Accuracy of Intraocular Lens Power Calculations According to Corneal Curvature in Short Eyes

JeongJae Oh; Jin Seok Choi

doi:10.3341/jkos.2014.55.6.826

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Oh and Choi: Accuracy of Intraocular Lens Power Calculations According to Corneal Curvature in Short Eyes

Original Article

J Korean Ophthalmol Soc 2014;55(6):826-832.

Published online: 30 August 2014

DOI: https://doi.org/10.3341/jkos.2014.55.6.826

Accuracy of Intraocular Lens Power Calculations According to Corneal Curvature in Short Eyes

JeongJae Oh, MD, Jin Seok Choi, MD, PhD

Department of Ophthalmology, Saevit Eye Hospital, Goyang, Korea

Address reprint requests to Jin Seok Choi, MD, PhD, Department of Ophthalmology, Saevit Eye Hospital, #1065, Jungang-ro, Ilsandong-gu, Goyang 410-817, Korea, Tel: 82-31-900-7700, Fax: 82-31-900-7777, E-mail: zenith716@gmail.com

Received 28 September 2013 Revised 24 January 2014 Accepted 23 May 2014

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose

To evaluate the accuracy of intraocular lens (IOL) power calculations between Hoffer Q and other formulas accordin to corneal curvature by comparing the results of cataract surgery and calculation of chosen formulas in short axial lengths.

Methods

We performed a retrospective analysis of patients who underwent cataract surgery from January 1st, 2012 to June 12th, 2012. The patients were selected if their axial length was below 23.00 mm and 77 patients (90 eyes) were included in the present study. The patients were divided into 2 groups according to mean corneal curvature below 44.0 D and over 45.0 D. IOL power was calculated using the Hoffer Q and SRK II, SRK-T and Holladay I formulas and the error between the calculations and refractive outcome of cataract surgery were measured. The accuracy of each formula was evaluated by comparing the error be-tween the 2 groups.

Results

Hoffer Q formula showed a higher predictive accuracy than other formulas regardless of corneal curvature in eyes with short axial lengths (p < 0.001, p = 0.023). Particularly, SRK II, SRK-T and Holladay I showed a lower predictive accuracy in eyes with flat corneal curvature than Hoffer Q (p < 0.001, p = 0.215).

Conclusions

In eyes with short axial lengths, preoperative predicted IOL power calculations showed better accuracy with Hoffer Q formula than SRK II, SRK-T and Holladay I formulas. SRK II, SRK-T and Holladay I formulas showed a lower predictive accu-racy in flat corneal curvature eyes than steep corneal curvature eyes with short axial lengths. We hypothesize that SRK II, SRK-T and Holladay I tend to underestimate effective lens position in eyes with short axial lengths indicating Hoffer Q formula is more accurate.

Keywords: Corneal curvature, Formula, Hoffer Q, IOL calculation, Short eye

References

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Table 1.

Preoperative demographic characteristics

Variables	Values
Number of patients	77
Number of eyes	90
Age (years)	67.32 ± 5.36 (49-90)
Sex (M:F)	17 (22 eyes):60 (68 eyes)

Values are presented as mean ± SD.

Table 2.

Preoperative biometry and target power

Group	Group I (flatter K group: mean K ≤ 44.0)	Group II (steeper K group: mean K ≥ 45.0)	p-value^*
Number (eyes)	42	48
Sex (male/female)	10/27	7/33	0.12
Flat K (diopter)	42.54 ± 0.63	45.25 ± 1.27	0.01^†
Steep K (diopter)	44.36 ± 0.68	47.68 ± 1.06	0.02^†
UCVA (log MAR)	0.41 ± 0.04	0.32 ± 0.06	0.71
BCVA (log MAR)	0.23 ± 0.06	0.27 ± 0.07	0.15
IOP (mm Hg)	15.32 ± 2.32	16.54 ± 2.68	0.31
Axial length (mm)	22.52 ± 0.41	22.73 ± 0.21	0.27
Target power
SRK II	-0.67 ± 0.13	-0.43 ± 0.25
SRK-T	-0.47 ± 0.24	-0.24 ± 0.54
Holladay I	-0.32 ± 0.35	-0.21 ± 0.36
Hoffer Q	-0.21 ± 0.18	-0.14 ± 0.22

Values are presented as mean ± SD.

K = corneal refractive power; UCVA = uncorrected visual acuity; BCVA = best corrected visual acuity; IOP = intraocular pressure.

^* Student's t-test;

^† p < 0.05.

Table 3.

Mean numerical error (MNE) and mean absolute error (MAE) according to intraocular lens power calculation formulas (SRK T, Holladay I, SRK II, Hoffer Q)

Group	Group I (flatter K group: mean K ≤ 44.0)	Group II (steeper K group: mean K ≥ 45.0)	p-value^‡
MNE (diopter)
SRK-T	-0.24 ± 0.16	-0.32 ± 0.06	0.124
Holladay I	-0.15 ± 0.06	-0.22 ± 0.05	0.140
SRK II	-0.55 ± 0.07	-0.28 ± 0.08	0.214
Hoffer Q	-0.07 ± 0.06	-0.18 ± 0.05	0.140
p-value^*	<0.001^†	0.215
MAE (diopter)
SRK-T	0.33 ± 0.05	0.52 ± 0.05	0.104
Holladay I	0.30 ± 0.04	0.38 ± 0.04	0.214
SRK II	0.57 ± 0.65	0.39 ± 0.05	0.141
Hoffer Q	0.20 ± 0.02	0.27 ± 0.03	0.181
p-value^*	<0.001^†	0.023^†

Values are presented as mean ± SD.

K = corneal refractive power.

^* ANOVA test;

^† p < 0.05;

^‡ Student's t-test.

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