With the conditions of small data size and low Signal-to-Noise Ratio (SNR), the application of Higher Order Statistics (HOS) is restrained not only by its high estimation variance,but also by its low estimation precis...With the conditions of small data size and low Signal-to-Noise Ratio (SNR), the application of Higher Order Statistics (HOS) is restrained not only by its high estimation variance,but also by its low estimation precision. Therefore, a modified HOS based Time Delay Estimation (TDE) algorithm is proposed to overcome these problems. Comparing with the conventional TDE algorithms, the estimation variance is improved greatly. A typical simulation example is completed in order to test the performance of the algorithm proposed, which shows that the proposed algorithm has advantages over the traditional ones in both detection performance and computation efficiency.展开更多
AIM:To investigate quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy(Trans PRK)in high myopia.METHODS:In a prospective interventional case-series,30 eyes with...AIM:To investigate quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy(Trans PRK)in high myopia.METHODS:In a prospective interventional case-series,30 eyes with high myopia(-6.00 to-8.75 D)with(up to-3.00 D)or without astigmatism were enrolled from Bina Eye Hospital,Tehran,Iran. One-step Trans PRK was performed with aberration-free aspherical optimized profile and SCHWIND AMARIS 500 laser. One-year follow-up results for refraction,visual acuities,vector analysis,ocular wavefront(OWF)and corneal wave-front(CWF)higher order aberrations(HOA),contrast sensitivity(CS),and postoperative haze were assessed.RESULTS:After the surgery,both photopic and mesopic CSs significantly improved(both P〈0.001). We detected significant induction of OWF coma and trefoil(P〈0.001 for both)HOAs; CWF coma(P=0.002),spherical(P〈0.001),and tetrafoil(P=0.003)HOAs in 6 mm analysis diameter; and CWF trefoil(P=0.04)HOA in 4 mm analysis diameter. The range of mean induction observed for various HOAs was0.005-0.11 μm. The 86.7% of eyes reached an uncorrected distance visual acuity of 20/20 or better; 96.7% of eyes were within ±0.5 D of targeted spherical refraction. In vector analysis,mean correction index value was 1.03 and mean index of success was 0.22. By 12mo after the operation,no eye lost any number of corrected distancevisual acuity lines. We detected no corneal haze greater than 1~+ throughout the follow-up.CONCLUSION:Our findings show promising effects of single-step Trans PRK on quality of vision in high myopic eyes. It also improves refraction and visual acuity.展开更多
基金Supported by the National Natural Science Foundation of China(No.60072027)
文摘With the conditions of small data size and low Signal-to-Noise Ratio (SNR), the application of Higher Order Statistics (HOS) is restrained not only by its high estimation variance,but also by its low estimation precision. Therefore, a modified HOS based Time Delay Estimation (TDE) algorithm is proposed to overcome these problems. Comparing with the conventional TDE algorithms, the estimation variance is improved greatly. A typical simulation example is completed in order to test the performance of the algorithm proposed, which shows that the proposed algorithm has advantages over the traditional ones in both detection performance and computation efficiency.
文摘AIM:To investigate quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy(Trans PRK)in high myopia.METHODS:In a prospective interventional case-series,30 eyes with high myopia(-6.00 to-8.75 D)with(up to-3.00 D)or without astigmatism were enrolled from Bina Eye Hospital,Tehran,Iran. One-step Trans PRK was performed with aberration-free aspherical optimized profile and SCHWIND AMARIS 500 laser. One-year follow-up results for refraction,visual acuities,vector analysis,ocular wavefront(OWF)and corneal wave-front(CWF)higher order aberrations(HOA),contrast sensitivity(CS),and postoperative haze were assessed.RESULTS:After the surgery,both photopic and mesopic CSs significantly improved(both P〈0.001). We detected significant induction of OWF coma and trefoil(P〈0.001 for both)HOAs; CWF coma(P=0.002),spherical(P〈0.001),and tetrafoil(P=0.003)HOAs in 6 mm analysis diameter; and CWF trefoil(P=0.04)HOA in 4 mm analysis diameter. The range of mean induction observed for various HOAs was0.005-0.11 μm. The 86.7% of eyes reached an uncorrected distance visual acuity of 20/20 or better; 96.7% of eyes were within ±0.5 D of targeted spherical refraction. In vector analysis,mean correction index value was 1.03 and mean index of success was 0.22. By 12mo after the operation,no eye lost any number of corrected distancevisual acuity lines. We detected no corneal haze greater than 1~+ throughout the follow-up.CONCLUSION:Our findings show promising effects of single-step Trans PRK on quality of vision in high myopic eyes. It also improves refraction and visual acuity.