Predictability of different calculators in the minimization of postoperative astigmatism after implantation of a toric intraocular lens

Figures & data

Table 1 Mean absolute error in predicted residual astigmatism for each calculator

Calculator	Mean ± SD (range) Diopters	95% CI for mean	p-value
Standard toric calculator based on anterior keratometry values	0.77±0.40 (0.01, 1.91)	0.65–0.86	-
PhysIOL toric calculator with Abulafia-Koch formula	0.35±0.29 (0.00, 1.36)	0.27–0.44	<0.001
Barrett calculator	0.40±0.29 (0.00, 1.07)	0.34–0.51	<0.001
Holladay calculator + Pentacam TCRP	0.72±0.41 (0.02, 1.87)	0.64–0.85	0.656
Holladay calculator + Cassini TCA	0.49±0.30 (0.00, 1.07)	0.37–0.60	0.002

Abbreviations: SD, Standard deviation; TCRP, Total Corneal Refractive power; TCA, Total corneal astigmatism.

Table 2 Centroid error in predicted residual astigmatism for each calculator

Calculator	Centroid (diopters ± SD @ angle) 95% CI	p-value x component (comparison with standard toric calculator)	p-value y component (comparison with standard toric calculator)
Standard toric calculator based on anterior keratometry values	0.39±0.41 @ 166 0.33–0.45	-	-
PhysIOL toric calculator with Abulafia-Koch formula	0.05±0.34 @ 167 0.00–0.10	<0.001	<0.001
Barrett calculator	0.07±0.28 @ 160 0.03–0.11	<0.001	<0.001
Holladay calculator + Pentacam TCRP	0.23±0.56 @ 158 0.16–0.31	0.134	0.078
Holladay calculator + Cassini TCA	0.10±0.44 @ 156 0.04–0.16	0.009	0.042

Abbreviations: SD, Standard deviation; TCRP, Total Corneal Refractive power; TCA, Total corneal astigmatism.

Table 3 Mean absolute and centroid errors in predicted residual astigmatism for eyes with with-the-rule (WTR) and against-the-rule (ATR) corneal astigmatism

Calculator	Eyes with WTR corneal astigmatism (n=27)		Eyes with ATR corneal astigmatism (n=16)
	MAE ± SD diopters (range) 95% CI	Centroid (diopters ± SD @ angle) 95% CI	MAE ± SD diopters (range) 95% CI	Centroid (diopters ± SD @ angle) 95% CI
Standard toric calculator based on anterior keratometry values	0.81±0.48 (0.25, 1.91) 0.72–0.90	0.49±0.59 @ 168 0.38–0.60	0.64±0.43 (0.01, 1.91) 0.54–0.75	0.38±0.44 @ 162 0.27–0.49
PhysIOL toric calculator with Abulafia-Koch formula	0.31±0.23 (0.00, 1.36) 0.27–0.35	0.08±0.39 @ 161 0.01–0.15	0.28±0.21 (0.00, 0.76) 0.23–0.33	0.01±0.26 @ 175 –0.05–0.07
Barrett calculator	0.35±0.25 (0.00, 1.07) 0.30–0.40	0.09±0.32 @ 155 –0.03–0.21	0.26±0.19 (0.00, 0.71) 0.21–0.31	0.01±0.25 @ 167 –0.05–0.07
Holladay calculator + Pentacam TCRP	0.73±0.42 (0.02, 1.31) 0.65–0.81	0.39±0.61 @ 177 0.28–0.51	0.54±0.54 (0.15, 1.87) 0.41–0.67	0.27±0.48 @ 179 0.15–0.39
Holladay calculator + Color-LED topography TCA	0.43±0.33 (0.01, 1.07) 0.37–0.49	0.12±0.43 @ 145 0.04–0.20	0.35±0.29 (0.00, 1.01) 0.28–0.42	0.07±0.39 @ 160 –0.03–0.17

Abbreviations: MAE, Mean absolute error; SD, Standard deviation; TCRP, Total Corneal Refractive power.

Figure 1 Double-angle plots illustrating the centroid prediction errors in residual astigmatism for each calculation method.

Figure 2 Percentage of eyes within 0.25D–1.00D of absolute astigmatic prediction error with each calculation method.