MRI of the Capsular Bag in Pseudophakic Human Donor Eyes

Abstract

Purpose: To investigate, using MRI, the effect of cataract surgery and IOL type on the capsular bag dimensions in multiple imaging planes.

Methods: MRI is not impeded by the iris or optical distortions and has the unique ability to visualize the entire intraocular lens (IOL) and its relationship to the surrounding anterior segment structures. Donor eyes (N=200, ages 50-99) were imaged 1.5T (General Electric) using a custom RF coil (MRI Research) and T1 weighting. The dimensions of the capsular bag were measured from the MRI images in multiple planes including those that were parallel and perpendicular to the haptic axis. A subset of donor eyes underwent gross and histopathological evaluation in order to further characterize the capsule.

Results: MRI revealed that the capsule is asymmetric after cataract surgery, being longer in the plane of the haptics and shorter in the orthogonal haptic free plane (mean difference = 0.649 mm, P < 0.0001). Differences in capsular dimensions were also observed for different lens types; with those of silicone 3-piece lenses (N=143) exceeding those of single-piece hydrophobic acrylic (N=57), (mean difference = 0.248 mm, P < 0.0006). Gross and histopathological analysis revealed the capsulorhexis shape, amount of optic covered by the capsulorhexis, and the presence of anterior or posterior capsular opacification.

Conclusions: MRI allows imaging in any desired plane providing complete characterization of the IOL and capsular bag dimensions and their geometric relationship to the intraocular structures. This study of adult pseudophakic eyes reveals differences in capsular dimensions with IOL type that are similar to those observed in a smaller gross analysis study of postmortem pediatric eyes undergoing experimental implantation. Our MRI findings have implications for IOL design, selection, and surgical technique. Additionally, combining MRI data with gross and histopathological data allows a more detailed view of the effects of cataract surgery on the capsular bag and the possibility of more completely characterizing the effects of recently introduced laser-created capsulorhexis.

Keywords: 567 intraocular lens • 445 cataract • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)