In fact, between 35-50% of individuals who undergo cataract surgery will develop a “secondary cataract” better known as posterior capsule opacification—but what is this and why does it occur?
Anatomy of Cataracts
In the center of the eye we have a structure called the lens. The lens helps to focus incoming rays of light onto the retina.
The lens is a transparent structure made up of several different layers—you can almost think about it like an onion.
The lens is held in place in the center of the eye via the capsular bag. The capsular bag is a thin membrane that the lens fits into—almost like a CD into a plastic disc holder.
The centermost part of the lens is called the embryonic nucleus, it is formed during fetal development.
Lens fibers originate at the anterior aspect of the lens. They migrate toward the equator of the lens and then elongate to form new layers.
This process occurs over and over throughout life and therefore the lens gets thicker over time.
As we age, older lens fibers begin to yellow and harden, creating dull, cloudy, yellowish-tinted vision.
For most individuals, this process occurs over many decades of life. Most cataracts are slow growing and many individuals may not even realize they have them.
As the cataract grows to become denser, it can affect our vision creating blur that is uncorrectable with glasses with increased glare from light scatter when light hits the cataract. At this point, your doctor may recommend you get cataract surgery.
Cataract Surgery
Cataract surgery involves removing the cloudy, hardened lens and replacing it with a clear implant.
In the past several years, cataract surgery has really advanced in comparison to what it was back in the day. It is now an outpatient procedure that only takes 5-15 minutes to complete.
An opening within the intracapsular bag is made and the natural cataract lens is broken down using phacoemulsification. Essentially, high frequency vibrations are used to break the cataract down into smaller tiny fragments that are then sucked out using a high-powered tube.
The artificial lens specially calculated to best correct your refractive error is then inserted into the capsular bag, and the surgery is done!
Post-operation care involves visits at the 1-day mark, 1-week mark, and 1-month mark, to see your doctor to watch for increases in eye pressure, unusual amounts of inflammation, or, rarely, infection. It also involves taking eye drops for about a month to reduce likelihood of developing secondary infections or other complications.
Posterior Capsule Opacification (PCO)
Posterior capsule opacification is often referred to as a secondary cataract, however that is not quite the case.
Theoretically speaking, PCO should occur in every individual who has cataract surgery; however it realistically only occurs in about 35-50% of cases.
As stated above, during cataract surgery the intracapsular bag is left intact. Microscopic lens epithelial cells are left behind post-surgery and can sometimes continue to replicate on the intracapsular bag surface.
This proliferation of cells can turn from a few cells, to little clumps of cells overtime. This process can occur within the first year post-operation or many years down the road. It can occur quickly (within months) or slowly (over years).
These little clumps of epithelial cells on the intracapsular bag can obstruct vision and cause increased glare if they are located within the visual axis or become large enough.
There is no way to predict who will experience PCO in comparison to others. It is currently hypothesized that a younger age of original cataract surgery may contribute to a higher likelihood of developing PCO as the body tends to be more metabolically active in our younger years, however this is not necessarily a tried-and-true fact.
Ultimately, some people are just lucky to not develop PCO!
If you happen to develop PCO, however, the treatment is quite simple. A laser called an Nd:YAG is used to create an opening in the center of the intracapsular bag. This essentially opens the bag at the center to clear the visual axis and thus improve vision.
The laser treatment is quick and painless. You will hear several “popping” sounds, but will not feel anything—no burning, pitching, or other pain.
The procedure only takes about 5 minutes and does not have a long recovery time. In fact, individuals are cleared to return to regular activities without eye drops or restrictions the next day!
Thus, while PCO may be annoying to the patient, it is easy to remove to get you back to your clear, bright, colorful life created post-cataract surgery.
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