Intra-ocular lens power calculation in patients with high axial myopia before cataract surgery.

PURPOSE To evaluate the accuracy of different formulas used for IOL power calculation in patients with high axial myopia undergoing cataract surgery. METHODS A prospective clinical study was carried out on 53 eyes of 51 patients with an axial length from 25.5 to 31.4 mm including 21 males (41.2%) and 30 females (58.8%). Calculation of the IOL power to be implanted was done by three available IOL power formulas; Haigis formula, SRK/T formula, and Holladay I formula. The mean error (ME) was calculated from the difference between the formula predicted refractive error and the actual post operative refractive error. RESULTS There was no statistically significant difference between the mean error of the three formulas used in the overall performance or in the axial length subcategories. SRK/T formula caused the smallest mean error, (+0.17 D). Haigis formula showed a higher ME (+0.21 D) and Holladay formula caused a myopic postoperative refractive error (-0.20 D). CONCLUSION The calculation of IOL power in patients with high axial myopia using the third or the fourth generation formulas help in improvement of the accuracy of the calculation and decreasing the post operative refractive error. SRK/T formula showed the lowest mean error, however, there was not statistically significant difference between the three formulas used, neither in the overall performance, nor in axial length subcategories.