At its introduction in 2009 to the New Zealand market the Crystalens had already been in use in the USA for more than seven years. It was the first and only accommodating IOL to be approved for use by the USA Food & Drug Administration. The Crystalens has undergone several model changes so as to improve results and reduce complications. The model introduced to New Zealand in 2009 was the Crystalens HD. Dr Kent started using the Crystalens AO in late 2009. The Crystalens HD was approved by the US FDA in early 2010.
The Crystalens relies on the normal, natural mechanism of accommodation of the eye. When you want to look at something close to you the brain sends signals to the ciliary muscle inside the eye causing it to contract. This happens regardless of your age and the ciliary muscle maintains its strength throughout life. The contraction of the ciliary muscle increases the pressure on the jelly-like vitreous of the eye and the vitreous pushes the Crystalens forwards in the eye. The Crystalens is unique in that it has hinges in the supporting part of the lens (haptics) that allow this forwards movement. As the IOL moves forwards it results in the focus of the eye changing onto closer objects.
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| Near Vision | Far Vision | Intermediate Vision |
Unlike the bifocal like effect of a multifocal IOL the Crystalens aims to restore the normal ability to continuously change the focus of the eye. The success of the Crystalens HD will depend on how well the lens moves forwards in your eye. In many cases it may not work straight away and the accommodation of the Crystalens is known to improve with time. Most cases will require that a YAG laser treatment to the capsule of the natural lens is performed before the Crystalens works properly.
Advantages of the Crystalens over the Alcon ReSTOR IOL:
- Fewer problems with halos and ghost images particularly for night driving.
- Quality of distance vision is slightly better as the Crystalens is just like a monofocal IOL for distance vision. The Crystalens delivers 100% of the available light at all distances whereas the multifocal splits the light to focus at two different places at the same time.
- Better unaided intermediate distance vision.
- Gives a continuous range of focus instead of two focal distances.
Disadvantages of the Crystalens compared to the Alcon ReSTOR
- A lower percentage of eyes read the very smallest reading test type – about 50% versus 80%. You may still need glasses to read fine print such as a telephone book.
- There is a complication called the Z-syndrome. This is displacement of the position of the Crystalens in the eye caused by contraction of the capsular bag of the natural lens. The result is that the focus (refraction) of the eye is not perfectly focused for distance any more. It can often be solved by using a YAG laser to make an opening in the capsule of the natural lens. The newer models of Crystalens such as the HD are less likely to suffer from the Z-syndrome than the older models. I have seen no cases of the Z-syndrome since I started to routinely use a capsular tension ring with the Crystalens in June 2009.
- The Crystalens is more expensive. There is an additional surcharge for this lens which includes 6-12 months of follow up, any laser refractive surgery that may be required as well as YAG laser capsulotomy. Basically a cost up front that means I will give you the best result that I can give you without further charge.