Automated lamellar keratoplasty (ALK) is a surgical procedure to correct severe myopia (near-sightedness) and mild hyperopia (farsightedness). An abnormal curvature in the cornea prevents it from properly focusing light on the retina. The effect is that the images created after refraction are blurry and unclear. The technique uses a microkeratome (an automated or manual handheld instrument) in two passes. One pass creates a flap on the cornea, and the second one takes away a determined quantity of underlying stromal tissue.
Because it carries more risks and complications, ALK has mostly been replaced by more predictable refractive surgical procedures that have less visual side effects. Such techniques include LASIK, conductive keratoplasty, intrastromal corneal ring segments, and photorefractive surgery.
Also Known As
Before the Procedure
The patient needs a responsible adult to drive them home because the eyes will be blurry after the procedure.
The patient will have their medical history taken alongside some eye tests. In the eye tests, the doctor takes measurements, including corneal thickness, pupil dilation, and refractive error. Patient education and counseling are equally important because the patient needs to understand the risks and benefits and form realistic expectations.
The patient should avoid wearing rigid gas permeable contact lenses (RGP) at least three weeks before the procedure. S/he should also not wear ordinary contact lenses for at least three days preceding surgery. The patient is advised to carry the prescription glasses they are currently using for review. The entire process will last about 10 minutes for both eyes.
On the day of the procedure, the patient is advised to eat light, avoid makeup, and avoid wearing accessories that could interfere with surgery. ALK is an outpatient procedure.
Before the surgery, the patient:
- Will be put under local anesthesia
- Have the conjunctival cul-de-sac irrigated to eliminate eyelid glandular secretions and debris
- Will be prepped and draped
In the procedure, the surgeon:
- During the draping process, creates a clear path where the microkeratome will pass
- Instructs the patient to view the microscopic light
- Places a spacer device in the microkeratome to establish how thick the cut is
- Places an adjustable suction ring on the eye
- Uses a stopper device to ensure a hinge is created in the incomplete corneal flap
- Before passing the microkeratome, uses a tonometer to take intraocular pressure
- Removes the suction ring following the initial incision
- Places a second spacer divider which corresponds to the desired myopic correction
- Replaces the suction ring then makes the second precise incision after checking pressure and diameter to reshape the cornea
- Replaces the flap and positions it without using sutures, allowing it to undergo natural healing
- Does not patch the eye
Risks & Complications
One of the risks associated with the procedure is that it increases the possibility of developing irregular astigmatism in patients who have undergone ALK.
There is also the risk (though rare) of developing corneal ectasia (dilation) leading to severe dry eye and extremely distorted vision. Corneal ectasia is brought about by the ring that was placed during surgery.
The visual function may be lost after ALK, requiring a patient to wear a large therapeutic contact lens.
There is also the possibility of developing a scar at the place where the corneal cap was placed, demonstrating that the cornea may not recover fully in some patients.
Side effects are rare in ALK and may include:
- Glaring of vision
- Under correction or overcorrection
- Difficulty wearing contact lenses (may be a permanent side effect)
Aftercare & Recovery
Antibiotic eye drops will be prescribed to the patient to manage inflammation and pain. The drops also help to prevent infection. Relatively quick healing should occur in a day, but full vision correction is a gradual process. The patient can expect clear vision over several weeks.
The first follow-up visit should take place the following day.
ALK may not be as accurate in correcting mild to moderate myopia when compared to other vision-correction methods. It becomes difficult to predict such a patient’s results.
The procedure is less commonly used due to the development of safer and more effective techniques.