Astigmatic Keratotomy (AK) Eye Surgery

Astigmatic keratotomy (AK; also known as limbal relaxing incision) is an eye surgery that corrects astigmatism.

The normal curvature of the cornea is spherical (resembling a basketball), and astigmatism causes a change in the corneal curvature making it football- or oval-shaped, leading to misshaping of the curvature (one end being flat and the other steep).

AK is a type of corneal relaxing incision surgery that helps correct astigmatism by making one or two incisions at the steepest part of the cornea, relaxing it, and turning it into a more rounded shape.

Astigmatic keratotomy (AK) may be ideal for people who have:

• A quest to reduce their dependence on glasses or contact lenses
• Mild to moderate astigmatism
  • Congenital astigmatism
  • Residual corneal astigmatism
  • Post-traumatic astigmatism
  • Astigmatism after corneal transplantation
• Stable glasses or lens prescription for at least a year
• Good general health
• No other eye problems affecting recovery, such as severe dry eyes

In some cases, AK is performed on people who have residual astigmatism after previously undergoing any of the following:

• Cataract surgery
• Corneal transplants (penetrating keratoplasty or partial thickness)
• Radial keratotomy

Pre-procedure

• A doctor evaluates the patient’s thorough medical history and tests their eyes to measure corneal thickness, refraction, corneal mapping, eye pressure, and pupil dilation.
• On the day of surgery, the patient is advised to eat a light meal and take all of the prescribed medications.
• The patient must avoid wearing eye makeup or bulky accessories in the hair that may interfere with the positioning of the head under the laser.

Procedure

• Under topical (anesthetic eye drops) anesthesia, the doctor makes one or two incisions using a diamond surgical blade at the steepest part or parallel to the edge of the cornea.
• These incisions help change the football shape of the cornea into a rounded shape for better vision.
• The entire procedure usually lasts not more than 10 minutes for both eyes. 

Post-procedure

• The eye may remain sensitive to light for a few hours after the surgery or give a feeling of a foreign object. 
• It is an outpatient procedure, which means the patient can go home shortly after the surgery.
• The patient may be asked to use eye shields/patch to protect the eyes.
• The doctor may prescribe antibiotic eye drops to prevent infection and inflammation and reduce irritation.
• Although a reduction in astigmatism is often observed immediately after surgery, it might take a few weeks before the stabilization of results.

Some of the pros of astigmatic keratotomy eye surgery include:

• A safe, effective, and quick way to correct astigmatism
• It can be used in conjunction with other vision-correction procedures
• A good option for older patients
• Corrects higher levels of astigmatism
• More affordable than laser refractive surgery

A few cons of astigmatic keratotomy eye surgery are as follows:

• Mild discomfort (usually lasting one to two days)
• Fluctuating vision (for the first few months post-surgery)
• Infection
• Red or itchy eyes
• Weaker corneal structure, making it more vulnerable to rupture (if injured)
• Higher risk of overcorrection
• Extended healing time is around three months
• The outcome is irreversible
• Glare/halos/starburst around lights (sometimes permanent)
• Light sensitivity

Although glasses and contacts are the most common treatment options for astigmatism, other procedures that may help correct astigmatism include:

• Laser in-situ keratomileusis: A laser eye surgery that corrects refractive errors, including astigmatism, myopia, and hyperopia
• Photorefractive keratectomy: Another type of laser refractive surgery done in people with thinner corneas or high prescriptions
• Refractive lens exchange: Astigmatism correcting procedure that removes the natural lens in the eye and replaces it with an intraocular lens (IOL) implant 
• Cataract surgery: Recommended for older patients who have cataracts along with astigmatism
• Phakic IOL implant surgery: A procedure that involves placing an implant in front of the iris (anterior chamber) or behind the iris (posterior chamber)