Accuracy of IOL Power Calculation Partial Coherence Interferometry and Various Formulas in Eyes With Axial Length Greater Than 24.0 mm
To assess the predictability of Intraocular Lens power calculations using IOL Master and four different IOL power calculation formulae (SRK/T, Holladay 1, Hoffer Q and Haigis) in eyes with axial length of > 24 mm.
This retrospective comparative study included 115 eyes of patients undergoing routine phacoemulsification with in-the-bag IOL implantation with axial length > 24 mm, from July 2012 to June 2014. Preoperative Axial Length and keratometric power were measured by IOL Master and power of the implanted IOL was determined using SRK/T, Holladay 1, Hoffer Q and Haigis formulas. Eyes were divided into mild (24-26 mm), moderate (26-28 mm), high (28-30 mm) and very high (> 30 mm) myopia. Predicted refractive outcomes were compared to actual refractive outcomes. Postoperative refractive errors one month after surgery were measured and were compared with the predicted postoperative power.
Mean Absolute Error for eyes with axial length between 24-28 mm using SRK/T, Holladay 1, Hoffer Q and Haigis formulae were 0.34, 0.47, 0.47 and 0.45 respectively, whereas for eyes with axial length > 28 mm MAE using SRK/T, Holladay 1, Hoffer Q and Haigis formulae were 0.79, 1.17, 1.17 and 0.56 respectively. The proportion with an absolute error (AE) of less than 1 D was greatest in the SRK-T formula (89.56%), followed by those in the Holladay 1 (81.74%), Hoffer Q (78.26%), Haigis formula (90.43).
The IOL power calculation using Haigis formula was most predictive for post-operative refractive status in eyes with axial length > 28 mm, whereas SRK-T formula was most predictive for eyes with axial length between 24-28 mm.