Strength of haptics of multipurpose intraocular lens

We measured the strength of haptics of two types of intraocular lens (IOL) made by Nidek Co. One has equal haptics in diameter (NR-84C) and the other unequal ones (NR-84K). We used a digital force guage to which the optics of each IOL was fixed. The end of haptics was pulled either parallel or vertical to the optics at the speed of 40 mm/min. We recorded the strength of the force at the break point of the haptics. When the power was applied parallel to the optics, the breaking power was significantly less for NR-84K than NR-84C (p < 0.05). The haptics broke at their end for either type of IOL. When the power was applied vertical to the optics, the breaking power was the same for both types of IOL. The haptics broke at the end of haptics for NR-84K and near the root for NR-84C. The findings show that haptics unequal in diameter are weaker than those with equal ones. Standardization in the strength of haptics is desired in order to avoid their break during transscleral fixation of IOL.