JAN 22, 2015
This prospective, randomized study found that implantation of a capsular tension ring (CTR) has no significant influence on postoperative axial IOL position.
To the authors’ knowledge, this is the first randomized controlled study showing that a CTR has no effect on postoperative anterior chamber depth.
This is a very important study as it has been bandied about that CTRs may change effective lens position and this study proves that they don't. I know of no nomogram that uses CTR as a variable for IOL power calculation and now we know that we don't need one.
Subjects included 30 patients who underwent bilateral small-incision cataract surgery with implantation of a hydrophobic acrylic single-piece IOL (Tecnis ZCB00) using a standard technique. The first eye to have surgery was randomly allocated to the CTR group or the control group (no CTR), with both patients and examiners masked to the allocation.
There was no significant difference in mean pre- or postoperative anterior chamber depth between the CTR and control groups. Furthermore, the preoperative anterior chamber depth measurements were only moderately good predictors of the postoperative IOL position.
The authors note that this study did not address the position of the IOL haptics relative to the CTR. Ultrasound biomicroscopy might help in understanding whether location of the IOL haptics in front of or behind the CTR could lead to a slight tilt. Further studies are needed to determine this relationship.