist about 30 minutes prior to the procedure to give you ample time to settle in and prepare for surgery.

The doctor clears the area around your eyes and applies a sterile drape. You then receive a sedative to help you relax during the procedure and also anesthetic eye drops to numb your eye.

When your eye is numb, the ophthalmologist places an eyelid holder in a position to keep you from blinking.

Next, the doctor makes a marker on your cornea. This is a temporary impression that shows where he will make the incisions.

Your age, prescription, and the amount of correction needed all factor in where the marker will go. The doctor makes one or two incisions on the cornea to make it more spherical. He then applies antibiotic drops and removes the eyelid holder.

After the procedure, you will get extra eye drops and an eye shield to protect the eye for a designated period. The doctor will further give you homecare instructions and any follow-up guidelines.

Results indicate that combined AK and CK is safe and effective for correcting high corneal astigmatism after surgery or trauma.

Recovery

After the surgery, you will likely experience some discomfort in your eye, as though it had a small foreign in it that you cannot remove. You may also have blurry vision and light sensitivity.

Other post-surgical side effects include teary, reddening and scratchy eyes. These should all go away within a few days.

Full recovery is two to three months after surgery, though you should gain improvement in your eyesight within a day or two.

Risks and Complications

AK surgery is a safe procedure. Complications are rare, but they sometimes occur. The main risks and complications associated with AK surgery are:

• Infection 
• A weaker corneal structure that is susceptible to injury if hit directly
• Some post-surgery symptoms like halos, light sensitivity, and glare could be permanent 
• Overcorrection or under correction 
• Fluctuating vision in the first months after surgery 
• Recurrent or irregular astigmatism

Pros and Cons

Astigmatic keratotomy offers several advantages, which explains the procedure’s preference with many doctors even with the advancement of astigmatism treatment by other methods, especially LASIK. AK’s benefits include:

• It is a quick and safe procedure.
• It is highly effective in correcting astigmatism.
• It is inexpensive.
• There is little to no discomfort during the procedure.
• It can be used along with other refractive methods.

Despite these advantages, AK has some downsides when compared to other procedures. The negatives include:

• Extended healing time is typically about three months.
• The outcome of the surgery is irreversible.
• You will experience some discomfort after the procedure for two to three days.
• There is a higher risk of overcorrection.

Alternative Surgical Options

AK is one of a few methods to correct astigmatism. The main alternatives are:

• LASIK (laser in-situ keratomileusis)
• PRK (photorefractive keratectomy)

Your doctor can help you evaluate AK vs. LASIK vs. PRK so you can pick the one that best serves your needs.

LASIK (Laser In-Situ Keratomileusis)

LASIK is a procedure that uses a computer-controlled excimer laser to reshape the cornea. It treats several refractive errors in addition to astigmatism, including near-sightedness and farsightedness. It has replaced most other eye procedures.  

PRK (Photorefractive Keratectomy)

PRK also uses a similar computer-aided excimer laser-like LASIK, and it also treats myopia and hyperopia. Doctors often use it in cases where LASIK does not do the best job, particular for people who have thin corneas or strong prescriptions. They also use it for people who do not want a corneal flap (a key part of LASIK surgery). People with active lifestyles (athletes, for example), sometimes dislike LASIK because the corneal flap limits their fun for a while. 

AK vs. LASIK

The main differences between AK and LASIK procedures are the manner of operation, the range of conditions treated, safety, recovery time and cost.

As the more modern treatment, LASIK takes advantage of technology and the accuracy that comes with computer assistance. It treats a wider range of refractive errors, not just astigmatism. 

LASIK is also faster and carries less of a risk of complications than AK. It also has a faster recovery time: you can resume work the following day with no eye discomfort.

AK, on the other hand, is, has longer recovery times and limited in the conditions it can treat. It is still a safe method, and because it is cheaper than LASIK, it can be a preferred method for most cases of mild astigmatism. 

FAQs 

What is AK eye surgery? 

AK surgery is a medical procedure used to correct astigmatism by making small incisions on the cornea to make it more spherical.

Can astigmatism be corrected through surgery? 

Yes, there are several surgical procedures, including AK, LASIK, and PRK, that reshape the cornea to correct astigmatism. 

What is an astigmatism keratotomy?

It is eye surgery to correct astigmatism.

References

1. The Experts’ Take on Astigmatic Keratotomy. (August 2020). Review of Ophthalmology.

2. Femtosecond laser-assisted astigmatic keratotomy: a review. (2018). Eye and Vision.

3. Astigmatic Keratotomy: A Consumer Guide. (October 2015). EyeHealthWeb.

4. Combined astigmatic keratotomy and conductive keratoplasty to correct high corneal astigmatism. (May 2015). Journal of Cataract and Refractive Surgery.

5. Astigmatic keratotomy: a review of basic concepts with case reports. (July 1990). Journal of Cataract and Refractive Surgery.

6. Astigmatic Keratotomy. Refractive Surgery (Second Edition).