Modulation Transfer Function Area Research Articles

Beam-Shaping Extended Depth of Focus Intraocular Lens: Optical Assessment With Corneas of Increasing Spherical Aberration.

To assess the optical quality and halo formation of a beam-shaping extended depth-of-focus (EDOF) intraocular lens (IOL) (AcrySof IQ Vivity; Alcon Laboratories, Inc) with corneas of long-range spherical aberration (SA) such as those resulting from myopic laser ablations. The optical quality of the EDOF IOL and a reference monofocal IOL was evaluated with three corneas (A, B, and C, with SA =+0.135, +0.290, +0.540 µm, respectively, for a 5.15-mm pupil at the IOL plane). The through-focus modulation transfer function area (MTFa) curves were obtained between -5.00 and +2.00 diopters (D) defocus range. The halo was also assessed with the three corneas. Through-focus MTFa curves for a 4.5-mm IOL pupil showed a slight decrease in the maximum MTFa value provided by the EDOF IOL compared to the monofocal IOL in the three corneal situations (A: 45.9 vs 38.6 units; B: 41.1 vs 33.1 units, and C: 26.9 vs 23.8 units). For the 3.0-mm pupil, the EDOF IOL also had lower maximum MTFa than the monofocal IOL; however, the depth-of-focus increased to -2.20 D. With corneas A and B, the halo induced was of low energy with both IOLs. With cornea C, the EDOF IOL created a much larger and intense halo. The EDOF IOL provided a good distance optical performance and an extended range of focus of approximately 2.00 D, with a halo of low intensity when evaluated with a corneal SA similar to the one induced by a low to moderate myopic ablation. With a high myopic ablation, the halo induced would be of considerable size and energy. [J Refact Surg. 2023;39(2):95-102.].

Optical and Clinical Outcomes of an Enhanced Monofocal Intraocular Lens for High Hyperopia.

To evaluate the optical and clinical performance of an enhanced monofocal intraocular lens (IOL) (TECNIS Eyhance ICB00; Johnson & Johnson Vision) in patients with high hyperopia and a short axial length. Power mapping, wavefront analysis, and the through-focus modulation transfer function area (TF-MTFa) were measured in vitro for three IOL powers (10.00, 20.00, and 30.00 diopters [D]). The clinical study included 22 patients with an axial length of less than 22.5 mm. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity and binocular defocus curve were evaluated 6 months postoperatively. For the three IOL powers, the power mapping revealed an increase in positive power from the periphery to the center of the lens, providing an extra positive correction of 1.00 D for a 2-mm pupil size. The TF-MTFa curves showed only a peak of maximum MTFa at the distance focus. As the pupil size became smaller, there was a focus extension effect, providing an extended depth of focus of up to -1.50 D for a 2-mm pupil size. No significant dependency of the IOL base power on the power profile, wavefront, or optical quality was found. The clinical outcomes showed that all patients achieved a binocular CDVA of 0.1 logMAR or better. The mean visual acuity was better than 0.1 logMAR between +0.50 and -1.50 D of defocus. At a vergence of -2.00 D, the visual acuity was 0.11 ± 0.13 logMAR. The monofocal enhanced IOL provided good distance optical and visual quality and optimal visual acuity up to an intermediate-near vision distance of 50 to 40 cm in patients with high hyperopia and a short axial length. [J Refract Surg. 2022;38(9):572-579.].

Optical and Clinical Outcomes of an Extended Range of Vision Intraocular Lens.

To assess the in vitro optical quality and halo formation of the AcrySof IQ Vivity intraocular lens (IOL) (Alcon Laboratories, Inc) and to evaluate the clinical outcomes in patients who had bilateral implantation of this IOL. The optical quality was evaluated with the PMTF optical bench (Lambda-X). Through-focus modulation transfer function area (MTFa) curves between -5.00 and +2.00 diopters (D) were obtained for 3- and 4.5-mm pupil apertures. The halo was assessed in vitro with a test bench. The clinical study included 30 patients. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity and binocular defocus curve were evaluated 6 months postoperatively. The through-focus MTFa curve for the 4.5-mm pupil size showed only one peak at distance focus (38.4 units). For the 3-mm pupil size, the through-focus MTFa showed a lower peak of MTFa (28.9 units), located at -0.70 D, and an extended depth of focus up to -2.20 D. The halo formed was larger and more intense compared to a standard monofocal IOL. The clinical outcomes at 6 months revealed satisfactory visual acuity outcomes. All patients achieved a binocular CDVA of 0.1 logMAR or better. The mean visual acuity was better than 0.2 logMAR between +1.00 and -2.00 D of defocus. At a vergence of -2.50 D, the visual acuity was 0.31 ± 0.09 logMAR. The AcrySof IQ Vivity IOL provided good distance optical and visual quality and an extended range of focus of approximately 2.00 D, obtaining an optimal or functional visual acuity up to 50 to 40 cm. The halo formed was low intensity overall, but higher intensity than a monofocal IOL. [J Refract Surg. 2022;38(3):168-176.].

Temporal MTF evaluation of slow motion mode in mobile phones

While slow motion has become a standard feature in mainstream cell phones, a fast approach without relying on specific training datasets to assess slow motion video quality is not available. This manuscript proposes a fast and generalized no-reference objective metric based on temporal loss in modulation transfer function (MTF) to evaluate interpolated slow motion mode in mobile phones. First, a standard chart embodying slanted edges is used to capture a slow-motion video. Second, the edge spread function is extracted from a region of interest in individual slow motion frames. Third, the line spread functions and MTFs are calculated. Finally, reference and interpolated frames are identified. Sharpness loss in slow motion mode is quantified by the MTF area difference between minimum interpolated frame and reference frame MTF scores. The proposed approach is evaluated in simulated and experimentally captured slow motion videos. In experiments, slow-motion videos are captured by moving mobile phones mounted on a motorized linear stage apart from the test chart at a constant speed while keeping the test chart still. The proposed MTF scores of several mainstream cell phones are analyzed and compared.

Influence of Lenslet Configuration on Short-Term Visual Performance in Myopia Control Spectacle Lenses.

Purpose: This study aimed to evaluate short-term visual performance and optical quality of three different lenslet configurations on myopia control spectacle lenses.Materials and Methods: This study utilized a cross-over design. Distance visual acuity (VA) was measured in 50 myopic children; contrast sensitivity (CS) was measured in 36 myopic children. For each test, four spectacle lenses were evaluated in a random order: single-vision lens (SVL), lens with concentric rings of highly aspherical lenslets (HAL), lens with concentric rings of slightly aspherical lenslets (SAL), and lens with honeycomb configuration of spherical lenslets (HC). The modulation transfer function (MTF) and MTF area (MTFa) were used to determine optical quality. All tests were performed monocularly on the right eye with full correction.Results: HAL and SAL had larger MTFa than HC. VA in lenses with lenslets was significantly reduced compared to SVL (all p < 0.01). The reduction in VA was worse with HC than with SAL (p = 0.02) and HAL (p = 0.03); no effect of lenslet asphericity was found (p > 0.05). VA changes induced by lenslets showed no correlation with spherical equivalent refraction (all p > 0.05) and were weakly positively associated with age for SAL (r = 0.36, p = 0.01) and HC (r = 0.31, p = 0.03), but not for HAL (p = 0.30). The area under the log contrast sensitivity function (AULCSF) decreased with HAL and HC (all p < 0.001) in all illumination levels, and AULCSF with HAL was higher than that with HC in a photopic condition (1.17 ± 0.10 vs. 1.10 ± 0.13, p = 0.0004). The presence of lenslets did not affect CS at 3 cycles per degree (cpd) (p = 0.80). At 6 to 18 cpd, CS was significantly reduced by HAL and HC (all p < 0.05), but not SAL (p > 0.05) compared to SVL. At high spatial frequencies (>12 cpd) both SAL and HAL reduced CS significantly less than HC (all p < 0.01).Conclusion: Short-term visual performance was minimally impaired by looking through the lenslet structure of myopia control spectacle lenses. Concentric rings with aspherical lenslets had a significantly lower impact on both VA and CS than honeycomb configuration with spherical lenslets.

Method of microscopic imaging quality evaluation for board lens based on image parameter extraction of pinhole imaging

The modulation transfer function area (MTFA) of pinhole imaging and the MTFA relative variation ratio were used as the image surface parameters to quantitatively evaluate the microscopic imaging quality of the board lens. The light spot images located in different fields of view positions were obtained by using the pinhole imaging method to extract the modulation transfer function (MTF) of microscopic imaging system for board lens. The MTF mathematical model of lens system for board lens was established, and the MTFA in sagittal direction and meridian direction of edge field of view as well as the MTFA relative variation ratio were extracted to measure the microscopic imaging definition and image surface flatness of the measured lens. An experiment which was for measuring the board lens was carried out, and the microscopic imaging performance of the measured lens was quantitatively evaluated by using the proposed model and method. The results show that the Lens 2 can obtain the optimal microscopic imaging quality. The definition value of average power spectrum value (APSV), the gray mean gradient (GMG) and the laplacian summation (LS) were calculated respectively from the RGB bitmap images captured by these measured lens. The results show that the maximum parameter value of the APSV, GMG and LS of Lens 2 bitmap images is equal to 2.720 2, 17.024 4 and 94.921 2, respectively. At the same time, the bitmap images have the highest definition, which is consistent with the image surface parameter evaluation results, indicating that the proposed method used in the quantitative evaluation of microscopic imaging performance of board lens is accurate and effective, which is of great significance and engineering value to improve the online image probe design of the on-line visual ferrograph (OLVF).

Trifocality Achieved Through Polypseudophakia: Optical Quality and Light Loss Compared With a Single Trifocal Intraocular Lens.

To compare the optical performance of a twointraocular lens (IOL) system with that of a single capsular bag trifocal IOL. The two-IOL configuration of a monofocal RayOne Aspheric (Rayner Intraocular Lenses, Ltd) and a Sulcoflex Trifocal (Rayner Intraocular Lenses, Ltd) lens was compared in vitro with a single-lens option (RayOne Trifocal; Rayner Intraocular Lenses, Ltd). Two samples of each IOL model were studied with an optical metrology device. The optical quality was assessed using the area under the modulation transfer function (MTF). The impact of the supplementary lens mis-alignment on the MTF was tested. The light loss was also measured using a power meter. The two-IOL system produced three well-defined focal peaks comparable to those of the single lens. The MTF area of the single- and two-IOL configuration was, respectively, 22.5 and 20.7 at far, 16.4 and 15.4 at intermediate, and 14.9 for each configuration at near. A moderate decentration (up to 0.6 mm) had a minimal effect at intermediate and near on the supplementary lens MTF and no impact at far. A 5° tilt did not alter the MTF. The supplementary lens caused a 1.3% decrease in the optical power. The optical quality of the two-IOL system matched that of the single trifocal lens. A low-power supplementary IOL demonstrated high tolerance to misalignment and minimal light attenuation. The reversibility of the two-IOL approach may prove advantageous clinically. [J Refract Surg. 2020;36(9):570-577.].

Prediction of Visual Acuity and Contrast Sensitivity From Optical Simulations With Multifocal Intraocular Lenses.

To evaluate whether the prediction of visual performance based on the modulation transfer function area (MTFa) calculated with optical simulations is better correlated with visual acuity or contrast sensitivity obtained from defocus curves in patients implanted with a trifocal intraocular lens. Biometric eye data from 43 patients were used to create a mean eye model. A trifocal intraocular lens with a power obtained from the mean of the eyes implanted was incorporated into the model and the MTFa was calculated at the 11 defocus planes corresponding the 11 defocus locations measured in clinical practice. Simulations were conducted for pupil diameters of 2.5, 3, 3.5, and 4 mm. The MTFa correlation with visual acuity and contrast sensitivity was evaluated with the mean obtained after stratification of the clinical sample in four groups according to the previous pupil diameters. A linear model predicted the visual acuity and contrast sensitivity from MTFa with similar accuracy to nonlinear models, with R2 approximately 0.50 for visual acuity and approximately 0.42 for contrast sensitivity. A change of -0.01 logMAR and -0.02 logC was produced per unit of MTFa for visual acuity and contrast sensitivity, respectively. The mean difference between the visual acuity and contrast sensitivity obtained from the model and that measured in clinical practice was close to zero, but the bias varied depending on the defocus lens used, with higher deviation at -0.50 and -3.00 diopters of defocus. The MTFa obtained from optical simulations can be used to predict the mean visual acuity and contrast sensitivity consistently, with contrast sensitivity being more sensitive but with higher bias. [J Refract Surg. 2019;35(12):789-795.].

The Light Sword Lens and its usefulness for presbyopia reduction

AbstractPurposeTo evaluate the light sword lens ‐ an optical imaging element with extended depth of focus and angularly varying optical power for compensation of presbyopia.MethodsTwo novel light sword lenses were compared with commercially available intraocular lenses with the help of an optical system for intraocular lens testing certified according to the requirements of the International Organization for Standardization. The point spread function, the modulation transfer function for 50 lines/mm and the modulation transfer function area (MTFa) ratio were measured.ResultsThe light sword lenses exhibit a point spread function with a distinct maximum in the whole designed defocus range (0‐3D or 0‐4D). Contrast transfer ratio maintains higher values than 0.2 for defocus at least up to 2.5 D.ConclusionsUnlike the hitherto known solutions, the light sword lens permits to obtain high uniformity of the contrast transfer function and focusing within a range of defocus extending to the value of 3D. Therefore the proposed concept seems to be very promising for a development of presbyopia‐correcting intraocular lenses capable to restore a high quality functional vision substituting lost accommodation range.

In Vitro Evaluation of the Optical Quality of Segmental Refractive Multifocal Intraocular Lenses

In customised patient care, it is important to know the optical quality of different intraocular lenses (IOL). In this study, the optical quality of three segmental intraocular lenses were compared. The LENTIS Comfort LS-313 MF15, LENTIS Mplus X LS-313 MF30 and LENTIS High Add IOL LS-313 MF80 (Oculentis, Berlin, Germany) with a far power of + 21 D were analysed at the optical bench OptiSpheric IOL PRO (Trioptics GmbH, Wedel, Germany). The lenses have almost the same optical design but differ in the power of the near segment. The MF15 has a + 1.5 D addition to improve vision in intermediate distances, the MF30 has a near addition of + 3 D and the MF80 has a near addition of + 8 D. The modulation transfer function area (MTFa) and the Strehl ratio were examined for apertures of 3 mm (photopic) and 4.5 mm (mesopic). The MTFa values for the far focus are 33.34/30.80/51.53 (MF15/MF30/MF80) with an aperture of 3 mm and 25.38/22.52/43.15 for 4.5 mm. The MTFa values for the intermediate focus are 29.85/16.21/6.25 for a 3 mm aperture and 23.92/8.05/3.08 for 4.5 mm. The MTFa values for the near focus are 9.75/21.49/33.12 for an aperture of 3 mm and 4.95/22.70/31.68 for 4.5 mm. The Strehl ratio of the far focus is 0.34/0.30/0.52 for an aperture of 3 mm and 0.24/0.22/0.43 for 4.5 mm. For the intermediate focus, the Strehl ratio is 0.30/0.17/0.07 for an aperture of 3 mm and 0.24/0.08/0.03 for 4.5 mm. The Strehl ratio of the near focus is 0.10/0.22/0.33 for an aperture of 3 mm and 0.05/0.23/0.32 for 4.5 mm. We confirmed that the addition influences the optical quality of segmental bifocal intraocular lenses. For the far focus, the results of the MF15 and MF30 are similar. In intermediate distances, the MF15 achieves the best results. For near distances, the MF30 achieves better optical values than the MF15. The lens MF80, which has been designed for patients with maculopathies, achieves good results for far and near distances.

Assessing the binocular advantage in aided vision.

Advances in microsensors, microprocessors, and microdisplays are creating new opportunities for improving vision in degraded environments through the use of head-mounted displays. Initially, the cutting-edge technology used in these new displays will be expensive. Inevitably, the cost of providing the additional sensor and processing required to support binocularity brings the value of binocularity into question. Several assessments comparing binocular, binocular, and monocular head-mounted displays for aided vision have concluded that the additional performance, if any, provided by binocular head-mounted displays does not justify the cost. The selection of a biocular [corrected] display for use in the F-35 is a current example of this recurring decision process. It is possible that the human binocularity advantage does not carry over to the aided vision application, but more likely the experimental approaches used in the past have been too coarse to measure its subtle but important benefits. Evaluating the value of binocularity in aided vision applications requires an understanding of the characteristics of both human vision and head-mounted displays. With this understanding, the value of binocularity in aided vision can be estimated and experimental evidence can be collected to confirm or reject the presumed binocular advantage, enabling improved decisions in aided vision system design. This paper describes four computational approaches-geometry of stereopsis, modulation transfer function area for stereopsis, probability summation, and binocular summation-that may be useful in quantifying the advantage of binocularity in aided vision.

Numerical Simulation of the Modulation Transfer Function in HgCdTe Detector Arrays

In this work, we develop a method for simulating the modulation transfer function (MTF) of infrared detector arrays, which is based on numerical evaluation of the detector physics. The finite-difference time-domain and finite element methods are used to solve the electromagnetic and electrical equations for the device, respectively. We show how the total MTF can be deconvolved to examine the effects of specific physical processes. We introduce the MTF area difference and use it to quantify the effectiveness of several crosstalk mitigation techniques in improving the system MTF. We then apply our simulation methods to two-thirds generation mercury cadmium telluride (HgCdTe) detector architectures. The methodology is general, can be implemented with commercially available software, has experimentally realizable analogs, and is extendable to other material systems and device designs.

Peripheral optical quality and myopia progression in children

To investigate the peripheral optical quality and its relationship with axial elongation, myopic progression in Japanese children. Twenty-nine Japanese children, ages 10 to 12 years old, with baseline refraction from +0.75 D to -5.5 D, were included and followed for 9 months. The central and peripheral point spread functions (PSFs; 0°, 10°, 20°, 30° nasally) were obtained at 0.25 D steps around ±2.5 D of best-focus PSF (BF-PSF) using double-pass PSF system. Modulation transfer function (MTF) area of the BF-PSF was calculated from BF-PSF to represent the peripheral optical quality. Relative peripheral defocus (RPD), the refraction of anterior/posterior focal lines, MTF area, and their correlations with myopia progression were analyzed. The average refractive change in 9 months was -0.5 ± 0.8 D. The change in axial length was significantly positively correlated with the amount of myopic progression (P = 0.0058) and RPD (P = 0.0007, 0.0036 and 0.0040, at 10°, 20°, 30° respectively) at the initial visit, but did not correlate with the peripheral MTF area. Myopic progression of more than 0.5 D with axial elongation was observed in seven children (MP group). The RPDs at 20° and 30° in the MP group were significantly more hyperopic than in the non-MP group (P = 0.002 and 0.007), whereas there was no significant difference in axial length, and central and peripheral MTF area between the MP and non-MP groups. MP group had more hyperopic focal lines compared with non-MP group at 20° and 30°. These results suggest that the progression of axial myopia in children is associated with hyperopic RPD and refraction of focal lines, not with peripheral optical quality.

Astigmatism correction with toric intraocular lenses: wavefront aberrometry and quality of life

Background/aimTo evaluate wavefront aberrations and subjective quality of life after toric intraocular lens (TIOL) implantation.MethodsThree groups of subjects who underwent unilateral cataract surgery with intraocular lens (IOL) implantation were compared:...

Optimization of resolution and color reproduction by controlling luminance and contrast levels of a liquid-crystal display monitor

The image quality of a color liquid-crystal display monitor is studied by changing the contrast and the luminance levels. The resolution is assessed with modulation transfer function area (MTFA) that is measured at nine different combinations of the luminance and contrast. At these combinations, we measure the chromaticity coordinates and luminance of red-green-blue channels as a function of the digital-analog convert value. We analyze the relations among MTFA value, constant-channel chromaticity, color gamut, and maximum luminance of a white pattern. From the results, the combination of levels is found that provides both high resolution and good color reproduction.

Image Quality Determines Differences in Reading Performance and Perceived Image Quality with CRT and Hard-Copy Displays

The effects of physical image quality on reading and on perceived image quality from CRT and hard-copy (photograph) displays were studied. The results showed that as the image quality of a display increased, indicated by an increase in the value of the modulation transfer function area (MTFA), the reading speed and subjective image quality ratings increased. This change in reading speed and perceived image quality occurred similarly for both hard-copy and soft-copy conditions. If the image qualities of the displayed text are similar, hard-copy and soft-copy displays will yield equivalent reading speeds.

Image Quality Determines Differences in Reading Performance and Perceived Image Quality with CRT and Hard-Copy Displays

The effects of physical image quality on reading and on perceived image quality from CRT and hard copy displays (photographs) were studied. The results showed that as the image quality of a display increased, indicated by an increase in the value of the modulation transfer function area (MTFA), the reading speed and subjective image quality ratings increased. This change in reading speed and perceived image quality occurred similarly for both hard-copy and soft-copy conditions. If the image qualities of the displayed text are similar, hard-copy and soft-copy displays will yield equivalent reading speeds.

Prediction of effects of weather on image quality: preliminary results of model validation

Using the atmospheric modulation transfer function area (MTFA) as a single-valued numerical criterion for image quality horizontally near the ground propagated through the atmosphere, a statistical study of atmospheric imaging data accumulated over a three-year period has led to the determination of regression coefficients with which to quantitatively predict image quality as a function of wavelength, over the 400-1000- nm wavelength region, according to weather forecast. Utilization of this procedure is simple: one plugs in expected values for wind speed, air temperature, and relative humidity in the regression coefficient expression for MTFA. The larger the expected MTFA, the better the expected image quality. Two sets of regression coefficient data have been obtained, one each for desert and nondesert climates, corresponding to summer and winter data here. Preliminary experimentation over a different line of sight indicates that the accuracy of the prediction is fairly reliable.

FORTRAN algorithms for evaluating Fourier transforms of line spread functions.

FORTRAN IV algorithms are presented for calculating the modulation transfer function, the phase transfer function, the modulation transfer function area, an information transfer function, and the optimum frequency response as well as plotting the curves for these matrices. An important feature of the programs is an editing routine.

The Effect of Image Quality on Search for Static and Dynamic Targets: MTFA-Performance Correlations

This report contains the results of two experiments which investigated the effects of the quality of a televised image on eye movements and search-related measures. The first experimental search task involved having subjects perform an air-to-ground search during a simulated flight. The quality of the image presented was varied by either passing, low-pass filtering, or attenuating the video signal and by adding electrical white noise to the video signal. Low to moderate correlations between modulation transfer function area (MTFA) and performance measures generally indicated that as MTFA increases performance improves and fixation durations decrease. The search task of the second experiment consisted of having the subjects search for a designated letter or numeral across a televised picture of randomly positioned letters and numerals. The quality of the picture was varied by either passing, low-pass filtering, high-pass filtering, or attenuating the video signal and by adding electrical white noise to the video signal. Correlations between MTFA and performance measures indicated that increases in MTFA lead to decreases in search time and decreases in fixation duration.