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AIM: To evaluate the effect of anterior capsule polishing on visual quality after phacoemulsification.METHODS: Prospective randomized control study. A total of 65 patients(73 eyes)with age-related cataract who underwent phacoemulsification combined with intraocular lens(IOL)implantation in the Emergency General Hospital between November 2021 and June 2022 were included. These patients were randomly assigned to two groups, with one group(anterior polishing group)underwent anterior and posterior capsule polishing(30 cases, 35 eyes), while the other(control group)receive routine posterior capsule polishing(35 cases, 38 eyes). Best corrected visual acuity was observed at 1wk, 1, 3 and 6mo after operation. Area of anterior capsule orifice was measured at 3 and 6mo after operation. Meanwhile, posterior capsular opacification(P score), IOL tilt and decentration were recorded by Pentacam Scheimpflug system. In addition, wavefront aberration, Strehl ratio(SR)of point spread function(PSF)and modulation transfer function(MTF)were evaluated by OPD-Scan Ⅲ.RESULTS: At 1wk, 1, 3 and 6mo after operation, best corrected visual acuity in anterior polishing group is significantly better than that of control group(P<0.05). There were no significant differences in area of anterior capsule opening, P score, IOL decentration, SR of PSF and MTF between two groups at 3 and 6mo after operation(P>0.05). At 3mo follow-up, no significant differences in IOL tilt and wavefront aberration were measured between two groups either(P>0.05). However, IOL tilt [(1.65±0.60)° vs.(2.34±0.43)°, P<0.001] and wavefront aberration(0.03±0.01μm vs. 0.06±0.03μm, P<0.001)in anterior polishing group were significant lower compared to control group at 6mo after operation.CONCLUSION: 360° polishing of anterior and posterior capsule during phacoemulsification can improve best corrected visual quality, with reduced IOL tilt, lower wavefront aberration and better visual quality.
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OBJECTIVE: To evaluate the preference of observers for image quality of chest radiography using the deconvolution algorithm of point spread function (PSF) (TRUVIEW ART algorithm, DRTECH Corp.) compared with that of original chest radiography for visualization of anatomic regions of the chest. MATERIALS AND METHODS: Prospectively enrolled 50 pairs of posteroanterior chest radiographs collected with standard protocol and with additional TRUVIEW ART algorithm were compared by four chest radiologists. This algorithm corrects scattered signals generated by a scintillator. Readers independently evaluated the visibility of 10 anatomical regions and overall image quality with a 5-point scale of preference. The significance of the differences in reader's preference was tested with a Wilcoxon's signed rank test. RESULTS: All four readers preferred the images applied with the algorithm to those without algorithm for all 10 anatomical regions (mean, 3.6; range, 3.2–4.0; p < 0.001) and for the overall image quality (mean, 3.8; range, 3.3–4.0; p < 0.001). The most preferred anatomical regions were the azygoesophageal recess, thoracic spine, and unobscured lung. CONCLUSION: The visibility of chest anatomical structures applied with the deconvolution algorithm of PSF was superior to the original chest radiography.
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Pulmón , Estudios Prospectivos , Radiografía , Radiografía Torácica , Columna Vertebral , TóraxRESUMEN
Objective To discuss the impact of an iterative reconstruction algorithm (True X) implemented with point spread function (PSF) on image quality and SUV in 18F-FDG PET, and compare with other reconstruction algorithms.Methods A total of 79 hypermetabolic lesions from 37 cancer patients (23 males, 14 females, age (63.38±15.25) years) were retrospectively studied.The PET images were reconstructed using the following six reconstruction algorithms, including FBP, FBP+TOF, iteration, iteration+TOF, True X, True X+TOF.Paired t test was used for statistical analysis.Results All six reconstruction algorithms showed significant difference in lesion SUVmax.The adoption of PSF increased SUVmax by 15%-16%, and decreased the dispersion of SUV in the liver parenchyma remarkably.Conclusions Lesion SUVmax calculated from different reconstruction algorithms has significant differences.Caution should be taken in using PSF, as it can improve image quality but may also increase lesion SUVmax.
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Objective To investigate the effects of the astigmatism values of children on wavefront aberration.Methods The children aged from 7 years to 10 years were dilated the pupils for 3 days,and the optometry examination was performed.Fifty-nine children who met the inclusion criteria were divided into three groups according to the degree of astigmatism:1.00 D ≤ astigmatism ＜2.00 D,2.00 D ≤ astigmatism ＜ 3.00 D,3.00 D ≤ astigmatism ＜ 4.00 D.In the meantime,OPD-SCAN-Ⅲ aberrometer was used to measure corneal topography,point spread function (PSF),modulation transfer function(MTF) and other optical images.Total higher order aberrations,total coma aberration,total spherical aberration,total trefoil aberration corresponding to the root mean square (RMS) value and the area ratio (AR) value of MTF,the strehl ratio (SR) value of PSF with a 4 mm pupil diameter were assessed.Three groups of higher order aberrations corresponding to the RMS value and the AR value of MTF,the SR value of PSF were respectively compared by one-way ANOVA.Results The RMS of total high-er order aberrations,coma aberrations and trefoil aberrations with a 4 mm pupil diameter of three groups significantly increased with the degree of astigmatism increase,and there were significant differences among three groups (all P ＜ 0.05).The RMS of total spherical aberrations of three groups significantly increased with the degree of astigmatism increase,and there was no significant difference among three groups (P ＞ 0.05).The AR and SR values decreased with the degree of astigmatism increase,and there were significant differences among three groups (all P ＜ 0.05).Conclusion Astigmatism has a significant influence on the higher-order aberrations,MTF and PSF in the children with the rule astigmatism.The rule astigmatism mainly has an effect on the asymmetric components of higher order aberrations.
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AIM:To explore relationship between the normal strehl ratio ( SR ) values of total aberrations/SR values of total higher-order aberrations and modulation transfer function ( MTF ) at total corneal at different pupil diameters in normal population. METHODS: To exam the SR values of total aberrations and SR values of total higher-order aberrations of total corneals in 200 people ( 400 eyes ) using SIRIUS 3D topography system and analysis the corresponding root-mean-square ( RMS) . RESULTS: The subjects with different pupil diameters (3. 0, 5. 0, 6. 0, 7. 0mm)'s exam results of total corneal were as following:SR value of total aberrations 100’(0. 45±0. 12), (0. 25±0. 06), (0. 17±0. 05), (0. 13±0. 04); SR value of total higher order ab cerrations 100’(0. 69±0. 14), (0. 34±0. 07), (0. 24±0. 05), (0. 16±0. 04);SR value of total aberrations 200’(0. 45±0. 12), (0. 24±0. 06), (0. 20±0. 04), (0. 16±0. 03); SR value of total higher order aberrations 200’(0.70±0. 13), (0. 35±0. 07), (0. 27±0. 06), (0. 20±0.04 ) . The SR values of each group decreases with the increases of pupil diameters. The SR values of total aberrations and SR values of total higher - order aberrations at total corneals are negatively correlated with corresponding RMS value. When the pupil diameter is small, the SR value of total aberrations is more related to higher frequency region of MTF. When the pupil diameter is big, the SR value of total aberrations is more related to lower frequency region of MTF. CONCLUSION: The visual performance of normal people can be well reflected by SR values of total aberrations and SR values of total higher - order aberrations at total corneal.
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Medical ultrasound imaging suffers from poor resolution due to its inherit imaging mechanism.In order to obtain the important diagnostic image in detail,restoration procedure needs to be performed.However,in practical ultrasound imaging,it's difficult to demonstrate the degradation process in detail.Therefore,blind image deconvolution is applied to estimate the original image from the degraded image with unknown point spread function or little available prior knowledge.In this paper,the main algorithms of medical ultrasound image restoration based on blind deconvolution are reviewed and classified into two categories,priori or joint with the image,according to the identification methods,and the basic theories and improved methods are analyzed and discussed.Finally,the future directions in blind restoration for medical ultrasound images are proposed.
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Stray light is a physical phenomenon that degrades visual quality when light scattering occurs in the human eye.It is a main cause of the disabling glare.Stray light originates in cornea,iris,sclera,lens and retina,and these ocular tissues contribute to the total amount of stray light in a normal eye.The light scattering intensity increases when the transparency of any optical element mentioned above reduces.Stray light can be measured by several different methods,but the measurements still lacks a standardized procedure and outcome.Further clinical study is necessary to quantify and standardize the measuring method of stray light.This article aims to introduce the concept,source and clinical significance of stray light,and to provide its advanced measurement techniques and methods.
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Background The evaluation of visual function after laser in situ keratomileusis(LASIK) mainly focuses on the study of contrast sensitivity funetion (CSF).However,CSF measurement is a subjective method and therefore has a limiting in application.A point spread function (PSF) is becoming a study topic because of its objectivity in assessing visual quality.Objective Present study was to evaluate the change of the modulation transfer function (MTF) of eyes and compare the optical and visual quality of human eyes after LASIK.Methods Thirty-six patients(72 eyes) were included in this study.The patients were divided into low myopia(-2.72±0.52 D),moderate myopia (-4.89+0.80 D) and high myopia (-8.00+0.98 D) groups according to the spherical equivalent (SE)diopter before the sugery.The uncorrected visual acuity (UCVA),best corrected visual acuity (BCVA) were examined before and after operation,and PSF data was obtained with Topoeon PSF-1000 analyzer under the 3.0 mm and 6.0 mm pupil size conditions.The follow-up visits of the patients were scheduled at the 7th days,1 st and 3rd months.Written informed consent was obtained from each patient before this study. ResuIts The MTF values among the three refractive groups were significantly different between 3 mm and 6 mm pupil preoperatively (P＜0.05).Under the condition of 3 mm pupil size,the MTF values in the spatial frequencies of 2.98 cpd and 14.88 cpd were significantly declined in different time points after operation in comparison with preoperative ones (P＜0.05).However,the MTF changes had no statistical significance in the spatial frequencies from 18.85-37.70 cpd among various time points(P＞0.05).Under the condition of the 6 mm pupil size,MTF values in low and moderate myopia groups were reduced after operation in comparison with before operation at the spatial frequencies from 2.98-7.44 cpd(P＜0.05),however,there were no obvious difference was found in the spatial frequencies of 9.42-37.70 cpd(P＞0.05).The MTF values of high myopia group was decreased significantly at all spatial frequencies(P＜0.05).The MTF values improved gradually as the prolong of time after operation but was still lower at the 3rd postoperative month than that of preoperation. Conclusion The postoperative visual quality is associated with refractive power and pupil diameter.PSF is a feasible method in assessing the early visual quality after LASIK.