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Leon N. Davies - One of the best experts on this subject based on the ideXlab platform.
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clinical evaluation of the grand seiko auto ref Keratometer wam 5500
Ophthalmic and Physiological Optics, 2010Co-Authors: Amy L. Sheppard, Leon N. DaviesAbstract:Purpose: A clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM-5500 (Japan) was performed to evaluate validity and repeatability compared with non-cycloplegic subjective refraction and Javal–Schiotz keratometry. An investigation into the dynamic recording capabilities of the instrument was also conducted. Methods: Refractive error measurements were obtained from 150 eyes of 75 subjects (aged 25.12 ± 9.03 years), subjectively by a masked optometrist, and objectively with the WAM-5500 at a second session. Keratometry measurements from the WAM-5500 were compared to Javal–Schiotz readings. Intratest variability was examined on all subjects, whilst intertest variability was assessed on a subgroup of 44 eyes 7–14 days after the initial objective measures. The accuracy of the dynamic recording mode of the instrument and its tolerance to longitudinal movement was evaluated using a model eye. An additional evaluation of the dynamic mode was performed using a human eye in relaxed and accommodated states. Results: Refractive error determined by the WAM-5500 was found to be very similar (p = 0.77) to subjective refraction (difference, -0.01 ± 0.38 D). The instrument was accurate and reliable over a wide range of refractive errors (-6.38 to +4.88 D). WAM-5500 keratometry values were steeper by approximately 0.05 mm in both the vertical and horizontal meridians. High intertest repeatability was demonstrated for all parameters measured: for sphere, cylinder power and MSE, over 90% of retest values fell within ±0.50 D of initial testing. In dynamic (high-speed) mode, the root-mean-square of the fluctuations was 0.005 ± 0.0005 D and a high level of recording accuracy was maintained when the measurement ring was significantly blurred by longitudinal movement of the instrument head. Conclusion: The WAM-5500 Auto Ref/Keratometer represents a reliable and valid objective refraction tool for general optometric practice, with important additional features allowing pupil size determination and easy conversion into high-speed mode, increasing its usefulness post-surgically following accommodating intra-ocular lens implantation, and as a research tool in the study of accommodation.
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Clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM-5500
Ophthalmic and Physiological Optics, 2010Co-Authors: Amy L. Sheppard, Leon N. DaviesAbstract:PURPOSE A clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM-5500 (Japan) was performed to evaluate validity and repeatability compared with non-cycloplegic subjective refraction and Javal-Schiotz keratometry. An investigation into the dynamic recording capabilities of the instrument was also conducted. METHODS Refractive error measurements were obtained from 150 eyes of 75 subjects (aged 25.12 +/- 9.03 years), subjectively by a masked optometrist, and objectively with the WAM-5500 at a second session. Keratometry measurements from the WAM-5500 were compared to Javal-Schiotz readings. Intratest variability was examined on all subjects, whilst intertest variability was assessed on a subgroup of 44 eyes 7-14 days after the initial objective measures. The accuracy of the dynamic recording mode of the instrument and its tolerance to longitudinal movement was evaluated using a model eye. An additional evaluation of the dynamic mode was performed using a human eye in relaxed and accommodated states. RESULTS Refractive error determined by the WAM-5500 was found to be very similar (p = 0.77) to subjective refraction (difference, -0.01 +/- 0.38 D). The instrument was accurate and reliable over a wide range of refractive errors (-6.38 to +4.88 D). WAM-5500 keratometry values were steeper by approximately 0.05 mm in both the vertical and horizontal meridians. High intertest repeatability was demonstrated for all parameters measured: for sphere, cylinder power and MSE, over 90% of retest values fell within +/-0.50 D of initial testing. In dynamic (high-speed) mode, the root-mean-square of the fluctuations was 0.005 +/- 0.0005 D and a high level of recording accuracy was maintained when the measurement ring was significantly blurred by longitudinal movement of the instrument head. CONCLUSION The WAM-5500 Auto Ref/Keratometer represents a reliable and valid objective refraction tool for general optometric practice, with important additional features allowing pupil size determination and easy conversion into high-speed mode, increasing its usefulness post-surgically following accommodating intra-ocular lens implantation, and as a research tool in the study of accommodation.
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Clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM‐5500
Ophthalmic and Physiological Optics, 2009Co-Authors: Amy L. Sheppard, Leon N. DaviesAbstract:Purpose: A clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM-5500 (Japan) was performed to evaluate validity and repeatability compared with non-cycloplegic subjective refraction and Javal–Schiotz keratometry. An investigation into the dynamic recording capabilities of the instrument was also conducted. Methods: Refractive error measurements were obtained from 150 eyes of 75 subjects (aged 25.12 ± 9.03 years), subjectively by a masked optometrist, and objectively with the WAM-5500 at a second session. Keratometry measurements from the WAM-5500 were compared to Javal–Schiotz readings. Intratest variability was examined on all subjects, whilst intertest variability was assessed on a subgroup of 44 eyes 7–14 days after the initial objective measures. The accuracy of the dynamic recording mode of the instrument and its tolerance to longitudinal movement was evaluated using a model eye. An additional evaluation of the dynamic mode was performed using a human eye in relaxed and accommodated states. Results: Refractive error determined by the WAM-5500 was found to be very similar (p = 0.77) to subjective refraction (difference, -0.01 ± 0.38 D). The instrument was accurate and reliable over a wide range of refractive errors (-6.38 to +4.88 D). WAM-5500 keratometry values were steeper by approximately 0.05 mm in both the vertical and horizontal meridians. High intertest repeatability was demonstrated for all parameters measured: for sphere, cylinder power and MSE, over 90% of retest values fell within ±0.50 D of initial testing. In dynamic (high-speed) mode, the root-mean-square of the fluctuations was 0.005 ± 0.0005 D and a high level of recording accuracy was maintained when the measurement ring was significantly blurred by longitudinal movement of the instrument head. Conclusion: The WAM-5500 Auto Ref/Keratometer represents a reliable and valid objective refraction tool for general optometric practice, with important additional features allowing pupil size determination and easy conversion into high-speed mode, increasing its usefulness post-surgically following accommodating intra-ocular lens implantation, and as a research tool in the study of accommodation.
Amy L. Sheppard - One of the best experts on this subject based on the ideXlab platform.
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clinical evaluation of the grand seiko auto ref Keratometer wam 5500
Ophthalmic and Physiological Optics, 2010Co-Authors: Amy L. Sheppard, Leon N. DaviesAbstract:Purpose: A clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM-5500 (Japan) was performed to evaluate validity and repeatability compared with non-cycloplegic subjective refraction and Javal–Schiotz keratometry. An investigation into the dynamic recording capabilities of the instrument was also conducted. Methods: Refractive error measurements were obtained from 150 eyes of 75 subjects (aged 25.12 ± 9.03 years), subjectively by a masked optometrist, and objectively with the WAM-5500 at a second session. Keratometry measurements from the WAM-5500 were compared to Javal–Schiotz readings. Intratest variability was examined on all subjects, whilst intertest variability was assessed on a subgroup of 44 eyes 7–14 days after the initial objective measures. The accuracy of the dynamic recording mode of the instrument and its tolerance to longitudinal movement was evaluated using a model eye. An additional evaluation of the dynamic mode was performed using a human eye in relaxed and accommodated states. Results: Refractive error determined by the WAM-5500 was found to be very similar (p = 0.77) to subjective refraction (difference, -0.01 ± 0.38 D). The instrument was accurate and reliable over a wide range of refractive errors (-6.38 to +4.88 D). WAM-5500 keratometry values were steeper by approximately 0.05 mm in both the vertical and horizontal meridians. High intertest repeatability was demonstrated for all parameters measured: for sphere, cylinder power and MSE, over 90% of retest values fell within ±0.50 D of initial testing. In dynamic (high-speed) mode, the root-mean-square of the fluctuations was 0.005 ± 0.0005 D and a high level of recording accuracy was maintained when the measurement ring was significantly blurred by longitudinal movement of the instrument head. Conclusion: The WAM-5500 Auto Ref/Keratometer represents a reliable and valid objective refraction tool for general optometric practice, with important additional features allowing pupil size determination and easy conversion into high-speed mode, increasing its usefulness post-surgically following accommodating intra-ocular lens implantation, and as a research tool in the study of accommodation.
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Clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM-5500
Ophthalmic and Physiological Optics, 2010Co-Authors: Amy L. Sheppard, Leon N. DaviesAbstract:PURPOSE A clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM-5500 (Japan) was performed to evaluate validity and repeatability compared with non-cycloplegic subjective refraction and Javal-Schiotz keratometry. An investigation into the dynamic recording capabilities of the instrument was also conducted. METHODS Refractive error measurements were obtained from 150 eyes of 75 subjects (aged 25.12 +/- 9.03 years), subjectively by a masked optometrist, and objectively with the WAM-5500 at a second session. Keratometry measurements from the WAM-5500 were compared to Javal-Schiotz readings. Intratest variability was examined on all subjects, whilst intertest variability was assessed on a subgroup of 44 eyes 7-14 days after the initial objective measures. The accuracy of the dynamic recording mode of the instrument and its tolerance to longitudinal movement was evaluated using a model eye. An additional evaluation of the dynamic mode was performed using a human eye in relaxed and accommodated states. RESULTS Refractive error determined by the WAM-5500 was found to be very similar (p = 0.77) to subjective refraction (difference, -0.01 +/- 0.38 D). The instrument was accurate and reliable over a wide range of refractive errors (-6.38 to +4.88 D). WAM-5500 keratometry values were steeper by approximately 0.05 mm in both the vertical and horizontal meridians. High intertest repeatability was demonstrated for all parameters measured: for sphere, cylinder power and MSE, over 90% of retest values fell within +/-0.50 D of initial testing. In dynamic (high-speed) mode, the root-mean-square of the fluctuations was 0.005 +/- 0.0005 D and a high level of recording accuracy was maintained when the measurement ring was significantly blurred by longitudinal movement of the instrument head. CONCLUSION The WAM-5500 Auto Ref/Keratometer represents a reliable and valid objective refraction tool for general optometric practice, with important additional features allowing pupil size determination and easy conversion into high-speed mode, increasing its usefulness post-surgically following accommodating intra-ocular lens implantation, and as a research tool in the study of accommodation.
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Clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM‐5500
Ophthalmic and Physiological Optics, 2009Co-Authors: Amy L. Sheppard, Leon N. DaviesAbstract:Purpose: A clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM-5500 (Japan) was performed to evaluate validity and repeatability compared with non-cycloplegic subjective refraction and Javal–Schiotz keratometry. An investigation into the dynamic recording capabilities of the instrument was also conducted. Methods: Refractive error measurements were obtained from 150 eyes of 75 subjects (aged 25.12 ± 9.03 years), subjectively by a masked optometrist, and objectively with the WAM-5500 at a second session. Keratometry measurements from the WAM-5500 were compared to Javal–Schiotz readings. Intratest variability was examined on all subjects, whilst intertest variability was assessed on a subgroup of 44 eyes 7–14 days after the initial objective measures. The accuracy of the dynamic recording mode of the instrument and its tolerance to longitudinal movement was evaluated using a model eye. An additional evaluation of the dynamic mode was performed using a human eye in relaxed and accommodated states. Results: Refractive error determined by the WAM-5500 was found to be very similar (p = 0.77) to subjective refraction (difference, -0.01 ± 0.38 D). The instrument was accurate and reliable over a wide range of refractive errors (-6.38 to +4.88 D). WAM-5500 keratometry values were steeper by approximately 0.05 mm in both the vertical and horizontal meridians. High intertest repeatability was demonstrated for all parameters measured: for sphere, cylinder power and MSE, over 90% of retest values fell within ±0.50 D of initial testing. In dynamic (high-speed) mode, the root-mean-square of the fluctuations was 0.005 ± 0.0005 D and a high level of recording accuracy was maintained when the measurement ring was significantly blurred by longitudinal movement of the instrument head. Conclusion: The WAM-5500 Auto Ref/Keratometer represents a reliable and valid objective refraction tool for general optometric practice, with important additional features allowing pupil size determination and easy conversion into high-speed mode, increasing its usefulness post-surgically following accommodating intra-ocular lens implantation, and as a research tool in the study of accommodation.
Samuel D. Friedel - One of the best experts on this subject based on the ideXlab platform.
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Effect of Keratometer and axial length measurement errors on primary implant power calculations
Journal of Cataract and Refractive Surgery, 1990Co-Authors: Jack R. Mcewan, R. K. Massengill, Samuel D. FriedelAbstract:Analytical predictions of primary implant power using presumptive errors in Keratometer and axial length measurements were performed using the modified Binkhorst, modified Colenbrander, Holladay, Hoffer, and SRK II™ equations. These predictions demonstrate that the contributions to primary implant power error resulting from inaccurate axial length and Keratometer measurements are algebraically additive. In eyes with a normal axial length, the resulting implant power determination error can be larger than differences in implant power prediction among these five IOL equations. Calculations using measurement errors of 0.2 mm in axial length and 0.50 diopter (D) in corneal curvature predicted a worst case primary implant power error of ± 1.17 D. These calculations were performed using an axial length and corneal curvature near the population mean. In contrast, implant equation variability was determined to be ± 0.19 D by calculating the standard deviation of the five implant power formulas with the measurement errors set to zero. Implant power prediction errors were increased when a flat cornea was paired with an axial hyperopic or an axial myopic eye. These combinations maximize the implant power error resulting from both implant formula variation and inaccurate measurements. Primary implant power error prediction tables are presented for emmetropic, axial hyperopic, and axial myopic eyes, as a function of presumed errors in axial length and corneal curvature. These error predictions clearly show that inaccuracy in axial length measurements and Keratometer readings can be first order determinants of postoperative spherical refractive error. © 1990, American Society of Cataract and Refractive Surgery. All rights reserved.
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effect of Keratometer and axial length measurement errors on primary implant power calculations
Journal of Cataract and Refractive Surgery, 1990Co-Authors: Jack R. Mcewan, R. K. Massengill, Samuel D. FriedelAbstract:Abstract Analytical predictions of primary implant power using presumptive errors in Keratometer and axial length measurements were performed using the modified Binkhorst, modified Colenbrander, Holladay, Hoffer, and SRK II™ equations. These predictions demonstrate that the contributions to primary implant power error resulting from inaccurate axial length and Keratometer measurements are algebraically additive. In eyes with a normal axial length, the resulting implant power determination error can be larger than differences in implant power prediction among these five IOL equations. Calculations using measurement errors of 0.2 mm in axial length and 0.50 diopter (D) in corneal curvature predicted a worst case primary implant power error of ± 1.17 D. These calculations were performed using an axial length and corneal curvature near the population mean. In contrast, implant equation variability was determined to be ± 0.19 D by calculating the standard deviation of the five implant power formulas with the measurement errors set to zero. Implant power prediction errors were increased when a flat cornea was paired with an axial hyperopic or an axial myopic eye. These combinations maximize the implant power error resulting from both implant formula variation and inaccurate measurements. Primary implant power error prediction tables are presented for emmetropic, axial hyperopic, and axial myopic eyes, as a function of presumed errors in axial length and corneal curvature. These error predictions clearly show that inaccuracy in axial length measurements and Keratometer readings can be first order determinants of postoperative spherical refractive error.
Jack R. Mcewan - One of the best experts on this subject based on the ideXlab platform.
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Effect of Keratometer and axial length measurement errors on primary implant power calculations
Journal of Cataract and Refractive Surgery, 1990Co-Authors: Jack R. Mcewan, R. K. Massengill, Samuel D. FriedelAbstract:Analytical predictions of primary implant power using presumptive errors in Keratometer and axial length measurements were performed using the modified Binkhorst, modified Colenbrander, Holladay, Hoffer, and SRK II™ equations. These predictions demonstrate that the contributions to primary implant power error resulting from inaccurate axial length and Keratometer measurements are algebraically additive. In eyes with a normal axial length, the resulting implant power determination error can be larger than differences in implant power prediction among these five IOL equations. Calculations using measurement errors of 0.2 mm in axial length and 0.50 diopter (D) in corneal curvature predicted a worst case primary implant power error of ± 1.17 D. These calculations were performed using an axial length and corneal curvature near the population mean. In contrast, implant equation variability was determined to be ± 0.19 D by calculating the standard deviation of the five implant power formulas with the measurement errors set to zero. Implant power prediction errors were increased when a flat cornea was paired with an axial hyperopic or an axial myopic eye. These combinations maximize the implant power error resulting from both implant formula variation and inaccurate measurements. Primary implant power error prediction tables are presented for emmetropic, axial hyperopic, and axial myopic eyes, as a function of presumed errors in axial length and corneal curvature. These error predictions clearly show that inaccuracy in axial length measurements and Keratometer readings can be first order determinants of postoperative spherical refractive error. © 1990, American Society of Cataract and Refractive Surgery. All rights reserved.
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effect of Keratometer and axial length measurement errors on primary implant power calculations
Journal of Cataract and Refractive Surgery, 1990Co-Authors: Jack R. Mcewan, R. K. Massengill, Samuel D. FriedelAbstract:Abstract Analytical predictions of primary implant power using presumptive errors in Keratometer and axial length measurements were performed using the modified Binkhorst, modified Colenbrander, Holladay, Hoffer, and SRK II™ equations. These predictions demonstrate that the contributions to primary implant power error resulting from inaccurate axial length and Keratometer measurements are algebraically additive. In eyes with a normal axial length, the resulting implant power determination error can be larger than differences in implant power prediction among these five IOL equations. Calculations using measurement errors of 0.2 mm in axial length and 0.50 diopter (D) in corneal curvature predicted a worst case primary implant power error of ± 1.17 D. These calculations were performed using an axial length and corneal curvature near the population mean. In contrast, implant equation variability was determined to be ± 0.19 D by calculating the standard deviation of the five implant power formulas with the measurement errors set to zero. Implant power prediction errors were increased when a flat cornea was paired with an axial hyperopic or an axial myopic eye. These combinations maximize the implant power error resulting from both implant formula variation and inaccurate measurements. Primary implant power error prediction tables are presented for emmetropic, axial hyperopic, and axial myopic eyes, as a function of presumed errors in axial length and corneal curvature. These error predictions clearly show that inaccuracy in axial length measurements and Keratometer readings can be first order determinants of postoperative spherical refractive error.
R. K. Massengill - One of the best experts on this subject based on the ideXlab platform.
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Effect of Keratometer and axial length measurement errors on primary implant power calculations
Journal of Cataract and Refractive Surgery, 1990Co-Authors: Jack R. Mcewan, R. K. Massengill, Samuel D. FriedelAbstract:Analytical predictions of primary implant power using presumptive errors in Keratometer and axial length measurements were performed using the modified Binkhorst, modified Colenbrander, Holladay, Hoffer, and SRK II™ equations. These predictions demonstrate that the contributions to primary implant power error resulting from inaccurate axial length and Keratometer measurements are algebraically additive. In eyes with a normal axial length, the resulting implant power determination error can be larger than differences in implant power prediction among these five IOL equations. Calculations using measurement errors of 0.2 mm in axial length and 0.50 diopter (D) in corneal curvature predicted a worst case primary implant power error of ± 1.17 D. These calculations were performed using an axial length and corneal curvature near the population mean. In contrast, implant equation variability was determined to be ± 0.19 D by calculating the standard deviation of the five implant power formulas with the measurement errors set to zero. Implant power prediction errors were increased when a flat cornea was paired with an axial hyperopic or an axial myopic eye. These combinations maximize the implant power error resulting from both implant formula variation and inaccurate measurements. Primary implant power error prediction tables are presented for emmetropic, axial hyperopic, and axial myopic eyes, as a function of presumed errors in axial length and corneal curvature. These error predictions clearly show that inaccuracy in axial length measurements and Keratometer readings can be first order determinants of postoperative spherical refractive error. © 1990, American Society of Cataract and Refractive Surgery. All rights reserved.
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effect of Keratometer and axial length measurement errors on primary implant power calculations
Journal of Cataract and Refractive Surgery, 1990Co-Authors: Jack R. Mcewan, R. K. Massengill, Samuel D. FriedelAbstract:Abstract Analytical predictions of primary implant power using presumptive errors in Keratometer and axial length measurements were performed using the modified Binkhorst, modified Colenbrander, Holladay, Hoffer, and SRK II™ equations. These predictions demonstrate that the contributions to primary implant power error resulting from inaccurate axial length and Keratometer measurements are algebraically additive. In eyes with a normal axial length, the resulting implant power determination error can be larger than differences in implant power prediction among these five IOL equations. Calculations using measurement errors of 0.2 mm in axial length and 0.50 diopter (D) in corneal curvature predicted a worst case primary implant power error of ± 1.17 D. These calculations were performed using an axial length and corneal curvature near the population mean. In contrast, implant equation variability was determined to be ± 0.19 D by calculating the standard deviation of the five implant power formulas with the measurement errors set to zero. Implant power prediction errors were increased when a flat cornea was paired with an axial hyperopic or an axial myopic eye. These combinations maximize the implant power error resulting from both implant formula variation and inaccurate measurements. Primary implant power error prediction tables are presented for emmetropic, axial hyperopic, and axial myopic eyes, as a function of presumed errors in axial length and corneal curvature. These error predictions clearly show that inaccuracy in axial length measurements and Keratometer readings can be first order determinants of postoperative spherical refractive error.
