An interview with Dr Mark Tomalla about his experience with the Crystalens HD IOL.
In another of its Ask the Expert series Ophthalmology Times Europe interviewed Dr Tomalla, MD, one of the surgeons, from one of four selected centres, which were the first to use the accomodative IOL Crystalens HD from Bausch & Lomb in Europe. Since 2005 he has been the Senior Physician at the Clinic for Refractive and Ophthalmic surgery in Duisburg, Clinic Niederrhein in Germany. He was also the first to perform Femtec femtosecond laser-controlled pKPL and endothelial transplantation worldwide. In addition he has invented and developed several instruments and implants and holds several patents.
Q: How did you come to be among one of the centres in Europe to conduct these implants?
In the last few years we have performed a lot of prospective studies on IOLs. For example, I have been involved in the development of phakic IOLs and also the rotation stability of different IOL models.
The Crystalens HD is a refractive IOL, with which cataract treatment and myopia or hyperopia correction can be performed at the same time. In addition, the lens has a central near-vision additive of 1.5 D, whereby presbyopia correction is made. The Crystalens HD is an accommodative IOL, with an IOL optic of the silicone material Biosil (Refractive Index 1.427) and haptics made of polyimide. This causes the IOL to grow together with the capsular bag, which is of course what is required. The lens can also move forward and so enables pseudophakic accommodation. Unlike multifocal or diffractive IOL models, the Crystalens works only with one focus so the patient perceives objects at different distances as continuous vision.
Q: Why did you decide to use it?
My main interest was to check the possible comfort it might afford and the differences the patients might experience with this accommodative IOL compared to diffractive or refractive IOL models. For example, I was curious to find out whether patients would have halos following implantation.
Q: What concerns did you have at the outset?
One concern was whether the 5 mm optic of the IOL would be too small, because we usually use 6 mm optics.
I was sceptical in the beginning, because after implantation of the Crystalens the patients could not read immediately after surgery. This is because the pupil is dilated for several days. Also, for these patients that time lasted longer than usual in order for them to gain the best possible visual acuity postoperative. So, compared to a standard cataract surgery their VA, at the beginning was worse. Our patients achieved best results 4-6 weeks after surgery.
Q: How does the implant procedure differ from standard cataract surgery?
Implantation of the Crystalens should only be performed by an experienced surgeon, because the implantation differs from standard cataract surgery.
When the IOL is placed in the injector, careful attention must be paid to the correct implantation direction, which can be controlled by the different ends of the haptics.
The capsulorhexis must always be larger than the optic of the IOL, i.e. a capsulorhexis of 6 mm must be selected for an IOL optic of 5 mm. The anterior capsular bag must be placed outside the optic.
When the lens is already placed in the capsular bag, it must be pushed backward until there is complete contact with the posterior capsular bag. At this stage of the surgery, the IOL should not move forward at all.
The polyimide material of the haptics causes the IOL to grow firmly together with the capsular bag by fibrosis. At this stage it is important that the patient does not accommodate during the first 3-5 days after implantation. To avoid premature accommodation, the pupil is dilated after surgery with a single dose of atropine and it takes 3-5 days for this accommodation blockade to abate. During that time, the patient suffers from severe glare and cannot read. It's therefore important that the patient is fully cognizant of this prior to the surgery.