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Comparison of intraocular lens calculation formulas depending on anterior chamber depth in patients with normal axial length

Poster Details

First Author: D.Rascevskis LATVIA

Co Author(s):    G. Laganovska                    

Abstract Details


To evaluate and compare predictability and accuracy of three IOL power calculation formulas (SRK/T, SRK II and Haigis) and to analyze the influence of various anterior chamber depths between the IOL formulas in cataract patients with normal axial length (AL; 22.0-24.5 millimeters, mm).


Study was made at Pauls Stradins Clinical University Hospital, Department of Ophthalmology.


Prospective study included 45 patients with normal AL who underwent phacoemulsification with IOL implantation. Preoperative IOL power calculations were made using Carl Zeiss IOL Master v5 optical biometer. Postoperative actual refraction and refraction predicted by the SRK II, SRK/T and Haigis formulas were analyzed. For analysis, preoperative anterior chamber depth (ACD) was divided into three subgroups: �â�‰�¤3, 3-3.5, and �â�‰�¥3.5 mm. The mean estimation error (EE), mean absolute estimation error (AEE) and the percentage of eyes within target refraction (EWTR) (�Â�±0.50 and �Â�±1.00 D) for all three formulas were calculated and compared. P < 0.05 was considered statistically significant.


In the overall study group the AEE were 0.51D, 0.34D and 0.61D with SRK II, SRK/T and Haigis formulas, respectively. The Haigis formula was a significantly weaker predictor than SRK/T (P < 0.007). The AEE with Haigis formula changed to 0.21D with ACD �â�‰�¥3.5 mm (P = 0.003). The AEE with SRK II changed to 0.17D with ACD �â�‰�¤3 mm (P = 0.009). There was no statistically significant difference between SRK/T formula in ACD subgroups (P > 0.05). The highest percentage of eyes within �Â�±0.50 and �Â�±1.00 D of the target refraction was found by using SRK/T (73% and 100%).


Better results can be obtained using SRK/T formula in patients with normal AL and ACD from 3-3.5 mm. The SRK II formula can predict refraction in patients with normal AL and ACD less than 3 mm with less error. The Haigis formula is the preferred in patients with a normal AL and ACD more than 3.5 mm.

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