A comparative evaluation of visual, refractive, and patient-reported outcomes of three diffractive trifocal intraocular lenses

@#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

True-false analysis reveals inherent flaws in multiple true-false tests

Background: Multiple true-false tests (MTF), a component of our assessment system, have consistently generated low scores and many failures. This was attributed to the negative marking scheme. However, no study was conducted to explore the issue further. Item analysis revealed that students omitted false options more frequently and answered them wrongly more frequently than true options. The aim of this study was to determine the performance discrepancy between true and false options of MTF tests and the reasons for such discrepancy and the poor performance of MTF in general.Methods: The student performance of past 7 years of year-3 medicine end-of-posting examinations was analysed. The item analysis reports of 23 MTF tests were used to determine the significance of the differences in omission rates, correct-answer rates and the discrimination index of true and false options.Results: There were statistically significant differences in the omission rates, correct-answer rates and discrimination index values of true and false options. This study revealed that the false options consistently let down student performance. Although negative marking could be partly blamed for the situation, no justification could be found for the use of false options to test knowledge.Conclusions: Some publications endorse MTF, but many highlight its drawbacks. The use of false options in MTF was seen as an inherent defect in this instrument. As viable alternatives like VSAQ and Constructed Response Tests are in the horizon, we conclude that MTF ought to be discarded as an assessment instrument.

Study on the Imaging Quality Evaluation of Aspheric Intraocular Lenses / 中国医疗器械杂志

The article is to study the objective evaluation method of the imaging quality of aspheric intraocular lens with different design concepts by establishing the model eye which is close to the actual corneal spherical aberration characteristics. Combined with the research data of corneal spherical aberration, the simulated cornea corresponding to Zernike c(4,0) coefficient 0.00 μm, 0.10 μm, 0.20 μm and 0.28 μm was established respectively. The optical quality of the measured simulated corneal lenses basically reached the theoretical design effect, and the deviation between the MTF value and the theoretical design value was equivalent to the MTF test repeatability. The establishment of model eye for artificial lens provides a research tool for the evaluation of aspheric intraocular lens imaging quality.

Objective Clinical Evaluation of Ocular Optical Instrument According to the Type of Lens Opacity

PURPOSE: To investigate the results using the OQAS and the Pentacam in cataract patients classified according to the type of lens opacity. METHODS: The present study included 124 eyes of 92 patients who had cataract surgery at Seoul St. Mary's Hospital from December 2011 to January 2012 and were classified into nuclear, cortical, and posterior subcapsular cataract patients. The lens opacity was determined with OSI, MTF, Strehl ratio, width 10%, width 50% and the opacity of Scheimpflug image by the OQAS and the Pentacam. Additionally, the correlation between subjective cataract classification and objective opacity value was analyzed. RESULTS: The nuclear cataract group showed a 6.40 +/- 2.41 OSI value and had high opacity. The cortical cataract group showed the highest MTF cut-off value (12.02 +/- 6.19 C/deg). When evaluating Pentacam results, the posterior subcapsular cataract group had the lowest average level of lens opacity (9.12 +/- 1.08) followed by in increasing order, the cortical cataract group (9.79 +/- 1.67) and the nuclear cataract group (11.08 +/- 1.84). The results were statistically significant (p < 0.001). The OSI value of the OQAS was significantly correlated with nuclear and posterior opacity (p = 0.049, p = 0.039, respectively) except cortical opacity (p = 0.781). MTF and nuclear opacity showed statistically significant correlation and the lens opacity of Pentacam was correlated with nuclear and posterior opacities. In cortical cataract with severe peripheral opacity, the cortical opacity showed significant correlation with Maximum. CONCLUSIONS: The OQAS and Pentacam results showed high correlation with the nuclear and posterior opacities which can be useful for cataract surgery.

Evaluation of Mean Glandular Dose and Modulation Transfer Function for Different Tube Potentials and Target-Filter Combinations in Computed Radiography Mammography

Background: Different target-filter combinations in computed radiography have different impacts on the dose and image quality in digital radiography. This study aims to evaluate the mean glandular dose (MGD) and modulation transfer function (MTF) of various target-filter combinations by investigating the signal intensities of X-ray beams. Methods: General Electric (GE) Senographe DMR Plus mammography unit was used for MGD and MTF evaluation. The measured MGD was compared with the dose reference level (DRL), whereas the MTF was evaluated using ImageJ 1.46o software. A modified Mammography Accreditation Phantom RMI 156 was exposed using different target-filter combinations of molybdenum-molybdenum (Mo-Mo), molybdenum-rhodium (Mo-Rh) and rhodium-rhodium (Rh-Rh) at two different tube voltages, 26 kV and 32 kV with 50 mAs. Results: In the MGD evaluations, all target-filters gave an MGD value of 0.05). Conclusions: Higher tube voltage and atomic number target-filter yield higher MGD values. However, the MTF is independent of the X-ray energy and the type of target-filter combinations used.

Changes in Optical Quality of Cataract Patients' Corrected Visual Acuity before and after Phacoemulsification

PURPOSE: To evaluate objectively the improvement level of a patient's visual function using the NEI-VFQ-25 questionnaire pre- and post-operatively and the OQAS results from the patient group who had the same corrected visual acuity pre- and post-operatively. METHODS: We examined and compared the NEI-VFQ-25 test, OSI, MTF cut-off, strehl ratio, OQAS, and width at 50% and 10% in 24 eyes of 24 patients who had cataract surgery between December 2011 and February 2012. The patients' corrected visual acuity in both eyes had no change (0.8 and 0.8) pre-operatively and 2 months post-operatively (1.0 and 1.0). RESULTS: The satisfaction level regarding the patients' visual function increased. The NEI-VFQ-25 test was 71.54 +/- 14.88 points pre-operatively and 85.70 +/- 6.17 points post-operatively. OSI decreased to 3.13 +/- 1.66 (OSI value) and 1.53 +/- 0.58 (OSI value), and MTF cut off value improved from 14.51 +/- 6.97 (C/deg) to 27.63 +/- 8.98 (C/deg). Strehl ratio was improved to 0.09 +/- 0.03 and 0.14 +/- 0.03, width at 50% improved to 8.44 +/- 3.73 and 4.52 +/- 1.90 and width at 10% improved to 35.30 +/- 15.22 and 18.04 +/- 8.87 pre- and post-operatively, respectively. CONCLUSIONS: The NEI-VFQ-25 test reflected the vision improvement in patients where after cataract surgery, determination of the visual function improvement only through vision would not be possible. In addition, the OQAS showed the quality of vision improved through quantified values.

Brain Activation in Response to Visually Evoked Sexual Arousal in Male-to-Female Transsexuals: 3.0 Tesla Functional Magnetic Resonance Imaging

OBJECTIVE: This study used functional magnetic resonance imaging (fMRI) to contrast the differential brain activation patterns in response to visual stimulation with both male and female erotic nude pictures in male-to-female (MTF) transsexuals who underwent a sex reassignment surgery. MATERIALS AND METHODS: A total of nine healthy MTF transsexuals after a sex reassignment surgery underwent fMRI on a 3.0 Tesla MR Scanner. The brain activation patterns were induced by visual stimulation with both male and female erotic nude pictures. RESULTS: The sex hormone levels of the postoperative MTF transsexuals were in the normal range of healthy heterosexual females. The brain areas, which were activated by viewing male nude pictures when compared with viewing female nude pictures, included predominantly the cerebellum, hippocampus, putamen, anterior cingulate gyrus, head of caudate nucleus, amygdala, midbrain, thalamus, insula, and body of caudate nucleus. On the other hand, brain activation induced by viewing female nude pictures was predominantly observed in the hypothalamus and the septal area. CONCLUSION: Our findings suggest that distinct brain activation patterns associated with visual sexual arousal in postoperative MTF transsexuals reflect their sexual orientation to males.

Signal and Noise Analysis of Indirect-Conversion Digital Radiography Detectors Using Linear-systems Transfer Theory / 의학물리

For the use of Indirect-conversion CMOS (complementary metal-oxide-semiconductor) detectors for digital x-ray radiography and their better designs, we have theoretically evaluated the spatial-frequency-dependent detective quantum efficiency (DQE) using the cascaded linear-systems transfer theory. In order to validate the developed model, the DQE was experimentally determined by the measured modulation-transfer function (MTF) and noise-power spectrum, and the estimated incident x-ray fluence under the mammography beam quality of W/Al. From the comparison between the theoretical and experimental DQEs, the overall tendencies were well agreed. Based on the developed model, we have investigated the DQEs values with respect to various design parameters of the CMOS x-ray detector such as phosphor quantum efficiency, Swank noise, photodiode quantum efficiency and the MTF of various scintillator screens. This theoretical approach is very useful tool for the understanding of the developed imaging systems as well as helpful for the better design or optimization for new development.

Comparison Study of Image Quality of Direct and Indirect Conversion Digital Mammography System / 의학물리

The purpose of this study is to comprehensively compare and evaluate the characteristics of image quality for digital mammography systems which use a direct and indirect conversion detector. Three key metrics of image quality were evaluated for the direct and indirect conversion detector, the modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE), which describe the resolution, noise, and signal to noise performance, respectively. DQE was calculated by using a edge phantom for MTF determination according to IEC 62220-1-2 regulation. The contrast to noise ratio (CNR) was evaluated according to guidelines offered by the Korean Institute for Accreditation of Medical Image (KIAMI). As a result, the higher MTF and DQE was measured with direct conversion detector compared to indirect conversion detector all over spatial frequency. When the average glandular dose (AGD) was the same, direct conversion detector showed higher CNR value. The direct conversion detector which has higher DQE value all over spatial frequency would provide the potential benefits for both improved image quality and lower patient dose in digital mammography system.