AIM:To evaluate the effectiveness,safety,predictability,precision and changes of higher-order aberrations(HOAs)on corneal front surface of selective corneal wavefront aberration-guided femtosecond laser-assisted in si...AIM:To evaluate the effectiveness,safety,predictability,precision and changes of higher-order aberrations(HOAs)on corneal front surface of selective corneal wavefront aberration-guided femtosecond laser-assisted in situ keratomileusis(CW-FS-LASIK)in patients with high myopia 1-year postoperatively.METHODS:Totally 74 eyes of 37 patients with high myopia or myopic astigmatism in both the eyes who underwent the CW-FS-LASIK procedure in Xi’an Gaoxin Hospital from January 2021 to June 2021 were included.The changes of uncorrected distance visual acuity(UDVA),best corrected visual acuity(BCVA),spherical equivalent refraction(SER),astigmatism,HOAs and Strehl ratio(SR)on the anterior surface of the cornea after 1y of the surgery were analyzed.RESULTS:At postoperative 1y,the UDVA(logMAR)of 74 eyes(100%)reached 0 or better,including 0 in 8 eyes(10.81%),-0.1 in 45 eyes(60.81%),and-0.2 in 21 eyes(28.38%).The effectiveness index was 1.29±0.134.There was no decrease in postoperative BCVA compared with preoperative BCVA in all patients.Postoperative BCVA was the same in 44 eyes(59.46%)as preoperative BCVA,increased by 1 line in 23 eyes(31.08%)and increased by 2 lines in 7 eyes(9.46%)compared with preoperative BCVA.The safety index was 1.11±0.159.The estimated corrected SER before surgery was(-7.76±1.21)D,and the actual corrected SER was(-7.83±1.25)D(Y=0.9811X+0.2156,R2=0.9084).There was a high correlation between the estimated corrected SER and the actual corrected SER.The postoperative SER in 74 eyes(100%)was within±0.75 D.The postoperative astigmatism of all was within-0.75 D to 0.Root mean square(RMS)HOAs of spherical aberration and SR within 5 mm of the corneal front surface were all increased compared with those before operation(P<0.01).The total coma,horizontal coma and vertical coma were all decreased compared with those before operation(P<0.01).There was no statistically significant difference in horizontal trefoil and vertical trefoil compared with preoperative ones(P>0.05).CONCLUSION:Selective CW-FS-LASIK for correction of high myopia is effective,safe,predictive,and accurate.For patients with preoperative RMS HOAs over 0.25 defocus equivalent,postoperative coma aberration can be significantly reduced,and SR value can be increased,thus corneal imaging quality can be improved.展开更多
AIM: To compare the wavefront aberrations and corneal surface regularity between dry eye(DE) patients and normal subjects and assess its diagnostic performance for DE measured with OPD Scan-Ⅲ.METHODS: Fifty right eye...AIM: To compare the wavefront aberrations and corneal surface regularity between dry eye(DE) patients and normal subjects and assess its diagnostic performance for DE measured with OPD Scan-Ⅲ.METHODS: Fifty right eyes of 50 DE patients and 31 right eyes of normal subjects were included.The examinations for ocular surface including logarithm of the minimum angle of resolution best-corrected distance visual acuity(logMAR BCVA) the ocular surface disease index(OSDI), tear film break-up time(TBUT) and corneal fluorescein staining(CFS).OPD Scan-Ⅲ was used to measure anterior corneal aberrations including total corneal aberrations, high order aberration(HOA), coma, trefoil, spherical aberration(SA), standard deviation of corneal power(SDP), surface regularity index(SRI) and surface asymmetry index(SAI).Statistical analysis were assessed with nonparametric tests and Spearman’s correlations.All parameters were also analyzed for sensitivity, specificity, and receiver operating characteristics(ROC) curves.RESULTS: Wavefront aberrations parameters including total corneal aberrations, HOA, coma, trefoil, and SA in DE group were significantly higher than those in normal group(P<0.001).Corneal surface regularity parameters including SRI and SAI in DE group were significantly higher than both in normal group(P<0.05).All the wavefront aberrations parameters had significant correlations with ocular surface parameters(P<0.05).The logMAR BCVA had positive correlations with SAI and SRI(all P<0.001).CFS scores had positive correlations with SAI and SRI(all P<0.001).All the wavefront aberrations parameters showed good diagnosis sensitivity and specificity, however, the corneal regularity parameters showed only good specificity but poor sensitivity.The cut-off value selected for trefoil in diagnosis DE showed the highest area under the curve(AUC, 0.921) values as compared to the other parameters with sensitivity of 0.955 and specificity of 0.867.CONCLUSION: Wavefront aberrations and corneal surface regularity are increased in DE patients and also correlated with ocular surface parameters.Wavefront aberrations parameters have potential to be indicators to diagnosis and monitor DE.展开更多
Wavefront aberration affects the quality of retinal image directly. This paper reviews the representation and reconstruction of wavefront aberration, as well as the construction of virtual eye model based on Zernike p...Wavefront aberration affects the quality of retinal image directly. This paper reviews the representation and reconstruction of wavefront aberration, as well as the construction of virtual eye model based on Zernike polynomial coefficients. In addition, the promising prospect of virtual eye model is emphasized.展开更多
Purpose: The purpose of this study was to evaluate the change in corneal wavefront aberrations in young adults who have been fit with multifocal soft contact lenses for myopia progression control. Findings have been a...Purpose: The purpose of this study was to evaluate the change in corneal wavefront aberrations in young adults who have been fit with multifocal soft contact lenses for myopia progression control. Findings have been analyzed for statistical significance and clinical relevance and compared to reportedly successful Orthokeratology outcomes. Methods: The dominant eye of 40 participants (27 women, 13 men;mean age 27.3 ± 3.2 years;range 23 to 39 years) was fit with Proclear Multifocal center distance lenses (Coopervision, Pleasanton, USA) having a variety of distance powers and reading additions. Refractive errors were limited to a range of –6.00 D up to +1.00 D of sphere, and no greater than –1.00 D of cylinder. Corneal wavefront measurements were performed over 6 mm diameters with a Zeiss Atlas 9000 corneal topographer (Zeiss Meditec, Dublin, USA) prior to, and following lens fitting. Data were converted into rectangular Fourier optics terms M, J0, J45 and RMS values for each reading addition were statistically analyzed. Following evaluation of statistical significance and clinical relevance, results were compared to published data from successful Orthokeratology treatments. Results: Statistically significant changes in higher order aberrations were detected for lenses of all reading additions. Lens groups with higher Add-powers demonstrated stronger changes with increased significance. Final RMS values relating to 2nd, 3rd and 4th Zernike Orders reached clinical significance with a wavefront error of 0.10 μm, the equivalent of 0.25D. Moreover, as Add-powers increased, 3rd and 4th order aberrations likewise showed an increase. Pre-fitting astigmatism values accounted for the highest recorded aberrations and remained predominantly unchanged. Conclusion: Proclear Multifocal center-distance contact lenses were found to increase higher order wavefront aberrations in a manner dependent on their Add-power. In comparison to successful Orthokeratology outcomes, the amounts of resulting aberrations are notably different.展开更多
To reduce the atmospheric turbulence-induced power loss, an Alex Net-based convolutional neural network(CNN) for wave-front aberration compensation is experimentally investigated for free-space optical(FSO) communicat...To reduce the atmospheric turbulence-induced power loss, an Alex Net-based convolutional neural network(CNN) for wave-front aberration compensation is experimentally investigated for free-space optical(FSO) communication systems with standard single mode fiber-pigtailed photodiodes. The wavefront aberration is statistically constructed to mimic the received light beams with the Zernike mode-based theory for the Kolmogorov turbulence. By analyzing impacts of CNN structures, quantization resolution/noise, and mode count on the power penalty, the Alex Net-based CNN with 8 bit resolution is identified for experimental study. Experimental results indicate that the average power penalty decreases to 1.8 d B from 12.4 d B in the strong turbulence.展开更多
Analysis of glass homogeneity using the attaching interferometric data model neglects body distribution.To improve analysis accuracy,we establish the three-dimensional gradient index(GRIN) model of glass index by anal...Analysis of glass homogeneity using the attaching interferometric data model neglects body distribution.To improve analysis accuracy,we establish the three-dimensional gradient index(GRIN) model of glass index by analyzing fused silica homogeneity distribution in two perpendicular measurement directions.Using the GRIN model,a lithography projection lens with a numerical aperture of 0.75 is analyzed.Root mean square wavefront aberration deteriorates from 0.9 to 9.65 nm and then improves to 5.9 nm after clocking.展开更多
We propose a new algorithm for wavefront sensing based on binary intensity modulation. The algorithm is based on the fact that a wavefront can be expended with a series of orthogonal and binary functions, the Walsh se...We propose a new algorithm for wavefront sensing based on binary intensity modulation. The algorithm is based on the fact that a wavefront can be expended with a series of orthogonal and binary functions, the Walsh series. We use a spatial light modulator(SLM) to produce different binary-intensity-modulation patterns which are the simple linear transformation of the Walsh series. The optical fields under different binary-intensity-modulation patterns are detected with a photodiode.The relationships between the incident wavefront modulated with the patterns and their optical fields are built to determinate the coefficients of the Walsh series. More detailed and strict relationship equations are established with the algorithm by adding new modulation patterns according to the properties of the Walsh functions. An exact value can be acquired by solving the equations. Finally, with the help of phase unwrapping and smoothing, the wavefront can be reconstructed. The advantage of the algorithm is providing an analytical solution for the coefficients of the Walsh series to reconstruct the wavefront. The simulation experiments are presented and the effectiveness of the algorithm is demonstrated.展开更多
Background: Individualized corneal refractive surgery requires an understanding of the basis of higher-order aberrations before surgery. To investigate the characteristics and distribution of anterior surface wavefron...Background: Individualized corneal refractive surgery requires an understanding of the basis of higher-order aberrations before surgery. To investigate the characteristics and distribution of anterior surface wavefront aberrations in patients suitable for corneal refractive surgery. Methods: A total of 121 myopic patients (121 eyes, 18 - 45 years old) who underwent corneal refractive surgery were recruited from January to May 2016 at Affiliated Hospital, Yanbian University. Patients were randomly selected by the Pentacam anterior segment analysis system with a spherical equivalent (SE) of -0.25 to -10.00 D. The corneal anterior aberrations (total higher-order aberration;spherical aberration;Coma;Trefoil) and Q and K values were detected, and a correlation analysis of the relevant parameters was carried out. Results: The root-mean-square (RMS) of the third to sixth order aberrations of the corneal anterior wavefront aberrations at a 6 mm analysis diameter showed a decreasing trend in patients suitable for the corneal refractive surgery, and the RMS of the third order aberrations accounted for 62.92% of the total HOAs. The coma ratio (coma/total cornea higher-order aberrations) was increased with the increasing diopters, while the spherical aberration ratio (spherical aberration/total cornea higher-order aberrations) was not changed. In addition, the spherical aberration was 0.203 ± 0.082 μm (range: 0.061 to 0.503 μm), and the Q30 was -0.19 ± 0.03 (range: -0.58 to 0.31). There were significant differences in the coma aberrations of preoperative corneal anterior surface (3, 1) between the low, middle and high myopia groups (P = 0.013). The spherical equivalent was positively correlated with the corneal coma of the anterior corneal surfaces (R =?-0.241, P = 0.009), and the Q value was positively correlated with the total higher-order aberrations (R = 0.326, P Conclusions: Individual wavefront aberrations on the anterior surfaces of the cornea are comparatively different, and the Zernike coefficients are related to the degree of myopia. Spherical aberrations are the most overriding aberrations of the cornea.展开更多
AIM:To evaluate the efficacy of custom-made soft keratoconus(KC)lenses on corneal aberrations and photic phenomena in two different optical zones in patients with KC.METHODS:Sixty eyes of 42 patients with KC were exam...AIM:To evaluate the efficacy of custom-made soft keratoconus(KC)lenses on corneal aberrations and photic phenomena in two different optical zones in patients with KC.METHODS:Sixty eyes of 42 patients with KC were examined at baseline and after fitting HydroCone(Toris K)soft silicone hydrogel lenses.Best spectacle-corrected visual acuity(BSCVA)and contact lens-corrected visual acuity(CLCVA)were recorded.Lower-and higher-order corneal aberrations(LOAs and HOAs)were measured with and without Toris K lenses and compared in central 4.5 mm and 7 mm zones.Mesopic pupil diameter and subjective photic phenomena were also assessed.RESULTS:Mean CLCVA was significantly improved compared to BSCVA(P<0.0001).Corneal curvature and refractive measurements were found to be significantly reduced by the use of Toris K lenses,except for posterior corneal curvature values.In the 4.5 mm central optical zone,all wavefront aberrations decreased significantly after lens fitting(P<0.0001).In contrast,in the 7 mm(peripheral)optical zone,values for HOAs,spherical and residual aberrations,and optical path differences were increased,while LOAs,trefoil,and quadrifoil coefficients were decreased.The rate of photic phenomena was significantly higher in participants with a pupil size>6.00 mm(85.7%).CONCLUSION:Toris K lenses provide good visual results and a significant reduction in central corneal aberrations in patients with KC but could cause an increase in peripheral aberrations.This practical and nonsurgical approach appears to be an effective method for the visual management of KC.展开更多
Strip-shaped chromatic aberration defects on the surface of an electro-galvanized fingerprint-resistant sheet were systematically studied using Thermo-Calc thermodynamic calculations,scanning electron microscope and X...Strip-shaped chromatic aberration defects on the surface of an electro-galvanized fingerprint-resistant sheet were systematically studied using Thermo-Calc thermodynamic calculations,scanning electron microscope and X-ray diffractometer analyses,and rapid heat treatment simulation technology.The formation mechanism of these defects was also analyzed.The results show a strong correlation between the defects and the uneven distribution of the Fe(001)component on the surface of the steel substrate.The relatively high proportion of Fe(001)components on the surface of the steel substrate affects the distribution density of the Zn crystal cells in different orientations during the electrodeposition process,which causes the reflection intensity of the light of the galvanized layer to differ from various visual perspectives,and macroscopic strip-shaped chromatic aberration defects are finally formed.The high proportion of the Fe(001)component on the surface of the steel substrate is mainly related to the following two factors.First,when the strip steel is hot-rolled,the finishing hot-rolling temperature is close to theγ→αphase transition temperature.When the local temperature on the upper surface of the strip steel is low,γ+αtwo-phase rolling easily occurs,and this results in an uneven stress distribution between theγandαphases after the hot-rolling process.This uneven distribution of hot-rolling stress results in the formation of a coarse grain structure in the local area on the surface of the hot-rolled sheet,which strongly affects the subsequent cold rolling and annealing process,and the annealed steel sheet substrate ultimately contains a greater proportion of the Fe(001)component.And second,a fast cooling rate(>10 K/s)during the slow cooling stage in the continuous annealing process inhibits the transformation of the Fe(001)to the Fe(111)component on the surface of the cold-rolled steel sheet,and it is then not possible to effectively eliminate the influence of the unevenly distributed Fe(001)component on the surface of the annealed steel sheet(originating from the uneven hot-rolled microstructure).This uneven distribution of the Fe(001)component on the surface of the annealed steel sheet following the continuous annealing heat treatment has a strong effect on the electrodeposition behavior of the Zn crystal cell in the subsequent electroplating process and the formation of macroscopic strip-shaped chromatic aberration defects on the surface of electro-galvanized fingerprint-resistant sheet.展开更多
文摘AIM:To evaluate the effectiveness,safety,predictability,precision and changes of higher-order aberrations(HOAs)on corneal front surface of selective corneal wavefront aberration-guided femtosecond laser-assisted in situ keratomileusis(CW-FS-LASIK)in patients with high myopia 1-year postoperatively.METHODS:Totally 74 eyes of 37 patients with high myopia or myopic astigmatism in both the eyes who underwent the CW-FS-LASIK procedure in Xi’an Gaoxin Hospital from January 2021 to June 2021 were included.The changes of uncorrected distance visual acuity(UDVA),best corrected visual acuity(BCVA),spherical equivalent refraction(SER),astigmatism,HOAs and Strehl ratio(SR)on the anterior surface of the cornea after 1y of the surgery were analyzed.RESULTS:At postoperative 1y,the UDVA(logMAR)of 74 eyes(100%)reached 0 or better,including 0 in 8 eyes(10.81%),-0.1 in 45 eyes(60.81%),and-0.2 in 21 eyes(28.38%).The effectiveness index was 1.29±0.134.There was no decrease in postoperative BCVA compared with preoperative BCVA in all patients.Postoperative BCVA was the same in 44 eyes(59.46%)as preoperative BCVA,increased by 1 line in 23 eyes(31.08%)and increased by 2 lines in 7 eyes(9.46%)compared with preoperative BCVA.The safety index was 1.11±0.159.The estimated corrected SER before surgery was(-7.76±1.21)D,and the actual corrected SER was(-7.83±1.25)D(Y=0.9811X+0.2156,R2=0.9084).There was a high correlation between the estimated corrected SER and the actual corrected SER.The postoperative SER in 74 eyes(100%)was within±0.75 D.The postoperative astigmatism of all was within-0.75 D to 0.Root mean square(RMS)HOAs of spherical aberration and SR within 5 mm of the corneal front surface were all increased compared with those before operation(P<0.01).The total coma,horizontal coma and vertical coma were all decreased compared with those before operation(P<0.01).There was no statistically significant difference in horizontal trefoil and vertical trefoil compared with preoperative ones(P>0.05).CONCLUSION:Selective CW-FS-LASIK for correction of high myopia is effective,safe,predictive,and accurate.For patients with preoperative RMS HOAs over 0.25 defocus equivalent,postoperative coma aberration can be significantly reduced,and SR value can be increased,thus corneal imaging quality can be improved.
文摘AIM: To compare the wavefront aberrations and corneal surface regularity between dry eye(DE) patients and normal subjects and assess its diagnostic performance for DE measured with OPD Scan-Ⅲ.METHODS: Fifty right eyes of 50 DE patients and 31 right eyes of normal subjects were included.The examinations for ocular surface including logarithm of the minimum angle of resolution best-corrected distance visual acuity(logMAR BCVA) the ocular surface disease index(OSDI), tear film break-up time(TBUT) and corneal fluorescein staining(CFS).OPD Scan-Ⅲ was used to measure anterior corneal aberrations including total corneal aberrations, high order aberration(HOA), coma, trefoil, spherical aberration(SA), standard deviation of corneal power(SDP), surface regularity index(SRI) and surface asymmetry index(SAI).Statistical analysis were assessed with nonparametric tests and Spearman’s correlations.All parameters were also analyzed for sensitivity, specificity, and receiver operating characteristics(ROC) curves.RESULTS: Wavefront aberrations parameters including total corneal aberrations, HOA, coma, trefoil, and SA in DE group were significantly higher than those in normal group(P<0.001).Corneal surface regularity parameters including SRI and SAI in DE group were significantly higher than both in normal group(P<0.05).All the wavefront aberrations parameters had significant correlations with ocular surface parameters(P<0.05).The logMAR BCVA had positive correlations with SAI and SRI(all P<0.001).CFS scores had positive correlations with SAI and SRI(all P<0.001).All the wavefront aberrations parameters showed good diagnosis sensitivity and specificity, however, the corneal regularity parameters showed only good specificity but poor sensitivity.The cut-off value selected for trefoil in diagnosis DE showed the highest area under the curve(AUC, 0.921) values as compared to the other parameters with sensitivity of 0.955 and specificity of 0.867.CONCLUSION: Wavefront aberrations and corneal surface regularity are increased in DE patients and also correlated with ocular surface parameters.Wavefront aberrations parameters have potential to be indicators to diagnosis and monitor DE.
基金National Natural Science Foundation of China (No. 61173182, No. 61179071)Applied Basic Research Project (No. 2011JY0124)International Cooperation and Exchange Project of Sichuan Province (No.2012HH0004)
文摘Wavefront aberration affects the quality of retinal image directly. This paper reviews the representation and reconstruction of wavefront aberration, as well as the construction of virtual eye model based on Zernike polynomial coefficients. In addition, the promising prospect of virtual eye model is emphasized.
文摘Purpose: The purpose of this study was to evaluate the change in corneal wavefront aberrations in young adults who have been fit with multifocal soft contact lenses for myopia progression control. Findings have been analyzed for statistical significance and clinical relevance and compared to reportedly successful Orthokeratology outcomes. Methods: The dominant eye of 40 participants (27 women, 13 men;mean age 27.3 ± 3.2 years;range 23 to 39 years) was fit with Proclear Multifocal center distance lenses (Coopervision, Pleasanton, USA) having a variety of distance powers and reading additions. Refractive errors were limited to a range of –6.00 D up to +1.00 D of sphere, and no greater than –1.00 D of cylinder. Corneal wavefront measurements were performed over 6 mm diameters with a Zeiss Atlas 9000 corneal topographer (Zeiss Meditec, Dublin, USA) prior to, and following lens fitting. Data were converted into rectangular Fourier optics terms M, J0, J45 and RMS values for each reading addition were statistically analyzed. Following evaluation of statistical significance and clinical relevance, results were compared to published data from successful Orthokeratology treatments. Results: Statistically significant changes in higher order aberrations were detected for lenses of all reading additions. Lens groups with higher Add-powers demonstrated stronger changes with increased significance. Final RMS values relating to 2nd, 3rd and 4th Zernike Orders reached clinical significance with a wavefront error of 0.10 μm, the equivalent of 0.25D. Moreover, as Add-powers increased, 3rd and 4th order aberrations likewise showed an increase. Pre-fitting astigmatism values accounted for the highest recorded aberrations and remained predominantly unchanged. Conclusion: Proclear Multifocal center-distance contact lenses were found to increase higher order wavefront aberrations in a manner dependent on their Add-power. In comparison to successful Orthokeratology outcomes, the amounts of resulting aberrations are notably different.
基金This work was supported by the National Natural Science Foundation of China(Nos.61971394 and 61631018)the Key Research Program of Frontier Sciences of CAS(No.QYZDYSSW-JSC003)the Fundamental Research Funds for the Central Universities(No.WK3500000006).
文摘To reduce the atmospheric turbulence-induced power loss, an Alex Net-based convolutional neural network(CNN) for wave-front aberration compensation is experimentally investigated for free-space optical(FSO) communication systems with standard single mode fiber-pigtailed photodiodes. The wavefront aberration is statistically constructed to mimic the received light beams with the Zernike mode-based theory for the Kolmogorov turbulence. By analyzing impacts of CNN structures, quantization resolution/noise, and mode count on the power penalty, the Alex Net-based CNN with 8 bit resolution is identified for experimental study. Experimental results indicate that the average power penalty decreases to 1.8 d B from 12.4 d B in the strong turbulence.
基金supported by the Major National Science and Technology Project of China(No.2009ZX02205)
文摘Analysis of glass homogeneity using the attaching interferometric data model neglects body distribution.To improve analysis accuracy,we establish the three-dimensional gradient index(GRIN) model of glass index by analyzing fused silica homogeneity distribution in two perpendicular measurement directions.Using the GRIN model,a lithography projection lens with a numerical aperture of 0.75 is analyzed.Root mean square wavefront aberration deteriorates from 0.9 to 9.65 nm and then improves to 5.9 nm after clocking.
基金Project supported by the National Innovation Fund of Chinese Academy of Sciences(Grant No.CXJJ-16M208)the Preeminent Youth Fund of Sichuan Province,China(Grant No.2012JQ0012)the Outstanding Youth Science Fund of Chinese Academy of Sciences
文摘We propose a new algorithm for wavefront sensing based on binary intensity modulation. The algorithm is based on the fact that a wavefront can be expended with a series of orthogonal and binary functions, the Walsh series. We use a spatial light modulator(SLM) to produce different binary-intensity-modulation patterns which are the simple linear transformation of the Walsh series. The optical fields under different binary-intensity-modulation patterns are detected with a photodiode.The relationships between the incident wavefront modulated with the patterns and their optical fields are built to determinate the coefficients of the Walsh series. More detailed and strict relationship equations are established with the algorithm by adding new modulation patterns according to the properties of the Walsh functions. An exact value can be acquired by solving the equations. Finally, with the help of phase unwrapping and smoothing, the wavefront can be reconstructed. The advantage of the algorithm is providing an analytical solution for the coefficients of the Walsh series to reconstruct the wavefront. The simulation experiments are presented and the effectiveness of the algorithm is demonstrated.
文摘Background: Individualized corneal refractive surgery requires an understanding of the basis of higher-order aberrations before surgery. To investigate the characteristics and distribution of anterior surface wavefront aberrations in patients suitable for corneal refractive surgery. Methods: A total of 121 myopic patients (121 eyes, 18 - 45 years old) who underwent corneal refractive surgery were recruited from January to May 2016 at Affiliated Hospital, Yanbian University. Patients were randomly selected by the Pentacam anterior segment analysis system with a spherical equivalent (SE) of -0.25 to -10.00 D. The corneal anterior aberrations (total higher-order aberration;spherical aberration;Coma;Trefoil) and Q and K values were detected, and a correlation analysis of the relevant parameters was carried out. Results: The root-mean-square (RMS) of the third to sixth order aberrations of the corneal anterior wavefront aberrations at a 6 mm analysis diameter showed a decreasing trend in patients suitable for the corneal refractive surgery, and the RMS of the third order aberrations accounted for 62.92% of the total HOAs. The coma ratio (coma/total cornea higher-order aberrations) was increased with the increasing diopters, while the spherical aberration ratio (spherical aberration/total cornea higher-order aberrations) was not changed. In addition, the spherical aberration was 0.203 ± 0.082 μm (range: 0.061 to 0.503 μm), and the Q30 was -0.19 ± 0.03 (range: -0.58 to 0.31). There were significant differences in the coma aberrations of preoperative corneal anterior surface (3, 1) between the low, middle and high myopia groups (P = 0.013). The spherical equivalent was positively correlated with the corneal coma of the anterior corneal surfaces (R =?-0.241, P = 0.009), and the Q value was positively correlated with the total higher-order aberrations (R = 0.326, P Conclusions: Individual wavefront aberrations on the anterior surfaces of the cornea are comparatively different, and the Zernike coefficients are related to the degree of myopia. Spherical aberrations are the most overriding aberrations of the cornea.
文摘AIM:To evaluate the efficacy of custom-made soft keratoconus(KC)lenses on corneal aberrations and photic phenomena in two different optical zones in patients with KC.METHODS:Sixty eyes of 42 patients with KC were examined at baseline and after fitting HydroCone(Toris K)soft silicone hydrogel lenses.Best spectacle-corrected visual acuity(BSCVA)and contact lens-corrected visual acuity(CLCVA)were recorded.Lower-and higher-order corneal aberrations(LOAs and HOAs)were measured with and without Toris K lenses and compared in central 4.5 mm and 7 mm zones.Mesopic pupil diameter and subjective photic phenomena were also assessed.RESULTS:Mean CLCVA was significantly improved compared to BSCVA(P<0.0001).Corneal curvature and refractive measurements were found to be significantly reduced by the use of Toris K lenses,except for posterior corneal curvature values.In the 4.5 mm central optical zone,all wavefront aberrations decreased significantly after lens fitting(P<0.0001).In contrast,in the 7 mm(peripheral)optical zone,values for HOAs,spherical and residual aberrations,and optical path differences were increased,while LOAs,trefoil,and quadrifoil coefficients were decreased.The rate of photic phenomena was significantly higher in participants with a pupil size>6.00 mm(85.7%).CONCLUSION:Toris K lenses provide good visual results and a significant reduction in central corneal aberrations in patients with KC but could cause an increase in peripheral aberrations.This practical and nonsurgical approach appears to be an effective method for the visual management of KC.
文摘Strip-shaped chromatic aberration defects on the surface of an electro-galvanized fingerprint-resistant sheet were systematically studied using Thermo-Calc thermodynamic calculations,scanning electron microscope and X-ray diffractometer analyses,and rapid heat treatment simulation technology.The formation mechanism of these defects was also analyzed.The results show a strong correlation between the defects and the uneven distribution of the Fe(001)component on the surface of the steel substrate.The relatively high proportion of Fe(001)components on the surface of the steel substrate affects the distribution density of the Zn crystal cells in different orientations during the electrodeposition process,which causes the reflection intensity of the light of the galvanized layer to differ from various visual perspectives,and macroscopic strip-shaped chromatic aberration defects are finally formed.The high proportion of the Fe(001)component on the surface of the steel substrate is mainly related to the following two factors.First,when the strip steel is hot-rolled,the finishing hot-rolling temperature is close to theγ→αphase transition temperature.When the local temperature on the upper surface of the strip steel is low,γ+αtwo-phase rolling easily occurs,and this results in an uneven stress distribution between theγandαphases after the hot-rolling process.This uneven distribution of hot-rolling stress results in the formation of a coarse grain structure in the local area on the surface of the hot-rolled sheet,which strongly affects the subsequent cold rolling and annealing process,and the annealed steel sheet substrate ultimately contains a greater proportion of the Fe(001)component.And second,a fast cooling rate(>10 K/s)during the slow cooling stage in the continuous annealing process inhibits the transformation of the Fe(001)to the Fe(111)component on the surface of the cold-rolled steel sheet,and it is then not possible to effectively eliminate the influence of the unevenly distributed Fe(001)component on the surface of the annealed steel sheet(originating from the uneven hot-rolled microstructure).This uneven distribution of the Fe(001)component on the surface of the annealed steel sheet following the continuous annealing heat treatment has a strong effect on the electrodeposition behavior of the Zn crystal cell in the subsequent electroplating process and the formation of macroscopic strip-shaped chromatic aberration defects on the surface of electro-galvanized fingerprint-resistant sheet.
