Effect of anterior chamber depth on the choice of intraocular lens calculation formula in patients with normal axial length

ABSTRACT

To compare the accuracy of Sanders-Retzlaff-Kraff II [SRK II] and 3[rd] and 4[th] generation intraocular lens [IOL] formulas and to compare the effect of different anterior chamber depths among the IOL formulas in cataract patients with normal axial length [AL; 22.0-24.5 millimeters, mm]. A retrospective chart review was performed of patients with normal AL who underwent cataract surgery. The SRK II and 3[rd] generation IOL formulas [Hoffer Q, SRK T, Holladay l] were compared to the 4[th] generation Haigis formula. For analysis, preoperative anterior chamber depth [ACD] was divided into three subgroups- =/<3, 3-3.5, and >/= 3.5 mm. The mean error [ME] and mean absolute error [MAE] of each formula was compared for each subgroup against the total. The difference between the ME and MAE of the formulas were compared for each ACD subgroup. P< 0.05 was considered statistically significant. The study sample was comprised of 309 eyes. The MAE were 0.56 D, 0.52 D, 0.51 D, 0.50 D, and 0.50 D with Haigis, Hoffer Q, SRK T, Holladay 1, and SRK II formulas, respectively The Haigis formula was a significantly weaker predictor than the SRK T [P < 0.00l] and Holladay 1[P= 0.035]formulas. The ME with Haigis formula was -0.23 D which changed to -0.06 D with ACD >/= 3.5 mm [P = 0.002]. The ME was -0.24 D with SRK II and changed to -0.09D with ACD 0.05, all comparisons]. The SRK II formula can predict refraction in patients with normal AL and ACD less than 3 mm with less error and is preferred over other formulas. The Haigis formula is the preferred choice in patients with a normal AL and ACD longer than 3.5 mm. The prediction accuracy of Hoffer Q, SRK T, and Holladay 1 is comparable in normal AL