Comparison of the Capsular Stability With Two Different IOL Models in Patients With Pseudoexfoliation Syndrome: an Exploratory Study

Pseudoexfoliation (PXF) is an age-related disease characterized by production of extracellular material in the anterior segment of the eye and other tissues of the body. While only 0.6% of people between 52 and 65 years are affected, 5% of people between 75 years and 85 years have Pseudoexfoliation syndrome. An estimated 70 million people may have PXF worldwide. PXF can be associated with glaucoma, cataract, reduced pupil dilatation, zonule weakness, and postoperative complications. After cataract surgery decentration and subluxation of the intra-ocular lens (IOL) is more likely in patients with Pseudoexfoliation syndrome due to the higher incidence of zonular weakness as well as the increased capsule fibrotic reaction. It has to be taken into account that an anterior chamber depth (ACD) shift, decentration, tilt or rotation of an IOL could result in a severe reduction in visual quality. For an aspherical IOL, for instance, it is essential not to be decentered and tilted more than 0.4 mm (0.8 mm 7) and 7° (10° 7), respectively. Otherwise it will be outperformed by a spherical IOL. We assume that the design of the IOL, more precisely the design of the anterior surface of the IOL, can influence the degree of capsule fibrosis and contraction, especially in patients who tend to have capsular instability like patients with PXF syndrome. The Tecnis 1-piece ZCB00 (AMO, California, USA), a single-piece hydrophobic acrylic open-loop IOL has its convex anterior surface not up to the edge of the IOL optic, but instead has a concave depression before reaching the edge. Due to this particular shape of the anterior surface, the anterior lens capsule typically only has contact at the IOL optic edge with the remaining central part up to the rhexis edge 'floating' over the optic without contact. Due to this situation, we expect less fibrotic reaction of the capsule because of a lack of contact between the lens epithelial cells of the anterior capsule not transdifferentiating into myofibroblasts and not laying down collagen that result in the typical contraction and whitening of the anterior capsule. On the contrary, another IOL, the ISERT 250 (HOYA, Japan), also a hydrophobic acrylic open-loop IOL, has an anterior surface which is convex all the way to the optic edge resulting in complete contact of the rhexis edge and overlying the anterior capsule on the IOL optic. This may aggravate the anterior lens capsule reaction to the IOL material which may result in more capsular contraction due to pronounced fibrosis of the capsule and in turn results in decentration and or tilt of the IOL.

Aim of this study is to assess the differences of IOL tilt and decentration in patients with pseudoexfoliation syndrome (PXF) with two different IOLs, the Tecnis 1-piece ZCB00, (AMO, USA) and the ISERT 250 (HOYA, Japan), measured with an AS-OCT, Scheimpflug imaging and Purkinjemeter.