Analyze the effect of keratometry on the calculation accuracy of intraocular lens diopter in patients with normal axial cataract / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To evaluate the effect of keratometry on the calculation accuracy of intraocular lens(IOL)diopter in patients with normal axial cataract.METHODS:Totally 157 cases(157 eyes)with age related cataract were collected in Kaifeng Central Hospital from June 2020 to June 2021. Patients were divided into 3 groups according to keratometry: group A(53 eyes)(K<42D), group B(55 eyes)(42D≤K≤46D), group C(49 eyes)(K>46D). The IOL diopter was calculated by SRK/T, Hoffer Q, Holladay 2, Haigis, Kane and Barrett Ⅱ formulas respectively. Subjective optometry was performed after 1mo operation. The average refractive prediction error(RPE)and mean absolute error(MAE)were calculated, and their differences were compared and analyzed.RESULTS:There were significant difference between RPE of each formula and 0D in groups A and C(<i>P</i><0.05), and Barrett Ⅱ formula was significantly different with SRK/T, Hoffer Q, Holladay 2 and Haigis formula(<i>P</i><0.01), but was no significantly different with Kane formula in RPE(<i>P</i>>0.01). There was no significant difference in RPE between group B and 0D(<i>P</i>>0.05). The ratio of Barrett Ⅱ formula in MAE≤0.5D in group A was significantly higher than SRK/T, Hoffer Q, Holladay 2 and Haigis formula(all <i>P</i><0.01), but there was no significant difference compared with Kane formula(<i>P</i>>0.01). In group B, there was no significant difference among Barrett Ⅱ formula and the other formulas in the ratio of MAE≤0.5D and ≤1.0D(all <i>P</i> >0.01). In group C, the ratio of SRK/T and Hoff Q formula in MAE≤0.5D was lower than Barrett Ⅱ formula(all <i>P</i><0.01), and there were no significant difference among Barrett Ⅱ formula and the other formulas in the ratio of MAE≤1.0D(<i>P</i> >0.01).CONCLUSION:If K<42D or K>46D before operation, the commonly used formulas will produce refractive error, but the accuracy of Kane and Barrett Ⅱ formulas are still higher than other formulas.

Refractive Changes after Removal of Anterior IOLs in Temporary Piggyback IOL Implantation for Congenital Cataracts

PURPOSE: To assess the refractive change and prediction error after temporary intraocular lens (IOL) removal in temporary polypseudophakic eyes using IOL power calculation formulas and Gills' formula. METHODS: Four consecutive patients (7 eyes) who underwent temporary IOL explantation were enrolled. Postoperative refractions calculated using IOL power calculation formulas (SRK-II, SRK-T, Hoffer-Q, Holladay, and the modified Gills' formula for residual myopia and residual hyperopia) were compared to the manifest spherical equivalents checked at 1 month postoperatively. RESULTS: The mean ages of temporary piggyback IOL implantation and IOL removal were 6.71 +/- 3.68 months (range, 3 to 12 months) and 51.14 +/- 18.38 months (range, 29 to 74 months), respectively. The average refractive error was -13.11 +/- 3.10 diopters (D) just before IOL removal, and improved to -1.99 +/- 1.04 D after surgery. SRK-T showed the best prediction error of 1.17 +/- 1.00 D. The modified Gills' formula for myopia yielded a relatively good result of 1.47 +/- 1.27 D, with only the variable being axial length. CONCLUSIONS: Formulas to predict refractive change after temporary IOL removal in pediatric polypseudophakia were not as accurate as those used for single IOL implantation in adult eyes. Nonetheless, this study will be helpful in predicting postoperative refraction after temporary IOL removal.

Refractive Changes after Removal of Anterior IOLs in Temporary Piggyback IOL Implantation for Congenital Cataracts

PURPOSE: To assess the refractive change and prediction error after temporary intraocular lens (IOL) removal in temporary polypseudophakic eyes using IOL power calculation formulas and Gills' formula. METHODS: Four consecutive patients (7 eyes) who underwent temporary IOL explantation were enrolled. Postoperative refractions calculated using IOL power calculation formulas (SRK-II, SRK-T, Hoffer-Q, Holladay, and the modified Gills' formula for residual myopia and residual hyperopia) were compared to the manifest spherical equivalents checked at 1 month postoperatively. RESULTS: The mean ages of temporary piggyback IOL implantation and IOL removal were 6.71 +/- 3.68 months (range, 3 to 12 months) and 51.14 +/- 18.38 months (range, 29 to 74 months), respectively. The average refractive error was -13.11 +/- 3.10 diopters (D) just before IOL removal, and improved to -1.99 +/- 1.04 D after surgery. SRK-T showed the best prediction error of 1.17 +/- 1.00 D. The modified Gills' formula for myopia yielded a relatively good result of 1.47 +/- 1.27 D, with only the variable being axial length. CONCLUSIONS: Formulas to predict refractive change after temporary IOL removal in pediatric polypseudophakia were not as accurate as those used for single IOL implantation in adult eyes. Nonetheless, this study will be helpful in predicting postoperative refraction after temporary IOL removal.