A CTR is a 270 degree open PMMA ring placed in the capsular bag during cataract surgery in cases with zonular instability or weakness. Capsular tension rings (standard type)For cases involving less than 4 clock hours (4 positions) of zonular dialysis, a standard CTR is suitable.Cionni rings with single and double loop.For cases involving greater than 4 clock hours or progressive zonular damage.Capsular tension segment.Partial ring used in cases that cannot be supported by CTR.