Capsular tension ring may increase tilt and decentration of plate haptic IOL
Capsular tension rings (CTR) are designed to increase the stability of intraocular lenses (IOL) in the capsular bag. However, a study of rotation, tilt, and decentration of a plate haptic IOL found no overall difference in rotation between lenses implanted with or without a CTR, while tilt and decentration were actually higher in the CTR group, Daniel Schartmüller MD said at a free paper session Sunday.
The prospective randomised study involved 130 eyes of 65 patients. Each was randomly implanted with an 11.00 mm Zeiss 409M plate haptic IOL and an Ophtec 276 13/11 mm CTR in one eye and the lens only in the fellow eye.
Regarding rotation, no lens in the CTR group rotated more than 5 degrees in the first hour after surgery, while four non-CTR lenses did, with one rotating nearly 24 degrees. Mean rotation was 1.3 degrees in the CTR group and 2.1 degrees in the non-CTR group, though the difference was not statistically significant. Mean rotation was also similar between the two groups at one week, one month, and six months after surgery, though there were more outliers in the non-CTR group at one month.
“There was no difference in mean absolute rotation but significantly lower proportion of outliers in the CTR group. There was no correlation between absolute overall rotation and lens thickness, axial length, and lens equatorial diameter. A decrease in rotation in the CTR group was observed within the first postoperative hour,” said Dr Schartmüller of the Medical University of Vienna, Austria.
Lens decentration and tilt were secondary results, Dr Schartmüller said. Both were measured in absolute terms and compared with measurements of tilt and decentration of the crystalline lens before surgery.
Six months after surgery, mean absolute decentration in the CTR group was 0.28 mm and in the non-CTR group 0.24 mm, which was not statistically significant. However, compared with preoperative measurements, the CTR group was significantly more decentred at a mean of 0.29 mm compared with 0.18 mm in the non-CTR group. The decentration increased at one month and six months after surgery as the capsules fibrosed, Dr Schartmüller said.
Six months after surgery, the mean tilt in the CTR group was 6.66 degrees compared with 5.55 degrees in the non-CTR group, a statistically significant finding. Tilt increased more in the CTR group as the capsule fibrosed. There were also more outliers in the CTR group, with lenses tilted up to 17.7 degrees six months after surgery.
“We see a negative impact on decentration and tilt when using a capsular tension ring with an 11.00 mm plate haptic IOL,” Dr Schartmüller concluded.