Comparison Of IOL Master And Traditional Methods In Eye Biometry And Intraocular Lens Calculation

Part One Comparison of Two Biological Measuring Methods and Applications of IOL Calculation Formula for The Cataract Patients.OBJECTIVETo compare the IOL Master with the traditional method at stability of measuring the axial length (AL) results and accuracy of intraocular lens (IOL) conclusion by different predictive methods for age-related cataract patients.METHODMeasured64cases (75eyes) of cataract patients with IOL Master and contact A ultrasound which combined with corneal topographer (traditional methods).Compared different instruments by the coefficient of variation (CV) at biometry of AL and the Haigis and SRK-T formula applied to two measuring method to calculate the mean absolute refractive error (MAFE) of IOL diopter with statistical analysis.RESULTS1. The CV of same technicians who used IOL Master and contact A ultrasound for multiple AL measurement were0.084±0.040and0.742±0.553%, the difference was significant (p=0.000).2.For the patients with normal AL examined by IOL Master, Haigis and SRK-T formula predicted the MAFE with0.46±0.40D and0.48±0.38D, there was no statistically difference (p>0.05). There was also no statistically difference (p>0.05) between Haigis and SRK-T formula predicted the MAFE with0.35±0.30D and0.37±0.27D for medium long AL patients.3.For the patients with normal AL examined by traditional method, Haigis and SRK-T formula predicted the MAFE with0.87±0.43D and0.51±0.47D, the difference was significant (p=0.000).There was also no statistically difference (p>0.05) between Haigis and SRK-T formula predicted the MAFE with1.14±0.66D and0.97±0.86D for medium long AL patients.4.By using the SRK-T formula, for the patients with normal AL,IOL Master and the traditional method predicted the MAFE with0.48±0.38D and0.53±0.52D, there was no statistically difference (p>0.05).But for the medium long AL patients, the MAFE were0.37±0.27D和0.98±0.79D. There was statistically difference (p<0.05).CONCLUSION1.IOL Master has the higher stability when measuring the AL of cataract patients than the contact A ultrasound.2.For patients with normal or medium long AL,both SRK-T or Haigis formula in IOL Master can offer accurately prediction of the IOL power and there was no difference between each other.3.For patients with normal AL,IOL Master and traditional methods predict the same accurately of IOL degrees. But for the medium long AL patients, the IOL Master predicts smaller error of the the IOL degrees.Part Two The Feasibility Studies of Combination A Ultrasound with Corneal Curvature of IOL Master for Intraocular Lens CalculationOBJECTIVETo realize the difference in detectablerate between different preoperative measuring instruments of cataract patients.For patients who unable to complete the IOL Master measuring,to explore the feasibility of combination between A ultrasound and corneal curvature of IOL Master for Intraocular Lens Calculation.METHODUsing IOL Master and A ultrasound combined corneal topography to do preoperative biometry for94(164eyes) patients, to compare different instruments’ and the overall detection rate.With59(70eyes) patients finished IOL Master measurements,to compare the mean absolute refractive error of combination between A ultrasound and corneal curvature of IOL Master with the corresponding results of the IOL Master. RESULTS1.There was significant difference in detectablerate of axial length between IOL Master with68.3%and A ultrasound with100%;there was significant difference in detectablerate of anterior chamber depth between IOL Master with96.3%and A ultrasound with100%;there was statistically difference in detectablerate of corneal curvature between IOL Master with97.0%and A ultrasound with90.9%;there was significant difference in overall detectablerate between IOL Master with64%and A ultrasound with90.9%.2.There was significant difference in corneal curvature measured by IOL Master with43.97±1.59D and corneal topography with43.62±1.47D.(p=0.000)3.There was no statistically difference in MAFE and its distribution of exploratory group and IOL Master in patients with normal AL or medium long AL.(All the p>0.05)4.For the patients with normal AL, exploratory group and IOL Master predicted the IOL diopter with20.54±2.14D and21.45±2.14D, there was significant difference (p=0.000).For the medium long AL patients,the IOL diopter were16.94±2.02D and17.54±1.70D.There was no statistically difference (p>0.05).CONCLUSION1.In addition to the corneal curvature measurement before cataract surgery,the detection rates of axial length, anterior chamber depth and total detection rates of IOL Master is lower than traditional methods.2.For patients were unable to complete the axial length measurement of IOL Master,calculating IOL diopters by A ultrasound combined with corneal curvature of IOL Master should be feasible.