Definition of YAG Laser Posterior Capsulotomy
Within 10 years of cataract surgery, 99 percent of patients have to undergo a YAG laser posterior capsulotomy for a condition known as a secondary cataract. The name is a bit of a misnomer, however, as it’s not really a cataract. Once the crystalline lens is removed, it can’t grow back.
A secondary cataract is better known by the medical profession as posterior capsular opacification (PCO), or posterior capsular haze (PC haze). This is a result of the epithelial cells that are left over after the cataract has been removed, which attach themselves to the capsule and begin to grow.
An ophthalmologist I worked for once told me his theory on why this occurs. He thought it was the body’s attempt to regrow the crystalline lens. When you think about the body’s incredible ability to heal, specifically the cornea, which can heal within 24 hours of injury by regenerating, it’s not so far-fetched.
The haze will get progressively worse until it is treated, sometimes leading to vision loss reminiscent of the original cataract. The only way to treat this haze is to essentially blow a hole in the middle of the capsule so the patient is able to see through it.
Symptoms of Posterior Capsular Opacification
Typically, the symptoms of posterior capsular opacification are the same as the symptoms for a cataract. The main complaint is blurry, foggy or hazy vision. Other symptoms include:
- Glare from lights (especially headlights), or the sun
- Problems driving at night
- Problems reading road signs
- Difficulty reading up close, or using a computer
- Loss of color perception
- Double vision
- Sensitivity to light, especially sunlight
Unlike a cataract in which the symptoms typically occur very slowly, the symptoms of posterior capsular opacification can occur suddenly, or gradually.
The YAG Laser Procedure
The capsulotomy requires the use of a Nd:YAG (Neodyium – doped yttrium, aluminum, and garnet) laser, which is generally just called a YAG. It is a cold laser and does not use heat to ablate (destroy) the capsule. The procedure was developed in the 1980s by Dr. D. Aron-Rosa and Dr. F. Fankhauser. It was subsequently patented.
The actual procedure only takes about 10 minutes and is performed in the office. The patient is dilated so that the ophthalmologist can open an area wide enough for the patient to see through even in the darkest conditions.
After dilation, the patient is put into an instrument very similar to the one used by the physician to examine the eyes called a slit lamp.
A lens is placed on the eye to magnify the area the doctor will be working on and to hold the eye still. It can be a bit uncomfortable, but the eye is anesthetized topically first. The only thing the patient feels is the lens against the eyelids.
The doctor will use the laser to cut through the portion of the capsule that is in the visual axis. This is usually done in a circular pattern.
Once the doctor is finished, the lens will be removed and the patient will be led to the waiting area where they will wait for approximately 30 to 45 minutes. After which time, the pressure of the eye will be checked and the patient will be given post-operative instructions.
Patients are usually given an eye drop such as Omnipred, Lotemax or FML to take four times a day for about a week.
This is to prevent inflammation and discomfort. Patients may also be given a drop to bring down their pressure if their post-operative readings were elevated.
By the time the dilation wears off, or at least by day after, patients can usually tell if their vision has improved.
Most ophthalmologists will see the patient a week later to make sure the procedure did in fact work, and to check the patient’s glasses prescription to see if it needs to be changed. Although rare, a glasses prescription can change slightly after the procedure.
Risks and Benefits
A YAG capsulotomy is not an invasive procedure, but it does have its risks. There is a negligible risk of infection because no incisions are made, but there is the risk of inflammatory disorders such as iritis, which can be painful and cause loss of vision if not treated. Other risks include:
- Retinal detachment
- Dislocation of the implant into the vitreous
- Posterior vitreous detachment
- Corneal edema (swelling)
- Elevated intraocular pressure
- Macular edema (swelling)
- Retinal tears
- Implant “pitting”
Implant “pitting” refers to a complication in which the laser causes divots or pits in the lens itself. This can cause permanent visual distortion. It is typically caused by a laser beam that is not properly focused posterior to the lens, or by a poor technique in making the opening in the capsule. However, I have found in 21 years that most people who have had a YAG laser have some degree of pitting on the implant. But it does not affect vision.
Because the IOL is held in place by the capsule, there is a risk of it becoming dislocated if too much laser is used on it. Sometimes, however, dislocation is unavoidable. Some people have weaker capsules than others, and although they tolerated cataract surgery well, a YAG laser may be too much. As seen in the video above, the procedure is aggressive and can cause excess stress on an already weakened capsule.
If you’ve had cataract surgery with a premium lens implant such as the Crystalens, it is important to find an ophthalmologist who is experienced in treating PCO with an accommodating lens.
There is a slightly higher risk of dislocation of a Crystalens if the procedure is not performed properly because this premium lens is more dependent on the capsule to hold it in place than a traditional IOL. For the Crystalens to work properly, the capsule needs to remain intact so that the zonular fibers can move the lens to focus it.
That said, in the past 10 years since the Crystalens was developed, I've yet to see one dislocate. However, the Crystalens is still fairly new considering the age of cataract surgery itself.
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© 2013 Melissa Flagg OSC