Comparison of Two Toric IOL Calculation Methods

Table 4

Comparison of the suggested lens power of sphere and cylinder including toric cylinder orientation by the standard and the Barrett calculator. Subgroup analysis for with-the-rule (WTR) and against-the-rule (ATR) astigmatism.

Subgroup	Calculator	Mean spherical power (D)	Mean cylinder power (D)	Lens orientation (°)
All ()	Standard	17.55 ± 5.95	3.22 ± 2.07	87.42 ± 35.76
	Barrett	17.28 ± 6.83	3.00 ± 1.54	87.92 ± 38.44
	value	0.01	0.26	0.49
WTR ()	Standard	17.67 ± 5.85	2.98 ± 1.32	89.53 ± 10.47
	Barrett	17.02 ± 7.01	2.75 ± 1.50	89.87 ± 12.63
	value	0.05	< 0.01	0.628
ATR ()	Standard	18.04 ± 5.83	4.71 ± 3.70	75.00 ± 75.49
	Barrett	19.17 ± 5.43	4.31 ± 1.36	75.17 ± 78.86
	value	0.08	0.50	0.84

The standard deviation must be considered when interpreting the toric cylinder orientation. For WTR and ATR, the mean values are almost the same. With regard to the standard deviation, most of the values indeed lie around 90° for WTR, whereas for ATR, only the mean is approximately 75° but the actual values are around 0° or 150°.