The Egyptian Journal of Cataract and Refractive Surgery
Purpose The aim of this study was to compare the predictability of different intraocular lens (IO... more Purpose The aim of this study was to compare the predictability of different intraocular lens (IOL) power calculation formulas [Sanders–Retzlaff–Kraff (SRK) II formula, SRK-T formula, Haigis formula, Hoffer Q formula] in axial hyperopic patients [axial length (AL) <22 mm] undergoing cataract surgery using IOL master. Patients and methods This study comprised 40 eyes of 26 patients who presented with cataract and axial eye length less than 22 mm. Before phacoemulsification and IOL implantation, AL measurement, keratometry measurement and anterior chamber depth measurement using the IOL master were done. IOL power was calculated using four different formulas (SRK-II, SRK-T, Haigis, Hoffer Q). Actual stabilized postoperative refraction (spherical equivalent) 1 month after surgery was measured and the accuracy of the four different formulas was compared. Differences between actual postoperative refraction and predicted refraction using the different formulas were analyzed. P value less than or equal to 0.05 was considered statistically significant. Furthermore, the percentage of eyes with mean absolute prediction error (MAE) within ±0.5 and ±1.0 diopter (D) for each formula was estimated, as well as the correlation coefficient (r) between the AL and MAE for each formula. Results There was a significant difference between the MAE of the four formulas, except there was no significant difference between the MAE of SRK-T and SRK-II. The Haigis formula had a smallest MAE of 0.47±0.36 D, then Hoffer Q with a MAE of 0.87±0.51 D, and then SRK-T with a MAE of 1.38±0.89 D. The SRK-II had the largest MAE of 1.70±1.06 D. The Haigis formula predicted more eyes with MAE within ±0.5 and ±1.0 D of the predicted spherical equivalent compared with other formulas. The correlation between AL and AE has shown a negative r value and P value of less than 0.05 for all formulas. Conclusion The Haigis formula provides more accurate results concerning the postoperative target of refraction in eyes with an AL of less than 22.0 mm. Hoffer Q could be also used as an alternative.
This retrospective study was performed to compare refractive outcomes measured by conventional me... more This retrospective study was performed to compare refractive outcomes measured by conventional methods and by use of the Lenstar biometer and to investigate the factors affecting intraocular lens (IOL) power calculation with Lenstar with and without IOL-constant optimization. The study included 100 eyes of 86 patients who underwent cataract surgery. Corneal curvature was measured with a manual keratometer (MK), automated keratometer (AK), and the Lenstar biometer, and axial length (AL) was measured by A-scan and Lenstar. Mean numerical error (MNE) and mean absolute error (MAE) were compared between AK and MK with A-scan, and Lenstar with and without optimization. Factors affecting the accuracy of the IOL power calculation by use of Lenstar with and without optimization were analyzed. No significant differences were observed in the MNE or MAE among the devices. The proportion of MAE within 0.5 D was higher for Lenstar with optimization (62.7%) than without optimization (46.2%). The proportion of MAE within 0.5 D was 62% and 58% for MK and AK with A-scan, respectively. Without optimization, the MAE was smaller in eyes with ALs between 23 mm and 25 mm (p=0.03), whereas it was smaller at higher corneal powers when the IOL constant was optimized (>44 D, p=0.03). The IOL power calculations showed no significant differences among the devices, but the results of MAE within 0.5 D by use of Lenstar without optimization were worse than those of conventional methods. The AL influenced the accuracy of refractive outcomes determined by using Lenstar without optimization, and corneal curvature was shown to affect the accuracy of refractive measurements using Lenstar with optimization.
The Egyptian Journal of Cataract and Refractive Surgery
Purpose The aim of this study was to compare the predictability of different intraocular lens (IO... more Purpose The aim of this study was to compare the predictability of different intraocular lens (IOL) power calculation formulas [Sanders–Retzlaff–Kraff (SRK) II formula, SRK-T formula, Haigis formula, Hoffer Q formula] in axial hyperopic patients [axial length (AL) <22 mm] undergoing cataract surgery using IOL master. Patients and methods This study comprised 40 eyes of 26 patients who presented with cataract and axial eye length less than 22 mm. Before phacoemulsification and IOL implantation, AL measurement, keratometry measurement and anterior chamber depth measurement using the IOL master were done. IOL power was calculated using four different formulas (SRK-II, SRK-T, Haigis, Hoffer Q). Actual stabilized postoperative refraction (spherical equivalent) 1 month after surgery was measured and the accuracy of the four different formulas was compared. Differences between actual postoperative refraction and predicted refraction using the different formulas were analyzed. P value less than or equal to 0.05 was considered statistically significant. Furthermore, the percentage of eyes with mean absolute prediction error (MAE) within ±0.5 and ±1.0 diopter (D) for each formula was estimated, as well as the correlation coefficient (r) between the AL and MAE for each formula. Results There was a significant difference between the MAE of the four formulas, except there was no significant difference between the MAE of SRK-T and SRK-II. The Haigis formula had a smallest MAE of 0.47±0.36 D, then Hoffer Q with a MAE of 0.87±0.51 D, and then SRK-T with a MAE of 1.38±0.89 D. The SRK-II had the largest MAE of 1.70±1.06 D. The Haigis formula predicted more eyes with MAE within ±0.5 and ±1.0 D of the predicted spherical equivalent compared with other formulas. The correlation between AL and AE has shown a negative r value and P value of less than 0.05 for all formulas. Conclusion The Haigis formula provides more accurate results concerning the postoperative target of refraction in eyes with an AL of less than 22.0 mm. Hoffer Q could be also used as an alternative.
This retrospective study was performed to compare refractive outcomes measured by conventional me... more This retrospective study was performed to compare refractive outcomes measured by conventional methods and by use of the Lenstar biometer and to investigate the factors affecting intraocular lens (IOL) power calculation with Lenstar with and without IOL-constant optimization. The study included 100 eyes of 86 patients who underwent cataract surgery. Corneal curvature was measured with a manual keratometer (MK), automated keratometer (AK), and the Lenstar biometer, and axial length (AL) was measured by A-scan and Lenstar. Mean numerical error (MNE) and mean absolute error (MAE) were compared between AK and MK with A-scan, and Lenstar with and without optimization. Factors affecting the accuracy of the IOL power calculation by use of Lenstar with and without optimization were analyzed. No significant differences were observed in the MNE or MAE among the devices. The proportion of MAE within 0.5 D was higher for Lenstar with optimization (62.7%) than without optimization (46.2%). The proportion of MAE within 0.5 D was 62% and 58% for MK and AK with A-scan, respectively. Without optimization, the MAE was smaller in eyes with ALs between 23 mm and 25 mm (p=0.03), whereas it was smaller at higher corneal powers when the IOL constant was optimized (>44 D, p=0.03). The IOL power calculations showed no significant differences among the devices, but the results of MAE within 0.5 D by use of Lenstar without optimization were worse than those of conventional methods. The AL influenced the accuracy of refractive outcomes determined by using Lenstar without optimization, and corneal curvature was shown to affect the accuracy of refractive measurements using Lenstar with optimization.
Uploads