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
Mathematical morphology can process the binary and grayscale image successfully. This theory cannot be extended to the color image directly. In color space, a vector represents a pixel, so in order to compare vectors,...Mathematical morphology can process the binary and grayscale image successfully. This theory cannot be extended to the color image directly. In color space, a vector represents a pixel, so in order to compare vectors, vectoriel orderings must be defined first. This paper addresses the question of the extension of morphological operator to the case of color images. The proposed method used the order by bit mixing to replace the conditional order. Our order is based on a combination of reduced and bit mixing ordering of the underlying data. Additionally it is a total ordering. Since it not only solves the problems of false color generated by the marginal order but also those of multiple extrema generated by reduced order. The performance of the introduced operators is illustrated by means of different applications: color gradients for segmenting, image smoothing (noise suppression) by median filter operator and Laplacian operators. Examples of natural color images and synthetic color images are given. Experimental results show the improvement brought by this new method.展开更多
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.
文摘Mathematical morphology can process the binary and grayscale image successfully. This theory cannot be extended to the color image directly. In color space, a vector represents a pixel, so in order to compare vectors, vectoriel orderings must be defined first. This paper addresses the question of the extension of morphological operator to the case of color images. The proposed method used the order by bit mixing to replace the conditional order. Our order is based on a combination of reduced and bit mixing ordering of the underlying data. Additionally it is a total ordering. Since it not only solves the problems of false color generated by the marginal order but also those of multiple extrema generated by reduced order. The performance of the introduced operators is illustrated by means of different applications: color gradients for segmenting, image smoothing (noise suppression) by median filter operator and Laplacian operators. Examples of natural color images and synthetic color images are given. Experimental results show the improvement brought by this new method.
