subjective refraction simulator

No mydriatic or cycloplegic agents were used in this study. FOIA Retinal images with a dot pattern as chart. As we have demonstrated in the present paper for the specific case of the JCC test, this software can help to gain a deeper insight and to improve different refraction techniques. Moreover, it can help to gain a deeper insight and to improve existing refraction techniques and it can be used for simulated training. & Tools, See All Second, the influence on final subjective refraction of small variations between the 3 methods was minimized by a high myopization and detailed refinement with Jackson's cross-cylinder in the gold-standard protocol. No, Is the Subject Area "Computer software" applicable to this article? Results in some reports suggest that close-view instrument yields consistent bias toward over-minus or under-plus refraction compared with open-view instruments35 or subjective refraction. CL1 is a centre-near bifocal design contact lens with three rings: an external distance-vision (D) zone and a central near-vision (N) zone separated by a transition (Int) zone having +1.00 D for intermediate vision. Comparison of refractive assessment by wavefront aberrometry, autorefraction, and subjective refraction. It is an indispensible test for pediatric patients, and is helpful in non- or preverbal patientsor when an autorefractor is unavailable. Visual acuity and subjective refraction can be affected by several factors, including pupil size, ocular and general health, and changes in accommodation in the fixation state.28 The ability of different persons to discern dioptric differences varies from 0.12 D to 1.00 D.36. Firstly, in order to determine the orientation of the astigmatic compensation, the cross cylinder axes must be placed parallel to the axis of the compensation we are going to introduce. Before calculating phase functions Wlens (x,y) and WJCC (x,y), a conversion of the lenses powerfrom the virtual phoropters plane to the exit pupil plane [1]was carried out so as to compute all phase functions in the same plane. For this reason, we want to show for the first time what happens when a JCC test is performed on a multifocal contact lens wearer. As far as we know, this is the first work where, in the context of a JCC test, retinal images for different charts have been shown. And, even if I could recruit real patients to practice on, I always felt guilty subjecting them to a fumbling, 20 minute refraction.. Interferometric images representing the phase function corresponding to each JCC position are shown in Fig 5. The interexaminer reproducibility and agreement with the gold standard were estimated using the following statistical parameters: limits of agreement from Bland-Altman analysis, significance between differences (P value), and intraclass correlation coefficient (ICC). The amount of defocus (in diopters) is indicated at the top of the figure. Despite this improvement, the truth is that some real-life scenarios, such as the presence high-order aberrations, spectacle magnification or the decision dilemma during Jackson Cross Cylinder test, are not taken into account in these simulation tools. Differences between variables were obtained using the Student t test for normally distributed variables and the Wilcoxon signed-rank test for non-normally distributed variables. Sheedy etal.31 measured the interexaminer reproducibility of subjective refraction between 2 sessions and 2 operators; the 95% LoA for M, J0, and J45 was 0.66 to +0.52 D, 0.40 to 0.34 D, and 0.25 to 0.21 D, respectively. https://doi.org/10.1371/journal.pone.0150204.g002. For this reason, some authors suggest that a chart comprising a dot pattern is preferable [17]. Villegas, Prieto, and Artal have financial interests in Voptica SL. having different sizes. The low variability in subjective refraction values between examiners indicated the good reproducibility of the adaptive optics visual simulator, with results similar to or better than those in previous studies that used standard techniques. However, when the CLC is out of the retina it becomes impossible to reach a situation in which both images were equally blurred, so determining the optimum cylinder power becomes very difficult, and the final result depends clearly on the person who judges the images. Bennett J.R., Stalboerger G.M., Hodge D.O., Schornack M.M. The visual simulator performs objective measurements (wavefront aberrations and objective refraction), subjective refraction, and visual simulation of optical profiles. 1Laboratorio de ptica, Universidad de Murcia, Murcia, Spain, 2Departamento de Fsica, Universidad de Murcia, and Voptica SL, Murcia, Spain. Data Availability: All relevant data are within the paper and its Supporting Information files. Yes In both cases a cross-cylinder with 0.50D power and a dot pattern (angular size of 50 arc minutes) was used. There are studies in the literature regarding this effect [14] but it has never been included nor mentioned in the context of simulation of refraction methods. The simulation software interface allows the user to decide whether or not they want to use the JCC test, as well as to choose the specific power of the cross cylinder lens. PLOS ONE promises fair, rigorous peer review, Bethesda, MD 20894, Web Policies https://doi.org/10.1371/journal.pone.0150204.g007. Astigmatic dials used in subjective refraction process frequently lead to confusing answers by the patients. Services for Employers, head straight to the website to learn about the features and sign up, Personal Nevertheless, in its current form, this software also has some limitations that cannot be ignored. The results yielded by our virtual refraction software confirm the influence of JCC tests CLC position on the final compensation. https://doi.org/10.1371/journal.pone.0150204.g011. The retinoscopy simulator allows the user to neutralize retinoscopy reflexes, using either trial lenses or a refracting instrument. After graduating from Illinois College of Optometry (ICO), Dr. Zarwell completed fellowship training in refractive surgery management and anterior segment disease at Davis Duehr Dean Eye Care Specialists. The cylinder values and orientation were adjusted with the Jackson cross-cylinder in the gold-standard protocol, while cylinder values from Hartmann-Shack refraction were not changed in the visual-simulator protocol. Among these, one of the most widely-used is the automated refractor [1], which is usually employed in clinical practice as a starting point for subjective-refraction determination. Moreover, the software allows the user to select or modify each individual Zernike aberration coefficient, which is especially useful to assess the influence of a specific aberration upon retinal image quality. The results reveal this softwares usefulness to simulate the retinal image quality that a particular visual compensation provides. The Is the Subject Area "Eye lens" applicable to this article? This is because the measurements in the reproducibility analysis were performed by both examiners using the visual simulator while the agreement was estimated using different techniques. The mean differences were close to zero for all 3 vectors. Statistical analysis was performed using R Core Team software (2016, R Foundation for Statistical Computing). Guides, Calculators Sheedy etal.31 reported a repeatability (expressed as the 95% CI) between visit 1 and visit 2 of approximately 0.16 logMAR, similar to our findings of 0.12 logMAR for interexaminer reproducibility. Donnelly W.J., III, Pesudovs K., Marsack J.D., Sarver E.J., Applegate R.A. Quantifying scatter in Shack-Hartmann images to evaluate nuclear cataract. Moreover, young children or patients with mental disability or language difficulties can make the examiner-patient interaction more difficult. Todd Zarwell, OD has launched a new tool for students learning and practicing subjective refraction and retinoscopy on EyeScholar. The software includes a virtual phoropter to simulate the adding of spherical and cylindrical lenses in front of the eye and the possibility to flip and rotate a Jacksons Cross Cylinder lens. Individual differences were approximately 1 or below 1 line, with the 95% LoA ranging between 0.10 logMAR and +0.12 logMAR (CI, 0.10). (1), Where (x,y) are transverse coordinates in the eyes exit pupil plane, is the wavelength (587 nm) and WT(x,y) is the total phase: When I was in optometry school we had a limited amount of space and a limited amount of time in the practice lanes, which made it difficult to get the repetition needed to become proficient at refracting and retinoscopy, says Dr. Zarwell. Resources, Hiring Instruction Courses and Skills Transfer Labs, Program Participant and Faculty Guidelines, LEO Continuing Education Recognition Award, What Practices Are Saying About the Registry, Provider Enrollment, Chain and Ownership System (PECOS), Subspecialty/Specialized Interest Society Directory, Subspecialty/Specialized Interest Society Meetings, Minority Ophthalmology Mentoring Campaign, Global Programs and Resources for National Societies, Patient-Reported Outcomes with LASIK Symptoms and Satisfaction, Optic Nerve Head: Clinical Diagnosis of Glaucoma and Nonglaucomatous Diseases, Myopia Control Measures in the United States in 2021, Myopic Maculopathy Due to Pathologic Myopia, Myopia Treatment Using Gas-Permeable Orthokeratology Lenses, International Society of Refractive Surgery. In this context, the most commonly applied end-point is that known as maximum plus to best visual acuity. It was approved by the Ethics Committee, University of Murcia. The repeatability of measurement of the ocular components. Besides, if we compare images in Fig 7B and Fig 9B, we found that the image obtained with the CLC out of the retina is worse when the CCJ test is performed with a line of letters. https://doi.org/10.1371/journal.pone.0150204.g001. Previous empirical work by Sims [4] shows that equal blur cannot always be achieved and that there are many factors that could affect the final decision. The simulator allows adjustment of spherical power, cylinder power, and cylinder axis. Cross cylinder power was 0.50 D and pupil radius was 3 mm. Each contact lens phase profile is fed into the simulation software. For instance, if we examine P1s simulation in Fig 3 (top), we can see that with no astigmatism compensation (first image) there is a clear candidate for the sharpest line (i.e., the vertical line), and equality can be then clearly reached by adding a cylinder lens of -0.75 D @180. It allows an external examiner to judge retinal image quality at each step of the refraction processfrom the fogging technique [1,2] to the cylindrical component estimation and the final adjustment of the sphere. broad scope, and wide readership a perfect fit for your research every time. Citation: Perches S, Collados MV, Ares J (2016) Retinal Image Simulation of Subjective Refraction Techniques. In our study, there were no significant differences in refraction measurements between the visual simulator and the gold standard, showing that accommodation had no affect. Scheme of the procedure followed to generate the retinal image of a line of letters (0.20 logMAR). and transmitted securely. Dr. Zarwell acknowledges that a simulator has limitations for teaching clinical skills. Secondly, the PSF and the paraxial image of a given optotype O(x,y) are convoluted to obtain the retinal image (Im (x, y)). The https:// ensures that you are connecting to the First, a complete description of the software is provided. Each contact lens design has +2.00 D of add power and has been evaluated for an emmetropic and aberration-free eye. Conceived and designed the experiments: SP MVC JA. This study used 2 examination protocols, 1 using the VAO adaptive optics visual simulator (visual simulator) and 1 using a trial frame (gold standard). Pupil radius was 2 mm. Before Goss D.A., Grosvenor T. Reliability of refraction a literature review. All tutorials and simulators are available in plus or minus cylinder. Maeda N., Fujikado T., Kuroda T., Mihashi T., Hirohara Y., Nishida K., Watanabe H., Tano Y. Wavefront aberrations measured with Hartmann-Shack sensor in patients with keratoconus. Walline J.J., Kinney K.A., Zadnik K., Mutti D.O. The Shapiro-Wilk test was used to assess normality of all variables analyzed. using the gold standard (ICC=0.76), with no significant differences (P>.05) and a mean difference of 0.010.05 logMAR. A review of the intraexaminer and interexaminer reliability of conventional subjective refraction by Goss and Grosvenor34 found that 95% of the differences were within 0.50 D, similar to our outcomes of 98.0% for interexaminer reproducibility of the adaptive optics visual simulator and 93.4% for the agreement between the visual simulator and the gold standard. First, 3 consecutive objective refraction measurements from Hartmann-Shack images were taken using the visual simulator. Ive been developing this tutorial for over 5 years, and Im very proud of it, but Ill be the first to admit that there is no substitute for physically spinning dials and interacting with a real patient, he says. No, Is the Subject Area "Pupil" applicable to this article? (A) A typical Jacksons Cross Cylinder. At present, the determination of the refractive error of an eye is performed in 2 steps. A comparison of M values between the 2 protocols showed that 67.1% of the differences were within 0.25 D and 93.4% were within 0.50 D; in 6.6% of cases, the values differed by more than 0.50 D. All differences in cylinder powers were within 0.25 D. There was a high linear correlation between the CDVA measurements taken by examiner E.A.V. Statistical methods for assessing agreement between two methods of clinical measurement. https://doi.org/10.1371/journal.pone.0150204.g003. Interexaminer reproducibility for subjective refraction was excellent (ICC 0.96; P>.05), with low 95% confidence interval (CI) values for the power vectors M (spherical equivalent of the given refractive error), J0 (Jackson cross-cylinder, axes at 180 degrees and 90 degrees), and J45 (Jackson cross-cylinder, axes at 45 degrees and 135 degrees) (0.51 diopter [D], 0.14 D, and 0.14 D, respectively). Next, in order to determine the power of the astigmatic compensation, the cross cylinder axes must be at 45 with respect to the compensation axis previously obtained. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. In the visual-simulator protocol, visual acuities were measured using the organic LED inside the instrument, which was placed at infinity. They require a long room, at least 4m, to allow measurement of far vision with relaxed accommodation. In addition, you can develop the mental fortitude to handle individuals who just cant seem to give straightforward one or two responses (e.g. ); the results were used to assess interexaminer reproducibility of thesubjective refraction and visual acuity measurements. https://doi.org/10.1371/journal.pone.0150204.g010. The .gov means its official. Inclusion criteria were no current ocular pathology, no history of ocular surgery, and astigmatism less than 3.0 diopters (D). Overall, 70% of the differences were between 0.05 logMAR and 92% within 0.10 logMAR. Linear correlation between vector refraction power values obtained with the visual simulator and gold standard (M=spherical lens equal to the spherical equivalent of the given refractive error; J0=Jackson cross-cylinder, axes at 180 degrees and 90 degrees; J45=Jackson cross-cylinder, axes at 45 degrees and 135 degrees). Thus, all results given are right eyes and left eyes together. Concerning the correlation between the measurements by the 2 examiners taken with visual simulator, the best fitting line was very close to the line of equality for all refractive parameters, with high linear correlation coefficients (ICC >0.96) and no significant differences (P>.05) (Figure1). Pupil radius was 2 mm for both subjects. learn more about available opportunities - spaces are limited. All statistical tests were 2-tailed, and P values less than .05 were considered statistically significant. the dioptric midpoint between the anterior and posterior focal linesmust be positioned on the retina of the subject [17]. As shown in Fig 4A, the cross cylinder is a combination of two cylinders of equal power but opposite signs whose axes are perpendicular to each other. Cnovas C., Prieto P.M., Manzanera S., Mira A., Artal P. Hybrid adaptive-optics visual simulator. In both protocols, visual acuity was measured using tumbling E charts with 5 random letters per line and 0.10 logarithm of the minimum angle of resolution (logMAR) steps between lines up to 0.2 logMAR, following the same configuration of the Early Treatment Diabetic Retinopathy Study test. Main screen of the simulation softwares GUI. Participants using ocular drugs that could affect vision were excluded. Refraction techniques are devoted to find the most appropriate sphero-cylindrical lens prescription (either spectacles or contact lenses) to achieve the best visual quality possible based on the patients visual needs and on specific environmental factors. Optics Laboratory, University of Murcia, Murcia, Spain. The VAO adaptive optics visual simulator combines aberrometry and adaptive optics technology for the measurement of ocular aberrations and the correction or simulation of optical patterns.10, 11 The instrument is 89cm long, 36cm wide, and56cm high. Nevertheless, it is difficult for a practitioner to fit regular training into their daily schedule; for this reason, a variety of simulation programs have been developed for subjective-refraction learning [6,7]. Repeatability and validity of astigmatism measurements. MacKenzie26 evaluated the subjective refraction measurements of the same patient performed by 40 optometrists and found a 95% CI of 0.55 D for M and 0.17 D for J0 and J45. In this context, simulation software is a useful method to gain a deeper insight into the difficulties that they encounter. Subjective refraction and visual acuity measurements taken with the visual simulator were validated, showing a good interexaminer reproducibility and agreement with the gold-standard method. Where Weye(x,y) is the phase for the reduced schematic eye together with the patients aberrometry data, Wlens (x,y) represents the phase of the lens that we place in the virtual phoropter and WJCC (x,y) represents the JCC tests cross-cylinders. Interferometric images shown in the simulation software representing the phase function for each position of the Jacksons Cross-Cylinder (JCC). Piers P.A., Fernandez E.J., Manzanera S., Norrby S., Artal P. Adaptive optics simulation of intraocular lenses with modified spherical aberration. Yes Furthermore, there was no significant difference in the CDVA measured by the 2 examiners with the visual simulator (P>.05). Ms. Hervella is an employee of Voptica SL. No, Is the Subject Area "Vision" applicable to this article? The next section shows several application examples of this simulation software. Besides, the software helps us to highlight the influence of the specific pattern chosen as chart when the CLC is not placed exactly on the retina. Laboratorio de ptica, Departamento de Fsica, Universidad de Murcia, and Voptica SL, Murcia, Spain. The patient has to identify first the sharpest line and then the optometrist has to add cylindrical lenses of varying power oriented at a specific angle until all the radii appear equally clear. According to the manufacturer, the device measures subjective refraction quicker than a phoropter or trial frame.A In addition, this instrument can simulate any optical profile or design before refractive surgery using the subjective refraction as the baseline. The images on the left (i.e., the first one of each row) correspond to the simulated retinal image when only spherical compensation has been virtually added. ISO; Geneva, Switzerland: 1994. The 75% CI was below 0.39 D for all parameters. Affiliation This software has also been used to evaluate visual quality when the JCC test is performed in multifocal-contact-lens wearers. Figure2 shows the Bland-Altman graphs of the refractive power vectors; that is, the differences between the 2 examiners as a function of the interexaminer mean value, suggesting good reproducibility between the 2 examiners. Eighty-one percent of the differences in the SE (M) between examiners were within 0.25 D. Moreover, more than 98% were within 0.50 D, the limit often considered of clinical significance in clinical practice. This method allow us to compute the retinal image of a range of optotypes (line of letters, single letter, Snellen chart, astigmatic dial, etc.) Competing interests: The authors have declared that no competing interests exist. Check out our open positions! In our software we assume that the lenses we add by means of the virtual phoropter are thin lenses, which implies that SM can be computed using the following expression: Three corrected distance visual acuities (CDVAs) with the subjective refraction were also measured. Contrariwise, for P2, even though it is possible to identify the sharpest line (i.e., the horizontal line), it would not be easy for the subject to know which cylindrical lens power is best to reach sharpness equality. As can be inferred from Fig 8, again when the CLC lies on the retina it is easy to identify for which particular pair both images were equally blurred. Visual quality is better when the CLC is on the retina throughout the CCJ test, as happened when the CCJ test was performed with a dot pattern (Fig 7). Besides providing the retinal image, the software also computes various related visual metrics [8,9] (among them, Visual Strehls ratio) so as to have an objective criterion to evaluate retinal images. National Library of Medicine Then, in 1970, he indicated that this lens could also be used to obtain the correcting cylinder axis [16]. Both examiners were masked to each other's results. Seventy-six eyes of 38 volunteers were measured. At present, the trial-frame and phoropter procedures are the gold standard; thus, their measurements are accepted as reference values9 against which new devices and procedures should be validated. Subjective refraction is a widely-used approach to find the best sphero-cylindrical refractive compensation and is based on the patients response to one or several sequential tests [13]. These tutorials allow you to actively work with a virtual patient by presenting them with choices while you manipulate the controls on a simulated refracting instrument. In order to computer-generate retinal images, a reduced schematic eye [12] having a focal length of 22.4 mm and a refractive index of 1.33 is assumed as starting point. The software also offers the possibility to change pupil size (entrance pupil). As could be expected, CL2 does not provide good VA for intermediate vision (shaded zone), where VA goes up to 1 logMar (i.e., it falls down to 0.1 in a decimal scale). Guidelines, criteria, and rules of thumb for evaluating normed and standardized assessment instruments in psychology. Defocus curves for CL1 (black dots) and CL2 (red squares) multifocal contact lenses. Third, subjective refinement of both examiners and in both protocols was independent. The sample limits the degree of confidence.25 The sample size for the reproducibility and agreement measurements was the same: 76 eyes, so that the degree of confidence in the LoA was also the same: 16%. Discover a faster, simpler path to publishing in a high-quality journal. From the standard deviation (SD) of differences between measurements, 75% and 95% confidence intervals (CIs) were calculated by multiplying the SD by 1.15 and 1.96, respectively. Hastings G.D., Marsack J.D., Nguyen L.C., Cheng H., Applegate R.A. Is an objective refraction optimised using the visual Strehl ratio better than a subjective refraction? This distortion effect is due to spectacle magnification (SM) and refers to the change in an objects apparent size when a lens is placed in front of the eye [13]. Monocular refraction was performed using the visual simulator in both eyes and without cycloplegia. Finance, Download Media Received 2018 Jun 20; Revised 2018 Jul 31; Accepted 2018 Aug 4. PMC legacy view The mean age of the 20 men and 18 women was 34.6years13.7 (SD) (range 21 to 72years). Subjective refraction results using the adaptive optics visual simulator agreed with those of the gold standard and can be used as the baseline for visual simulation of any optical corneal profile or intraocular lens design for refractive surgery patients. The purpose of the tutorial is to give students the ability to learn these clinical skills at their own pace and to allow them to practice on many different types of patients. One of the optometrists (L.H.) sharing sensitive information, make sure youre on a federal The program virtually flips the cross cylinder when the appropriate picture is clicked. Letter-by-letter scoring was performed in which a score of 0.02 logMAR was given for every letter read correctly. In the present study, the 95% LoA were narrower (0.54 to 0.49 D, 0.15 to 0.12 D, and 0.13 to 0.14 D, respectively) than in previous works.31 Themean interexaminer difference in the M values with the adaptive optics visual simulator were lower (0.02 D) than that reported by Leinonen etal.28 for subjective conventional refraction (+0.05 D) and Bullimore etal.30 for automated subjective refraction (0.12 D). CL2 is a centre-near bifocal design contact lens with no intermediate-vision zone. Retinoscopy/autorefraction: which is the best starting point for a noncycloplegic refraction? Optical profiles or designs selected for a refractive surgery are not based on the previous visual performance of the patient. Refraction techniques make it possible to determine the most appropriate sphero-cylindrical lens prescription to achieve the best possible visual quality. Accuracy (Trueness and Precision) of Measurement Methods and Results. performed the gold-standard examination; the results were used to determine the agreement between the subjective refraction and visual acuity measurements and the visual-simulator measurements taken by the other optometrist (E.A.V.). Leinonen J., Laakkonen E., Laatikainen L. Repeatability (test-retest variability) of refractive error measurement in clinical settings. For the subject P1 (S1 Table), Fig 6 shows two different procedures: JCC test while maintaining the CLC on the retina (left column) and JCC test when the CLC is elsewhere (right column). In: Benjamin W.J., editor. McAlinden D., Khadka J., Pesudovs K. Statistical methods for conducting agreement (comparison of clinical tests) and precision (repeatability or reproducibility) studies in optometry and ophthalmology. (ISO 5725-1:1994). However, our agreement outcomes were similar to or better than those of earlier comparisons of other methods used to measure refraction. Regarding VS ratio, the values obtained with both designs are relatively high for far and near distances, but it is worth pointing out that CL1 provides better visual quality and higher VS for intermediate vision. Pesudovs K., Parker K.E., Cheng H., Applegate R.A. The mean manifest spherical refractive error was 0.942.26 D (range 5.00 to +4.50 D), and the mean cylinder was 0.570.53 D (range 2.25 to 0.00 D). In the gold-standard protocol, after the best sphere was identified, a Jackson cross-cylinder test was performed to refine the power and axis of the astigmatism in eyes with astigmatic objective refractions. In this paper, we present a novel simulation software that enables the examiner to calculate and evaluate retinal image quality at each step of the subjective refraction, starting from the patients aberrometry assessment [1]. EyeScholar offers digital tutorials on refraction and retinoscopy for optometry students, plus simulations of many different kinds of patientswho aren't your classmates! Part 1. Kit. Again, the cross cylinder flips and the patient has to compare the two blurred images and choose the best one. In the context of step-wise subjective refraction, Jacksons Cross-Cylinder (JCC) test is the main technique that is used to measure the power and axis of the cylindrical correction. These improvements will be addressed in future research studies in order to increase the quality of this simulation software. with the visual simulator and measurements taken by examiner L.H. Therefore, in order to improve their skills and to make the most of the technique the eye-care professional should train with many patients and over a wide range of situations. Test yourself until you've mastered the techniques. No, Is the Subject Area "Radii" applicable to this article? EyeScholar: A New Tool for Learning How to Refract. Finally, our findings suggest that the VAO adaptive optics visual simulator provides consistent and reproducible subjective refraction and that its measurements are comparable to those of the gold-standard technique in healthy eyes.

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