Astigmatic Keratotomy (AK) is a safe and effective eye surgery that corrects astigmatism and eliminates or reduces dependence on eyeglasses. Astigmatism refers to a refractive error caused by a corneal defect that prevents light rays from focusing on the retina, leading to distorted images. In recent years, LASIK, limbal relaxing incision (LRI), and Femtosecond laser-assisted AK (FSAK) have primarily replaced AK.
The cornea in astigmatism is shaped like a football where it is steep in one meridian and flat in the other. AK is performed to reshape the cornea to a more spherical shape such as a basketball, therefore decreasing the degree of astigmatism. The best success in AK is obtained in people with mild prescriptions. Those with severe astigmatism may have their vision corrected but may still need to use eyeglasses or contact lenses.
AK can also be performed in combination with regular keratotomy (RK) and other laser-related vision-correction procedures.
Also Known As
- Arcuate Keratotomy
Before the Procedure
The patient will have their medical history evaluated and eye tests conducted. In the eye tests, the doctor takes measurements including corneal thickness, pupil dilation, and refraction.
The patient should not wear rigid gas permeable contact lenses for at least three weeks before the surgery. S/he should also not wear ordinary contact lenses for at least three days before the procedure. The patient is advised to carry the prescription glasses s/he is currently using for review.
The entire process will last about 10 minutes for both eyes. The patient needs a responsible adult to drive them home because the eyes will be blurry at first after the procedure.
The patient is prepped for surgery. After cleaning the site of the surgical procedure, the doctor will apply a sterile drape. The patient may also be given a sedative for relaxation purposes. The eyes are numbed using a local anesthetic in the form of eye drops.
In the procedure, the surgeon will:
- Place an eyelid holder between the eyelids to prevent blinking
- Place a temporary marker on the cornea to determine where to make the incision. The marks are based on a formula that considers the prescription, amounts of astigmatism to be corrected, and age.
- Make two microscopic incisions at varying distances from the apex of the steepest corneal region. The incisions cause the cornea to relax and take a spherical shape.
- Apply antibiotic eye drops on the site
- Remove the eyelid holder
Risks & Complications
There are visual side effects that will be experienced by patients who go through AK. However, these effects are usually mild and will most often diminish over time. However, some, such as photophobia (sensitivity to light), glare, and halos, may persist for life. For the cataract surgical patient, glare or starburst around lights from the spread of the scar toward the pupil may present a potential problem. This is because the patient needs a good quality of vision after cataract surgery.
Other side effects include discomfort that may last up to three days following the surgery. Infection close to the cornea's center may also result, especially in cataract patients, leading to serious ramifications. It is for this reason that most surgeons prefer limbal relaxing incision.
Although the risks and complications involving AK are infrequent, they may include:
- Difficulty when fitting contact lenses
- Irreversible results, whether desirable or undesirable
- A slow process of healing that takes about three months
- The cornea weakening, making it susceptible to rupture should it be hit directly
- Fluctuation of vision particularly in the first few months following the surgical procedure
Aftercare & Recovery
The patient’s eye is shielded for protective purposes after the surgery. Additional eye drops are prescribed to help prevent infection and inflammation. The patient can take over-the-counter pain relievers for any pain or discomfort that may accompany the surgery. Following the procedure, the patient may experience watering or swelling of the eye and sensitivity to light for a few days, but these should resolve. S/he may also feel like there is a foreign body in the eye.
For some patients, dramatic improvements in vision are noted within the first day. Such patients can resume regular activity in one to two days. However, others may take longer to note improvements in vision. In such cases, the patient may experience blurry vision for several weeks.
Severe cases of astigmatism may only have the defect reduced but not eliminated. The patients usually need new eyeglass prescriptions a month after the procedure. Another problem that affects astigmatic patients is farsightedness. Such patients may experience worse vision after AK and may need to undergo LASIK later to achieve good vision without having to use eyeglasses.