In the world of optics, intraocular lenses, or IOLs, tend to slip below the public radar. They’re more expensive and intrusive than corrective lenses and don’t quite have the sci-fi appeal or mass-marketing muscle of LASIK. For all that, they remain widely used in the treatment of cataracts as well as myopia. Follow along, and we’ll give you a quick introduction to the wide world of IOLs, then go into a little more detail about the safety and future of these little lenses.
What is an IOL?
It’s all in the name. Intraocular lenses are small, synthetic lenses surgically implanted into the eye. They come in a few different varieties.
Pseudophakic IOLs are used primarily to treat cataracts, or small, vision-impairing deposits that frequently form in the eye’s lens as an individual ages. A serious case of cataracts interferes with the normal passage of light through the eye, resulting in blurred vision and increased difficulties with glare, if left untreated, a case can even progress to blindness. One solution is to simply replace the affected lens with a pseudophakic IOL, a procedure that – while not without some downsides – has been shown to provide clear vision for patients with mild to severe cataracts.
Phakic IOLs are a slightly different variation. Rather than replacing a clouded lens like pseudophakic IOLS, phakic IOLs are instead placed over the top of an existing, clear lens in order to correct for refractive disorders, such as myopia (nearsightedness).
Finally, you’ll find a third category in aphakic IOLs. Rarer than the other two, aphakic lenses are used in a case in which no natural lens exists. While they were used in the past for postoperative cataract patients, this role has largely been phased out by the development of better pseudophakic options. However, aphakic IOLs are still useful in treating some eye injuries and congenital disorders.
How Does an IOL Work?
Intraocular lenses work by either altering or replacing the eye’s lens. In a healthy, well-functioning eye, the lens focuses light onto the retina, a light-sensitive membrane at the back of the eye that works to send visual signals to the brain. In the case of cataracts, small bodies form in the lens, rendering it a fuzzier, less reliable focusing apparatus. Replacing it with a clear, appropriately shaped synthetic lens at least theoretically solves the problem.
In a myopic eye, the lens is often too long to accurately focus light. Instead, the lens will have a focal point somewhere in front of the retina, so by the time that light actually does reach the back of the eye, perceived images will be out of true – at least for distant objects. A phakic IOL fixes this by essentially acting as an extension of the eye, working with it to form a more appropriately focused lens. Unlike pseudophakic IOLs, phakic lenses are generally elective. We’ll be focusing largely on them for the rest of the article
On paper at least, IOLs make a great deal of sense. They provide what seems like a common-sense fix to a couple of extremely common vision disorders. In practice, they’ve proven to be effective, but come with some definite drawbacks.
Pros & Cons of Intraocular Lenses
We’ll start by saying that phakic IOLs do have a lot going for them. As mentioned before, they do have a relatively straightforward premise, and studies have found that they do generally improve the conditions that they’re designed to treat.
Some practitioners have also found them to be a less risky option when compared to laser surgery – the main competing therapy – as instead of removing tissue, they add it, leaving a patient’s original vision more or less intact regardless of the treatment’s outcome.
Finally, while the field is largely lacking in long-term, large-scale studies, some researchers have found that IOL recipients have reported higher satisfaction and better vision those who opted for laser surgery. However, it’s important to note that this should be taken with a grain of salt, given that more research on just about all aspects of IOLs is still needed.
Intracocular lenses today suffer from a severely negative image gained in the first years of the treatment. IOL technology has been around for a long, long time – the first procedure is officially credited to an English opthalmologist who performed an implantation in 1949. After that, early IOLs were found to pose some severe risks, and in the latter half of the 20th century, the operation was severely stigmatized by a poor track record.
While more recent advances have resulted in much, much safer options, phakic IOL usage is still a relatively small field when compared to laser eye surgery. While many physicians are familiar with IOLs, and even know how to implant them, the field doesn’t gain an enormous amount of attention from researchers, and remains highly expensive and largely out of the public eye (literally and figuratively).
As a result, anyone interested in a phakic IOL is likely to encounter a lot of unknowns. The FDA, despite approving some IOLs for commercial use, still lists “risk taker” as one of the essential attributes of anyone considering having the surgery.
Other known problems include corneal clouding, infection, increased intraocular pressure, and multiple treatments. The latter is a surprisingly widespread problem. One study found that a large number of over or undertreated patients ran into problems simply because of physician error. And while this is obviously a problem for any procedure, a mistake with IOLs can be costly, and require additional surgeries to sort out.
Given everything listed above, it’s not easy to recommend phakic IOL treatment to anyone looking for a fix to their myopia. While that may change as the field is better studied, funded, and popularized, there’s a good chance that may never happen.