Hi Glenn, the articles I've read all mention this happening with PIOLs. What exactly is it, or more specifically, what are the effects of too much endothelial cell loss? Does one's vision change?

Am I sensing a growing worry factor about the safety of PIOLs? You also mentioned that PIOLs are temporary and that they may need to be taken out later. Are there any studies of the typical length of time a person can expect to wear them? I realize this may vary dramatically with individuals and individual eye surgeons, but at the cost, I would hope to get more than "temporary" mileage out of them.

Thanks!

P-IOLs have been in Europe and Asia for a long time and their relative safety is reasonably well understood. The key to success is patient selection. For some, P-IOLs are everything all the hype could be. For others they can portend future and present troubles. Much of the concern lies in what is just above or just below the P-IOL.

The Artisan/Verisyse P-IOL approved for the US are plastic lenses placed in front of the iris immediately behind the cornea. The concern is that the lens causes an acceleration of loss of the endothelial cells that are the backmost layer of the cornea – and are closest to the P-IOL. Different studies provide different rates, but it appears that the loss of endothelial cells after a Verisyse P-IOL is about 2-3% per year, with significantly more in the first year (due mostly to trauma of surgery).

Endothelial cells are a very important part of the process to nourish the cornea. Without them, the cornea is not “fed” and would become diseased and require a transplant.

The density of endothelial cells varies greatly from person to person. P-IOLs may be appropriate for someone with a high endothelial cell count, but not appropriate for someone with a low count. What is very important is to count those cells. Without knowing how dense the cells are before surgery, the doctor is shooting in the dark. And the counting should not end at surgery. The patient needs to be re-evaluated on a regular basis to see how their endothelium is holding up. This is one of the indications when the P-IOL needs to be removed. If the endothelial cell count gets too low, its time for the P-IOL to come out.

Our organization raised these – and other – concerns in testimony to the FDA and they adopted a method of calculation based on preoperative cell count and a projected duration of use of the P-IOL. If followed, the patient’s safety is all but assured. The problem is that once approved, surgeons may elect NOT to follow the recommended protocol. If you are talking with doctors about P-IOLs, pay attention to how many tell you that you will need to come back every 1-5 years for an endothelial cell count. This will be a good indication of someone who truly understands the limitations of this technology.

Another reason to remove the P-IOL is when a patient develops a cataract. A cataract means that the natural lens of the eye has become cloudy and restricts light from reaching the retina and being “seen”. Cataracts are a natural part of the aging process or can be caused by trauma. Cataract surgery is a process of replacing the natural lens with a artificial lens. The P-IOL is not needed and is actually in the way for cataract surgery.

Another P-IOL lens that is in the process of being approved for the US is the STAAR ICL. This P-IOL is placed behind the iris in front of the cataract. While this lens does not seem to be disruptive to the endothelial cells after the initial shock of surgery, its proximity to the natural lens can lead to a trauma induced cataract.

Like all surgery, every patient needs to be evaluated carefully. For some – particularly high myopes under age 40 with no astigmatism and a healthy endothelium cell count – P-IOLs may be the best option for refractive surgery.

Glenn Hagele
http://www.USAEyes.org

I am not a doctor.