Test Chart Research Articles

Titration vs. GC-MS Analysis to Determine the Factors Affecting the Esterification Activity of Candida rugosa Lipase Immobilized onto Celite

The activity of lipases to catalyze the synthesis of esters in a non-aqueous environment can be assessed by performing a simple esterification study. In such tests, titration of the remaining acid has been one of the most used methods to determine the reaction progress due to its simplicity. Nonetheless, the execution of the titration is not always as simple as it sounds. In this study, Candida rugosa lipase is immobilized onto celite matrix, and its esterification activity was evaluated by catalyzing the reaction between butanol and butyric acid. Among the factors affecting the esterification activity of the immobilized enzymes are celite:CRL ratio, buffer pH during immobilization, and post-immobilization drying time. The titration results were analyzed using factorial design, ANOVA test, and Pareto chart. Here, the ambiguity of the titration results is showcased. On the other hand, analyzing the esterification results using GC-MS allowed optimization of the immobilization method to be performed. Finally, factors affecting the activity of the immobilized enzyme can be better assessed when the esterification results were analyzed using GC-MS.

A Comparative Study of the Sensitivity and Specificity of the Ishihara Test With Various Displays

Visual colour differentiation in clinical research requires colour-competent (CC) participants. The Ishihara colour charts (ICC) have established themselves as the standard for CC screening of colour vision deficiencies (CVD). However, the extent to which the results can be compared with a presentation of the colour charts on a smartphone display (SD) is currently unknown. The aim of this in vitro study was to determine the sensitivity and specificity of the Ishihara colour deficiency test depending on the presentation mode. Dental students (female n = 28; male n = 10; mean age, 23.5 ± 2.65 years; median age, 23.0 ± 13.0 years) evaluated 25 Ishihara test plates on their SD (n = 38) and/or a calibrated monitor (HP monitor, 22-inch; n = 18). The median size of the SD was 6.0 inches. Datasets with more than 2 failed charts were scored. When the Ishihara test charts were presented on a PC screen, the sensitivity was 94.4% and the specificity was 82.4% (0 mistakes: n = 14, <3 failures: n = 3, 14 false answers: n = 1). On the SD, a sensitivity of 96.0% and a specificity of 94.7% were calculated (89.5% were correct; 4 participants [10.5%] made <3 errors; and 1 participant made 21 errors). No significant difference between display modi (PC vs SD) was evaluated (P > .05). The presentation of ICC on an SD is useful and can be used for the investigation of a possible CVD of large groups. Comparable results to data projection can be achieved with a high degree of certainty. For CVD screening of larger groups (eg, students in preclinical training as part of CC training), the presentation of ICC on the SD can be used. This research was able to demonstrate that the sensitivity and specificity of the usual presentation method (Ishihara's booklet or data projection) is comparable.

난시검사 시표의 자각적 인지도 비교 연구

난시검사 시표의 자각적 인지도 비교 연구

2-mm-thick large-area CdTe double-sided strip detectors for high-resolution spectroscopic imaging of X-ray and gamma-ray with depth-of-interaction sensing

We developed a 2-mm-thick CdTe double-sided strip detector (CdTe-DSD) with a 250μm strip pitch, which has high spatial resolution with a uniform large imaging area of 10 cm2 and high energy resolution with high detection efficiency in tens to hundreds keV. The detector can be employed in a wide variety of fields for quantitative observations of hard X-ray and soft gamma-ray with spectroscopic imaging, for example, space observation, nuclear medicine, and non-destructive elemental analysis. This detector is thicker than the 0.75-mm-thick one previously developed by a factor of ∼2.7, thus providing better detection efficiency for hard X-rays and soft gamma rays. The increased thickness could potentially enhance bias-induced polarization if we do not apply sufficient bias and if we do not operate at a low temperature, but the polarization is not evident in our detector when a high voltage of 500 V is applied to the CdTe diode and the temperature is maintained at −20 °C during one-day experiments. The “Depth Of Interaction” (DOI) dependence due to the CdTe diode’s poor carrier-transport property is also more significant, resulting in much DOI information while complicated detector responses such as charge sharings or low-energy tails that exacerbate the loss in the energy resolution.In this paper, we developed 2-mm-thick CdTe-DSDs, studied their response, and evaluated their energy resolution, spatial resolution, and uniformity. We also constructed a theoretical model to understand the detector response theoretically, resulting in reconstructing the DOI with an accuracy of 100 μm while estimating the carrier-transport property. First, we evaluated the energy resolution using 22Na, 133Ba, and 57Co reconstructing the DOI effect from the energy correlation on both the anode and cathode sides. We obtained an energy resolution of 4.3 keV (FWHM) at 356 keV. Second, we formulated a theoretical detector-response model that reproduced the experimental data. Using the model, we determined the mobility-lifetime products of carriers μτe,h=(4±1)×10−3,(1.15±0.05)×10−4 [cm2/V] with the space charge density of nsp=−6.0×1010 [1/cm−3] and then reconstructed the DOI with an accuracy of 100 μm. Finally, we evaluated the spatial resolution and demonstrated to resolve patterns of 250-μm-width slits with an X-ray test chart. We found no positional variation in the detector response. We realized the detector that has high energy resolution and high 3D spatial resolution with a uniform large imaging area.

Natural language processing and expert follow-up establishes tachycardia association with CDKL5 deficiency disorder

PurposeCDKL5 deficiency disorder (CDD) is a developmental and epileptic encephalopathy with multisystemic comorbidities. Cardiovascular involvement in CDD was shown in animal models but is yet poorly described in CDD cohorts. MethodsWe identified 38 individuals with genetically confirmed CDD through the Cleveland Clinic CDD specialty clinic and matched 190 individuals with non-genetic epilepsy to them as a comparison group. Natural language processing was applied to yield Human Phenotype Ontology (HPO) terms from medical records. We conducted HPO association testing and manual chart review to explore cardiovascular comorbidities associated with CDD. ResultsWe extracted 243,541 HPO terms from 30,512 medical encounters. Phenome-wide analysis confirmed well-established CDD phenotypes and identified association of tachycardia with CDD (Odds ratio 4.2, 95% confidence interval (CI) 1.75-9.93, Padj < .001). We found a 99.6-fold enrichment of supraventricular tachycardia (SVT) in CDD encounter notes (Padj < .001), which led to identification of 2 cases of fetal/neonatal onset SVT previously undescribed in CDD. Tachycardia in CDD individuals was associated with the presence of other autonomic symptoms (Odds ratio 5.63, 95% CI 1.08-40.3, P = .038). ConclusionCDD is associated with tachycardia, potentially including early-onset SVT. Alongside prospective validation studies, semiautomated genotype-phenotype analysis with matched controls is a scalable, rapid, and efficient approach for validating known and identifying novel phenotype associations.

Unilateral visual impairment: impact on binocular function of school children in rural communities of Saki-East, Southwest Nigeria

PurposeThis study was designed to determine the impact of unilateral visual impairment or blindness on binocular visual function in children. MethodsA multistage, cross-sectional study was conducted among primary and secondary school students in the Saki-East Local Government Area of Oyo State between May and July 2021. Unilateral visual impairment was defined as presenting visual acuity <+0.3 LogMAR. Stereopsis, contrast sensitivity and peripheral visual fields were assessed with the Titmus fly test chart, Mars Contrast sensitivity chart and Lister perimeter respectively. Chi-squared test and Logistic regression were performed to assess the association between the degree of unilateral visual impairment and the other independent variables. ResultsFifty-one of 3671 (1.4%) children had unilateral visual impairment or blindness. The mean age was 10.7 ± 3.6 years. Stereopsis was weak or absent in 38 (74.5%) participants, contrast sensitivity values were impaired in 50 (98%) participants, and 29 (61.7%) participants had constricted peripheral visual fields. The level of stereopsis of participants worsened with increasing severity of the unilateral visual impairment, and this was statistically significant (p < 0.001). ConclusionChildren with unilateral visual impairment had poor binocular function. This correlated with stereopsis, worse in participants with severe visual impairment.

High-resolution and high-sensitivity X-ray ptychographic coherent diffraction imaging using the CITIUS detector.

Ptychographic coherent diffraction imaging (PCDI) is a synchrotron X-ray microscopy technique that provides high spatial resolution and a wide field of view. To improve the performance of PCDI, the performance of the synchrotron radiation source and imaging detector should be improved. In this study, ptychographic diffraction pattern measurements using the CITIUS high-speed X-ray image detector and the corresponding image reconstruction are reported. X-rays with an energy of 6.5 keV were focused by total reflection focusing mirrors, and a flux of ∼2.6 × 1010 photons s-1 was obtained at the sample plane. Diffraction intensity data were collected at up to ∼250 Mcounts s-1 pixel-1 without saturation of the detector. Measurements of tantalum test charts and silica particles and the reconstruction of phase images were performed. A resolution of ∼10 nm and a phase sensitivity of ∼0.01 rad were obtained. The CITIUS detector can be applied to the PCDI observation of various samples using low-emittance synchrotron radiation sources and to the stability evaluation of light sources.

Evaluation of the spatial resolution of Gafchromic™ HD-V2 radiochromic film characterized by the modulation transfer function

The Modulation Transfer Function (MTF) characteristics of radiochromic film (RCF) dosimetry with optical systems were evaluated with an RCF, HD-V2, which is transferred with the line patterns of the resolution test chart. In the evaluation using a GT-X980 flatbed scanner, a high contrast spatial resolution with an MTF of ≥0.8 is limited to about 83.3 μm due to artifacts such as scattering of the HD-V2 transmitted light. To achieve high contrast at higher spatial frequencies, a test bench microdensitometer (TBMD) was developed, and its optical performance, dose equivalent response, and spatial resolution characteristics with MTF were evaluated. The TBMD had a minimum readout focal diameter of 13 μm, and its high contrast spatial resolution with an MTF of ≥0.8 is about 11.9 μm. The result that the optical density error increases with decreasing focal diameter in the TBMD supports our hypothesis that these errors are based on the non-uniformity of the shading and surface roughness of the HD-V2 active layer monomers.

Image Contrast and Spectral Transmission in Intraocular Lenses with Nd:YAG Pits

Purpose Neodymium yttrium aluminum garnet (Nd:YAG) laser capsulotomy is considered as safe and effective method in the treatment of posterior capsule opacification. Nevertheless, side effects are described. The incorrectly adjusted focus of the laser beam during the procedure can lead to so-called YAG-pits or YAG-shots. In this experimental study, we measured spectral transmission to evaluate the image contrast and analyze the impact of YAG-pits in intraocular lenses (IOL). Methods Acrylic, foldable, one-piece IOLs with 6.0 mm optic and different material properties were studied. These included: monofocal IOLs and enhanced monofocal IOLs with water content of 0.3%, 26.0%, and 4.0% and a refractive index of 1.49, 1.46, and 1.54, respectively. All measurements were done with new, unaltered IOLs and IOLs with YAG-pits. Damage was intentionally created, performing YAG-pits (n = 7) in the central zone (3.5 mm) using a photodisruption laser (2.0mJ). All laboratory measurements were repeated: These included surface topography characterization, United States Air Force (USAF) resolution test chart analysis, spectral transmittance measurements and through focus contrast measurement. Results Significant differences were found between the unaltered lenses and lenses with defects. The YAG-pits within the optic of the IOLs decreased the image contrast and spectral transmission and changed results of USAF test images at the focal position by 62%, 57% and 54%, respectively. In all IOLs a reduction of the relative intensity of total transmitted light was observed between 450 and 700 nm wavelength. Conclusion This experimental study confirmed that the IOL image performance deteriorates with YAG-pits. The total intensity of transmitted light or transmittance (without scattering) was reduced in the wavelength between 450 and 700 nm. The contrast was significantly reduced and USAF test targets showed much worse results compared to unmodified counterparts. There was no systematic difference between monofocal and enhanced monofocal lenses. Further experiments should investigate the effect of YAG-pits on diffractive IOLs.

Evaluation of a portable retinal imaging device: towards a comparative quantitative analysis for morphological measurements of retinal blood vessels.

This study investigated the possibility of using low-cost, handheld, retinal imaging devices for the automatic extraction of quantifiable measures of retinal blood vessels. Initially, the available handheld devices were compared using a Zeiss model eye incorporating a USAF resolution test chart to assess their optical properties. The only suitable camera of the five evaluated was the Horus DEC 200. This device was then subjected to a detailed evaluation in which images in human eyes taken from the handheld camera were compared in a quantitative analysis with those of the same eye from a Canon CR-DGi retinal desktop camera. We found that the Horus DEC 200 exhibited shortcomings in capturing images of human eyes by comparison with the Canon. More images were rejected as being unevaluable or suffering failures in automatic segmentation than with the Canon, and even after exclusion of affected images, the Horus yielded lower measurements of vessel density than the Canon. A number of issues affecting handheld cameras in general and some features of the Horus in particular have been identified that might contribute to the observed differences in performance. Some potential mitigations are discussed which might yield improvements in performance, thus potentially facilitating use of handheld retinal imaging devices for quantitative retinal microvascular measurements.

Enhancement Reinforcing Concrete Beams Using Polypropylene Cord-Knitted Bars

Currently, technical fabrics play a major role in many industries due to their multiple characteristics. The aim of this research was to utilize composite knitted bars to reinforce concrete beams. Six cord-knitted samples with two different polypropylene yarn counts (outer layer) and three different core materials were manufactured and immersed in a local epoxy material (Kemapoxy 150). Composite knitted bars were prepared in this way. Several tests were conducted for fabrics and knitted bar samples. All data were collected and analysed using two different tools: ANOVA test and radar chart area. Finally, three concrete beams with a varying number of cord-knitted bars (one bar, two bars and three bars) were produced. The results indicated that the differences in outer and core yarns for cord-knitted samples have a significant effect on several fabric and bar characteristics. The knitted bars with PP core yarn can be more beneficial for concrete that do does not require high stress, while the knitted bars using glass fibres and polypropylene (50% and 50% PE) as core materials are not appropriate for applications that require more flexibility and extensibility. Reinforced concrete beams were improved significantly with cord-knitted bars, taking into account the number of bars per area, which may cause the minimizing of flexure force through an increase in that number of bars per area.

Telemedical Support Using Smartphones for Spine Surgery in Low- and Middle-Income Countries.

Objective: Low- and middle-income countries (LMICs) face many challenges compared to industrialized nations, most notably in regard to the health care system. Patients often have to travel long distances to receive medical care with few reliable transportation mechanisms. In time-critical emergencies, this is a significant disadvantage. One specialty that is particularly affected by this is spine surgery. Within this field, traumatic injuries and acutely compressive pathologies are often time-critical. Increasing global networking capabilities through internet access offers the possibility for telemedical support in remote regions. Recently, high-performance cameras and processors became available in commercially available smartphones. Due to their wide availability and ease of use, this could provide a unique opportunity to offer telemedical support in LMICs. Methods: We conducted a feasibility study with a neurosurgical institution in east Africa. To ensure telemedical support, a commercially available smartphone was selected as the experimental hardware. Preoperatively, resolution, contrast, brightness, and color reproduction were assessed under theoretical conditions using a test chart. Intraoperatively, the image quality was assessed under different conditions. In the first step, the instrumentation table was displayed, and the mentor surgeon marked an instrument that the mentee surgeon should recognize correctly. In the next evaluation step, the surgical field was shown on film and the mentor surgeon marked an anatomical structure, and in the last evaluation step, the screen of the X-ray machine was captured, and the mentor surgeon again marked an anatomical structure. Subjective image quality was rated by two independent reviewers using the similar modified Likert scale as before on a scale of 1-5, with 1 indicating inadequate quality and 5 indicating excellent quality. Results: The image quality during the video calls was rated as sufficient overall. When evaluating the test charts, a quality of 97% ± 5 on average was found for the chart with the white background and a quality of 84% ± 5 on average for the chart with the black background. The color reproduction, the contrast, and the reproduction of brightness were rated excellent. Intraoperatively, the visualization of the instrument table was also rated excellent. Visualization of the operative site was rated 1.5 ± 0.5 on average and it was not possible to recognize relevant anatomical structures with the required confidence for surgical procedures. Image quality of the X-ray screen was rated 1.5 ± 0.9 on average. Conclusion: Current generation smartphones have high imaging performance, high computing power, and excellent connectivity. However, relevant anatomical structures during spine surgery procedures and on the X-ray screen in the operating room could not be identified with reliability to provide adequate surgical support. Nevertheless, our study showed the potential in smartphones supporting surgical procedures in LMICs, which could be helpful in other surgical fields.

Color Field Test Charts Vs HVFA In Detection Visual Field Defect Chronic Primary Glaucoma

Introduction: Glaucoma is syndrome consist of glaucomatous optic neuropathy, destruction of retinal nerve fiber layer, and typical visual field defects. Color field test charts (CFTC) is a simple and generous instrument used to detect central and paracentral scotoma in neuro-ophthalmology patient. Diagnostic study will perform in this research to compare visual field defects, detecting in chronic primary glaucoma patient between CFTC and HVFA SITA 10-2 as gold standard. Methods: Seventy two eyes from 50 patients with chronic primary glaucoma were examined visual acuity, funduscopy, color blindness, HVFA SITA 10-2 and CFTC. The results CFTC and HVFA were read by 2 ophthalmologists, and kappa agreement was done. Analysis was done to get sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, positive and negative likelihood ratio (LR). Result: The sensitivity of CFTC was 87.93%, specificity 85.71%, PPV 96.22%, NPV 63.16%, accuracy 87.5%, positive LR 6.15 and negative LR 0.14 in detecting visual field defect chronic primary glaucoma patient compared to HVFA SITA 10-2. Area Under Curve (AUC) in this research was 0.86 (95% CI 0.751-0.985, p&lt;0.001). Sensitivity, PPV, and accuracy was higher in MD &gt;-12dB compared to &lt;-12dB. There was strong correlation between it in location of defect (Cramer’s correlation; V=0.679, p&lt;0.001), although the large of visual field defect was significantly different between 2 instruments (p&lt;0.05). Conclusion: Color field test charts is comparable to HVFA SITA 10-2 in detecting visual field defect chronic primary glaucoma moderate and advance stage.

The Relationship Between Fall Risk, Balance, Posture, Strength, and Functional Parameters In Healthy Adults

The aim of this study is to examine the relationship between posture, fall risk, balance, strength, and functional parameters in healthy adults with exercise habits. In our study, 45 individuals over 55 years of age who came to Denizli province 1200 Asmalı Evler Healthy Aging Center were included. The quadriceps, hamstring, and hand grip strengths of the participants were measured with a dynamometer. Their balance was assessed with the functional reach test, their posture with the New York Posture Rating Chart, their fear of falling with the fall effectiveness scale (FES-1), their functionality with the 30-second sit-stand test, and their flexibility with the sit and reach test. According to the correlation analysis, moderate and high levels of significant positive correlation between hamstring strength and hand grip strength; A weak to moderate positive correlation was found between quadriceps strength and hand grip strength and functional reach test. A moderately significant negative correlation was found between quadriceps strength (right), functional reaching test and fall activity scale and sit and reach test, between quadriceps strength (left) and functional reaching test, waist/hip ratio, and New York Posture Rating Chart (p&amp;lt;0.05). There was no significant relationship between other parameters (p&amp;gt;0.05). These results support that hand grip strength is a valid method for estimating lower extremity strength among healthy adults at the group level. However, there is a weak relationship between balance and hand grip strength.

Complex aspherical singlet and doublet microoptics by grayscale 3D printing.

We demonstrate 3D printed aspherical singlet and doublet microoptical components by grayscale lithography and characterize and evaluate their excellent shape accuracy and optical performance. The typical two-photon polymerization (2PP) 3D printing process creates steps in the structure which is undesired for optical surfaces. We utilize two-photon grayscale lithography (2GL) to create step-free lenses. To showcase the 2GL process, the focusing ability of a spherical and aspherical singlet lens are compared. The surface deviations of the aspherical lens are minimized by an iterative design process and no distinct steps can be measured via confocal microscopy. We design, print, and optimize an air-spaced doublet lens with a diameter of 300 µm. After optimization, the residual shape deviation is less than 100 nm for the top lens and 20 nm for the bottom lens of the doublet. We examine the optical performance with an USAF 1951 resolution test chart to find a resolution of 645 lp/mm.

Visual acuity charts in the Russian Empire, the USSR and modern Russia

Visual acuity is the quantitative parameter of the visual system characterizing its functional spatial resolution. Special test charts are commonly used for visual acuity assessment. The development of foreign tests for visual acuity is comprehensively covered in the literature, while the history of improving visual acuity charts in modern Russia, the USSR, and in the territory of the Russian Empire is only considered fragmentarily. In particular, there are almost no mentions of D.A. Sivtsev's work on proper letter-signs selection, and of A.A. Kryukov's tests. The purpose of this article is to review the history of developing visual acuity assessment methods in the Russian Empire, the USSR and modern Russia. One of the first sets of tests for visual acuity assessment available in the Russian Empire was developed by A.A. Kryukov; it was republished several times, but some criticism of the test can be encountered in the literature of that period. Subsequently, a task of developing a more accurate method was presented, which was implemented in the form of several editions of the visual acuity charts by D.A. Sivtsev and S.S. Golovin. The authors put a lot of effort into selecting the letters for the most reliable results of visual acuity assessment, excluded some unsuccessful characters (Cyrillic letters 'Ж' and 'Ю') and changed the size levels of the chart (the lines corresponding to the visual acuity levels of 1.25 and 1.5 were substituted by 1.5 and 2.0). Around the same period, A. Holina's chart appeared in print, but due to its poor structure the chart did not gain popularity, although it had a number of advantages. The review also considers some modern tests: the RORBA chart (named after the authors Rosenbaum, Ovechkin, Roslyakov, Bershanskiy, Aizenshtat), the vanishing optotypes by S.A. Koskin et al., the three-bar optotypes by the Institute for Information Transmission Problems (IITP), and the "Quartet" optotypes. Despite a large number of options, the search for the best method of measuring visual acuity for various medical and scientific tasks continues.

Display Performance of X-ray Image Output from DICOM-embedded Printer to Paper-based Hard Copy Print: Comparison with X-ray Image on LCD

We have been using a paper-based hard copy print (paper print) system of X-ray images, in which digital imaging and communications in medicine (DICOM) data can be directly output on papers from medical imaging systems or from a picture archiving and communication system (PACS) server, and they are utilized as patient referral materials or for preoperative planning. The purpose of this study was to compare the display performance of X-ray images on the printed paper and that on the liquid crystal display (LCD). We measured contrast response to verify consistency of image appearance on both display systems. The contrast resolution was assessed by a CDRAD phantom. The spatial resolution was assessed by an X-ray test chart. The contrast response of the paper printer was not concordant with the grayscale standard display function (GSDF). The difference between the measured contrast response and the ideal GSDF on the paper was large in the high-density area. The low-contrast resolution on the paper was inferior to that on the LCD. The spatial resolving power on the paper was superior to that on the LCD. The display performance of the paper printer for X-ray images was clarified. X-ray images printed on the paper should be used carefully taking account of their characteristics of display performance.

Spectral Multiplexing of Fluorescent Endoscopy for Simultaneous Imaging with Multiple Fluorophores and Multiple Fields of View

Complex clinical procedures and small-animal research procedures can benefit from dual-site imaging provided by multiple endoscopic devices. Here, an endoscopic system is proposed which enables multiple fluorescence microendoscopes to be spectrally multiplexed on a single microscope base, enabling light sources and optical relays to be shared between endoscopes. The presented system is characterized for resolution using USAF-1951 resolution test charts and for modulation transfer function using the slanted edge method. Imaging is demonstrated both directly and with microendoscopes attached. Imaging of phantoms was demonstrated by targeting USAF charts and fiber tissues dyed for FITC and Texas Red fluorescence. Afterwards, simultaneous liver and kidney imaging was demonstrated in mice expressing mitochondrial Dendra2 and injected with Texas Red-dextran. The results indicate that the system achieves high channel isolation and submicron and subcellular resolution, with resolution limited by the endoscopic probe and by physiological movement during endoscopic imaging. Multi-channel microendoscopy provides a potentially low-cost means of simultaneous multiple endoscopic imaging during biological experiments, resulting in reduced animal harm and potentially increasing insight into temporal connections between connected biological systems.

Evaluating impact of Nd: YAG laser associated defects on optical quality of hydrophilic and hydrophobic intraocular lenses using visualization of light propagation and USAF test targets

BackgroundNeodymium:yttrium aluminum garnet (Nd:YAG) laser capsulotomy is a well-accepted, safe, and effective measure in the treatment of posterior capsule opacification. However, iatrogenic intraocular lens damage is a relatively common side effect that happens due to inappropriate focusing during the procedure. This experimental study analyzes the impact of YAG-pits to obtain qualitative information.MethodsAcrylic, monofocal hydrophilic and hydrophobic intraocular lenses (IOLs) with 6.0 mm optic and the with the same power (21D) were studied. First, all measurements were done with unmodified IOLs. Damage was intentionally created, performing YAG-pits (n = 5) in the central area of the lens optic (3.0 mm) using a photodisruption laser with the same energy level of 1.8 mJ. To simulate the cruciate pattern, the 5 defects were created in a cross shape within the 3.0 mm optical zone. Afterwards, all laboratory measurements were repeated: These included the United States Air Force (USAF) resolution test chart to study the imaging performance of the IOL, light field measurements to show the course of the rays behind the IOL and the modulation transfer function (MTF) measurements were analyzed.ResultsEvaluating USAF showed that unmodified lenses produced a sharper image. Damaged lenses led to a more blurred image and to the impression of a lower contrast with a kind of halo/glare effect. The light field measurement showed that YAG-pits led to a kind of dispersion and scattering effect, which was higher in hydrophobic IOLs. MTF showed a deterioration in damaged hydrophilic and hydrophobic IOLs, respectively.ConclusionOur experimental study confirms that YAG-pits can reduce imaging quality of intraocular lenses. These defects behave as a new Huygens source, distribute a spherical wave that additionally illuminate the background of the USAF target. It can be assumed that material properties of the IOL (water content, refractive index) play an important role and affect results. The impact level is strongly dependent on the number, size and position of YAG-pits within the optic. Limitation: Only monofocal IOLs have been investigated so far, further tests with various IOL optics have to follow. In addition, simulating the circular pattern of YAG capsulotomy is necessary.

Visual Acuity as a Measurement of Visual Function.

Visual acuity (VA) is a traditional measure of central visual function, particularly the ability of the eye to perceive details. In a clinical setting, standardized charts are commonly used to quickly assess VA. Namely, the Early Treatment of Diabetic Retinopathy Study (ETDRS) VA test chart is the gold standard for VA testing in the clinical setting. This chapter outlines the standard procedures associated with measuring VA.