snellen to etdrs conversion

When using a LogMAR chart, visual acuity is scored with reference to the logarithm of the minimum angle of resolution, as the chart's name suggests. It is very TRUE: plus/minus Smart System Reg U.S. Pat. The Snellen chart, which dates back to 1862, is also commonly used to estimate visual acuity. 2014 Sep-Oct;3(5):277-85. doi: 10.1097/APO.0000000000000007. equivalent to 0.02 logmar (assuming 5 letters in a row in a chart), NA is assigned to strings such as "." However, eye is also variable (a dimension of your observation), and it can also be stored in a separate column. Since 1990, M&S Technologies has served eye care professionals. Most retrospective reviews convert Snellen visual acuity measurements obtained during routine clinic visits to logarithm of the minimum angle of resolution (logMAR) units so that statistical manipulations can be performed. Beck, Roy W, Pamela S Moke, Andrew H Turpin, Frederick L Ferris, John Paul SanGiovanni, Chris A Johnson, Eileen E Birch, et al.2003. A Computerized Method of Visual Acuity Testing. American Journal of Ophthalmology 135 (2). However, just as all original technology does, there came a point when the Snellen chart needed reform. 10.1016/s0002-9394 (02)01825-1 Internet Explorer). Am J Ophthalmol. <>/PageLabels 249 0 R>> Therefore, we recommend the following for data entry in excel. In 1982, the chart was renamed the ETDRS chart as it was recommended to be used in the Early Treatment Diabetic Retinopathy Study (note: the terms ETDRS chart and logMAR chart are not interchangeable logMAR is not a type of chart, but rather a term to describe visual acuity notation. in Snellen. The results of this study suggest that for both clinical and research purposes, both Snellen and ETDRS can be used interchangeably. convertVA returns a vector of three classes: One of snellen, snellendec, logmar, etdrs or quali. The findings suggest that caution must be taken when comparing clinical trial VA results with routine clinical outcomes. RVACC Visual Acuity Testing Procedures Manual Revised 2013-02-15.docx Page 7 of 12 Show a 20/800 letter . 2023 Jan 19;9:1100241. doi: 10.3389/fmed.2022.1100241. - https://doi.org/10.1167/iovs.05-0981, (No) light perception are converted following the suggestions by 8 0 obj Careers. - https://doi.org/10.1167/iovs.05-0981 Holladay, Jack T. 2004. Visual Acuity Measurements. Journal of Cataract and Refractive Surgery 30 (2): 28790. males. Qualitative visual acuity lower than counting fingers is assigned 0 test design: Snellen fractions increase/decrease only by lines. The "ETDRS" chart is another vision chart that is often used for ophthalmic studies as it is easy to convert the letters on this chart for statistical values to help better understand published results. Qualitative visual acuity entries any case allowed. 2023 M&S Technologies 5715 W. Howard Street, Niles, IL, 60714 USA In the clinical setting, there is still a mixed use of Snellen acuity charts and ETDRS acuity charts. To which Snellen notation to convert: "m", "dec" or "ft", how +/- entries are evaluated. Your message has been successfully sent to your colleague. Calling va() without specifying the to argument will simply clean the visual acuity entries - any notations will be accepted, no plausibility checks yet performed. https://doi.org/10.1097/iae.0b013e3181d87e04. convertVA returns a vector of three classes: One of snellen, snellendec, logmar, etdrs or quali. integer coding 0:1 and 1:2, right eye being the lower number. The Apple iPod Touch (Figure 2), communicating with the EVA PC via Wi-Fi, provides . ISSN 0950-222X (print), Using an excel spreadsheet to convert Snellen visual acuity to LogMAR visual acuity, https://doi.org/10.1038/s41433-020-0783-6, Three-dimensional heads-up system assisted pars plana vitrectomy and subretinal recombinant tissue plasminogen activator injection for submacular hemorrhage, Anatomical and functional outcomes of retinal detachment associated with nontraumatic giant retinal tears compared to simple rhegmatogenous retinal detachment, Stabilization of refractive error and associated factors following small incision phacoemulsification cataract surgery, Effect of time to operative repair within twenty-four hours on visual acuity outcomes for open globe injuries, Comment on: Conversion of Snellen visual acuity to LogMAR visual acuity. Bailey IL, Lovie JE (2013). Stephenie Tiew. ), logMAR and ETDRS. For access, try logging in If you are subscribed to this group and have noticed abuse, report abusive group. Chen FK, Agelis LE, Peh KK, Teong J, Wong EN. For entries with mixed notation, use va_mixed instead. The basic principle of tidy data is: one column for each dimension and one row for each observation. endobj "etdrs", "logmar" or "snellen" - 2023 Jan 30;59(2):263. doi: 10.3390/medicina59020263. stream any case allowed. For some more details see VA conversion. The etdrs values for NLP and PL are deliberately set at those values because Unable to load your collection due to an error, Unable to load your delegates due to an error. This is intended for integration into rmarkdown reports, or for easy copy / pasting. You can find with eye:::va_chart. The conversion of Snellen data to logMAR can also be misleading as the abstract and results sections of papers that use this process sometimes give the impression that data have been collected using logMAR charts suggesting the data are more reliable that they actually are. which_va(). <> unambiguous value to visual acuity, with non-arbitrary thresholds based on psychometric functions. https://doi.org/10.1016/s0002-9394(02)01825-1. 11 0 obj 4 5 The ETDRS charts are now considered as the most accurate and standard method of VA recording, . endobj Please try after some time. Publishers note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. If smallstep = TRUE, each snellen optotype will be considered CAS Conversion of Snellen visual acuity to LogMAR visual acuity. Must be atomic. [in press]. Outside of the U.S., eye doctors may use a logMAR visual scale or a similar scale to the Snellen visual chart in which they measure vision in . Cleans and converts visual acuity notations (classes) In the meantime, to ensure continued support, we are displaying the site without styles M]D_*zcP?VpON`7?44N]p+8arMa*\ x\M6/@}dh=-C%96%FdVD_?n\uBi^/.h:G`}}p:`D-5G 8!H#oRT~oR}'xHry176F{0#yx[iLL!jP"G%*/o$:a m71m]G?B&!M+_\L]/ZwKvw*/*5QRNEHc3WGk^.ST A linear relationship exists between true ETDRS letter scores, approxETDRS letter scores, and logMAR units. The ESV-3000 is the only large-format standardized ETDRS testing device. 1997;13:38891. 2006. Visual Acuities Hand Motion and Counting Fingers Can Be Quantified with the Freiburg Visual Acuity Test. Investigative Ophthalmology & Visual Science 47 (3): 123640. . The notation will be detected automatically and converted to the desired notation. Ovid Technologies (Wolters Kluwer Health): 104650. Plausibility checks are performed for the automatically or manually defined Ferris FL, Kassoff A, Bresnick GH, Bailey I. In this case, the argument var will be used to name the resulting variable. Off. Better just "VA", #> [1] "Id" "Eye" "FollowupDays" "BaselineAge", #> [5] "Gender" "VA_ETDRS_Letters" "InjectionNumber". ## automatic detection of VA notation and converting to logMAR by default, #> [1] "20/320" "20/80" "20/32" "20/70", ## And the decimal snellen notation, so much loved in Germany, ## Remove weird entries and implausible entries depending on the VA choice, #> From snellen. Thus, the authors said, the specific retinal disease state and extent of edema may play a role in the variability between the measurements. and it has internal reasons that make conversion easier. However, it may be noteworthy to mention the subtle distinction of periods and durations, which are an idiosyncrasy of time measurements and well explained in this thread. The cluster of optotypes as row space decreased would produce the crowding phenomenon, which has been shown to cause inaccurate acuity measurements. The formula to convert Snellen visual acuity measurements to approxETDRS letter scores is 85 + 50 x log (Snellen fraction), which may be rounded to the nearest letter. Bookshelf between Snellen (decimal, meter and feet), ETDRS, and logMAR. Conversion of Snellen visual acuity fractions to approxETDRS letter scores for the purpose of performing statistical manipulations provides more readily interpretable outcomes compared with the current strategy of converting Snellen visual acuity fractions to logMAR units. [1] Each line of the LogMAR chart comprises the same number of test letters (effectively standardizing the test across letter size); the letter size change from one line to the next is a constant ratio, as is the spacing between lines (making the chart easy to use at nonstandard viewing distances). [ 7 0 R] Please enable scripts and reload this page. ignoring plus/minus entries and just returning the increase/decrease Snellen fractions by lines. in very weird Snellen values that have no correspondence to common charts. https://doi.org/10.1038/s41433-020-0783-6, DOI: https://doi.org/10.1038/s41433-020-0783-6. (ETDRS) Chart uses a LogMAR design. Mean patient age was 62.8 years (range, 25-93 years), and there was a mean of 27.2 days between measurements. Firstly, each letter was scored using linear interpolation. doi: 10.1016/s0002-9394 (02)01825-1 Hand movements and counting fingers are converted following Schulze-Bonsel et al. A more intuitive approach is presented here which uses the conversion of Snellen visual acuity fractions to Early Treatment Diabetic Retinopathy Study (ETDRS) letter scores for statistical manipulations. Coney JM, Zubricky R, Sinha SB, Sonbolian N, Zhou L, Hull TP, Lewis SA, Miller DG, Novak MA, Pendergast SD, Pham H, Platt SM, Rao LJ, Schartman JP, Singerman LJ, Donkor R, Fink M, McCoy J, Karcher H. Int J Retina Vitreous. Proper method for calculating average visual acuity. The Snellen visual acuity (VA) chart is routinely used in clinical practice, while that developed in the Early Treatment Diabetes Retinopathy Study (ETDRS) is the gold standard for ophthalmic clinical trials. It is more user friendly, since it avoids decimal values and is more intuitive, since higher values indicate better vision. This notation has long been abandoned for the use of equivalent notations, where the numerator is standardized to a fixed value, regardless of the true viewing distance. Ferris proposed a method termed letter scoring to incorporate gained or missed letters [2]. if one of CF, HM, LP, PL, NLP, or NPL: Snellen fractions (meter/ feet) need to be entered as fraction with /. However, back-conversion should not be will force to evaluate from which notation to convert - Must be Schulze-Bonsel, Kilian, Nicolas Feltgen, Hermann Burau, Lutz Hansen, and Michael Bach. This, again, requires a certain format of names and codes - See Names and Codes. Snellen-Logmar Calculator. In the group of patients, the eyes with the lower visual acuity, and the right eyes of the healthy subjects, were . FALSE: Eye The formula to convert Snellen visual acuity measurements to approxETDRS letter scores is 85 + 50 log (Snellen fraction), which may be rounded to the nearest letter. Results: Clipboard, Search History, and several other advanced features are temporarily unavailable. National Vision Research Institute of Australia, Early Treatment Diabetic Retinopathy Study, "Reading aids for adults with low vision", https://en.wikipedia.org/w/index.php?title=LogMAR_chart&oldid=1135496931, LogMAR VA = 0.1 + LogMAR value of the best line read 0.02 X (number of optotypes read), LogMAR VA = LogMAR value of the best line read + 0.02 X (number of optotypes missed), This page was last edited on 25 January 2023, at 00:42. Again, good names and tidy data always help! Snellen to logMAR: logMAR = -1 * log10(snellen_frac) Snellen to ETDRS: ETDRS = 85 + 50 * log10(snellen_frac) Gregori et al.. ETDRS to logMAR: logMAR = -0.02 * etdrs + 1.7 Beck et al. doi: 10.1016/s0002-9394(02)01825-1, Hand movements and counting fingers are converted following Trabelsi O, Bouladi M, Ouertani A, Trabelsi A. Clin Ophthalmol. Qualitative visual acuity lower than counting fingers is assigned 0 Conversion from Snellen to Logmar | Print | The Snellen Chart, which traditionally has been used to measure visual acuity, is easily recognised as one of the hallmarks of the ophthalmologist's consulting room. your express consent. Mean Snellen VA was 0.40 logMAR (20/50 Snellen equivalent), and mean ETDRS measurement was 0.27 logMAR (20/40 Snellen equivalent). By default, numbers smaller than or equal to 12 will be real English, all other numbers will be numbers. No. The authors have no commercial or proprietary interest in any product or corporation mentioned in this article. <> Purpose: This is a simple function and should not require much explanation. As for myop and of course blink, a specific column naming is required for a reliable automatic detection of patient and eye column(s) ( see Names and codes). Although there seems to be no good statistical reason to convert Calculate from Logmar to Snellen. [6] The formula used in calculating the score is: Given that each line has 5 optotypes, the equivalent formula is: The LogMAR chart is designed to enable more accurate estimates of acuity as compared to other acuity charts (e.g., the Snellen chart). You can also decide to simply clean your VA vector with cleanVA(x). ISSN 0950-222X (print), https://doi.org/10.1038/s41433-021-01764-y, Comment on: Conversion of Snellen visual acuity to LogMAR visual acuity. This chart and VA conversion formulas are based on charts in Cleans and converts visual acuity notations (classes) Although kind of nice, blink is more a nerdy extra and is not likely to be used much. [1][3] They described their motivation for designing the LogMAR chart as follows: "We have designed a series of near vision charts in which the typeface, size progression, size range, number of words per row and spacings were chosen in an endeavour to achieve a standardization of the test task.". Efficacy of small-incision lenticule extraction surgery in high astigmatism: A meta-analysis. Trans Am Ophthalmol Soc. Zero LogMAR indicates standard vision, positive values indicates poor vision, and negative values indicates good vision. It uses an S3 generic under the hood with methods for atomic vectors, data frames, and lists of either atomic vectors or data frames. Beck et al. In 1862, Snellen used a fractional notation in which the numerator indicated the actual viewing distance. Snellen are unfortunately often entered with +/-, which is a violation of psychophysical methods designed to assign one (!) % Visual acuity is a vital outcome measure in determining efficacy of treatments and interventions in ophthalmology. Snellen visual acuity measurements were converted to approximate ETDRS (approxETDRS) letter scores for statistical manipulations and then converted back to Snellen equivalent fractions. eye works smoother with tidy data, and with good names (any package does, really!). If you have different codes, you can change the recognized strings with the eyestrings argument, which needs to be a list. The Bailey-Lovie chart was also designed to be scored in logMAR units, making it easier to convert results based upon various viewing distances. numeric (for logMAR), or integer (for ETDRS). the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in A solution would be to remove or simply rename the eye column and then let myop do the work. and JavaScript. A conversion to snellen gives a good gauge of how the visual Normal visual acuity (which is better than 1.0 (20/20) ) is represented by negative logMAR values. doi: 10.1016/s0002-9394 (02)01825-1 Hand movements and counting fingers are converted following Schulze-Bonsel et al. #> blink , #> Data , #> , #> 1 a right TE 21 11 0.88 0.80, #> 2 a left TE 31 11 0.88 0.80, #> 3 b right TE 22 12 0.86 0.78, #> 4 b left TE 32 12 0.86 0.78, #> 5 c right SLT 23 13 0.84 0.76, #> 6 c left TE 33 13 0.84 0.76, #> 7 d right SLT 24 14 0.82 0.74, #> 8 d left SLT 34 14 0.82 0.74, #> Count of patient and eyes , #> Counts , #> Visual acuity , #> Intraocular pressure , #> $IOP_eyes (right and left eyes), #> Warning: Data seems already myopic - no changes made. For this study, the authors assessed data from 12 prospective clinical trials conducted at a large urban retina practice in the United States. To obtain Must be atomic. entries equivalent to 0.02 logmar. Have a thought about this article? 2001;85:4326. - https://doi.org/10.1167/iovs.05-0981 Gregori et al.doi: 10.1097/iae.0b013e3181d87e04. However, you need to be very careful in those cases if resulting data frame is plausible. <> This will remove all entries that are certainly no VA. va() (and of course, its wrappers) cleans and converts visual acuity notations (classes) between Snellen (decimal, meter and feet), ETDRS, and logMAR. A Snellen score of 6/6 (20/20), indicating that an observer can resolve details as small as 1 minute of visual angle, corresponds to a LogMAR of 0 (since the base-10 logarithm of 1 is 0); a Snellen score of 6/12 (20/40), indicating an observer can resolve details as small as 2 minutes of visual angle, corresponds to a LogMAR of 0.3 (since the base-10 logarithm of 2 is near-approximately 0.3), and so on. You may search for similar articles that contain these same keywords or you may to maintaining your privacy and will not share your personal information without In the meantime, to ensure continued support, we are displaying the site without styles <> a specific range (0-100). Eye 34, 21482149 (2020). See Also visual acuity , Snellen , ETDRS , statistics , logMAR. As with eyes(), myop() requires a specific data format. 1, 35 The first 4 columns contain VA equivalents as they are currently understood, and the fifth column contains the expected 95% ETDRS CI for each Snellen . 18 0 obj Pesky visual acuity notations are now a matter of the past. VAwrapper, Letter Score logMAR Snellen Equivaent 0-3 1.70-1.64 <20/800 4 to 8 1.62-1.54 20/800 9 to 13 1.52-1.44 20/640 14 to 18 1.42-1.34 20/500 Indeed, in my experience R often needs eyes to be in a single column, with each other variable having their own dedicated column. notation for qualitative entries is simplified. Snellen visual acuity measurements were converted to approximate ETDRS (approxETDRS) letter scores for statistical manipulations and then converted back to Snellen equivalent fractions. Mean value for Snellen Visual Acuity was 0.043 and that of ETDRS was 0.02365 LogMAR. Christina Lim. We present an excel spreadsheet formula to convert Snellen visual acuity to logMAR acuity. P30 EY014801/EY/NEI NIH HHS/United States. Suprachoroidal injection of triamcinolone acetonide plus intravitreal bevacizumab in diabetic macular edema: a randomized pilot trial. This can compromise data quality and accuracy of outcomes. <> See also "VA classes", logMAR to ETDRS: logMAR rounded to the first digit and converted with a specific range (0-100). Tiew, S., Lim, C. & Sivagnanasithiyar, T. Using an excel spreadsheet to convert Snellen visual acuity to LogMAR visual acuity. The site is secure. <> doi: 10.1097/iae.0b013e3181d87e04, ETDRS to logMAR: logMAR = -0.02 * etdrs + 1.7 Real Life Multicenter Comparison of 24-Month Outcomes of Anti-VEGF Therapy in Diabetic Macular Edema in Turkey: Ranibizumab vs. Aflibercept vs. Ranibizumab-Aflibercept Switch. "etdrs", "logmar", "snellen" or "snellendec". <> The PubMed wordmark and PubMed logo are registered trademarks of the U.S. Department of Health and Human Services (HHS). Table: Different notations of visual acuity values as decimal values, Snellen fractions, MAR and LogMAR. ContentAdmin Dr. Hermann Snellen's chart standardized vision testing and established a reliable process of diagnosis in its time. VA classes Holladay et al.doi: 10.1016/j.jcrs.2004.01.014, Beck et al. The arguments id and eye arguments overrule the name guessing for the respective columns. Even more so, as the given conditions should work for charts with 4 or 5 optotypes in a line, and visual acuity is not always tested on such charts. They will be recoded to r and l, Myopization: The actual work is done with, All columns with an eye string at first position will be selected pivoted to two long colums (, Identification of the index of the VA and IOP columns, Character columns if they are not coding for Snellen fractions or qualitative visual acuity, Those with unique values in the range of the vector defined by the argument fct_level. It can be rear or front illuminated. "/". "etdrs", "logmar", "snellen" or "snellendec". VA cleaning Internet Explorer). This chapter explains how you can improve names and codes so that eye will work like a charm. Snellen fractions need to be entered with "/". Schulze-Bonsel et al. Description plausibility_methods, the VA chart are used. However, back-conversion should not be ISSN 1476-5454 (online) Out of convenience, data is often entered in a wide format: In eye research, there will be often two columns for the same variable, one column for each eye. Conversion directly from one cell of Snellen fraction into another cell without manipulation or re-formatting of the original Snellen fraction (Fig. The Snellen visual acuity notation was developed by Hermann Snellen in 1862, during the time of the Civil War. - https://doi.org/10.1167/iovs.05-0981, (No) light perception are converted following the suggestions by The World Health Organization established criteria for low vision using the LogMAR scale. A linear relationship exists . Switching to brolucizumab: injection intervals and visual, anatomical and safety outcomes at 12 and 18months in real-world eyes with neovascular age-related macular degeneration. The test-retest variability of the charts was similar, with the 95% tolerance limit for change being +/-0.14 logMAR for ETDRS, +/-0.16 for reduced logMAR and +/-0.18 for Snellen. Our data set consists of 100 patients who underwent corneal collagen cross linking. they are unlikely to happen by chance as a wrong entry (and as integers), 7 0 obj The cols argument takes a tidyselection. proposed the line scoring method [3]. An official website of the United States government. Trans Am Ophthalmol Soc. Thank you for visiting nature.com. eyes_to_string() parses the output of eyes into text under the hood. endobj The value of each letter was calculated by dividing. Read about tidyselection. You can get creative with your snellens. 8600 Rockville Pike Since there are 5 letters per line, the total score for a line on the LogMAR chart represents a change of 0.1 log units. 6 0 obj See names and codes If there is already a column called eye or eyes, myop will not make any changes - because the data is then already assumed to be in long format. Elsevier BV: 194205. back to Snellen, it is a very natural thing to eye specialists to think 10 0 obj The ESV-3000 is designed specifically for clinical trials where large-format ETDRS testing (up to 20/200) is performed at 4 meters. Visual Acuity Reporting in Clinical Research Publications. Notation for qualitative entries is simplified (NPL becomes NLP, PL becomes LP). eye is dedicated to facilitate ophthalmic research, providing convenient application programming interfaces (API) for common tasks: eye includes a visual acuity conversion chart. Could be etdrs, logmar, snellendec. Snellen fractions (meter/ feet) need to be entered as fraction with numeric (for logMAR), or integer (for ETDRS). ## will automatically detect VA class and convert to logMAR by default, ## snellen, mixed with categories. #> Unclear which is the eye column. PURPOSE: To develop a computerized method of visual acuity testing for clinical research as an alternative to the standard Early Treatment for Diabetic Retinopathy Study (ETDRS) testing protocol,. Plausibility checks are performed for the automatically or manually defined sharing sensitive information, make sure youre on a federal 13 0 obj It will remove duplicate rows, and pivot the eye variable to one column and generate a single column for each variable, thus shaping the data for specific types of analysis. see "Examples", ETDRS must be integer-equivalent between 0 and 100 (integer equivalent It will look for VA and for IOP columns and provide the summary stats for the entire cohort and for right and left eyes for each VA and IOP variable. Rosser et al. they are unlikely to happen by chance as a wrong entry (and as integers), Reference values for these are customizable and can be left as CF, HM, LP and NLP (Appendix S1). The same outcomes (in Snellen fractions) were obtained with statistical manipulation of either approxETDRS letter scores or logMAR conversions. and JavaScript. Provided by the Springer Nature SharedIt content-sharing initiative, Eye (Eye) Then the column names can consist of eye strings only. 11 Confusion 2. In ETDRS charts, the Sloan letters are used (Sloan letters are perfectly square approximately equally legible one from another), while the BaileyLovie chart used rectangular (5:4) letters based on the Transport typeface, as set out in British Standard 4274:1968.[1]. Gregori, Ninel Z MD*; Feuer, William MS*; Rosenfeld, Philip J MD, PhD*. may email you for journal alerts and information, but is committed & Tiew, S. Using an excel spreadsheet to convert Snellen visual acuity to LogMAR visual acuityfurther explanation. This chart is included in the package as va_chart. If smallstep = TRUE, each snellen optotype will be considered endobj ETDRS must be integer-equivalent between 0 and 100 (integer equivalent means, it can also be a character vector), snellendec must be greater than 0 and smaller or equal to 2, Qualitative must be either of PL, LP, NLP, NPL, HM, CF (any case allowed), Any element which is implausible / not recognized will be converted to NA. #> id eye surgery iop_preop iop_postop va_preop va_postop, #> , #> 1 a right TE 21 11 41 45, #> 2 a left TE 31 11 41 45, #> 3 b right TE 22 12 42 46, #> 4 b left TE 32 12 42 46, #> 5 c right SLT 23 13 43 47, #> 6 c left TE 33 13 43 47, #> 7 d right SLT 24 14 44 48, #> 8 d left SLT 34 14 44 48, #> id surgery r_iop_preop r_iop_postop r_va_preop r_va_postop l_iop_preop, #> , #> 1 a TE 21 11 41 45 31, #> 2 b TE 22 12 42 46 32, #> 3 c SLT 23 13 43 47 , #> 4 c TE 33, #> 5 d SLT 24 14 44 48 34. If a subject can read a line at 20 feet and the "normal" observer can see the same line at 40 feet, then the subject has 20/40 Snellen acuity.

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