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AIM: To evaluate the clinical efficacy of femtosecond laser-assisted cataract surgery combined with PanOptix trifocal intraocular lens implantation.METHODS:The retrospective study enrolled 22 cases(26 eyes)of cataract patients who underwent femtosecond laser-assisted cataract surgery combined with PanOptix trifocal intraocular lens implantation from August 2020 to August 2021. Follow-up to 3mo after surgery, the changes of far, intermediate and near visual acuity, aberration, Strehl ratio(SR)and modulation transfer function cutoff(MTF-cutoff)frequency were compared. Defocus curve at 1mo postoperatively was made, and the visual quality and satisfaction were evaluated after 3mo of surgery.RESULTS: The visual acuity of all patients was better than 0.1(LogMAR)at the far, intermediate and near distance at 1d, 1wk, 1 and 3mo postoperatively, and it was significantly improved compared with those before surgery(all P<0.01). The defocus curve transitioned smoothly between +0.5 and -3.0D at 1mo after surgery, and visual acuity was better than 0.63. The total aberration and spherical aberration in the whole eye were significantly lower after surgery than before, and the SR and MTF-cutoff were significantly improved at 1d and 1wk after surgery(all P<0.05). With high satisfaction and good visual quality, patients could watch at far, intermediate and near distance without wearing glasses at 3mo after surgery.CONCLUSION: Femtosecond laser-assisted cataract surgery combined with PanOptix trifocal intraocular lens implantation gave patients a comfortable and satisfactory full-course vision.
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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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Femtosecond laser small incision lenticule extraction(SMILE)is one of the most advanced corneal refractive operations at present. Different from other traditional corneal refractive operations, SMILE achieves minimally invasive and valveless operation. Therefore, the evaluation of postoperative visual quality of SMILE also has its own characteristics, at present, the latest research at home and abroad has confirmed that the naked eye vision can be significantly improved and the refractive status is stable after SMILE. However, there are different understandings of the objective visual quality indexes and their influencing factors, such as higher-order aberration, modulation transfer function cut off(MTF cut off)and objective scatter index(OSI)after SMILE. This paper reviews the postoperative visual quality and its influencing factors after SMILE to provide clinical help.
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Epilepsy is a neurological disease with disordered brain network connectivity. It is important to analyze the brain network mechanism of epileptic seizure from the perspective of directed functional connectivity. In this paper, causal brain networks were constructed for different sub-bands of epileptic electroencephalogram (EEG) signals in interictal, preictal and ictal phases by directional transfer function method, and the information transmission pathway and dynamic change process of brain network under different conditions were analyzed. Finally, the dynamic changes of characteristic attributes of brain networks with different rhythms were analyzed. The results show that the topology of brain network changes from stochastic network to rule network during the three stage and the node connections of the whole brain network show a trend of gradual decline. The number of pathway connections between internal nodes of frontal, temporal and occipital regions increase. There are a lot of hub nodes with information outflow in the lesion region. The global efficiency in ictal stage of α, β and γ waves are significantly higher than in the interictal and the preictal stage. The clustering coefficients in preictal stage are higher than in the ictal stage and the clustering coefficients in ictal stage are higher than in the interictal stage. The clustering coefficients of frontal, temporal and parietal lobes are significantly increased. The results of this study indicate that the topological structure and characteristic properties of epileptic causal brain network can reflect the dynamic process of epileptic seizures. In the future, this study has important research value in the localization of epileptic focus and prediction of epileptic seizure.
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Humans , Epilepsy , Brain , Seizures , Electroencephalography , Occipital LobeABSTRACT
Objective:To investigate and compare the changes of modulation transfer function (MTF) after small-incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis(FS-LASIK).Methods:A cohort study was conducted.One hundred and two myopic patients (102 eyes) who underwent SMILE and FS-LASIK in Tianjin Eye Hospital from December 2015 to June 2016 were enrolled and divided into SMILE group with 53 eyes and FS-LASIK group with 49 eyes according to different surgical methods.The ocular aberrations and corneal morphology of all patients were measured by the Hartman-Shack wave-front analyzer and Pentacam topography before surgery and 1, 3 and 6 months postoperatively.MTF of optic system was calculated and analyzed.The changes of MTF values were compared between the two groups at different time points under different spatial frequencies, after removal of low-order aberrations at postoperative 6 months, and after removal of vertical coma aberration, horizontal coma aberration and spherical aberration in the SMILE group at postoperative 6 months.The study protocol complied with the Declaration of Helsinki and was approved by an Ethics Committee of Tianjin Eye Hospital (No.TJYYLL-2014-17). Written informed consent was obtained from each patient before surgery.Results:Compared with the preoperative MTF, there were significant increases in postoperative 1-, 3- and 6-month MTF at all spatial frequencies in the SMILE group and FS-LASIK group (all at P<0.05). MTF values at all spatial frequencies in the SMILE group were significantly higher than those in the FS-LASIK group at 1, 3, and 6 months after surgery (all at P<0.05), except at 55 c/d and 60 c/d at 6 months postoperatively.The postoperative 6-month MTF values at all spatial frequencies without low-order aberration were higher in the SMILE group than those in the FS-LASIK group, showing significant differences between the two groups (all at P<0.05). In the SMILE group, the postoperative 6-month MTF values at 1 c/d spatial frequency without the horizontal coma aberration and spherical aberration were significantly higher than the preoperative MTF values (both at P<0.01); the postoperative 6-month MTF values at 1 c/d and 3 c/d spatial frequency without vertical coma aberration were significantly higher than the preoperative MTF values (both at P<0.05), and there were no statistically significant differences between the postoperative 6-month MTF values at the other spatial frequencies with and without single high-order aberrations (all at P>0.05). Conclusions:Optic quality has been obviously improved after SMILE and FS-LASIK, and the SMILE is superior to FS-LASIK in the MTF value.
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Cardiovascular disease is one of the important factors that threaten the health of residents, ranking the first among various causes of death, so the monitoring and diagnosis of human cardiovascular health is particularly important. Compared with traditional brachial artery pressure, central arterial pressure (CAP) has a higher correlation with the occurrence of many cardiovascular events. The measurement of CAP can more accurately reflect the real situation of human blood pressure, and provide an important basis for diagnosis and disease prevention. Therefore, the realization of high-precision, high-generalization ability and low-cost non-invasive measurement of CAP has always been the research focus in this field. This article combines the relevant literature in China and abroad to summarize the current status of CPA measurement, introduces related research progress from two aspects, namely parameter measurement and waveform measurement, and discusses the characteristics of the existing methods and the future development.
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@#AIM: To observe the changes of the vault height and the correlation analysis of visual quality under different pupil diameters after ICL surgery.<p>METHODS: Retrospective case study. Selected 43 patients(86 eyes)who implanted V4c ICL surgery successfully at Shanghai Aier Eye Hospital and followed up regularly to meet the measurement requirements from January 2018 to January 2019, Routine parameters and iTrace were checked before and 1wk, 1mo, and 3mo after surgery. Visante-OCT was used to measure the vault height under the pupils of 3mm and 5mm. <p>RESULTS: The vault height under the 3mm pupil at 1wk, 1mo and 3mo after surgery were(586.06±24.49, 560.16±21.31, 508.19±21.17)μm, the values under the 5mm pupil were(698.13±20.98, 667.69±20.16, 613.28±19.79)μm(<i>F</i><sub>Time</sub>=40.160,<i>P</i><sub>Time</sub><0.001; <i>F</i><sub>Groups</sub>=56.835,<i>P</i><sub>Groups</sub><0.001). The wave of vaule under the different pupils was(112.06±8.91, 107.53±6.94,101.01±10.64)μm(<i>F</i>=16.875, <i>P</i>>0.05). The total high-order aberration(HOA)and RMS of the whole eye after ICL were significantly reduced(<i>F</i>=29.847, 85.019; <i>P</i><0.001). The MTF and SR value were significantly higher than before surgery(<i>F</i>=47.653, 33.264; <i>P</i><0.001), and there was no statistical difference after ICL. At 3mo after surgery, the RMS and MTF values at 3mm and 5mm pupils were compared. The RMS value of the total HOA under the pupil of 5mm is significantly higher than that at 3mm, and the increase of spherical and trefoil aberration is significant(<i>t</i>=21.812, 17.136; <i>P</i><0.001). No significant difference in coma value(<i>t</i>=2.028, <i>P</i>>0.05). The MTF at 5mm pupils were significantly lower than those at 3mm at spatial frequencies of 5, 10, 15, 20, 25, 30c/d(<i>t</i>=15.138, 9.147, 7.018, 4.693, 3.814 and 3.075, all <i>P</i><0.05).<p>CONCLUSION: The impact of pupil movement on vault height fluctuation is about 110μm. It is recommended that the minimum vault height should be above 300μm. It can significantly reduce the root mean square value of total high-order aberration and aberration of the whole eye, and significantly increase the MTF and SR values after ICL surgery. The pupil size has a significant effect on visual quality after ICL. The spherical aberration and trefoil aberration increase under the condition of large pupil, and the MTF value generally decreases.
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@#AIM: To investigate the characteristics of optical modulation transfer function(MTF)of the eyes after femtosecond laser small incision lenticule extraction(SMILE), and to evaluate the relationship between visual acuity(VA), contrast sensitivity(CSF)and MTF. <p>METHODS: From June to November, 2015, 34 myopia patients(68 eyes)who underwent SMILE surgery in Tianjin Eye Hospital were selected in cross-section. The postoperative eye condition was stable for more than 3mo after surgery. The residual diopter of the eyes after SMILE was less than ±0.50D. Under bright vision, measured VA by International standard visual acuity chart and CSF by CSV-1000E. The wavefront aberration of the whole eyes were measured by WaveScan, and MTF of the eyes were obtained by using aberration formula conversion and Matlab programming. The MTF of(3, 6, 12, 18)c/d frequency region were counted. <p>RESULTS: CSF values in 3, 6, 12, 18 c/d frequency range were 63.19±3.18, 110.25±5.22, 57.65±3.76, 16.15±1.04; MTF values in 3, 6, 12, 18 c/d frequency range were 0.80±0.02, 0.56±0.03, 0.30±0.02, 0.19±0.02. In 6, 12, 18 c/d frequency range, visual acuity was significantly correlated with CSF(<i>r</i>=0.548, 0.337, 0.324,<i> P</i><0.01,=0.005, 0.007). In 18c/d frequency range, CSF was significantly correlated with MTF(<i>r</i>=0.241,<i> P</i>=0.048). <p>CONCLUSION: The change of optical quality(MTF)after SMILE was different from that of visual quality(visual acuity and contrast sensitivity). Although the aberration of refractive system changed, the SMILE surgery had no effect on CSF, which indicated that neuro-brain had a compensatory effect on visual quality. Computational MTF has certain theoretical and clinical value in evaluating the optical quality after refractive surgery.
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@#OBJECTIVE: To compare the visual, refractive, and patient-reported outcomes of eyes implanted with one of 3 trifocal intraocular lenses (IOLs). METHODS: This is a cross-sectional, comparative, non-interventional study wherein subjects implanted with FineVision Micro F, AT LISA tri 839MP or AcrySof IQ PanOptix trifocal IOL after phacoemulsification were recruited. Manifest refraction, uncorrected and corrected visual acuity (VA) at distance, intermediate and near vision, contrast sensitivity, modulated transfer function (MTF) values and questionnaire answers were compared among the 3 groups using analysis of variance (ANOVA). RESULTS: Fifty-seven (57) eyes were included in the study: 21 eyes with FineVision (group A), 21 eyes with LISA tri (group B), and 15 eyes with PanOptix IOL (group C). The post-operative mean manifest spherical equivalent was -0.01D, -0.07D, and 0.05D, respectively (p=0.083). Uncorrected distance VA and best-corrected distance VA were similar among the groups. Groups A and C had better uncorrected and corrected intermediate VA at 80 cm and at 60 cm compared to group B. Group A had significantly better uncorrected near visual acuity than groups B and C (p=0.032). Mesopic contrast sensitivity testing showed group C had higher contrast sensitivities without glare in at the spatial frequency of 6 CPD (p=0.038) and with glare at 3 CPD (p=0.039) and at 12 CPD (p=0.009). MTF average height analysis showed that the group A had significantly superior resolution in far targets compared to groups B and C (p=0.001). At near targets, groups A and C had better resolutions compared to group B (p=0.017). There was no significant difference in patient satisfaction for far, intermediate and near VA among the groups. CONCLUSION: Eyes implanted with any of the 3 trifocal IOL designs achieved excellent uncorrected and bestcorrected distance, intermediate and near vision. FineVision and PanOptix provided significantly better intermediate vision than LISA tri at both 80 cm and 60 cm testing distance. FineVision had better near visual outcomes than PanOptix and LISA tri. Patient satisfaction was high in all 3 trifocal IOLS
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Lenses, Intraocular , Vision, OcularABSTRACT
Objective To investigate the possible electroencephalograph network connectivity mech-anism of working memory disorder in patients with frontal lobe epilepsy ( FLE). Methods Seventeen adult FLE patients were enrolled as the case group and 22 normal adults were selected as the control group. The behavioral data and 34-channel electroencephalographs were recorded in the working memory behavioral par-adigm. The directed transfer function was used to construct the causal connectivity brain network of theta band of working memory delay period. Two-sample t-test or tˊ-test was used to analyze the differences in be-havioral and frontal causal connectivity between the two groups. Results (1) Compared with control group, working memory behavioral data of FLE group showed significantly lower correct rate ((92. 778±4. 399)%, (96. 258±2. 470)%,tˊ=-2. 925,P<0. 01),and significantly longer reaction time ((978. 586± 65. 161) ms,(798. 671±196. 207)ms,tˊ=4. 023,P<0. 001). (2) Compared with control group,causal connectivity of FLE group showed significantly reduced whole brain ( tˊ=-6. 008, P<0. 001), Fz channel ( tˊ=-7. 703,P<0. 001),frontal region (tˊ=-14. 667,P<0. 001),frontal-temporal interval ( t=-14. 467,P<0. 001),and frontal-central interval (t=-3. 501,P<0. 001). The causal connectivity of frontal-occipital in-terval had no significant difference( t=1. 056,P=0. 281). Conclusions Working memory disorders were found in FLE patients. The abnormal causal connectivity of frontal brain network in theta band may be one of its potential neurophysiological mechanisms.
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BACKGROUND@#To develop human space exploration, it is necessary to study the effects of an isolated and confined environment, as well as a microgravity environment, on cerebral circulation. However, no studies on cerebral circulation in an isolated and confined environment have been reported. Therefore, we investigated the effects of a 14-day period of confinement in an isolated environment on dynamic cerebral autoregulation.@*METHODS@#We participated in an isolation and confinement experiment conducted by the Japan Aerospace Exploration Agency in 2016. Eight healthy males were isolated and confined in a facility for 14 days. Data were collected on the days immediately before and after confinement. Arterial blood pressure waveforms were obtained using a finger blood pressure monitor, and cerebral blood flow velocity waveforms in the middle cerebral artery were obtained using transcranial Doppler ultrasonography for 6 min during quiet rest in a supine position. Dynamic cerebral autoregulation was evaluated by transfer function analysis between spontaneous variability of beat-to-beat mean arterial blood pressure and mean cerebral blood flow velocity.@*RESULTS@#Transfer function gain in the low- and high-frequency ranges increased significantly (0.54 ± 0.07 to 0.69 ± 0.09 cm/s/mmHg and 0.80 ± 0.05 to 0.92 ± 0.09 cm/s/mmHg, respectively) after the confinement.@*CONCLUSION@#The increases observed in transfer function gain may be interpreted as indicating less suppressive capability against transmission from arterial blood pressure oscillation to cerebral blood flow velocity fluctuation. These results suggest that confinement in an isolated environment for 14 days may impair dynamic cerebral autoregulation.@*TRIAL REGISTRATION@#UMIN000020703 , Registered 2016/01/22.
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Adult , Humans , Male , Middle Aged , Young Adult , Cerebrovascular Circulation , Physiology , Confined Spaces , Homeostasis , Physiology , Space FlightABSTRACT
Objective To observe the long-term visual quality and clinical effect of aspheric diffractive multifocal intraocular lens (IOL) implantation for congenital and developmental cataracts in childhood.Methods A retrospective cohort study on multifocal IOL implantation for congenital and developmental cataracts in childhood (aged 8 to 14 years) was performed in the First Affiliated Hospital of Zhengzhou University from August 2013 to January 2015.The clinical data of 67 eyes from 46 congenital cataract patients who received phacoemulsification with IOL implantation were collected.The AMO (ZMB00) IOL was implanted in 34 eyes of 24 patients in the multifocal IOL group,and Bausch & Lomb (MI60) IOL was implanted in 33 eyes of 22 patients in the monofocal IOL group.The distance,intermediate and near vision acuity were analyzed in 3,6 and 12 months after surgery,including uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA).The wavefront aberrations,modulation transfer functions (MTF) and stereopsis were obtained with iTrace Analysis System,Optec-6500 Visual Functional Analyzer and Titmus Stereo Test Chart,respectively in 12 months after surgery.The near additional degree,removing glasses rate and myopic shift were compared between the two groups in postoperative 12 months.Results The intermediate and near UCVA in the multifocal IOL group were obviously better than those in the monofocal IOL group 3,6 and 12 months after surgery (intermediate:Z=-3.74,-4.36,-3.66;all at P=0.00.near:Z=-2.67,-2.50,-2.33;all at P＜0.05).There were no significant differences between the two groups in total aberration,high and low order total aberrations,comatic aberration,trefoil aberration,spherical aberration and secondary astigmatism under the 5.0 mm optical zone in 12 months after surgery (all at P＞0.05).The MTFs under the 5.0 mm optical zone and 5,10,15,20,25,30 c/d in the multifocal IOL group were insignificantly lower than those in the monofocal IOL group (all at P＞0.05).In addition,the near stereopsis,near additional degree and myopic shift (AD) were reduced in the multifocal IOL group compared with monofocal IOL group (both at P＜0.05).The glasses removing rate was 93.3％ in the multifocal IOL group,which was significantly higher than 33.3％ in the monofocal IOL group (x2 =23.25,P =0.00).No significant difference in the incidence of posterior capsular opacification was found between the two groups (P＞0.05).The myopic shifting rates were 16.7％ and 83.3％ in the multifocal IOL group and monofocal IOL group,with a significant difference between the two groups (x2=15.02,P=0.00).Conclusions The aspheric multifical IOL implantation can achieve good and stable distance,intermediate and near visual acuities,provide better near stereopsis,reduce postoperative dependence on spectacles and decrease the incidence of myopic shift in child cataract patients.
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Objective To study the optical imaging quality of multifocal intraocular lens (IOL) following Nd∶YAG laser damage.Methods Three hydrophobic acrylate discs used to make multifocal IOL were placed in line,and the Nd∶YAG laser was used to emit the posterior surface,mid-plane and anterior surface of the discs by gradually increasing the emitting energy to determine the damaged threshold energy of various planes.Eight multifocal IOLs were divided into 2 groups.IOL damage models were established by emitting 12 points along 12 clocks on circle of 3.0 mm in diameter in the group 1 (IOLs NO.1,2,3,4) and 6 points with 1-clock interval on circle of 1.0 mm in diameter in the group 2 (IOLs NO.5,6,7,8) with Nd∶YAG laser.The modulation transfer function (MTF),line spread function (LSF) and United States air force (USAF) test target images of the IOLs were tested under the optical aperture at 2.0,3.0 and 4.5 mm.Results The damage thresholds of laser power were not significantly different among three hydrophobic acrylate discs (Fgroup =1.100,P =0.337),and the thresholds were significantly different among different planes in the discs (Fposition =195.279,P=0.000),with the highest damage threshold in the anterior surface and the lowest damage threshold in the mid-plane of the discs(all at P＜0.01).The shifts of far focus and near focus MTF curves,LSF curves and USAF target images of the IOLs under the 2.0,3.0 and 4.5 mm optical aperture after laser damage were in coincidence with those before laser damage both in group 1 and group 2.The glare phenomenon of the USAF target image was observed at near focus under the 4.5 mm optical aperture both before and after laser damage.Conclusions Multifocal IOL is vulnerable to injury when the laser beam focuses on the midplane,and the anterior surface of IOL can tolerate certain degree of damage.In standard model eye,the MTF curves,LSF curves and USAF target images of multifocal IOL was not impacted by laser induced spots injuries under different pupil diameters.
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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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Lung , Prospective Studies , Radiography , Radiography, Thoracic , Spine , ThoraxABSTRACT
The hearing-aid transducer is ubiquitous in the hearing-aid industry. For example, the balanced armature receiver (BAR), first invented by A.G. Bell, has been used in all telephone earphones because it has the highest output and best frequency response. Nevertheless, previous electro-mechanical studies on these miniature speakers are quite primitive, given the price of the transducers. Thus, more detailed analysis is critically important for the field of hearing science. This review study was motivated by Hunt's parameter calibration (1954), a widely used commercial hearing-aid receiver (ED series, manufactured by Knowles Electronics, Inc.). In the body of the study, the transfer function of the BAR system (i.e., pressure over voltage) was calculated from Hunt's parameters, solely from the electrical terminals of the device. The computed transfer function was then further investigated by comparing to the pole-zero fitting method using the methods of Gustavsen and Semlyen (1999) and Prony (1975). Based on our short experiment, the better fitting result was achieved with Gustavsen and Semlyen's method. By decomposing results of the transfer function fitting into all-pass and minimum-phase parts, the system was confirmed as a delay system. We conclude that the BAR system is linear, time-invariant, stable, and causal while providing an evidence-based understanding of the hearing-aid receiver system.
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Calibration , Hearing , Methods , Telephone , TransducersABSTRACT
Objective To establish a quantitative evaluation of quality control image for the onboard imaging system of medical linear accelerator.Methods An MV planar image of electronic portal imaging device (EPID) is acquired by both Elekta iViewGT and Varian aS1000,and a kV planar image and cone-beam computed tomography (CBCT) images of CBCT are acquired by both Elekta X-ray volume imaging (XVI) and Varian On-board Imager (OBI).Phantoms used here included Las Vegas,TOR18FG,and Catphan504.A series of image quality indicators were evaluated by analyzing the images mentioned above using a quantitative method.Results A quantitative value was calculated to represent the contrast resolution of EPID.A modulation transfer function (MTF) to describe spatial resolution and a quantitative value representing contrast resolution were calculated for the kV planar image.As for the CBCT system,a series of quantitative results of noise,uniformity,CT value accuracy,and contrast resolution and a MTF were calculated to represent the performance of CBCT system.Conclusions Based on common phantoms,a complete set of quantitative methods to evaluate the image quality of EPID and CBCT has been developed,which could provide a very good reference for the establishment of quality control system for image-guided radiotherapy.
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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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Background The current evaluation of corneal optical quality after small incision lenticule extraction (SMILE) is based on the single factor,such as scattering,diffraction or aberration,and all of them are not comprehensive and objective methods.Modulation transfer function (MTF) and Strehl ratio (ST) are novel parameters of corneal optical quality,which can be used to assess the optical quality comprehensively.Objective This study was to evaluate the change of MTF and SR under the photopic and scotopic environment (3 mm and 6 mm pupil size,respectively) after SMILE procedure.Methods The study protocol was approved by Ethic Committee of Tianjin Eye Hospital,and written informed consent was obtained from each patient before any medical procedure.A series cases-observational study with self-control design was carried out.Sixty-three eyes of 32 myopia or myopic astigmatism patients who underwent SMILE surgery in Tianjin Eye Hospital were included from December 2013 to March 2014.The uncorrected visual acuity (UCVA),best corrected visual acuity (BCVA) (LogMAR),the effective index (postoperative UCVA/preoperative BCVA) and refractive diopter were examined,and the MTF,SR and root mean square (RMS) on the anterior corneal surface were measured under the 3 mm and 6 mm pupil size at different spatial frequencies (10,20,30,40,50 and 60 c/d) by Sirius anterior analyzer before surgery and 1 week,1 month and 3 months after surgery,respectively.Results UCVA was ≥0.8 in 59,62 and 63 eyes in 1 week,1 month and 3 months after SMILE,with the percentage of 93.65％,98.41％ and 100％,and the effective index was 1.104± 0.128,1.126±0.145 and 1.158±0.208,respectively.The refractive diopter was normal in the eyes at postoperative 3 months.The MTFs of various spatial frequencies on the vertical and horizontal meridian under the 3 mm pupil size after SMILE were significantly higher than those before SMILE,while under the 6 mm pupil size,the MTFs were higher only on vertical meridian and 10,20,30 and 40 e/d,and there were not significant differences on the horizontal meridian (all at P＜0.05).The SRs under the 3 mm and 6 mm pupil size showed increasing softly after surgery in comparison with before surgery,and the SRs were higher under the 3 mm pupil size than those under the 6 mm pupil size at various time points (all at P＜0.05).There were not significant differences in RMS among different time points under both 3 mm pupil size and 6 mm pupil size (3 mm pupil size:F =1.348,P =0.184;6 mm pupil size:F=1.990,P=0.137).Conclusions SMILE provides a great improvement in corneal optical quality for myopia or myopic astigmatism patients,which is more distinct in photopic condition than that in scotopic condition.
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Background The progenesis and development of dry eye is closely associated with the stability of tear-film.Dry eyes often show the visual disturbance.Therefore,to evaluate the stability of tear-film based on visual quality and explore the relevant dynamic vision change in dry eyes is of important significance.Objective The aim of this study was to evaluate the dynamic changes of objective scattering index (OSI),modulation transfer function cut off (MTF cut off),objective visual acuity (OVA) with tear-film in the patients with mild or moderate dry eye disease using Optical Quality Analysis System.Methods A clinical diagnosis test was performed.Forty-two eyes of 42 consecutive patients with mild or moderate dry eyes were included in Tianjin Eye Hospital from December 2013 to May 2014 based on ‘ The Clinical Diagnosis and Treatment Recommendations for Dry Eye from Consensus of Expert Advice in 2013’,and 29 normal eyes of age-and gender-matched 29 healthy volunteers were simultaneously included as the healthy control group.The dynamic retinal images under non-blinking condition during 15 seconds were recorded by OQAS-Ⅱ system,and the OSI,MTF cut off and OVA values at 0,5,10 and 15 seconds were obtained,and the differences of OSI,MTF cut off and OVA between 0 second and 15 seconds were calculated (△OSI,△MTF cut off,△OVA).The dynamic changes of △OSI,△MTF cut off and △OVA with time were evaluated.The sensitivity and specificity of △OSI,△MTF cut off and △OVA for the differential diagnosis of dry eyes were analyzed by receiver operating characteristic curve (ROC curve).Results The OSI values at 5,10 and 15 seconds in the mild or moderate dry eye group were significantly higher than those at 0 second or those in the healthy control group (all at P＜0.05),and the MTF cut off values and OVA values at 5,10 and 15 seconds in the mild or moderate dry eye group were significantly lower than those at 0 second or those in the healthy control group (all at P＜0.05).The △OSI,△MTF cut off and △OVA values were 1.03±1.53,(-8.37±9.64)c/d and-0.30±0.32 in the mild or moderate dry eye group,which were significantly higher than 0.06± 0.16,(-0.37 ± 5.27) c/d and-0.03 ± 0.18 in the healthy control group (t=4.10,-5.19,-5.28,all at P＜0.05).The area under ROC curve was 0.90,0.79 and 0.78 in △OSI,△MTF cut off and △OVA,respectively.The sensitivity and specificity of △OSI was 78.6％ and 93.1％ respectively at the diagnostic cut off of 0.3.Conclusions The optical quality parameters related with tear-film stability are gradually reduced with extending of time in mild or moderate dry eyes,but they are stable in healthy eyes.The detecting outcomes by OQAS-Ⅱ system can reflect the dynamic status of tear-film,and this method is of important clinical value for the differential diagnosis and optical quality evaluation in dry eyes.
ABSTRACT
Background The residual astigmatism following Toric intraocular lens (IOL) rotation have received much attention.However,the variation of the optical performance and the wavefront abrrveation with Toric IOL rotation are unclear.Objective The aim of this study was to evaluate the optical performance,wavefront abrrveation and residual diopter spherical and cylinder lens with Toric IOL rotation.Methods T3,T4 and T5 Toric IOLs of +22.0 D were placed in Hwey-Lan Liou model eye respectively,with the posterior surface flat on the X axis and steep on the Y axis.Corneal astigmatism model was established by mimicing the model eye with Toric IOL using Zemax optical software.Then the Toric IOLs were rotated 5° to 10° individually under the 4 mm pupil diameter and 550 nm monochromatic light,and the image performance and wavefront abrrveation were recorded with all conditions,including modulation transfer function (MTF),out-of-focus aberration,astigmatism aberration,coma,trefoil aberration and spherical aberration.The refractive error of spherical power and cylinder power were calculated.Results Corneal astigmatism was fully corrected when Toric IOLs in the middle,and the MTF curves were near in T3,T4,T5 Toric IOLs.The image performance was worse under the high spatial frequency with the increase of rotation degrees of Toric IOLs,showing the gradually low of MTF curves,especially T5 Toric IOL.No obvious changes was seen in coma,trefoil aberration and spherical aberration after rotation of Toric IOLs,while out-of-focus aberration,astigmatism aberration were obviously increased.In addition,residual astigmatism and spherical error increase with the rotation of Toric IOLs.Conclusions Toricl IOL rotation leads to increase of astigmatism and spherical refractive error but not high order aberration.