Comparing the effect to refraction after operation in appling intraooular lens biyometry formulas

SUMMARY Purpose: The evaluation of correctly estimating the formulas of SRK/T, SRK II, Binkhorst II and Holladay following refraction of cataract operation. Material and Methods: The 137 eyes of 137 patients carefully studied which cataract extractions and intraocular lens was implanted. The cases were divided into 3 groups according their axial length as < 22 mm short(n=17), 22-24 mm normal(n=105) and >24mm long(n=15) eyes. Before operation the axial length and keratometry measurement was made and according to the 4 formulas intraocular lens calculation was made. After the operation in the 3rd month the refractions on cases became stable and refractive measures was made. The refraction error after the operation were calculated as real refractive error and absolute error. Results: For group 1 when SRK/T, SRK II, Binkhorst II and Holladay formulas compared, the average absolute refractive error values are respectively 1.14±0.68, 1.12±0.67, 1.27±0.74, 1.18±0.70 and for all formulas the average is 1.18±0.69, but between the 4 formulas statistically significant difference was not determined(p=0.93). For group 2 significant difference was not determined between the order above and average absolute refractive error values 0.86±0.80, 0.8Ü0.79, 0.94±0.93, 0.92±0.85 and the average of 4 formulas is 0.88±0.84 and statistically significant difference was not determined(p=0.71). For grup 3 the average absolute refractive error values of the 4 formulas are in the same order as 1.17±1.11, 1.11±1.08, 1.42±1.05, 1.31±1.0 and the average of the 4 formulas is 1.25Ü.06 and between the formulas for absolute refractive error, statistically significant difference was not determined. 51When we look at the complete cases, the percentages of absolute refractive error less than 0.5 diopty according to the formulas of SRK/T, SRK II, Binkhorst II and Holladay were respectively %33, %39, %31, %30. The absolute refractive error percentages less than 1.0 dioptry were found respectively as %69, %69, %60, %64. The absolute refractive error percentages less than 2.0 dioptry according to the formulas as in the same order above were %91, %88, %87 and %90. Conclusion: Between the formulas of SRK/T, SRK II, Binkhorst II, Holladay which are used to calculate the intraocular lens stregth, for short, normal and long axial eyes and for all eyes to estimate the refraction correctly after operation there is not significant difference. 52