Accuracy of Intraocular Lens Power Calculation Formulas in Myopic Eyes with Target Refractions of Emmetropia and Intentional Myopia

Figures & data

Table 1 Characteristics of the Patients and Implanted IOLs

	Target		p value
	Emmetropia (n = 26)	Intentional Myopia (n = 24)
Age (years), mean±SD	74.1 ± 8.3	69.8 ± 9.9	0.10
Female, n (%)	8 (30.8%)	10 (41.7%)	0.42
Axial length (mm)
Mean ± SD	25.15 ± 0.43	25.19 ± 0.40	0.76
Range	24.56–26.00	24.53–25.96
Average keratometry (D)
Mean ± SD	43.49 ± 1.55	44.24 ± 1.14	0.06
Range	39.86–47.87	42.65–47.19
Anterior chamber depth (mm)
Mean ± SD	3.32 ± 0.30	3.37 ± 0.36	0.57
Range	2.69–4.02	2.75–4.05
Lens thickness (mm)
Mean ± SD	4.37 ± 0.47	4.31 ± 0.47	0.66
Range	3.30–5.18	3.33–5.11
Central corneal thickness (μm)
Mean ± SD	551.61 ± 30.75	545.12 ± 39.69	0.52
Range	503.00–620.00	454.20–612.01
White to white (mm)
Mean ± SD	11.98 ± 0.44	11.92 ± 0.26	0.57
Range	11.05–12.74	11.20–12.43
IOL power (D)
Mean ± SD	16.6 ± 2.6	19.4 ± 1.9	<0.001*
Range	9.0–22.0	13.5–22.5

Notes: *Significant at p <0.05 (unpaired t-test or chi-square test).

Abbreviations: IOL, intraocular lens; SD, standard deviation.

Table 2 Comparison of the Mean Numerical Errors of the IOL Power Calculation Formulas Between Eyes with Target of Emmetropia and Intentional Myopia

	Target
	Emmetropia (n = 26***)	Intentional Myopia (n = 24)	p value
SRK/T
Numerical error (D), mean ± SD	0.09 ± 0.40	−0.39 ± 0.53**	<0.001*
Myopic error (%)	10 (38.5%)	18 (75.0%)
Holladay 1
Numerical error (D), mean ± SD	0.48 ± 0.38**	0.14 ± 0.48	0.008*
Myopic error (%)	4 (15.4%)	10 (41.7%)
Hoffer Q
Numerical error (D), mean ± SD	0.27 ± 0.37**	−0.02 ± 0.48	0.02*
Myopic error (%)	6 (23.1%)	13 (54.2%)
Holladay 2
Numerical error (D), mean ± SD	0.11 ± 0.38	−0.23 ± 0.47**	0.007*
Myopic error (%)	11 (42.3%)	18 (75.0%)
Haigis
Numerical error (D), mean ± SD	0.03 ± 0.35	−0.13 ± 0.48	0.17
Myopic error (%)	12 (46.2%)	15 (62.5%)
Barrett Universal II
Numerical error (D), mean ± SD	0.21 ± 0.36**	−0.01 ± 0.48	0.08
Myopic error (%)	9 (34.6%)	13 (54.2%)

Notes: *Significant at p <0.05 (unpaired t-test). **Significantly different from zero at p <0.05 (one sample t-test). ***Holladay 2: n = 25.

Abbreviations: SRK/T, Sanders, Retzlaff, and Kraft/theoretical; SD, standard deviation; Myopic error, Postoperative refraction is relatively myopic compared to predicted refraction.

Figure 1 Box and whisker plots of numerical errors in eyes with a target of emmetropia and intentional myopia (SRK/T = Sanders, Retzlaff, and Kraft/theoretical). The horizontal line in the box represents the median. The top and bottom of the box represent the upper and lower quartiles, respectively. The whisker above the box represents the values within 1.5 times the interquartile range plus the upper quartile, and the whisker below the box represents the values within 1.5 times the interquartile range minus the lower quartile. Values, which are not included between whiskers, were plotted as outliers.

Table 3 Comparison of the Mean Absolute Errors of the IOL Power Calculation Formulas Between Eyes with Target of Emmetropia and Intentional Myopia

Absolute Error (D), Mean ± SD	Target
	Emmetropia (n = 26**)	Intentional Myopia (n = 24)	p value
SRK/T	0.31 ± 0.26	0.54 ± 0.37	0.02*
Holladay 1	0.51 ± 0.33	0.37 ± 0.33	0.13
Hoffer Q	0.38 ± 0.26	0.37 ± 0.29	0.97
Holladay 2	0.31 ± 0.23	0.40 ± 0.32	0.26
Haigis	0.29 ± 0.18	0.39 ± 0.30	0.18
Barrett Universal II	0.33 ± 0.24	0.35 ± 0.32	0.81

Notes: *Significant at p <0.05 (unpaired t-test). **Holladay 2: n = 25.

Abbreviations: SRK/T, Sanders, Retzlaff, and Kraft/theoretical; SD, standard deviation.