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Objective:To investigate an accurate and quantitative method to measure the eyeball morphological parameters of guinea pigs through a method that combines programmed digital techniques and mathematical geometric principles.Methods:Twenty-two three-week-old clean-grade male tricolor guinea pigs were selected and sacrificed by anesthesia overdose.Eyeballs were enucleated.The horizontal and sagittal images of the eyeball were taken with the high-speed photographic model of 13 million pixels macro meter, and the pictures were imported into pycharm programming software.Using the pre-written analysis program of Python 3.9, the conversion coefficient between the photo pixel and the actual length was obtained by a scale, and then the corneal surface was fitted by arc fitting and conic curve fitting.The results of arc fitting were converted to calculate the corneal radius of curvature.The corneal eccentricity was calculated according to the general conic equation (Ax 2+ Bxy+ Cy 2+ Dx+ Ey+ F=0). The corneal asphericity was evaluated by curve fitting between the central 3-mm and the whole cornea.The use and care of the animals complied with Regulations for the Administration of Affairs Concerning Experimental Animals by State Science and Technology Commission.The study protocol was approved by the Ethics Committee of Shanghai Public Health Clinical Center (No.2022-A009-01). Results:The digital method of Python programming can show the corneal contour of guinea pigs completely and clearly.In the transverse plane, there was no significant difference in the corneal curvature measurements among the digital fitting in central 3-mm cornea, digital fitting in whole cornea and curvature meter ( F=1.693, P=0.190). In the sagittal plane, there was a significant difference in the corneal curvature measurements among the three methods ( F=3.500, P=0.030), and the corneal curvature measurements of the whole cornea measured by the curvature meter were significantly greater than those measured by the digital fitting ( P<0.05). There was no statistical significance in the measurements of corneal curvature radius among the three methods in the transverse plane and the sagittal plane ( F=1.817, P=0.170; F=2.050, P=0.133). The horizontal and sagittal corneal eccentricity measured by digital fitting in central 3-mm cornea were 0.55±0.15 and 0.53±0.17, which were lower than 0.66±0.10 and 0.64±0.14 measured by digital fitting in whole cornea, and the differences were statistically significant ( t=-4.860, -5.210; both at P<0.01). Conclusions:It is feasible to use Python programming digital method to measure the corneal curvature and eccentricity of guinea pigs.
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AIM: To observe the effect of eccentricity of the optical treatment zone on retinal defocus after wearing orthokeratology lens for 12mo.METHODS: In this case-control study, a total of 120 myopic patients(120 eyes)who completed the fitting in our hospital from March 2021 to September 2021 and insisted on wearing orthokeratology lenses for 12mo were selected. According to the eccentricity after wearing lenses for 12mo, they were divided into the low eccentricity group(<0.5mm, 58 cases, 58 eyes)and the moderate and high eccentricity group(≥0.5mm, 62 cases, 62 eyes). The optical treatment zone diameter(OTZD), eccentricity, axial length(AL), pupil diameter(PD)and refraction difference value(RDV)were evaluated after 12mo of wearing orthokeratology lenses, and the correlation between RDV and eccentricity was analyzed.RESULTS: After wearing orthokeratology lenses for 12mo, AL growth and RDV at 30°～40° and 40°～53° from the fovea were significantly lower in the moderate and high eccentricity group than in the low eccentricity group(all P<0.05). In all patients, RDV at 40°～53° from the fovea was positively correlated with AL growth and OTZD(rs=0.544, 0.333, both P<0.01), and negatively correlated with eccentricity(rs=-0.224, P=0.014).CONCLUSION: Peripheral retinal defocus is related to eccentricity and OTZD after wearing orthokeratology lenses. The greater eccentricity and the smaller OTZD within a certain range can induce more peripheral retinal myopic defocus, leading to a better control of AL growth.
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Purpose: To analyze the refractive shift during off?the?axis retinoscopy under cycloplegic drugs in myopic patients during ocular examination. Methods: Prospective cross?sectional study was carried out among 10 myopic patients having refractive errors of ?3.00 D or less. All the subjects underwent cycloplegic refraction by a single examiner at 0°, 10°, and 20°. Descriptive data were analyzed as mean and standard deviation. Paired t?test was used to compare the mean differences between on?axis (0°) and off?axis (10° and 20°) retinoscopy. Result: The mean spherical equivalent refraction of 10 myopic patients showed an increase in myopic shift with approximately 7% and 18% for 10° and 20° of eccentricity, respectively. Similarly, the mean spherical equivalent measure on axis (0°) and off axis (10° and 20°) were ?2.5495, ?2.737, and ?3.0265, respectively. The mean spherical equivalent differences between on?axis (0°) and off?axis (10° and 20°) showed statistically significant differences with P < 0.05. Conclusion: This study concluded that a greater degree of eccentricity will induce a greater amount of errors in retinoscopy
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Objective To study the effect of plaque eccentricity on stent performance and stress distributions of artery and plaque during stent implantation in stenotic vessels. Methods The stent and idealized stenotic vessels were constructed, and 4 different eccentricities (0%, 20%, 40%, 60%) were attributed to the plaque. Then the stent recoil, stent foreshortening, and stress distributions of artery and plaque when the stent was expanded to the target displacement were analyzed by the finite element method. Results Along with the increase of plaque eccentricity, both stent recoil and stent foreshortening gradually grew. At the same time, the stress of artery and plaque also showed an increasing tread, and high-stress areas gradually approached the narrow side. The maximum von Mises stress of the plaque was much greater than that of the artery. Conclusions Plaque eccentricity had a certain effect on performance of the stent and stress distributions of stenotic vessels. In stent design, the geometry of the plaque should be considered to improve clinical effect of the stent in interventional treatment.
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@#AIM: To explore the dynamic distribution of pupil size and center, the eccentricity distribution of corneal light reflection, and its correlation analysis about suitable for femtosecond laser combined with excimer laser <i>in situ</i> keratomileusis.<p>METHODS: Randomly selected 225 patients(407 eyes)who underwent femtosecond laser combined with excimer laser <i>in situ</i> keratomileusis at Yanbian University Hospital in 2019 from January to May, preoperative use of Wavelight Allegro Topolyzer Corneal Topography to measure the pupil size and center position, the German Wavelight EX500 excimer Laser(500Hz)records the deviation between the pupil center and the coaxially sighted corneal light reflex when the patient is supine. <p>RESULTS:The average displacement distribution between the center of the cornea and the center of the pupil is 0.322±0.194mm, and 64% of the eyes are ≤0.40mm. The average displacement distribution of P-Dist(the eccentricity between the pupil center and the coaxially sighted corneal light reflex point)is 0.225±0.102mm, and 80% of the eyes are ≤0.30mm. The coaxially sighted corneal light reflex point is mainly deviated to the superior temporal side of the corneal center(34%). The X-axis of the left eye in low light conditions: -0.061±0.084mm, and the X-axis of the right eye: -0.016±0.059mm(<i>P</i>=0.002)(the left eye shifted to the temporal side in the dark light). The corneal transverse diameter(WTW)was positively correlated with changes in pupil diameter(dark pupil diameter-bright pupil diameter)(<i>r</i>=0.270, <i>P</i><0.001).<p>CONCLUSION: The left eye should be adjusted to a position of the machining center within 0.061mm. If the cornea is too large, try to maintain a dark light environment during the operation to improve the efficiency of pupil matching. This study further confirms the necessity of rationally positioning the cutting center under different angle kappa states.
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@#AIM:To explore the effect of eccentricity of overnight orthokeratology(OK)lenses on 2-year eye axial growth and visual quality.<p>METHODS:Based on the degree of eccentricity of OK lenses, patients were divided into three groups: a low degree of eccentricity group(degree of eccentricity ≤0.5 mm), a group of moderate eccentricity(eccentric degree >0.5-≤1.0 mm)and a group with a high degree of eccentricity(eccentric degree >1-≤1.5 mm). The degree of eccentricity of the OK lens, spherical equivalent(SE), the uncorrected visual acuity after wearing OK lenses(UCVA), axial length before and after wearing OK lenses(AL), total higher-order aberrations(HOA), comas, and spherical aberrations(SA)for 3 mm pupils were analyzed. The difference among the three groups for all parameters was compared using the Kruskal-Wallis H Rank-Sum test.<p>RESULTS:The study retrospectively analyzed 75 cases(139 eyes). In the low eccentricity group(53 eyes), the mean age was 11.4±2.4 years, SE was -3.24±1.48 D, and AL was 24.85±1.01 mm. In the moderate eccentricity group(53 eyes), the mean age was 11.4±2.2 years, SE was -3.22±1.29 D, and AL was 25.15±0.92 mm. In the high eccentricity group(31 eyes), the mean age was 11.5±1.9 years, SE was -3.54±1.43 D, and AL was 24.95±0.84mm. After two years, there was no significant difference in the changes of the axis among the three groups(<i>P</i>=0.089). The HOA, SA, and coma in the high eccentric group were significantly higher than in the middle eccentric group(<i>P</i><0.05). The HOA, SA, and coma in the high eccentric group were also significantly higher than those in the low eccentric group(<i>P</i><0.05).<p>CONCLUSION:For OK lenses, it is unnecessary to strictly require the absolute centralization of the lens position. An unnecessary change of the lenses may delay the eye-axis control. However, the balance between axial control and visual quality should be assessed.
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Objective@#To evaluate changes in corneal high-order aberrations after the wearing of orthokeratology contact lenses and to study the factors influencing those changes.@*Methods@#A series of case-observational method was used.Data on 46 right myopic eyes of 46 children fitted for orthokeratology were continuously collected from January to April 2018.The corneal morphology, the e values of the anterior and posterior corneal surface in the nasal, temporal, superior and inferior zones within 6 mm were measured with Pentacam Anterion Segment Analysis System before and one month after the wearing of orthokeratology contact lens.Zernike Analysis System was used to calculate the values of Z33, Z3-3, Z31, Z3-1, and Z40 on the anterior and posterior surfaces and on the total cornea within a diameter of 6 mm.This study conformed to the tenets of the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Baoding Yinghua Eye Hospital (No.YKLL-2018-1-01). Written informed consent was obtained from each child and their guardians prior to entering the study cohort.@*Results@#Compared to the values recorded prior to orthokeratology contact lens wear, the horizontal coma, vertical coma, and spherical aberration of the total cornea and anterior corneal surface were drifted positively after lens wear; the horizontal coma and spherical aberration of the posterior corneal surface were drifted negatively after lens wear; and the differences were statistically significant (all at P<0.05). Before wearing orthokeratology contact lenses, eNf, eTf, eIf, eSf and eMf values were 0.580(0.450, 0.670), 0.455(0.378, 0.513), 0.485(0.268, 0.553), 0.665(0.578, 0.740) and 0.505±0.015, respectively, and after wearing orthokeratology contact lenses, eNf, eTf, eIf, eSf and eMf values were 0.285(-0.635, 0.665), -0.605(-0.813, -0.335), -0.545(-0.765, 0.305), -0.335(-0.705, 0.423) and -0.247±0.058, respectively.Compared with the conditions prior to wearing orthokeratology contact lens, the anterior corneal surface in all parts changed from steep to flat after lens wear, with statistically significant differences between them (all at P<0.05). The results of multiple stepwise linear regression showed that after wearing orthokeratology contact lens, the spherical aberration of the total cornea was moderately negatively correlated with the corneal e value and the initial diopter (rs=-0.626, -0.450; both at P<0.05), the horizontal coma of the total cornea was moderately negatively correlated with the temporal e value (rs=-0.391, P=0.004); the spherical aberration of the anterior corneal surface was moderately negatively correlated with the corneal e value and the initial diopter (rs=-0.612, -0.432; both at P<0.05); the horizontal coma of the anterior corneal surface was moderately negatively correlated with the temporal e value (rs=-0.400, P=0.003); and the horizontal coma of the posterior corneal surface was negatively correlated with the horizontal coma of the anterior corneal surface (rs=-0.380, P=0.009).@*Conclusions@#The spherical aberration and coma of the total cornea and anterior corneal surface drift positively after wearing orthokeratology contact lens, and the spherical aberration and horizontal coma of the posterior corneal surface drift negatively.The refraction and deformation of the anterior surface of the cornea are important factors affecting variation in corneal high-order aberrations.
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Objective To evaluate changes in corneal high-order aberrations after the wearing of orthokeratology contact lenses and to study the factors influencing those changes.Methods A series of case-observational method was used.Data on 46 right myopic eyes of 46 children fitted for orthokeratology were continuously collected from January to April 2018.The corneal morphology,the e values of the anterior and posterior corneal surface in the nasal,temporal,superior and inferior zones within 6 mm were measured with Pentacam Anterion Segment Analysis System before and one month after the wearing of orthokeratology contact lens.Zernike Analysis System was used to calculate the values of Z33,Z3-3,Z31,Z3-1,and Z40 on the anterior and posterior surfaces and on the total cornea within a diameter of 6 mm.This study conformed to the tenets of the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Baoding Yinghua Eye Hospital (No.YKLL-2018-1-01).Written informed consent was obtained from each child and their guardians prior to entering the study cohort.Results Compared to the values recorded prior to orthokeratology contact lens wear,the horizontal coma,vertical coma,and spherical aberration of the total cornea and anterior corneal surface were drifted positively after lens wear;the horizontal coma and spherical aberration of the posterior corneal surface were drifted negatively after lens wear;and the differences were statistically significant (all at P＜0.05).Before wearing orthokeratology contact lenses,eNf,eTf,eIf,eSf and eMf values were 0.580(0.450,0.670),0.455 (0.378,0.513),0.485 (0.268,0.553),0.665(0.578,0.740) and 0.505±0.015,respectively,and after wearing orthokeratology contact lenses,eNf,eTf,eIr,eSf and eMf values were 0.285(-0.635,0.665),-0.605 (-0.813,-0.335),-0.545 (-0.765,0.305),-0.335 (-0.705,0.423) and -0.247±0.058,respectively.Compared with the conditions prior to wearing orthokeratology contact lens,the anterior corneal surface in all parts changed from steep to fiat after lens wear,with statistically significant differences between them (all at P＜0.05).The results of multiple stepwise linear regression showed that after wearing orthokeratology contact lens,the spherical aberration of the total cornea was moderately negatively correlated with the corneal e value and the initial diopter (rs =-0.626,-0.450;both at P＜0.05),the horizontal coma of the total cornea was moderately negatively correlated with the temporal e value (rs =-0.391,P =0.004);the spherical aberration of the anterior corneal surface was moderately negatively correlated with the corneal e value and the initial diopter (rs =-0.612,-0.432;both at P＜0.05);the horizontal coma of the anterior corneal surface was moderately negatively correlated with the temporal e value (rs =-0.400,P =0.003);and the horizontal coma of the posterior corneal surface was negatively correlated with the horizontal coma of the anterior corneal surface (rs =-0.380,P =0.009).Conclusions The spherical aberration and coma of the total cornea and anterior corneal surface drift positively after wearing orthokeratology contact lens,and the spherical aberration and horizontal coma of the posterior corneal surface drift negatively.The refraction and deformation of the anterior surface of the cornea are important factors affecting variation in corneal high-order aberrations.
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@#AIM: To investigate the effect of inclination and eccentricity of intraocular lens(IOL),on optical imaging quality <i>via</i> wavefront aberration optical path system.<p>METHODS: The spherical IOL Sensar AR40e, the aspherical monofocal IOL Tecnis ZA9003, and the aspheric multifocal IOL Tecnis ZM900 were measured at the center of the center using a laboratory-built Hartmann-Shack IOL wavefront aberration path system at 5.0mm simulated pupil diameter. 0, 0.2, 0.4, 0.6, 0.8mm, the effect on the optical imaging quality when tilting 5°, 10°, 15°, 20°, 25° to the nasal side and the temporal side, and quantitative imaging quality by high-order aberration and modulation transfer function.<p>RESULTS: The Temnis ZA9003 MTF value was higher than AR40e and Tecnis ZM900 when inclinationed within 5°, while the three IOL MTF values were significantly different when inclinationed 5°, 10°, 15°, and 20°. Tecnis ZA9003 The IOL inclination angle was significantly positively correlated with the coma(<i>r</i>=0.842, <i>P</i><0.001), and there was no significant correlation with the spherical aberration(<i>r</i>=0.229, <i>P</i>=0.241). The three IOL MTF values were obtained when the eccentricity was 0.6 and 0.8 mm. Significant differences(both <i>P</i><0.001), the imaging quality of the Tecnis ZM900 eccentricity greater than 0.4mm decreased significantly.<p>CONCLUSION: When the inclination of aspheric IOL(-0.27μm spherical aberration)is less than 5°and the eccentricity is less than 0.4mm, aspherical IOL has a better imaging quality than that of spherical IOL. Tecnis ZM900 IOL has a lower optical imaging quality than that of spherical and aspheric IOL when the eccentricity of IOL is more than 0.4mm.
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Objective To investigate the shaping rules of the femoral heads in the morphological perspective.The research objects are hips of normal children and children who have developmental dysplasia of the hip(DDH) and after closed reduction or limited open reduction.At the same time measuring and analyzing normal hip femoral head form changing with the children's age.Methods Collecting the DDH cases that after closed reduction and limited open reduction from June 2013 to December 2015.The follow-up period was more than 1 year.MRI images were collected before surgery,6 months after surgery,1 year after surgery,and 2 years after surgery.In addition,normal hip joint MRI images from 0 to 18 years old were collected for controlled study.Descriptive data on the affected side,healthy side and normal hip joint morphology of the hip dislocation were statistically analyzed.Results (1) The mean eccentricity of femoral head in normal hip decreased from (0.362 ±0.069) at 1-2 years to(0.141 ±0.028) at 18-19 years.(2) The eccentricity of femoral head before closed reduction and limited open reduction were both greater than those of healthy side.There was no significant difference in the eccentricity of the femoral head between the healthy side and the affected side at 1 year after closed reduction (P =0.211).There was no significant difference in the diameter of the bilateral femoral heads (P =0.871).The eccentricity of the bilateral femoral heads remained different at 2 years after limited open reduction (P =0.028),and the diameter of the affected femoral head exceeded the healthy side 1 year after surgery (P =0.001).Conclusion The shape of the femoral head of normal children gradually approaches the spherical shape with age.One year after closed reduction of DDH,the shape and size of the affected femoral head are close to the healthy side,and the femoral head of the affected side increases more than the healthy side in 1 ～ 2 years after open reduction and the morphology is still different.
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@#AIM: To explore the correlation between eccentricity in the optical treatment area and tear film function and corneal morphology after orthokeratology. <p>METHODS:Eighty patients(80 eyes)with myopia who were treated with orthokeratology were selected as subjects. The eccentric distance, tear film function and corneal morphology of the patient's optical treatment area were detected at different time points before and after wearing the lens. According to the median eccentric distance, the patients were divided into low eccentricity group and high eccentricity group. The differences of tear film function and corneal morphology at different time points before and after wearing were compared between the two groups. Pearson correlation coefficient was used to analyze the correlation between total eccentricity and tear film function and corneal morphological parameters at 12mo after wearing glasses. <p>RESULTS:Compared with before wearing lenses, the corneal surface asymmetry index and corneal surface regularity index of the two groups were significantly increased at 1wk, 3, 6 and 12mo after wearing lenses(<i>P</i><0.05). Patients in the high eccentric group were more significantly elevated than in the lower eccentric group, and the differences were statistically significant(<i>P</i><0.05). The time of tear film rupture, corneal curvature, basic tear secretion, and central corneal thickness were significantly lower, and the differences were statistically significant(<i>P</i><0.05). Compared with the patients with lower eccentricity, the patients with high eccentricity group had more significant reduction in tear film rupture time and basic tear secretion, and the difference was statistically significant(<i>P</i><0.05), however, the degree of corneal curvature and central corneal thickness decreased less(<i>P</i><0.05). There was no significant difference in corneal endothelial cell density between 1wk after wearing lenses and 3mo after wearing lenses(<i>P</i>>0.05). The difference was statistically significant at 6mo and 12mo after wearing lenses(<i>P</i><0.05). At 12mo after wearing the lens, the total eccentric distance was positively correlated with the asymmetry index of the corneal surface and the regularity index of the corneal surface(<i>r</i>=0.869, 0.815; <i>P</i><0.05). At 12mo after wearing the lens, the total eccentric distance was negatively correlated with tear film rupture time, corneal curvature, basic tear secretion, and central corneal thickness(<i>r</i>=-0.865, -0.745, -0.912, -0.713; all <i>P</i><0.05), and there was no significant correlation with corneal endothelial cell density(<i>r</i>=0.185, <i>P</i>=0.199). <p>CONCLUSION:The eccentricity of the optical treatment area occurs at the beginning of wearing lenses. And the total eccentric distance has a significant correlation with the changes of tear film function and corneal morphology after keratoplasty.
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Background@#Left ventricular (LV) eccentricity index (EI) is a measure of the LV shapre obtained with a commonly used quantitative software for mycardial perfusion scintigraphy (MPS). However, there are limited studies evaluating its correlation with other MPS parameters, for which this study was done. @*Methodology@#All patients who underwent 99mTc-sestamibi stress MPS from 2013 to 2015 were screened. A total of 353 patients, 228 (65%) males and 125 (35%) females, met the inclusion criteria. One hundred twenty-nine (37%) underwent exercise stress while 224 (63%) were given dipyridamole. Spearman's rho correlation was used to determine the correlation of rest and post-stress EI with the other study variables. @*Results@#Among males, rest EI showed negative correlation with summed stress score (SSS) (rs = -0.182, p<0.005), transient ischemic dilatation (TID) (rs=-0.172, p=0.009), rest LV end-diastolic volume (EDV) (rs=-0.291, p < 0.001), rest LV end-systolic volume (ESV)(rs=-0.316, p < 0.001), p0-st-streSS LVEDV (rs= -0.218, p < 0.001), and post-stress LVESV (rs= -0.331, p < 0.001). There was positive correlation with rest LV ejection fraction (EF) (rs= 0.291,p < 0.001) and post-stress LVEF (r5 = 0. 336, p < 0. 001). No sig11ifico11t relationship with any of the MPS parameters was observed among females. For both exercise and dipyridamole groups. EI exhibited negative correlation with SSS, and rest and stress LVESV; and positive cotrelation with rest and post-stress LVEF. Significant relationship with rest and stress LVEDV was only observed in the dipyridamole group.@*Conclusions@#This study shows that EI is correlated with most, if not all, of the MPS parameters with different levels of association depending on the patient's sex and the type of stress employed. More spherical LV is correlated with more severe perfusion defects, larger LV cavity volumes and poorere LV systolic function.
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Tecnecio Tc 99m Sestamibi , DipiridamolRESUMEN
PURPOSE: To compare the differences of parameters of 9.3 mm and 8.8 mm rigid gas permeable lenses (RGP lenses) that were prescribed by trial lens fitting. METHODS: Ninety-three eyes of 49 patients were prescribed RGP contact lenses (YK spherical lens, Lucid Korea, Bonghwa, Korea) by a single ophthalmologist at the same hospital. We analyzed the differences of parameters of 9.3 mm and 8.8 mm rigid gas permeable lenses (RGP lenses) that were prescribed by trial lens fitting. Steep keratometric value (Ks), flat keratometric value (Kf), and corneal astigmatism (Kast) were measured by keratometer. Simulated steep keratometric value (Sim Ks), simulated flat keratometric value (Sim Kf), simulated corneal astigmatism (Sim Kast), white to white corneal diameter (WTW), and eccentricity were measured by corneal topography. We also analyzed the differences of back optic zone radius (BOZR) and lens power between the two groups. RESULTS: In this study, 40 eyes wearing 8.8 mm lenses and 53 eyes wearing 9.3 mm lenses were included. Keratometric value and eccentricity were significantly higher in the 8.8 mm lens group, while WTW and BOZR were significantly lower. Corneal astigmatism (Kast, Sim Kast) and lens power were not significantly different between the groups. CONCLUSIONS: RGP lenses with a smaller diameter were likely to be prescribed to patients with higher keratometric value, higher eccentricity, and shorter WTW, and the average BOZR of the prescribed RGP lenses with a smaller diameter was likely to be steeper.
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Humanos , Astigmatismo , Lentes de Contacto , Topografía de la Córnea , Corea (Geográfico) , Radio (Anatomía)RESUMEN
A percepção visual depende do arcabouço sensorial e do processamento atencional. Este trabalho estudou o efeito, sobre o tempo de reação manual (TR), do tamanho, excentricidade e previsibilidade de estímulos visuais. No experimento 1 (n=8), um alvo foi apresentado aleatoriamente em uma de quatro excentricidades diferentes, possuindo três possíveis tamanhos. O experimento 2 (n=12) apresentava configuração similar, porém uma pista indicava o quadrante de maior probabilidade (70%) de apresentação do alvo. Os resultados mostraram um aumento do TR em função da excentricidade do alvo, além de uma diminuição do TR com o aumento do tamanho do alvo e indicação correta da pista. Uma análise das interações sugere uma superposição de mecanismos atencionais e puramente sensoriais compartilhando um estágio comum do processamento visual.
Visual perception depends on the sensory framework and on attentional processing. This study examined the effects of the size, eccentricity and predictability of a visual stimulus on manual reaction time (RT). In experiment 1 (n=8), a target was presented randomly in one of four different eccentricities, with three possible sizes. Experiment 2 (n=12) had a similar configuration but a cue indicated the higher predictability (70%) of target presentation quadrant. The results showed an increase in RT as a function of target eccentricity, and a decrease in RT with increasing target size or accuracy of the cue. An analysis of interaction effects suggests an overlay of attentional and purely sensory mechanisms sharing common stages of visual processing.
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Humanos , Masculino , Femenino , Adulto , Atención , Psicología Experimental , Tiempo de ReacciónRESUMEN
Conventional excimer laser keratectomy have been proved to achieve better visual function,but the traditional therapy of corneal spherical cutting line generally flat profile will make the cornea more oblate shape and the contours of the cornea and lcad to spherical aberration.The alteration of non.spherical nature cause the increase of corneal spherical aberration,which further affects the night vision and contrast sensitivity and other visual quality.Wavefront optimization based on total number of adjustments are to retain the previous visual aberrations of eyes and optimize the non-spherical nature of cornea to create a ideal model based on individual adjustments.Ocular wavefront-guided measurement and ablation in exeimer laser keratectomy can achieve better visual outcome.In this paper,wavefront guided and wavefront optimized treatment outcome for the spherical aberration correction are reviewed.
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Introducción: El índice de excentricidad (IE) obtenido con SPECT miocárdico permite evaluación de esfericidad ventricular izquierda en remodelación patológica. Objetivo: conocer IE en adultos con diversas condiciones cardíacas. Método: Grupo I: Controles (n=44) con >2 factores de riesgo cardiovascular exceptuando Diabetes Mellitus (DM); Grupo II: DM 2 (n=41). Ambos grupos asintomáticos sin enfermedad coronaria conocida. Grupo III: Con alteración de motilidad segmentaria y/o infarto de miocardio (n=64). Grupo IV: Dilatados (n=21) con alteraciones de motilidad difusa o miocardiopatías. Se utilizó Sestamibi-Tc99m y procesamiento QGS. (IE esfera valor
Background: The Eccentricity Index (EI) obtained with myocardial SPECT allows adequate assessment of left ventricular shape in pathological myocardial remodeling. Aim: To compare EIs in adults with different cardiac conditions. Methods: 170 patients were studied. Group I (n=44) were control subjects with >2 cardiovascular risk factors not including Diabetes Mellitus (DM); Group II (n=41) had type II DM. Patients in both groups were asymptomatic without known coronary artery disease or wall motion abnormalities. Group III (n=64) had seg-mental wall motion abnormality and/or myocardial infarction; Group IV (n=21) included patients with dilated ventricles and diffuse abnormal wall motion. We used gated 99mTc Sestamibi SPECT and QGS processing (EI sphere
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Humanos , Masculino , Femenino , Persona de Mediana Edad , Disfunción Ventricular Izquierda , Tomografía Computarizada de Emisión de Fotón Único , Ventrículos CardíacosRESUMEN
PURPOSE:To report the change of corneal asphericity and the relationship between asphericity and visual acuity after wearing the reverse-geometry lens. METHODS: The authors reviewed out-patient records of 37 consecutive patients wearing reverse-geometry lenses. The patients were followed up from July 2004 to December 2007. The unaided visual acuity (VA), spherical equivalent (SE) and asphericity before and after wearing the lens were compared. The relationship of SE and final VA, initial astigmatism and final VA, and asphericity and final VA was also analyzed. In addition, the relationship between the increment of VA and asphericity was determined. RESULTS: VA and SE improved and the asphericity decreased after wearing the lens (p<0.05). There was high correlation between the spherical equivalent and final visual acuity (p<0.001), and no correlation between asphericity and final visual acuity (p=0.358) was observed. However, the lower the initial asphericity, the greater the increment of visual acuity observed (p=0.048). CONCLUSIONS: Initial corneal asphericity can be a predictor of increment of VA after wearing reverse-geometry lenses.