Hello, welcome to those of you that are here for course 411, Occupational Vision Testing, making sense of when it doesn't. My name is Jeff Weaver, and welcome. It looks like we have about enough room for everyone to have their own table. Definitely a big room, and I hope I can make this as engaging as was the business meeting that we had just prior. So for those of you that have been to some of my other courses, either in attendance here at AOHC or during the November virtual meetings, they made this a little bit different because we really wanted to try to make sense of when it doesn't. This was kind of inspired because of when we were looking at hiring a couple new medical review officers for eye and vision issues. One of the candidates reviewed some of the notes that were coming in from the consultation examinations and just saying, okay, looks good, and let it go. It's like, wait, look at this, this doesn't make sense. This is inconsistent with what you know, and his response was, well, who am I to say something that my colleague wrote down in the record and on their examination is not accurate? It's like, well, that's what your job is, is medical review. You have to make sure everything makes sense, and then to make sure that you make the appropriate decision, whether it's a hiring decision or a retention decision, based on that. So that was the inspiration for this. I have no conflict of interest that I am aware of. So here's the general outline we're going to follow. I hope to bring up some points that will help you in your occupational vision assessments and standards determination, especially related to these issues we're covering. So from the history, when did we start testing for occupational purposes? For those of you in occupational medicine, this is probably a review for you, but just as a reminder, Chinese civil servant examinations date back to as early as 2200 BC, so it's a long time. Interestingly, examinations were conducted only for the purpose of evaluating whether civil servants should continue in office, a practice that took place every three years. At some point, Chinese rulers decided the examination should also be used to choose the candidates for their initial positions, and those actually continued until 1905, at which time they were superseded by university credentialing. And these examinations represent the earliest documented use of testing for widespread selection of evaluation purposes. Early research in experimental psychology was focused on the study of physical sensation. German psychophysical laboratories in the early 1800s, early and mid-1800s, such as those as the Wilhelm Wundt, were concerned with obtaining precise estimates of reaction time, visual and auditory perception, and other physical sensations under various conditions. And note that Wundt was a protege of Hermann von Helmholtz, who you might know that name. He's the father of physiological optics and the inventor of the ophthalmoscope. So I am an optometrist, and I am pursuing a PhD in industrial organizational psychology, which I should finish this calendar year. So I'm hoping to tie back together Wundt and Helmholtz and try to look at some of the crossovers between psychology and visual function. So a major influence on research at this time was the publication of Darwin's Origin of Species in 1859. It was actually Darwin's cousin, Francis Galton, who wrote several works on the hereditability of scientific aptitude. Galton is well-known for the establishment of laboratories that started in the 1884 International Health Exhibition in London for the collection of physical measurements such as height, weight, strength of pull, and discrimination of color, so of the visual functions. He thought color vision was probably one of the more important ones. But here was Galton's recording form from 1884. It's not so different from the occupational medical examination forms you might use today. And notice we have eyesight, if you can read that, greatest distance in inches being able to read. So this is a measure of visual acuity. Color sense, obviously color vision, and the judgment tasks related to stereopsis and depth perception, three of the categories we're going to be looking at today. In our roles, we're looking for physical competence for a position. And in Lohmann's position competency model, that is based on determining the knowledge, skills, and abilities, and other attributes needed to function in a particular role. So what we refer to now as job analysis, job task analysis, may be attributed to Munsterberg In his studies in the early 1900s, starting with his examination of sea captains, and in his text, Munsterberg argued that the best way to improve efficiency and productivity is to match the character and mental abilities of people in position. So, I mean, this shouldn't be news to any of us, obviously. But Munsterberg's early application of his theories were prompted by safety concerns. Train worker fatality rates had skyrocketed near the turn of the 20th century. And safety is certainly also the primary reason for today's vision standards. The typical vision categories for employees of all types, in terms of evaluating whether they're visually fit for a role, are visual acuity, visual field, depth perception, color vision. This holds true for the Department of Homeland Security, for which I review applications on an ongoing basis. And our safety concerns, particularly in law enforcement, is not just for the employee, right? It's for the public. I actually had just a recent one over this past week. I'm not sure how it got to this point with me, but he had ocular albinism. So his best uncorrected visual acuity was 2,200, best corrected, 2,100. Really? We're going to put this person out there with a handgun or any type of weapon? I don't think so. I'm not sure how it really got to that point, but sometimes they do. So for each of these important attributes that we're going to be talking about, if they're going to require a standard for the job, it's important they're evaluated in relation to essential job function. You know, that comes from the Americans with Disabilities Act, because safety and efficiency are really the two critical reasons for both pre- and post-hire evaluation. So I do want to mention briefly pre-hire and post-hire testing, because remember, the main reason for testing is to assure safety and efficacy. The number of vision-impaired individuals in the workplace is higher than you might imagine. So whether it's a pre-hire or post-hire, jobs where safety and visual efficiency are needed really should have visual standards and be tested on a regular basis. The big four categories for which roles that have these probably fall into transportation, law enforcement, military, and then any inspection task, which obviously requires good visual acuity. We do some things, I think, that are probably inconsistent with the Americans with Disabilities Act, because you're really not supposed to ask any medical procedures have been done in eye care that's refractive surgery, typically, maybe cataract surgery, maybe a glaucoma procedure, whether they're using any prescription medications related to the eye, which would let us know they have glaucoma or even dry eye, or has a condition that affects vision or causes visual impairment, such as maybe macular degeneration or diabetes. But it seems like we do that. And maybe we can get away with it in certain means in the effort of safety. But again, as long as we are keeping it related to performing essential job function, hopefully we don't get in trouble. On an ongoing evaluation, definitely look at aging effects. That's one thing, that's the one risk factor and one problem that anyone in a role cannot get around. They're getting older. So particularly of the four areas we're looking at today, visual acuity and color vision may be affected just by age, even without anything else. So let's look at visual acuity first. Unless you argue contrast sensitivity, and I doubt if anybody in this room would do that, my colleagues might, visual acuity is the best measure that we have to measure a person's ability to see fine detail. So that's why it's assessed for many occupation at distance and or near, uncorrected and or corrected. So if it's measured properly, it can be a good indicator of refractive error. Unfortunately, in occupational medical settings, we often use one of the worst devices to assess it, the chart in the occupational vision testers. Now I know we had three different companies with these testers in the exhibit hall, and I don't really want to slam any of them in, you know, specifically. But just in general, there are some limitations to the equipment. So while the optics of these instruments create optical infinity for assessing distance visual acuity, knowing how close the instrument is to our eyes often causes the examinee to accommodate. We call this proximal accommodation, creating a false myopia or a greater degree of myopia perhaps than that is truly present already. So one good thing that these do have is they have internal lighting. So they have really good contrast on the charts because it has the internal illumination. But better assessment may be obtained outside the instrument with a log mar chart, which really are the standard for measurement in clinical trials. So what's a log mar chart? It is the modern acuity chart that has replaced the Snellen chart in most situations. Log mar means the logarithm of the minimum angle of resolution. As you may know, a 2020 letter subtends five minutes of arc with the critical detail subtending one minute of arc, critical detail being the letter strokes. If you look at a capital E, for instance, each stroke, the space, the stroke, the space and the stroke, each one minute of arc in a 2020 letter. The original log mar chart was designed by a colleague of mine, Ian Bailey, originally in Australia, now at University of California, Berkeley in Jan Lovey Kitchen in the mid 1970s. And the design was adopted and modified a bit for use in the early treatment diabetic retinopathy study, the EDTRS landmark study in diabetic retinopathy in the early 1980s and has become pretty much the standard going forward. So it does have the logarithmic progression of letter sizes instead of going up kind of randomly like a Snellen chart did, the same number of letters in each row. Anyone ever see on a visual acuity form 2200 minus one? I think 2200, there's usually only one letter anyway, so did they get it or they did not get it? So once you get to the higher visual acuities, the worst visual acuities, those minus ones make or are a lot worse than, you know, 2020 minus one perhaps. So the same number of letters in each row and there's an equal difficulty of letters throughout the chart. If you would blur this chart out in a Gaussian blur that might be done like a ground glass apparatus that you might see in a, you know, bathroom so people can't see through it unless you get up real close to it, all these letters blur out approximately equally. So there are some letters that are easier to recognize and they made sure they didn't put anything outside of kind of the norm on this chart. Regardless of its qualities, you do still have to have appropriate illumination. If you put an EDTRS chart of any type, a log mark chart in a dark room, it's not going to help. It needs to be well lit. So despite that also, there's how do you get this variation in response? What will go both directions? Cytophobia, doesn't this guessing response thing, does the cytophobia sound like a made up word? What's really a condition, I thought it was a made up word when I first ran across it, but there are some patients, candidates, employees who just don't want to guess wrong. You know, they take off their glasses to do their uncorrected visual acuity and you say, what can you see? Well, everything's blurry. Well, I understand that. You took your glasses off. What can you see? Well, I can see them, but they're blurry. Well, what can you see? Take a guess. And some people just don't want to do that. So you may get some much worse visual acuity than expected based on the refractive error based on the cytophobia. On the other direction, typically somebody who really wants to get a job is significant squinting and this can vary based on how much they try to squint. Squinting improves visual acuity based on the pinhole effect. I mean, if you look through the tiny pinhole of your fingers, your visual acuity is going to improve, but it also can vary a bit based on the refractive error. If someone has even a stigmatism of whether it's a with the rule, which is a minus cylinder axis 180, this is beyond the scope of the course. I won't test you guys in this, but, or a plus cylinder, if you see prescriptions written in plus cylinder format, axis 90, that is going to improve your squint ability. So if you will, by improving visual acuity more so than an against the rule type of stigmatism. Regardless, you'll often see perhaps visual acuity is recorded for someone that's extremely high myopia and they're 20, 40 uncorrected. I don't think so. They must've been squinting a lot or something else was going on. That's one of those things that doesn't make sense. One thing that I think we have to be aware of is looking for different visual acuity between the eyes. And this could be done by someone taking a visual acuity and not being as careful as they might be in being aware that this could occur. So you check the right eye perhaps and they're 20, 20 and they read whatever the line happens to be. The one chart, the classic is TZV, ECL. Okay, let's check the left eye. Oh yeah, it's still TZV, ECL. Sure it is, but can they really see it out of that eye? We don't know unless we make sure. Perhaps they just want to get the job and they know they have to have good vision in each eye. So be aware of this and there's a lot of causes for differences between the two eyes. You can have different refractive error, one relatively normal refractive error, one high myopia or hyperopia, amblyopia or lazy eye, if you will, for a number of different reasons. Could have had injury to that eye, any type of ocular disease process that's affecting only one eye. But it's safer definitely to at least have the individual read another line, just go up a line. Okay, TZV, ECL, just double check that. Apply the line above that and if they can't read that, then you know, aha, they're trying to trick me here. Another thing for people really trying to get a job also is wearing contact lenses in there. Are you really checking uncorrected acuity or is the person wearing contact lenses just not admitting it? And so individuals with real high refractive error that probably wouldn't meet a law enforcement cutoff, for instance, or conditions like keratoconus, probably the best example for individuals that perhaps can't see very well even with glasses due to the irregularity of the astigmatism in the keratoconic patients, they're probably not going to be as forthcoming about wearing contact lenses. So look very carefully. Sometimes it's very difficult to see, especially with some of the modern soft contact lenses, the daily disposables. You have to look pretty closely to see that they're there. So here's some of the common pitfalls we talked about just as a kind of a summary chart for you. Proximal accommodation from the vision tester, be aware of that. So test the acuity chart outside the instrument, ideally with a Log-Mar chart versus a Snellen to get even better objective visual acuities. Make sure you have good lighting on whatever chart you have. Assure the candidate it's okay to miss so you don't have that decidophobia. Make sure they're not overly squinting. Now, if they just slightly, perhaps, decrease their palpebral fissure size, it's fine. But if they're really heavily squinting, that's probably not the intent of the vision standard set for a particular job. And we do want to correlate their visual acuity with refractive errors, which we'll do on the next slide. Make sure the person's not wearing contact lenses for an uncorrected examination and look very, you know, do some tricks to make sure that if a person does have one bad eye that you're truly measuring the visual acuity in that eye. So I said there's a correlation between refractive error and visual acuity. And I think this is one of the best ways, perhaps, if we had to do vision standards over again, maybe vision standards would be based on refractive error and not visual acuity. Because it's a lot, there's a lot less variability in refractive error. A person might change by a quarter or so in one meridian or another. But visual acuity, depending on how you test or who's testing it, could be pretty different from day to day even. One of the, so this is a box and whisker plot of refractive error as a function of visual acuity. So I've added a couple of visual acuity lines that can be used for comparison. And an important one is 2100 because that's typical for use in law enforcement. So if you look at where that 2100 line intersects the box and where that box is on the x-axis, it's about minus three. So it's very, if you're looking at myopia, it's very unlikely the person worse than about minus three or myopia higher than about a minus three will have 2100 or better acuity. So if you're looking at some of the numbers and a person brings in their contact lens prescription or their eyeglass prescription and it's minus six and they're still getting 2100, they're probably squinting or they've memorized the chart or something. So that's just definitely something you can use to make sense of this. Another thing that I didn't mention on the overall thing, remember that visual acuity is additive, and it's almost always based on the best eye. So if you have one eye that is a little different, if you have a 20-20 with the right eye, 20-40 in the left eye, if you have something other than 20-20 with both eyes together, there's another clue that something's amiss. It should be really the best eye acuity. It should be additive, not subtractive. All right, so let's move into binocular depth perception or stereopsis, something a person I was speaking to earlier said that they had the least idea of what this is about. So binocular depth perception or stereopsis, a true depth perception, is the elegant sense of relative depth or the ability to be able to see a fine bulge or surface irregularity. So when the eyes are aligned, you can see detail from two directions at the same time. So how does that work? On a near task, you know, your right eyes are converging, so your right eye is coming in this direction and your left eye this direction. So this is important for inspection tasks, and it's really useful in law enforcement to see hidden weapons, contraband, and helpful to sort out fine detail like discriminating a weapon from a distractor. But what if something's far away? Do you really need both eyes in that disparity to be able to appreciate depth? Well, here's a pretty easy way to test this one. Can you close one eye and tell which car is closer or further? Well, sure you can. There's a lot of monocular clues to depth there. Even if you were looking at a real three-dimensional car, but even on a flat screen with one eye, you can tell from a number of things. Certainly the linear perspective that we learned in art class, relative size, interposition of one car in front of another, and motion parallax if you move your head in a real-life situation. A lot of different monocular clues. So where does the stereopsis end in monocular clues to depth cut off? Is it 6 feet, 10 feet, 20 feet? No one really knows the answer to that, but that's something for someone to solve. Here's a typical booklet test that you will see, and perhaps if you're not testing within the instruments, within the vision testers, and there are two types of tests on this booklet. And this particular one is a RANDOT, probably one of the more common ones you see out there. They test both global and local stereo acuity. So global stereo acuity, does anyone remember those Magic 3D, I think there was even whole stores where you could go in and pick out your Magic 3D poster and you'd look at this thing and all of a sudden it would pop, and then you could see what was the hidden figure in there. Well, that's what global stereopsis does. It's a larger area of the retina, and on the right-hand side of this booklet, those are all the global stereopsis. The circles, probably more commonly tested, are just local stereo acuity, and that's really derived from the macula area, a very small area in the center of the retina. So what are some common pitfalls in depth perception? Well, memorization. There's not too many of these tests out there, and where can you find these tests these days? Amazon. If you have a problem with stereopsis and really want a job, I'm buying up all these tests on Amazon, memorizing where they are and going in and passing the test. So use multiple tests. Maybe somebody's not going to buy all of them, but if it's questionable, especially if you see an obvious strabismus or eye turn and they're still scoring well on stereopsis, something is amiss. So the glasses correction, glasses contact lens correction, should be in place when they put on the 3D glasses or the cross-polaroid glasses to make sure that they have their best correction on while they're looking at this. Remember what we said about local versus global stereopsis. Typically, these local stereopsis, any of these tests will only go down to about 12.5 seconds of arc. Global stereopsis, I think the lowest I've seen is about 100. So if anybody puts on a form that it's global and it's 20 seconds of arc, something is amiss there. And then I want to say something about distance versus near stereopsis. We talked about how you can see monocular clues to depth. The vision testers actually have a stereopsis at distance, but really the depth is monocular at distance, so I'm not sure what you're testing on this, you know, Titmus or other vision testers you have there. But also definitely be aware if somebody has strabismus, they are not going to have any either local or global stereopsis. So remember the results are accurate only when they're wearing their best correction. They must wear their cross-polarized glasses if there's a need in a specific test, and most of them require those glasses. I actually saw someone back at the Army Aviation Research Laboratory at Fort Rucker, whatever it's called now, had him put on his glasses. He goes, no, no, no, I don't want those. I do better without them. It's like, no, you have to have them. Otherwise, all you're testing is you're able to see the blur of those circles of the separation that define how, you know, the degrees of stereopsis. So not everybody else has let me do that before. It's like, I'm not going to let you because that's not, you're not testing stereopsis. You're just, so even in a place like that where you think is stereopsis important for flying helicopters? I would think so. So normal findings are likely only when you have equal visual acuity and there's no strabismus. So not only if a person has strabismus, if they have a big difference between refractive error or visual acuity or both between the eyes, they're probably going to have reduced stereopsis as well. And also be aware of monovision contact lenses in those over 40. So a contact lens wearer over 40 now has some good multifocal contact lens choices, but many still prefer monovision, wearing one eye for distance, one eye for near, and that potentially reduces stereopsis. There is a plane crash that may have been the result of monovision. This is back in 1996 at LaGuardia. This Delta Airlines McDonnell Douglas 88 aircraft struck the approach light system and runway deck structures, and due to the great impact, the landing gear separated from the aircraft body, leading to the sliding of the aircraft down the runway on its fuselage belly almost into Flushing Bay, but stopped short of going into the bay. In the investigation by the National Transportation Safety Board, they determined the main cause was the captain's use of monovision contact lenses. That's one eye distance, one eye near, and they ruled that the brain would be unable to fuse the disparate images causing degraded depth perception. And while monovision contact lenses previously were prohibited, the NTSB ruled that enforcement should be increased by anyone doing the testing. So was this really due to monovision contact lenses? What are the distances that a pilot is dealing with flying a plane? Beyond that 10 feet, 20 feet? Yeah, hundreds of feet. So there were probably monocular clues to depth that were being used, not true stereopsis, but they still attributed it to the monovision contact lenses, and we have to be more diligent. I'm sure there are still a lot of pilots illegally flying out there with monovision contacts. Okay, visual field. The human eye can see temporally 95 to 100 degrees, past the 90-degree mark there. Moms, 360 degrees. But typical 95 to 100 on most humans. Nasally, about 60 degrees if you're looking at each eye. And this yields a binocular visual field of about 200 degrees with 120 degrees of overlap. So on our vision screening testers, I really don't mean to knock these things because we use them all the time, but if you think about this, it's really testing three points temporally. This TITMUS-2 that I have here, it'll test 85 degrees, 70 degrees, 55, and then it does a nasal, which I believe is 45 degrees on TITMUS. And so you really don't have a very robust measurement of the horizontal visual field by any means. So better options that are out there are an arc perimeter. So that's the one in kind of the middle on the bottom, if you can find a dinosaur like that. But to the right, bottom right, is a hand disc perimeter that kind of replaces that arc perimeter, a perimeter arc, if you will, that will measure in the horizontal meridian, and you can measure to it. It's labeled on there, so you can measure exactly to the degree of visual field there. The future is probably head-mounted virtual reality visual field machines that are being used for everything to include visual field tests that we do for glaucoma, which is probably the big reason to do a visual field. For testing such as that, this is the instrument that's used. This is a Humphrey Zeiss threshold visual field. You know, it will test temporal and nasal limits, and that's what you're doing in screening. If what we're looking for in screening for disease process, such as glaucoma, retinitis pigmentosa, or retinal detachment, not often an absolute loss of visual field, but a relative loss. So the test strategies for all of these instruments, these sophisticated instruments, are kind of driven by glaucoma, and that doesn't always include as wide as we need to test for occupations. So they're not always ideal. This may be beyond the scope of the course as well, but let me point out a couple things here. This is what you will see in a single-field analysis from a Humphrey field that is done on a glaucoma patient. Obviously, the OS on the left-hand side there, much worse than the right. You can see by the darkness in the grayscale, the blacker the worse on that. So you can get a lot of clues from the deviation there, but what I've boxed, and it's not boxed on a real printout, but there's a few things there that will help you out in knowing whether a person has a reasonable field or not. GHT means glaucoma hemifield test, and there is usually a difference between the superior and inferior field on glaucoma, and it does a statistical analysis of whether that is, if there's any differences there. One thing that I think is very helpful to you probably is the next one, which is VFI, visual field index, and that's on a percent basis. So on this one, the right eye is a 99%, the left eye is a 61%. So I think that's pretty consistent with what you can see with the grayscale and the blackness. And I think any other discussion about these we can have offline. So we normally think about a visual field being in each eye, but this is an estermen visual field that's performed binocularly, which is really the intent of things such as the CDL standard for driving, and it is not really validated for things like glaucoma, but it's a really good setting to have on this instrument for many occupational vision standards that are based on the horizontal meridian. And you can see this person had a lot of misses along the midline on the right field. So common pitfalls. There's some limitations to the vision testers. Use other methods if it's really critical. And provide a specific test that should be run. If you're just sending it out for consult, don't say run a visual field on this person. Let whoever's doing the testing know what you need to have done. One thing I didn't mention before, a lot of these forms, particularly from state driver's license forms, they'll put visual field right or left. Does that mean visual field of the right eye, which should be what, 90 degrees plus 60 degrees or 150 maybe? Or do they mean the right field, which is more like 90 degrees from straight ahead fixation to the side? And sometimes nobody knows the answer to that, but it really should be on the form. Do you need right eye or right field? But whatever you're putting down there, again, should make sense. And you're all aware of the CDL requirement. The original thought was 140 degrees binocularly, but we need this in each eye, so let's just divide that by two. That's why we have the rather ridiculous 70 degrees in each eye as a requirement for CDL licensure, which is probably inadequate as written, but no accidents to show that it's inadequate at this point. So the vision tester, as much as we use it, is probably more limited on visual field than on any other, especially if, you know, do you see the flash to the right? Yes, I do. Good, you passed. It's not robust at all. So consider further evaluation if fields are critical to the job. Glaucoma field, since it's limiting to 30 degrees, 30-2 means it's a 30-degree field, probably not fully adequate for the horizontal meridian all the way out to 90 degrees that we need. And make sure that we measure right eye, left eye, right eye, right field, left eye, left field, binocular. Got to interpret it correctly. Okay, so color vision, more dear to my heart than anything, I suppose. So color vision deficiencies can be kind of labeled a number of different ways. One good way of doing it is congenital versus acquired, and you know what congenital means, but these are typically stable because it's due to a function of the rods in the retina. I'm sorry, the cones in the retina and something irregular about them. And it's going to be the same right and left, affect the entire field of vision. Acquired, though, are really probably more problematic because that means something's going on from a health standpoint. It's just not a conditional X-linked issue of the retina. And it can affect one or both eyes, just a portion of the visual field, and you can see some of the conditions there that could cause acquired color vision deficiencies. There's a lot of color vision deficiencies out there, particularly in males, of course, about 8% of Caucasian males, less than half percent of Caucasian females, roughly the square of male percentages because you have to have two bad X chromosomes in a female to be color deficient. Other races, other than Caucasians, do have less color deficiency than do Caucasians. It's somewhere in the 4% to 5% range, but still significant. All right, so as we move forward to function, I would encourage everyone, and I have struggled with even my optometric colleagues, saying colorblind. It's like, no, it's not colorblind unless they're moderatochromatic. Of course, bad slide here because they do use blind, but that's what I needed for the photos there. But a person's color deficient. They can still see color, they just don't see it like a normal human does, and we really should use that terminology. And you get kind of an idea of what an individual can see. Fortunately, most of the color deficiencies that are out there, if you compare these to the percentages we saw on the previous slide, it's those bottom three to the right there, just the protanomaly, a deuteranomaly, a tredanomaly, which we typically understood as being just a shift in the cone, one of the cone's maximum absorption efficiencies. So those people still see fairly well compared to the upper left normal vision, but just different. So that's really just to prove that, to point that deficiency is a better term than blind. You're familiar with the typical types of color tests, the color plates, color arrangement tests, and there are some other ones out there. Color plates have about the best sensitivity and specificity of any test you can do. They're really designed to determine color vision normals versus color vision deficients. And sensitivity and specificity on most of these tests, particularly the Ishikara and HRR4th edition, the two that we're probably using most, are pretty close to 100%. So if a person passes it, they're good. If they fail it, they're bad. Not too many on the in-between. But there are some things that affect that, just like visual acuity, probably even more importantly, lighting, because we don't want just quantity of lighting like we do in visual acuity. We need quality of lighting. It can't be a 40-watt incandescent bulb. Fortunately, those are mostly gone away. But the corrected color temperature of the light needs to be greater than about 5,000 degrees Kelvin. The color rendering index, which you probably haven't necessarily looked at unless you hang out at Home Depot and Lowe's, like I often do and read these. But those are good measures of how adequately it's going to render the test plates that you're seeing. You can, if you look at appropriate lighting, that upper left picture there is called a Macbeth easel lamp. You may have seen those. Especially those of us in the room, they're a little bit older. I don't see them too often anymore, just because there are other light sources that are adequate and you don't have to have that magical Macbeth lamp. But you can get a hood, like the photo in the center, and you can even change the color temperature on those typically, or any light source that you can either get from a commercial source like Clear Sun or just go to Lowe's and Home Depot and look at the numbers. So the Ishihara plates, one of the things that's probably done incorrectly on these, where do you normally hold Ishihara plates? Arm's length, right? No, they're really supposed to be done at 30 inches. That is what the manufacturer says. And how long do you let them respond? Three seconds is all they're really allowed to respond if you're going to do these accurately. Ishihara is one of the most common pseudo-isochromatic plates, and they do have a demonstration plate. Even if you're one of those broad monochromats, you should be able to see demonstration plate number one. If a person cannot, something is awry. There are screening plates, which gives you that 100% or close to it, sensitivity and specificity, and then diagnostic plates to determine whether, for instance, a person has a PROTAN or DUTAN defect, if that's of concern. And there's also, similarly, on the Ishihara, most of the editions have a traceable one just as another way to check, even if you think a person has memorized what the numbers are on an Ishihara, because they bought one of these off of Amazon to test, they can't memorize the trace, especially since you can rotate it in different directions. Replacing the Ishihara in most agencies, I think, certainly governmental agencies, is the Hardy Rand Riddler 4th edition plates. It's really becoming the standard for occupational. Which are equivalent to or better than the Ishihara when done properly. But it can help eliminate cheating or memorization because we're able to rotate. It's not numbers, it's shapes. So you can rotate it all four positions of the shapes, and the way most organizations are doing it, instead of going through just the test plates and then the diagnostic plates of which the HR 4th edition has even more than the Ishihara, is do all 24 plates and then go back and let the experts decide what the person has, how severe of a color deficiency they might have. So on the HR 4th edition, for instance, there's four demo plates, not just one, that everybody should be able to see, even if they're a raw monochromat. There's six test plates, two for Tritan, four for Protan-Dutan, and then, so that only takes you up to 10, right? So test plates 11 through 24 are all determining the type and severity of the color deficiency, which in the past you may have had to, if you really wanted to do that, send out for some of the arrangement tests, which we'll talk about here in a moment. So here's a score sheet, and once you score these appropriately, you can tell whether a person has a color deficiency, how severe, and what type it is, whether it's a Protan-Dutan, Tritan or Tartan, which doesn't technically even really exist, but they put it on the form. So the color arrangement tests were designed, and this is where you have to be careful about these. They don't test pass-fail. If you pass a D15, that doesn't mean you have normal color vision. The Farnsworth D15 and other arrangement tests, the D means dichotomize, to separate. So how these have been done in most occupational standards is if a person fails an Ishihara, then we need to find out, do they have a mild, medium, or severe defect? So let's have them do a D15. If they can pass a D15, then it's at least mild to moderate. If they fail a D15, they're pretty severe. So if you fail an Ishihara or anything else, and fail a D15, and you need color vision for your job, it's not looking good for you. You can further dichotomize by using a desaturated D15, which is called a Lanthony. If you're able to pass that as well, then it's definitely just a mild. You've probably also seen the Farnsworth Munsell 100 hue for fine color discrimination. I think I have that on the next slide. Yes. So a trivia question, how many caps on a 100 hue test? 85. I'm not sure why. It's not the 85 hue test. At least mine. Maybe there's 15 lost. No. There's 85 in an intact one coming from the manufacturer. But there's only very small color differences between these, and this generates a total error score, and this isn't done too often. Maybe for individuals in paint manufacturing, another one that is likely to do this is someone who's a gemologist, a master gemologist has to have a total error score of less than 25, I believe. It's very difficult. Even if you have normal color vision and you go through this, you're probably going to have something on here. So that's another one I hadn't even thought of, I don't think. Total error score of zero, particularly for a person that you think might have a color deficiency, something is awry. I've seen that before. So the availability of tests online, Amazon purchase or otherwise, really makes our jobs more challenging because applicants who really want a position are willing to practice and memorize just like they are on the stereopsis test. So if you really suspect them of doing something like that, a different test can be administered, and again, that's the advantage of the HR fourth edition. You can just rotate. In addition to don't always go plate one, two, three, four in order, go change the order up to that. So there's a lot of variation you can use on the HR fourth edition. One of the acceptable alternate tests for Federal Aviation Administration test is the Farnsworth lantern, and I want to talk about this briefly. It's meant to simulate the signal light gun. You can see a signal light gun in the tower up in the upper right there. But it is the least good, if you will, test of color vision. Because even if you fail everything else, you may well pass a Farnsworth lantern. Military services have gotten away from it, even though it came from the Navy. But the FAA still has it, and I really didn't make this up. Somebody last year at this meeting said to me, Farnsworth lantern's gone from the FAA. You'll see it reflected in the aviation medical examiner guide very soon, a matter of weeks. Still looking. Farnsworth lantern's still there. It's still expected to be gone. We've been still expecting it to be gone for what, 20 years now? No. Ah, politics always come into play, yes sir. Here's the more modern version that works very similar to the Farnsworth lantern, but does not also function as a boat anchor like that other one does. It weighs about 20 pounds, I think. This one's much lighter. We'll come back to the Farnsworth lantern in a second. But I have to mention online color tests, because this is the wave of the future. There are some good ones, and there are some bad ones. The ones that have been fully calibrated are the ones on the left here. The City University, or the CAD test, Cambridge Color Test, CCT, the Wagner Color Vision Test, Terry Wagner was an old Navy aviator guy, and the Rabin Cone Contrast Sensitivity Test all work extremely well. There's some online ones, though, that are just not validated at all, but people will take them, and sometimes they'll even use them for evaluating an individual. Maybe they're okay, but they really shouldn't be for the job that we're trying to do, for safety and efficacy. So they're using scan plates. They really have to have the appropriate wavelength emission from that screen, from the online source, and you can't trust the other ones that are out there. So common pitfalls, we talked about lighting, assure that color temperature, boy, that got cold, that's 5,000 Kelvin, not 500 Kelvin, sorry about that typo on there, coloring index of greater than 90, X-chrome, or colored contact lenses, remember the old red contact lens on one eye that kind of shows a luster between the two, examine the person closely to make sure they don't have one of those in before they're testing. More modern is the Enchroma Spectacles. Has everyone seen the advertisements for, you know, finally a cure for color vision? No, there's no cure for color vision. If you put Enchroma Spectacles on, you're going to see things differently than you do. Just like anyone who puts on a different colored sunglass lens, you're going to see things differently, but it's not a cure for color vision, and we need color vision for safety. I didn't do my demonstration like I often do to show the importance of that, but color is really needed for safety. There was an exhibitor last year that said, hey, you must know about the Enchroma lenses, you're talking about color vision, which I emphasized last year. I said, yes, I'm aware of them. She goes, yeah, aren't they great? Not really for occupational things. She goes, oh, we get a lot more people passed if we have them wear the Enchroma lenses. You can't do that. That's the premise of color vision testing. So I hope they're not doing that anymore, but beware. Memorization, we've talked about memorization on many things. And watch out for replacement candidates. I'll see these once in a while, persons had come in to try to get a job within Customs and Border Protection Agency, you know, 2018, 2020 fails miserably, 2023, no errors on any of the plates. No way. This isn't like having refractive surgery and getting rid of your color vision. If you're a congenital color vision deficiency, once you are, you're always deficient, even if you're wearing Enchroma spectacles. So do a positive ID check because you could just have a ringer in there taking your color vision test for you. So here's a practical application of color vision. This is a precision approach path indicator. Does anyone a pilot or know about these or just interested enough in what the pilot sees to look out of their plane when they're coming in for a landing? Well, on any airport now, you'll see these PAPI lights off to the side. And it's, you know, right along the edge of the runway. The four horizontal lights. So pilots look at these as an incremental guide to determine whether they're on the correct glide path. Are they coming in too steep or too shallow? You need to be on the correct glide slope for landing. So four whites, two high, four reds, two low, all the other increments. You really want two reds and two whites. So what's this leading up to? Another plane crash. The whole reason for potentially getting rid of the Farnsworth Lantern, 2002, 22 years ago now. So it was a FedEx flight. And it crashed upon landing in Tallahassee, Florida. So the story is that the first officer told the captain that the PAPI lights were four white, too high, go lower. Okay, one, if I'm the pilot, I could probably look for myself, too. But he didn't. And upon adjusting and going lower, the plane crashed short of the runway. And the good thing was that the only thing that died was some packages. So if you're still waiting in Florida, waiting for your FedEx package from 2002, it's probably not coming. But the two individuals lived so that they could go back and do some medical testing afterward. What's the cause of the crash? Turned out that the first officer failed all color vision tests he's ever taken except for Farnsworth Lantern and, of course, signal light gun because it's a simulation of that. So the NTSB recommended research on the effectiveness of the FAA color tests and 22 years now, we still have the Farnsworth Lantern despite this and probably despite everyone knowing that the phalant is not the best test by any means. So making sense of color vision, many agencies are switching to the HR fourth edition. If you haven't used it, I would encourage you to take a look at it and see what you think. It's definitely a much more user-friendly test than the Ishihara and it has fewer or less pitfalls because there's no very unlikely the person's going to memorize. Remember that the arrangement tests are ancillary. If someone passes a D15 and the person writes on their normal color vision, not true. Maybe it's true, but they also have to be able to pass plates to prove that. But if they pass a D15, all it means is they don't have horrible color vision. So there's good correlation between the tests and there's no way that a person with a previously confirmed color deficiency is going to recover normal color vision. So look closely for things like colored contact lenses, spectacles, make sure you use proper lighting. And in conclusion, we did a little history there. Testing goes all the way back to 4,000 years ago. It's a reminder that standards must be based on essential job function. The common visual standards that we use are visual acuity, stereopsis, visual field, and color vision. These are the four most common ones, but tests really need to make sense. If they don't make sense, go back and look at it again because your accuracy on visual function tests does assure safety of that individual in the job and the public. And that is all I have. So maybe have a little time for questions if you would like. So thank you for coming and staying despite our late start. Thank you. Karen Hoiple. Yes, ma'am. Thank you for your presentation. Yes. It was awesome. Are you going to have the slides available for us? We would absolutely love it. I thought I had provided the PDFs to ACOM, but I noticed they weren't on there. But I noticed a lot of them weren't on there. So I will, if you can give me your, anybody who wants them for sure, give me your email address. I'll be happy to send them. That was the intent. I'll also resend to ACOM if I, I'm pretty sure I sent them in, but they didn't show up on there. But yes, I'm happy to do that. Thank you. And second question might be a silly question. Yes. My contact information is on there. So if anybody wants to reach out to me at any time, feel free to do so. Are those places that still use the Macbeth light? Oh, nice. Do you test it with the lights in the room off or the lights in the room on, including the Macbeth bot light on? Typically with that, you can turn the other lights off. That creates adequate enough lighting for the task involved. But as long as you're not overcoming it with some really bad off-color lighting, like if you have a window or something and you're getting true daylight, which is fine as a test source, then you can do that. But as long as you're not, you know, have a red light in the room or something like that, you can keep lights on. But if you turn them all off, you're safe because that's adequate illumination there. Thank you. Okay. Thank you. I enjoyed the presentation. Thank you. I enjoyed the presentation, especially the history part. Yes. Oh, good. In terms of monocular vision with sudden loss of one eye, how long does it really take to really be able to accommodate for, say, safe driving and so forth? Okay. Well, that's an excellent question. And one would argue never because you haven't grown up with it. And here was a case in point. Anybody remember Longaberger baskets of all obscure? You know, the real fine hardwood maple basket. The ladies in the room probably had them. The guys had to put up with them. Not to be genderish here. But I did a job task analysis for that organization. And we were looking at their tow motor operators, their forklift operators. And, you know, looking at what they do, aligning the forks. You need stereopsis for this. So how did we kind of do a test to see what, you know, if that was really needed or not? Well, my co-investigator and myself patched an eye and tried to drive a tow motor terribly. We poked holes in boxes and everything. And we said, yes, we definitely need to have a certain level of stereopsis, 70 degrees of stereopsis, which is a typical cutoff value. And, in fact, but we went back, talked with the safety officer, how many lost time accidents have occurred based on anybody, you know, if you have somebody that does have reduced stereopsis. And I want to come to play, and I forget the exact numbers, but something like they had 10 tow motor operators, 8 of them hedged their business. So it's like, what? Oh, you got crossed eyes. You need to go drive a tow motor for us. You can't do anything else. And there was no lost time accidents. So how do you overcome on an essential job function, that's what they do, and they haven't had any lost time accidents from not having it, so it must be monocular clues to depth. But my point of that is we tried to be an acquired, you know, immediately just a minute ago acquired monocular vision, and we did terribly. These people have been functioning that way all their life. They get along just fine. You don't see anybody with strabismus running into walls, tripping over stairs, and they've learned that over years, and certainly years is the answer, but never probably to the level of someone who's had a congenital monocular issue. Yes, sir. Oh, I didn't. Oh, you know why? Because there's still another education after this, isn't there? No, I can't. It's jlweaverod at gmail.com. And it should be, I think, I'm pretty sure it's on my, if you look me up on the app. Yes, sir. Hi there. Perhaps you've already answered this, but why do we need to test both global and local stereopsis? Can you tell me what perhaps distinguishes that? Because I always assume that if you do global, you've got it. You can see stereopsis. So what's the level of precision? So you're testing just global, not local primarily, or you're making global the primary? Yeah, we're doing both. Okay. Just I'm not clear as to, so we do the stereofly test. They pass the stereofly, and then we do the circles, and we get them down to, so we do a nine thing. So I think it's 40 arcs. Yes, 40. And we get them to do all nine to pass, and I don't know if that's actually necessary. Okay, I don't know if you all heard that. It seemed like the mic wasn't as loud as some, but he was looking at global versus local stereopsis. Local on the fly is like 3,500 seconds of arc. I mean, to see those fly wings, you don't need a lot of tests to see if you can do it. But, again, that's large retina. For inspection-type tasks, local is more important because you're using the maculas, the foveas, to look at those variability of line, small bulges or irregularities in the surface. So I'd argue that local stereopsis and doing 40 seconds, probably even just 70 seconds, is probably adequate for most things. The global is nice to know, but if you have to have one, I would just go with local. Does that say stop completely? Yes. We are over time. Thank you for this wonderful discussion, and if there's additional discussion, please maybe at the end of the talk. Thank you very much, everyone.

occupational vision testing

testing results interpretation

color vision tests

visual acuity assessment

stereopsis testing

visual field assessment

color vision standards

occupational safety

lighting conditions in testing

monocular vision clarification