When VA was assessed by subgroups, eyes with worse vision had a greater difference between Snellen and ETDRS scores: Eyes 20/25 or better were a mean +1.9 letters better on ETDRS testing, and eyes 20/160 or worse were a mean +12.6 letters better on ETDRS testing (p < .05 for both). This is based on the assumption of 5 optotypes in a row. This is less intuitive than other VA notations. 11 Confusion 2. sharing sensitive information, make sure youre on a federal Eyes were included if a Snellen VA measurement was performed at the visit preceding the initial trial screening and VA was better than counting fingers. You can also decide to simply clean your VA vector with cleanVA(x). Careers. Snellen to ETDRS: ETDRS = 85 + 50 * log10 (snellen_frac) doi: 10.1097/iae.0b013e3181d87e04 ETDRS to logMAR: logMAR = -0.02 * etdrs + 1.7 Beck et al. But remember to put the strings for right eyes first, or pass a named list. Ferris FL, Kassoff A, Bresnick GH, Bailey I. We analyzed `r eyestr(amd2)` gives: We analyzed 3357 eyes of 3357 patients We analyzed `r eyestr(head(amd2, 100))`gives: We analyzed eleven eyes of eleven patients We analyzed `r eyestr(amd2, english = "all")` gives: We analyzed three thousand three hundred and fifty-seven eyes of three thousand three hundred and fifty-seven patients `r eyestr(head(amd2, 100), caps = TRUE)` were analyzed gives: Eleven eyes of eleven patients were analyzed We analyzed `r eyestr(head(amd2, 100), english = "none")` gives: We analyzed 11 eyes of 11 patients. FALSE: Christina Lim. This, again, requires a certain format of names and codes - See Names and Codes. 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. ePd*D _@!(N|u!0!gL0F6?%='=N]baTcdCA?$wdEBjFOV{cP0 |1?28SjVH*5)y91M3z-wfr?X}wIt.,U3[,{x|.27w"FX`K K W;I D{c2drIDn?jokscrMjc-"Xv5Z3&p{-w/UnS200ue0 `8=e&"1w+8CE~2y'f%k>-$Ge;TGO^5EJ}bEBn>b%;-+k7, 6#:(ku(\EJcbCpsQu+1zhYmTGXLv"iQ=(6-Vc+)&RZ(Vd|FuiQM+EJ}bEj![XVU+1uY[(Vu+1+!E7\E=T@P[iTn'4]eQP'\]O[+#WFOIu >JI5)9Ejz1_h*:N7bg0ke rxn or "", "n/a" or " ". Trabelsi O, Bouladi M, Ouertani A, Trabelsi A. Clin Ophthalmol. 2010. Novel Method for Analyzing Snellen Visual Acuity Measurements. Retina 30 (7). eyes_to_string() parses the output of eyes into text under the hood. E.g., preop instead of pre_op, or simply VA instead of VA_ETDRS_Letters, Thanks to Hadley Wickham and all developers of the. The Snellen visual acuity notation was developed by Hermann Snellen in 1862, during the time of the Civil War. Plausibility checks are performed for the automatically or manually defined As with eyes(), myop() requires a specific data format. This overrides the smallstep argument. The VAS scale (VAS = Visual Acuity Score) serves the same purpose. unambiguous value to visual acuity, with non-arbitrary thresholds based on psychometric functions. Arguments to eyes_to_string are passed via : eyestr will create a string which you can paste into a report. Must be atomic. official website and that any information you provide is encrypted Trans Am Ophthalmol Soc. considered an exact science and any attempt to use formulas will result va_methods, 7 0 obj Plausibility checks are performed for the automatically or manually defined Internet Explorer). You can use recodeye for very convenient recoding. For access, try logging in If you are subscribed to this group and have noticed abuse, report abusive group. Value In this case, the argument var will be used to name the resulting variable. Donders diagnosed vision problems by asking people to look at a chart on a wall and tell him what they could see. Depending a lot on how the data was entered, the results could become quite surprising. 8 0 obj 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. set out to compare the variability between the two measurements of best-corrected visual acuity (BCVA). Other VA converter: See Also NhNxJ*6~+a2""7oPTpc$N0>6o?#',pzz\$B] 2c<NR#F6`+5a'I0w /5ap0EfQa\JMX"2-r$'I;mzL&!D .3aO*3aOI:?tHGdc %gLT"M?npz&~r=e`V1$%#2 The Apple iPod Touch (Figure 2), communicating with the EVA PC via Wi-Fi, provides . For counting eyes, eyes need to be coded in commonly used ways. 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. Eye 36, 1708 (2022). difficult to justify a "negative" letter score in a test which only has Suprachoroidal injection of triamcinolone acetonide plus intravitreal bevacizumab in diabetic macular edema: a randomized pilot trial. In 1862, Snellen used a fractional notation in which the numerator indicated the actual viewing distance. No. <. <> You can read the full text of this article if you: Keywords The ESV-3000 is designed specifically for clinical trials where large-format ETDRS testing (up to 20/200) is performed at 4 meters. The formula can be copied and paste into the subsequent cells in the logMAR column (column D) to facilitate bulk analysis of data. Contact Us and let us know. 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. endobj 11 Confusion 2. 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. Accessibility Visual acuity testing. For more information, please refer to our Privacy Policy. You can get creative with your snellens. For some more details see VA conversion. notation for qualitative entries is simplified. The letter size is described in LogMAR units where LogMAR 0.00 is equivalent to 6/6 (20/20) in snellen scale or 85 ETDRS letter Score. In the clinical setting, there is still a mixed use of Snellen acuity charts and ETDRS acuity charts. <> You can change the way numbers are converted to english with the english argument. It will be left in the package as such. Snellen "+/-" entries 2023 M&S Technologies 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. Vector with visual acuity entries. 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]. P30 EY014801/EY/NEI NIH HHS/United States. He was a colleague of Dr. Franciscus Donders. test design: Snellen fractions increase/decrease only by lines. Unable to load your collection due to an error, Unable to load your delegates due to an error. Logmar-Snellen Conversion Table. MeSH This may then result in a vector of "mixed" VA notations. Results: Mean Snellen VA was 0.40 logMAR (20/50 Snellen equivalent), and mean ETDRS measurement was 0.27 logMAR (20/40 Snellen equivalent). Character vectors will be omitted (and it should give a warning that it has done so). 18 0 obj Holladay, Jack T. 2004. Visual Acuity Measurements. Journal of Cataract and Refractive Surgery 30 (2): 28790. 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. Although there seems to be no good statistical reason to convert ETDRS charts (within about 2% of the letter size at each logMAR level). Snellen to ETDRS: ETDRS = 85 + 50 * log10 (snellen_frac) doi: 10.1097/iae.0b013e3181d87e04 ETDRS to logMAR: logMAR = -0.02 * etdrs + 1.7 Beck et al. entries equivalent to 0.02 logmar. Cleans and converts visual acuity notations (classes) ETDRS letter, in order to keep it as a measurement (not: NA). LogMAR charts have a number of advantages over Snellen charts and have become the gold standard method for assessing visual acuity. PubMedGoogle Scholar. 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. The https:// ensures that you are connecting to the ContentAdmin Dr. Hermann Snellen's chart standardized vision testing and established a reliable process of diagnosis in its time. 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. Therefore I decided to stop the work on it. You can get creative with your snellens. and it has internal reasons that make conversion easier. From the *Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida; and the Ophthalmology Service, Miami Veterans Affairs Medical Center, Miami, Florida. The development of a record logMAR visual acuity chart for use in routine clinical practice. Eye You can find with eye:::va_chart. You are using a browser version with limited support for CSS. Snellen visual acuity measurements were converted to approximate ETDRS (approxETDRS) letter scores for statistical manipulations and then converted back to Snellen equivalent fractions. Gregori et al.doi: 10.1097/iae.0b013e3181d87e04. (ETDRS) Chart uses a LogMAR design. doi: 10.1016/s0002-9394(02)01825-1, Hand movements and counting fingers are converted following Unauthorized use of these marks is strictly prohibited. By default, plus/minus entries are evaluated as intended by the The interconversion between Snellen visual acuity measurements, logMAR units, and approxETDRS letter scores was prepared in a tabular form for easy reference. Supported by an unrestricted grant from Research to Prevent Blindness, Inc. and National Eye Institute core center grant P30 EY014801 to the University of Miami. blink() is more than just a wrapper around myop(), eyes(), va() and reveal(). ## `eye` won't be able to recognize IOP and VA columns, ## But `eye` will fail to understand those variable names, #> eye surgery var mean sd n min max, #> 1 left SLT iop_preop 34.0 NA 1 34 34, #> 2 left SLT iop_postop 14.0 NA 1 14 14, #> 3 left SLT va_preop 44.0 NA 1 44 44, #> 4 left SLT va_postop 48.0 NA 1 48 48, #> 5 right SLT iop_preop 23.5 0.7 2 23 24, #> 6 right SLT iop_postop 13.5 0.7 2 13 14, #> 7 right SLT va_preop 43.5 0.7 2 43 44, #> 8 right SLT va_postop 47.5 0.7 2 47 48, #> 9 left TE iop_preop 32.0 1.0 3 31 33, #> 10 left TE iop_postop 12.0 1.0 3 11 13, #> 11 left TE va_preop 42.0 1.0 3 41 43, #> 12 left TE va_postop 46.0 1.0 3 45 47, #> 13 right TE iop_preop 21.5 0.7 2 21 22, #> 14 right TE iop_postop 11.5 0.7 2 11 12, #> 15 right TE va_preop 41.5 0.7 2 41 42, #> 16 right TE va_postop 45.5 0.7 2 45 46, ## If no second date given, the age today, ## If the second argument is specified, the age until then, https://doi.org/10.1016/s0002-9394(02)01825-1, https://doi.org/10.1097/iae.0b013e3181d87e04, https://doi.org/10.1016/j.jcrs.2004.01.014. Their revised chart included the same amount of letters on each line, a standardization of legibility, and equidistant rows, to name just a few adjustments. equivalent to 0.02 logmar (assuming 5 letters in a row in a chart), NA is assigned to strings such as "." Purpose: 2023 Feb 8;17:515-525. doi: 10.2147/OPTH.S400156. Visual acuity data must be standardized in a logMAR format to allow for statistical analysis [1]. The arguments id and eye arguments overrule the name guessing for the respective columns. increase/decrease Snellen fractions by lines. All Snellen and ETDRS VA measurements were converted to logMAR units for direct comparison, and the variability between measurements was calculated. endobj Prospective evaluation of visual acuity assessment: a comparison of snellen versus ETDRS charts in clinical practice (An AOS Thesis). ), logMAR and ETDRS. any case allowed. You can find with eye:::va_chart. Gregori et al.doi: 10.1097/iae.0b013e3181d87e04. Each letter has a score value of 0.02 log units. Any element which is implausible/ not recognized will be converted to NA. To obtain Therefore, Snellen matching the nearest ETDRS and logMAR value in and JavaScript. 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 ## Mildly messy data frame with several variables spread over two columns: ## the variable has not been exactly named, (but it is probably IOP data), ## you can specify the dimension with the var argument. [7], Recording visual acuity using the LogMAR chart, Low vision and blindness definition with LogMAR. . 9 0 obj The chart was developed at the National Vision Research Institute of Australia in 1976, and is designed to enable a more accurate estimate of acuity than do other charts (e.g., the Snellen chart). 2 0 obj It is not really intended to replace other awesome data exploration packages / functions such as skimr::skim, and it will likely remain focussed on summarizing numerical data only. If you have columns with VA or IOP that contain only 0 and 1 for example (which is unlikely, but not impossible), you can just set, Getting the new names based on the indices of the columns, Creating a vector of expected new names for the summary after myopization, Do not use numeric coding for eyes in column names, Separate eye and VA and IOP codes with underscores (bcva_l_preop, VA_r, left_va, IOP_re), Dont use underscores when you dont need to: Consider each section divided by an underscore as a relevant characteristic of your variable. Article Snellen Notation (logMAR to Snellen conversion for 65 letters): 20/50. a specific range (0-100). It is very In the meantime, to ensure continued support, we are displaying the site without styles Get new journal Tables of Contents sent right to your email inbox, NOVEL METHOD FOR ANALYZING SNELLEN VISUAL ACUITY MEASUREMENTS, Articles in PubMed by Ninel Z Gregori, MD, Articles in Google Scholar by Ninel Z Gregori, MD, Other articles in this journal by Ninel Z Gregori, MD, BACILLARY LAYER DETACHMENT: MULTIMODAL IMAGING AND HISTOLOGIC EVIDENCE OF A NOVEL OPTICAL COHERENCE TOMOGRAPHY TERMINOLOGY: Literature Review and Proposed Theory, GEOGRAPHIC ATROPHY INCIDENCE AND PROGRESSION AFTER INTRAVITREAL INJECTIONS OF ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR AGENTS FOR AGE-RELATED MACULAR DEGENERATION: A Meta-Analysis, CHOROIDAL INVOLVEMENT IN HEREDITARY TRANSTHYRETIN AMYLOIDOSIS PATIENTS, A NEW HEAVY SILICONE OIL (HWS 46-3000) USED AS A PROLONGED INTERNAL TAMPONADE AGENT IN COMPLICATED VITREORETINAL SURGERY: A Pilot Study, BIOCOMPATIBILITY OF BRILLIANT BLUE G IN A RAT MODEL OF SUBRETINAL INJECTION, Privacy Policy (Updated December 15, 2022). We successfully present an excel spreadsheet method to easily and efficiently convert Snellen visual acuity to LogMAR visual acuity. and JavaScript. It is more user friendly, since it avoids decimal values and is more intuitive, since higher values indicate better vision. J Refractive Surg. The value of each letter was calculated by dividing. 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 Calling va() without specifying the to argument will simply clean the visual acuity entries - any notations will be accepted, no plausibility checks yet performed. To help those who are using the standard Snellen chart in their practice and wish to convert it to LogMAR, we have produced 81 possible combinations of Snellen visual acuity and their true. Specific types of logMAR chart include the original Bailey-Lovie chart,[3] as well as the ETDRS charts, developed for the Early Treatment Diabetic Retinopathy Study. 13 0 obj You may be trying to access this site from a secured browser on the server. However, visual acuity measurements expressed as logMAR units are not intuitively interpretable by clinicians. will force to evaluate from which notation to convert - Must be Again, good names and tidy data always help! US: 877-225-6101 -- International: 00 1 847 763 0500, US Toll-Free: 877-225-6101 -- International: 00 1 847 763 0500, NEW, from M&S Technologies, the CTS 5.5 Ultra-High Resolution Display for use in ophthalmic researc, M&S Technologies Launches the Smart System Virtual Reality Headset Including Critical Eye Tracking, Dynamic Voice Recognition capability available for M&S Technologies Smart System 2 | 2020. the visual acuity chart (see section VA chart), Snellen to logMAR: logMAR = -1 * log10(snellen_frac), Snellen to ETDRS: ETDRS = 85 + 50 * log10(snellen_frac) acuity for the patients are. Notation for qualitative entries is simplified (NPL becomes NLP, PL becomes LP). Ovid Technologies (Wolters Kluwer Health): 104650. 8600 Rockville Pike Holladay et al.doi: 10.1016/j.jcrs.2004.01.014, Beck et al. [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.". 2020;43:21489. 2001;85:4326. Arguments You may search for similar articles that contain these same keywords or you may modify the keyword list to augment your search. Download Visual Acuity for macOS 10.9 or later and enjoy it on your Mac. See also "VA classes", logMAR to ETDRS: logMAR rounded to the first digit and converted with government site. HHS Vulnerability Disclosure, Help #> Specify eye column with "eye_col" argument, #> patid sex age avdays_induc ethnicity loaded time injgiven va regimen, #> , #> 1 id_1 m 60-69 28 se_asian TRUE 0 TRUE 0.30 ranibi, #> 2 id_1 m 60-69 28 se_asian TRUE 28 TRUE 0.30 ranibi, #> 3 id_1 m 60-69 28 se_asian TRUE 56 TRUE 0.30 ranibi, #> 4 id_1 m 60-69 28 se_asian TRUE 91 TRUE 0.40 ranibi, #> 5 id_1 m 60-69 28 se_asian TRUE 131 TRUE 0.46 ranibi, #> 6 id_1 m 60-69 28 se_asian TRUE 173 TRUE 0.40 ranibi, #> 7 id_1 m 60-69 28 se_asian TRUE 236 TRUE 0.50 ranibi, #> 8 id_1 m 60-69 28 se_asian TRUE 278 TRUE 0.50 ranibi, #> 9 id_1 m 60-69 28 se_asian TRUE 411 TRUE 0.60 ranibi, #> 10 id_1 m 60-69 28 se_asian TRUE 453 TRUE 0.54 ranibi, #> # with 118,245 more rows, and 1 more variable: pre2013 , #> [1] "name" "oculus" "eyepressure" "vision". entries equivalent to 0.02 logmar. 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. proposed the line scoring method [3]. Conclusion: The Bailey-Lovie chart was also designed to be scored in logMAR units, making it easier to convert results based upon various viewing distances. Mean patient age was 62.8 years (range, 25-93 years), and there was a mean of 27.2 days between measurements. 3,575,655. 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. Internet Explorer). 2023 Jan 27;23(1):40. doi: 10.1186/s12886-023-02790-y. "etdrs", "logmar", "snellen" or "snellendec". Charts with the Snellen E and the Landolt C (Precision Vision) which mimic the ETDRS charts were used to assess visual acuity. eye works smoother with tidy data, and with good names (any package does, really!). Because the standard testing . The name was chosen because its a contraction of eyes and strings and its a tiny bit easier to type than eyetxt. test design: Snellen fractions increase/decrease only by lines. In order to calculate with qualitative entries counting fingers, Trans Am Ophthalmol Soc. the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in difficult to justify a "negative" letter score in a test which only has Effect of letter separation on computerised visual acuity measurements: comparison with the gold standard Early Treatment Diabetic Retinopathy Study (ETDRS) chart. Rosser et al. Ophthalmic Physiol Opt. Schulze-Bonsel, Kilian, Nicolas Feltgen, Hermann Burau, Lutz Hansen, and Michael Bach. in very weird Snellen values that have no correspondence to common charts. 2017 Jun 1;135(6):651-653. doi: 10.1001/jamaophthalmol.2017.0932. & Tiew, S. Using an excel spreadsheet to convert Snellen visual acuity to LogMAR visual acuityfurther explanation. https://doi.org/10.1016/s0002-9394(02)01825-1. #> 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. endobj any case allowed. FALSE: vector of va class. Schulze-Bonsel et al. Usage The cluster of optotypes as row space decreased would produce the crowding phenomenon, which has been shown to cause inaccurate acuity measurements. This is a common misconception). We present an excel spreadsheet formula to convert Snellen visual acuity to logMAR acuity. 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. back to Snellen, it is a very natural thing to eye specialists to think 1982;94:916. This overrides the smallstep argument. 4 0 obj VAwrapper, "etdrs", "logmar" or "snellen" - eyes recognizes integer coding 0:1 and 1:2, with right being the lower number. Gregori, Ninel Z, William Feuer, and Philip J Rosenfeld. The findings suggest that caution must be taken when comparing clinical trial VA results with routine clinical outcomes. If you are not happy with the automatic column selection, you can manually select the VA and IOP columns with the arguments va_cols or iop_cols. numeric (for logMAR), or integer (for ETDRS). However, back-conversion should not be logMAR to ETDRS: logMAR rounded to the first digit and converted with the visual acuity chart (see section VA chart) Snellen to logMAR: logMAR = -1 * log10 (snellen_frac) Snellen to ETDRS: ETDRS = 85 + 50 * log10 (snellen_frac) 10.1097/iae.0b013e3181d87e04 ETDRS to logMAR: logMAR = -0.02 * etdrs + 1.7 Beck et al. However, back-conversion should not be convertVA returns a vector of three classes: One of snellen, snellendec, logmar, etdrs or quali. 17 0 obj in very weird Snellen values that have no correspondence to common charts. You can capitalise the first number with the caps argument. <> Both accept tidyselection. Stephenie Tiew. Bailey IL, Lovie JE (2013). 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. integer coding 0:1 and 1:2, right eye being the lower number. logMAR to ETDRS: logMAR rounded to the first digit and converted with the visual acuity chart (see section VA chart) Snellen to logMAR: logMAR = -1 * log10(snellen_frac) Snellen to ETDRS: ETDRS = 85 + 50 * log10(snellen_frac) doi: 10.1097/iae.0b013e3181d87e04 ETDRS to logMAR: logMAR = -0.02 * etdrs + 1.7 <> Schulze-Bonsel et al. You don't have permission to access this content. reveal() is basically a slightly complicated wrapper around mean(), sd(), length(), min() and max() (with na.rm = TRUE and length() counting only non-NA values). Would you like email updates of new search results? Read reviews, compare customer ratings, see screenshots and learn more about Visual Acuity. The notation will be detected automatically and converted to the desired notation. Off. Entries with mixed VA notations The user can specify the original VA notation, but va will check that and ignore the argument if implausible. Mean value for Snellen Visual Acuity was 0.043 and that of ETDRS was 0.02365 LogMAR. This is intended for integration into rmarkdown reports, or for easy copy / pasting. Anyone you share the following link with will be able to read this content: Sorry, a shareable link is not currently available for this article. [7] Blindness is defined as a best-corrected visual acuity worse than 1.3 LogMAR. Reference values for these are customizable and can be left as CF, HM, LP and NLP (Appendix S1). This can compromise data quality and accuracy of outcomes. The authors declare no competing interests. The Snellen chart, which dates back to 1862, is also commonly used to estimate visual acuity. To which Snellen notation to convert: "m", "dec" or "ft", how +/- entries are evaluated. [Repeatability and reliability of the visual acuity examination on logMAR ETDRS and Snellen chart].