All told, 413 patients (773 eyes) met the inclusion criteria for this study. The authors declare no competing interests. BCVA endobj
<>
modify the keyword list to augment your search. Snellen decimal ETDRS Letters Snellen feet Snellen meter logMAR 2.00 100 20/10 6/3 -0.3 1.60 95 20/12.5 6/4 -0.2 1.25 90 20/16 6/5 -0.1 1.00 85 20/20 6/6 0 J Refractive Surg. All Snellen and ETDRS VA measurements were converted to logMAR units for direct comparison, and the variability between measurements was calculated. 2009;107:31124. You can also decide to simply clean your VA vector with cleanVA(x). 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. Kucukevcilioglu M, Yeilta YS, Durukan AH, Unlu N, Onen M, Alp MN, Kalayci D, Acar MA, Sekeroglu MA, Citirik M, Altintas AGK, Hazirolan D, Ozdal PC, Toklu Y, Bicer T, Ugurlu N, Budakoglu O, Yazar Z, Zeki NIU, Serdar K, Doguizi S, Erol YO, Atilgan CU, Yorgun MA, Soba DO, Berker N, Baskan C. Medicina (Kaunas). endobj
We present an excel spreadsheet formula to convert Snellen visual acuity to logMAR acuity. endobj
Have a thought about this article? 9 0 obj
Thus, the authors said, the specific retinal disease state and extent of edema may play a role in the variability between the measurements. 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. the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in To which class to convert. back to Snellen, it is a very natural thing to eye specialists to think VA conversion Vector with visual acuity entries. Using ANOVA, this difference between testing times was. VAwrapper, Must be atomic. You don't have permission to access this content. 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. Conversion directly from one cell of Snellen fraction into another cell without manipulation or re-formatting of the original Snellen fraction (Fig. Bailey IL, Lovie JE (2013). The etdrs values for NLP and PL are deliberately set at those values because 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). #> 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. Snellen visual acuity measurements were converted to approximate ETDRS (approxETDRS) letter scores for statistical manipulations and then converted back to Snellen equivalent fractions. Outcome measures included absolute VA and VA variability among disease states. "/". Snellen acuity is given in terms of a Snellen fraction S, which is defined as Typical testing distances for the Snellen chart are 20 feet and 6 meters. Plausibility checks are performed for the automatically or manually defined Results: A linear relationship exists between true ETDRS letter scores, approxETDRS letter scores, and logMAR units. Eye notation. ## If the dimension is already part of the column names, this is not necessary. LogMAR charts have a number of advantages over Snellen charts and have become the gold standard method for assessing visual acuity. In the era of big data, there needs to be an efficient way of tidying up data to facilitate analysis. 8600 Rockville Pike Eye. 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. acuity for the patients are. Mean patient age was 62.8 years (range, 25-93 years), and there was a mean of 27.2 days between measurements. ## if you only want to rename one or a few columns: #> [1] "patID" "oculus" "eyepressure" "VA", ## information on the tested dimension is included ("iop"), ## VA and eye strings are separated by underscores, #> [1] "id" "surgery_right" "surgery_left" "iop_r_preop", #> [5] "iop_r_postop" "iop_l_preop" "iop_l_postop" "va_r_preop", #> [9] "va_r_postop" "va_l_preop" "va_l_postop", ## Id and Eye are common names, there are no spaces, ## VA is separated from the rest with an underscore, ## There is an unnecessary underscore (etdrs are always letters). Accepted VA formats / Plausibility checks ETDRS charts (within about 2% of the letter size at each logMAR level). considered an exact science and any attempt to use formulas will result PubMed Central The PubMed wordmark and PubMed logo are registered trademarks of the U.S. Department of Health and Human Services (HHS). Gregori et al.doi: 10.1097/iae.0b013e3181d87e04. There is basically a nearly infinite amount of possible combinations of how to enter data, and it is likely that myop will not be able to deal with all of them. 2010 Mar;30(2):200-3. doi: 10.1111/j.1475-1313.2009.00700.x. [4], The chart was designed by Ian Bailey[5] and Jan E. Lovie-Kitchin at the National Vision Research Institute of Australia. Br J Ophthalmol. Holladay et al.doi: 10.1016/j.jcrs.2004.01.014, Beck et al. 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). <>
It is more user friendly, since it avoids decimal values and is more intuitive, since higher values indicate better vision. eye is dedicated to facilitate ophthalmic research, providing convenient application programming interfaces (API) for common tasks: eye includes a visual acuity conversion chart. blink() is more than just a wrapper around myop(), eyes(), va() and reveal(). A linear relationship exists between true ETDRS letter scores, approxETDRS letter scores, and logMAR units. Trans Am Ophthalmol Soc. Three out of 5 optotypes per line had to be correctly identified, while wrong answers were monitored. Next convert the metric distance to a foot equivalent. Prospective evaluation of visual acuity assessment: a comparison of snellen versus ETDRS charts in clinical practice (An AOS Thesis). 2014 Sep-Oct;3(5):277-85. doi: 10.1097/APO.0000000000000007. You are using a browser version with limited support for CSS. Asia Pac J Ophthalmol (Phila). 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. 3 0 obj
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). endobj
The site is secure. The notation will be detected automatically and converted to the desired notation. Schulze-Bonsel et al. If there are only eye columns in your data (should actually not happen), myop will create identifiers by row position. 2023 M&S Technologies For entries with mixed notation, use va_mixed instead. The ETDRS chart is the chart used most often in clinical research. The value of each letter was calculated by dividing. If smallstep = TRUE, each snellen optotype will be considered Fazel F, Malekahmadi M, Feizi A, Oliya B, Tavakoli M, Fazel M. BMC Ophthalmol. The score was further modified by adding/subtracting 0.02 logMAR to converted values for letters correctly/incorrectly identified on previous/next line. All told, 413 patients (773 eyes) met the inclusion criteria for this study. As you can imagine, a lot of those steps rely hugely on reasonable naming of your columns and this is what makes this function unfortunately a bit fragile. Low vision is defined as a best-corrected visual acuity worse than 0.5 LogMAR but equal or better than 1.3 LogMAR in the better eye. Therefore, transforming +/- notation to actual results is in itself problematic and the below suggestion to convert it will remain an approximation to the most likely true result. will force to evaluate from which notation to convert - Must be Please always check the result for plausibility. "etdrs", "logmar", "snellen" or "snellendec". The interconversion between Snellen visual acuity measurements, logMAR units, and approxETDRS letter scores was prepared in a tabular form for easy reference. An official website of the United States government. 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. Could be etdrs, logmar, snellendec. Usage Snellen are unfortunately often entered with +/-, which is a violation of psychophysical methods designed to assign one (!) This chart and VA conversion formulas are based on charts in "/". Convert Snellen to logMAR Snellen numerator: Snellen denominator: Convert logMAR to Snellen logMAR: Usage: In addition to interactive use of the calculator, links to the calculator may contain either logMAR or Snellen values that will be automatically evaluated. and it has internal reasons that make conversion easier. 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. 1997;13:38891. 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. myop will work reliably if you adhere to the following: An exception is when there is only one column for each eye. ISSN 1476-5454 (online) doi: 10.1097/iae.0b013e3181d87e04, ETDRS to logMAR: logMAR = -0.02 * etdrs + 1.7 Accessibility <>/PageLabels 249 0 R>>
Description plus and minus from Snellen entries are converted: if entry -2 to +2 : take same Snellen value, if < -2 : take Snellen value one line below. In the clinical setting, there is still a mixed use of Snellen acuity charts and ETDRS acuity charts. 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. Conclusion: Publishers note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. See Fig. Provided by the Springer Nature SharedIt content-sharing initiative, Eye (Eye) Table: Different notations of visual acuity values as decimal values, Snellen fractions, MAR and LogMAR. Roser DA, Laidlaw DAH, Murdoch IE. 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. the VA chart are used. back to Snellen, it is a very natural thing to eye specialists to think va_methods, 1 for an example of our spreadsheet. any case allowed. It will return a list object which gives you easy access to the data. You may be trying to access this site from a secured browser on the server. Some error has occurred while processing your request. To which class to convert. However, you need to be very careful in those cases if resulting data frame is plausible. PubMedGoogle Scholar. This is intended for integration into rmarkdown reports, or for easy copy / pasting. You can also more globally change recognized codes with set_eye_strings(). When I started with R, I found it challenging to rename columns and I found the following methods very helpful: Ive got a data frame with unfortunate names: To rename only specific columns, even if you are not sure about their exact position: For even more methods, I found those two threads on Stackoverflow very helpful: reveal() offers a simple API to show common summary statistics for all numeric columns of your data frame. Could be snellen, logmar, snellendec, etdrs, #> 6x NA introduced for: 0.8, 34, , ., -, NULL, #> [1] "20/20000" NA NA "20/400" "20/2000" "20/50", #> [7] NA NA NA NA, #> 8x NA introduced for: 34, 3/60, 2/200, 20/50, , ., -, NULL, #> [1] "20/20000" "20/25" NA NA NA NA, #> 8x NA introduced for: 0.8, 3/60, 2/200, 20/50, , ., -, NULL, #> [1] "20/20000" NA "20/200" NA NA NA, #> [1] "20/20000" "20/125" NA NA NA NA, ## "plus/minus" entries are converted to the most probable threshold (any spaces allowed), ## or evaluating them as logmar values (each optotype equals 0.02 logmar), ## or you can also decide to completely ignore them (converting them to the nearest snellen value in the VA chart), #> [1] "20/200" "20/20" "20/50" "20/20" "20/32", #> [1] "r" "r" "r" "r" "l" "l" "l" "l" "b" "b", #> [1] "od" "od" "od" "od" "os" "os" "os" "os" "ou" "ou", #> Missing values and/or meaningless strings contained, ## If you are using different strings to code for eyes, e.g., you are using a different language, you can change this either with the "eyestrings" argument, ## or change it more globally with `set_eye_strings`, # to restore the default, call set_eye_strings empty. To obtain Unable to load your collection due to an error, Unable to load your delegates due to an error. The term LogMAR is an acronym for the Logarithm of the Minimum Angle of Resolution. This is based on the assumption of 5 optotypes in a row. The World Health Organization established criteria for low vision using the LogMAR scale. eCollection 2023. The formula is subsequently validated with manual conversion by two independent clinicians (CL and TS). Holladay J. However, just as all original technology does, there came a point when the Snellen chart needed reform. endobj
A logMAR chart (Logarithm of the Minimum Angle of Resolution) is a chart consisting of rows of letters that is used by ophthalmologists, orthoptists, optometrists, and vision scientists to estimate visual acuity. The ETDRS chart is fully accessible on modern computerized vision testing systems, thanks to Dr. Bailey and Dr. Lovies work to create a more accurate chart! Department of Ophthalmology, University Hospitals of Leicester NHS Trust, Infirmary Square, Leicester, LE1 5WW, UK, Christina Lim,Ian De Silva&Stephenie Tiew, You can also search for this author in Value But remember to put the strings for right eyes first, or pass a named list. Mean value for Snellen Visual Acuity was 0.043 and that of ETDRS was 0.02365 LogMAR. National Library of Medicine Efficacy of small-incision lenticule extraction surgery in high astigmatism: A meta-analysis. See also Examples. Bookshelf 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. However, additional letters read or missed letters are not accounted for. a specific range (0-100). If NULL (default), will simply "clean up" VA entries. Proper method for calculating average visual acuity. By default, plus/minus entries are evaluated as intended by the 2023 Jan 27;23(1):40. doi: 10.1186/s12886-023-02790-y. see "Examples", ETDRS must be integer-equivalent between 0 and 100 (integer equivalent The cols argument takes a tidyselection. doi: 10.1016/s0002-9394(02)01825-1, Hand movements and counting fingers are converted following Google Scholar. Although there seems to be no good statistical reason to convert 2023 Feb 8;17:515-525. doi: 10.2147/OPTH.S400156. 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. doi: 10.1016/s0002-9394(02)01825-1, Hand movements and counting fingers are converted following Internet Explorer). sharing sensitive information, make sure youre on a federal 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. Snellen visual acuity measurements were converted to approximate ETDRS (approxETDRS) letter scores for statistical manipulations and then converted back to Snellen equivalent fractions. We measured their. ignoring plus/minus entries and just returning the This overrides the smallstep argument. Each class can be converted from one to another. acuity for the patients are. The name was chosen because its a contraction of eyes and strings and its a tiny bit easier to type than eyetxt. Qualitative visual acuity lower than counting fingers is assigned 0 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. Qualitative visual acuity lower than counting fingers is assigned 0 Calculate from Logmar to Snellen. set out to compare the variability between the two measurements of best-corrected visual acuity (BCVA). endobj
Search for Similar Articles
will force to evaluate from which notation to convert - Must be 6 0 obj
(ETDRS) Chart uses a LogMAR design. which_va(). The user can specify the original VA notation, but va will check that and ignore the argument if implausible. in very weird Snellen values that have no correspondence to common charts. ?myop for help, #> From etdrs. PubMed 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. 4 5 The ETDRS charts are now considered as the most accurate and standard method of VA recording, . A conversion to snellen gives a good gauge of how the visual 12 0 obj
%
Any fractions allowed. 15 0 obj
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. FALSE: As each row grew smaller, the amount of space between each row decreased. <>
Results: stream
https://doi.org/10.1016/j.jcrs.2004.01.014. Firstly, each letter was scored using linear interpolation. No. 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. 2023 Feb 1;9(1):8. doi: 10.1186/s40942-023-00445-0. This chapter explains how you can improve names and codes so that eye will work like a charm. Correspondence to endobj
There was complete correlation between the manual conversion and excel spreadsheet formula. You can get creative with your snellens. Vector with visual acuity entries. 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. Basically the opposite of myop() - a slightly intelligent wrapper around tidyr::pivot_longer() and tidyr::pivot_wider(). Schulze-Bonsel et al. Ophthalmic Physiol Opt. hand movement and (no) perception of light, use logMAR ! in Snellen. 8 0 obj
You may search for similar articles that contain these same keywords or you may
Thank you for visiting nature.com. 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. or "", "n/a" or " ". 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. #> maintained, but will be kept in the package. MeSH These conversions were done via our excel spreadsheet formula taking into account methods from our literature searches. endobj
Other VA converter: https://doi.org/10.1038/s41433-020-0783-6, DOI: https://doi.org/10.1038/s41433-020-0783-6. In order to calculate with qualitative entries counting fingers, Rosser et al. snellen_steps, See also "VA classes", logMAR to ETDRS: logMAR rounded to the first digit and converted with We examined two different methods of scoring individual letters on a Snellen chart. ISSN 1476-5454 (online) difficult to justify a "negative" letter score in a test which only has A linear relationship exists between true ETDRS letter scores, approxETDRS letter scores, and logMAR units. 10.1016/s0002-9394 (02)01825-1 2023 Jan 30;59(2):263. doi: 10.3390/medicina59020263. proposed the line scoring method [3]. Also dealing with those "plus/minus" entries, ## Any fraction is possible, and empty values, ## but this not any fraction when converting from one class to the other, Accepted VA formats / Plausibility checks. Indeed, in my experience R often needs eyes to be in a single column, with each other variable having their own dedicated column. endobj
<>
endobj
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. endobj
https://doi.org/10.1097/iae.0b013e3181d87e04. 2010. Novel Method for Analyzing Snellen Visual Acuity Measurements. Retina 30 (7). plausibility_methods, E.g., preop instead of pre_op, or simply VA instead of VA_ETDRS_Letters, Thanks to Hadley Wickham and all developers of the. Visual acuity testing. Article In a retrospective chart review, Yu et al. If smallstep = TRUE, each snellen optotype will be considered Please enable scripts and reload this page. PubMedGoogle Scholar. M&S holds US Patent Numbers 7,354,155; 7,926,948; 8,167,429; 8,419,184; The authors declare that they have no conflict of interest. means, it can also be a character vector), Qualitative must be either of PL, LP, NLP, NPL, HM, CF (any case allowed). 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. "etdrs", "logmar" or "snellen" - . #> # with 3 more variables: l_iop_postop , l_va_preop , #> The lifecycle of blink() has expired. See also "VA classes", logMAR to ETDRS: logMAR rounded to the first digit and converted with Vision Research 90: 2-9. The same outcomes (in Snellen fractions) were obtained with statistical manipulation of either approxETDRS letter scores or logMAR conversions. The Apple iPod Touch (Figure 2), communicating with the EVA PC via Wi-Fi, provides . doi: 10.1016/s0002-9394 (02)01825-1 Hand movements and counting fingers are converted following Schulze-Bonsel et al. We successfully present an excel spreadsheet method to easily and efficiently convert Snellen visual acuity to LogMAR visual acuity. Examples. Christina Lim. HHS Vulnerability Disclosure, Help From the data presented in the current study, a conversion chart was created to aid appreciation of empiric Snellen and ETDRS equivalents compared with theoretic conversion standards . Methods: Snellen visual acuity measurements were converted to approximate ETDRS (approxETDRS) letter scores for statistical manipulations and then converted back to Snellen equivalent fractions. 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 Front Med (Lausanne). New visual acuity charts for clinical research. Ignored if the value should not be plausible. Purpose: Your message has been successfully sent to your colleague. 4 0 obj
), DETECT THE HIDDEN DANGER OFTHYROID EYE DISEASE (TED), 2022 Horizon Therapeutics plc DA-UNBR-US-01273 12/22, VA Variability: Snellen Versus ETDRS Outcomes, 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, Dr. Richard Mills' Opinions, 2002 to 2016, International Society of Refractive Surgery.