Phakic Intraocular Lenses
What are Phakic Intraocular Lenses?
A phakic intraocular lens (pIOL) is a lens implant that can be placed in your eye without removing the eye’s natural lens. It is one of the techniques available for correcting a spectacle prescription and is an alternative to laser correction.
A pIOL is placed in front of the eye’s natural lens, either just in front of the iris or just behind it.
Patients may be deemed unsuitable for laser eye surgery by virtue of having a very high spectacle prescription (also known as the ‘refractive error’), or a thin cornea, or because of some other concern arising from the pre-operative examination. In these cases, further measurements would be required to establish suitability for pIOL implantation. The most important factors to consider are:
- The refractive error should be within the range that is correctable by a pIOL.
- There must be sufficient space in the eye to accommodate the pIOL.
- There must be a sufficient number of cells in the inner layer of the cornea, called the endothelium. These cells are required to maintain the clarity of the cornea. We will measure the endothelial cell count (ECC) before and after surgery.
Advantages of pIOL implantation
- Because of the eye’s natural lens is left in place, you will retain your natural ability to read up close and adjust for objects farther away. This ability to zoom out and in is called ‘accommodation’. It is gradually lost as we get older and need reading glasses (presbyopia), and is also lost if the eye’s natural lens is removed (e.g. clear lens exchange surgery).
- No permanent change is made to the shape or structure of the cornea.
- Reversible procedure. The pIOL may be removed at any time after implantation, if necessary. For example, you may develop a cataract in later life and it’s removal will dictate that the pIOL be removed at the same time.
Effectiveness of pIOL implantation
Vision without glasses or contact lenses after pIOL implant
Candidates who choose pIOL surgery generally have high refractive errors or astigmatism. These are inherently less straightforward to correct and some people may be left with a residual refractive error, as shown in the table above. Residual refractive errors may be treated with spectacles or contact lenses when needed. For example, you may find that after pIOL implant surgery you can see in the distance satisfactorily, but may need glasses to read for long periods.
An alternative approach to correcting a residual refractive error is to proceed with laser refractive surgery. All options will be discussed at your initial consultation and you will be given individualised advice.
It is essential that you are clear about what you want the surgery to achieve. Mr Muhtaseb will discuss all your options with you and provide plenty of time to answer all your questions.
As with any surgical procedure, there are risks of which you must be aware. Your doctor will explain these risks to you and ensure that you understand them completely. You will be given time to discuss all issues to your satisfaction.