Phakic IOLs are used to correct the refractive errors of patients that are too high to correct with the Excimer laser alone. With such patients attempting to correct their vision with laser alone is not an option as too much tissue would have to be removed with the Excimer laser to achieve the desired result. This would result in the patient's cornea being thinned to a dangerous degree. In the Optical work-up it would have been determined as to how much tissue there was in the patient's cornea using Pachymetry. If this showed that the patient did not have sufficient tissue in their cornea then other measurements are made to determine whether their refractive error would be better treated using a Refractive Lens Exchange or else a Phakic implant. Factors such as the age of the patient, their occupation and the surgical principles of corrective eye surgery will determine which is the most idea technique for each individual.
There are two basic types of Phakic implants. The first type is anterior chamber implants and the second type is posterior chamber implants. In the anterior chamber group you can use either an implant that is fixated in the anterior chamber angle or else an implant that is fixated onto the mid peripheral iris.
The Ardfallen Eye Clinic uses an iris-fixated type of anterior chamber Phakic IOL known as the Veriseye. This implant is very stable within the eye and is available in a wide range of powers to correct both myopia and hyperopia. It is also available with an inbuilt toric correction to correct the patient's astigmatism as well as their spherical error. The determination of whether a Veriseye implant is suitable for any patient is determined by the amount of space available in the patient's anterior chamber (which is measured by both ultrasound and optically with a Pentacam or an OCT). It is also dependant on the patient having a healthy population of endothelial cells on their cornea and this is ensured by their having a cell count performed on this cell layer pre-operatively. The Veriseye was originally only available as a rigid implant which required a 6.2mm incision to implant it. This meant that a suture was used to seal the wound and that this would then be removed some weeks later. It also meant that there was period of time (again usually a few weeks) of recovery after the surgery during which the vision gradually improves. It is now available (in a limited range of powers) in a flexible form. The Veriflex can be implanted through a 3.2-3.5mm incision that does not require a suture to seal it post-operatively and therefore visual rehabilitation is faster that with the rigid implant.
The type of posterior chamber Phakic implant used by the Ardfallen Eye Clinic is the Visian ICL manufactured by STAAR Surgical Company. This implant is fixated in the ciliary sulcus behind the patient's iris and in front of the patient's crystalline lens. It requires that there is sufficient space in this part of the patient's eye to enable the Visian ICL to be safely implanted there. As the Visian is flexible it is loaded into an injector system and then it can be injected into the eye via a small self sealing incision. The implication of this is that there is rapid visual recovery with this implant. This will have been ensured during the course of the patient's pre-operative assessment utilising an investigation known as OCT.
During follow-up in both types of Phakic implants it is important to perform repeat measurements of their endothelial cell counts (usually every six months) and to repeat their Pentacam and OCT images. With both types there is a small inherent risk of inducing Lens opacities. If these should occur later on then the Phakic implant can be removed and a Refractive Lens Exchange undertaken to correct the refractive error. The same applies should a decrease (i.e. over an above the normal age-related reduction in the cell count with time) in the endothelial cell count be noted. It is important to note that with both Phakic IOL types that the operation is reversible.
Please click on our link to corrective eye surgery or on any of the other links to our Eye Library for further information on the topics highlighted.
Click here to review testimonials of some of Ardfallen Eye Clinic's previous patients treated with Phakic IOLs.
