Lecture: An Overview of Cerebral Vision Impairment

The goal of this live webinar is to enhance the knowledge of and to stimulate eye care providers to take on the challenge of appreciating and diagnosing the range of individuals with CVI and to work within their communities to assure appropriate approaches to habilitation are provided within their communities by appropriately trained personnel.

Lecturer: Dr. Barry S Kran, OD, FAAO, New England College of Optometry, Boston, USA


(To translate please select your language to the right of this page)

DR KRAN: Hello, everyone, and welcome to an overview of cerebral vision impairment, what it is, and considerations regarding evaluation and management. When I agreed to do this lecture, it became an exercise in: Well, what do I present? Where is everybody on this topic? And I reached out to colleagues from around the world, and asked for their ideas, regarding what should be included in this lecture. And I tried to whittle down and distill as much as I could, all the feedback that I received, and put together something that I hope, regardless of what your level of knowledge is with CVI, there’s something you can take away from this lecture. And I hope those of you that have more to share are able to do so in a venue like this, going forward. My thoughts today are to cover some issues around brain development and pediatric brain damage, what the C in CVI means — cortical, cerebral, complex, or should it not be anything at all? Should it be brain-based vision impairment? Talk about how your approach to care is different than with typical patients, and then a few slides on starting a clinic, and several slides on resources needed within your setting, in the community, and resources for yourself, regarding additional knowledge on cerebral vision impairment. So to get started, we have a polling question here, and if you could just respond to that. Okay, so it appears that two thirds of you are in a major city within a tertiary care center, or have resources to that, and about three quarters of you are either in a medium or major-sized city. So we have both ends of a bell-shaped curve here. One group in a rural setting and a larger group in an urban setting. That’s important to understand. And this polling question here: How comfortable are you in making a diagnosis of cerebral vision impairment? Okay, so the majority of you are either very comfortable or comfortable making the diagnosis, and a little bit less than half are not comfortable. It would be interesting to see by the end of the presentation whether or not your sense of what CVI is or is not has changed. Let’s begin with pediatric brain damage. So it’s brain damage rather than brain injury, as we see in adults or teens. When the brains are fully developed, the pathways are very much laid out. Whereas in the developing brain, quite the opposite is the case. And so we talk about brain damage, versus brain injury. And we’ll see here on this slide: Here’s the first trimester, second trimester of brain development, and here is the third trimester of brain development. Note what the brain looks like at the beginning of the third trimester, and as it appears in the newborn. So there’s a lot going on, and a lot that can happen in the neonatal intensive care unit, rather than in the mother’s womb. From 24 weeks to term, each cortical neuron, it’s estimated, establishes 1,000 synaptic connections. And you can see in this picture here the white matter will increase fourfold, and the surface area with all the undulations will increase eightfold. And synapse formation and myelination occurs from 24 weeks to four years of age, and it includes cellular proliferation period, as well as critical periods of brain development and modulation. Encephalopathy is a term that’s used for any diffuse disease of the brain that can alter function or structure. So encephalopathy can be caused by many factors. Infectious agents, metabolic or mitochondrial dysfunction, brain tumor, increased pressure in the skull from a variety of factors, prolonged exposure to toxic elements, chronic progressive trauma, poor nutrition, or a lack of oxygen to the brain. Any of these things can lead to brain damage and cerebral vision impairment, among other things. So there are various terms that are used to describe the brain damage at that time. So one term is encephalopathy of prematurity or white matter damage of immaturity. Both of which include PVL, periventricular leukomalacia, which is where the white matter linings of the ventricles become damaged as a result of encephalopathy. Due to immature vascularization and the inability to deal with any sort of inflammatory issue. It can also include encephalopathy of prematurity damage to the thalamus, basal ganglia, brain stem, and cerebellum, as well as reduced growth and development of the posterior corpus callosum and its connections. So here we see the white matter, ventricles, and the grey matter, and associated with brain damage of the premature infant would include cerebral palsy, gross and fine motor skills, poor adaptive functioning, perhaps lower intelligence quotient, behavioral and emotional problems, visual pathway abnormalities that we’re all familiar with, but also cortical or cerebral impairment, and of course in the premies, asthma from the developing lung. Brain injury at full term is a little different. The connections are a little tighter. The blood vessels are a bit more developed. The immune response or dealing with inflammation is a bit more nuanced. However, it’s still somewhat immature, and there can still be some areas of the brain, as a result of encephalopathy, that can become damaged. And at the full term, it impacts grey and white matter. It can be more diffuse than PVL, and also, like in the preterm, there can be problems with motor control, cognition, emotions, learning, and can result, again, with cerebral vision impairment. So the main causes of cerebral vision impairment are really dependent upon maternal health, complications during pregnancy, of which it could be everything that could cause inflammation to the brain of the developing fetus, including trauma, anoxia, hypoxia, infection, seizures in the neonate, genetic situations that could impact biochemical pathways in the brain, and some that do not but can impact the functioning of the brain, and abnormal development without an identifiable cause. So another polling question: Which of the following examples have you suspicious for a possible diagnosis of cerebral vision impairment? Check all that may apply. Okay. So with decreasing… Well, not until the last one is there a significant… So everyone pretty much agrees that the first patient has CVI. About half of you on the second two examples — on the last example, about a third of you agree that that patient might have CVI. Let’s see what happens as the presentation continues. And I want to thank everyone for attending this presentation either at the beginning of your clinic day or perhaps for many of you at the end of a long clinic day. And I appreciate you watching at this time. So as most of you know, cerebral vision impairment is the number one cause of pediatric vision impairment in the developed world. There’s a tremendous variation, with either many misdiagnosed or not diagnosed at all. And I have an example of that later in the presentation. That is someone who made it through late teens, without being diagnosed, even though they were under active eyecare. Individual born prematurely with significant visual, motor, and intellectual issues. Three quarters of you felt that that patient does in fact have CVI. Many with a reduced acuity, contrast, and an inferior field defect. Or someone who cannot read well without excessive enlargement. Even though they have good acuity, the letters are too close together and too little space for them to make sense out of it, and need enlargement in order to compensate. Or masking or other techniques. They can’t cross the street or recognize familiar people by sight. Understanding movement in the visual world is extremely complex, too complex for them, and difficult to process. Also, there could be some disconnection between temporal and spatial processing. That is, hearing and vision. Although that will not be discussed much further in today’s presentation. It is present in a very significant number of individuals with cerebral palsy and other comorbidities, which is why Dr. El Zordabis, Dr. Fazi, who well published neurologists on the topic of cerebral vision impairment, have contributed so much to the literature in the cerebral palsy clinics that they run. So what’s the C in CVI? Where did it even come from? About a century ago, around World War I, soldiers were surviving gunshot wounds to the brain, and they had various issues with their vision as a result of a gunshot to the occipital back and surrounding areas. It was termed cortical blindness, with the basic understanding of, essentially, good eyes, bad brain, or bad visual brain. And that term is the term in code that we still use today, to code for cortical or cerebral visual impairment, because there is no diagnosis code for CVI. Cortical vision impairment, then, became a commonly used term, at least here in the United States, back in the late ’80s into the ’90s, with the hope that vision that starts out extremely poorly can in fact develop and improve. And obviously if it improves within the first year of life, then the appropriate diagnosis would be delayed visual maturation. If it doesn’t improve within the first year of life or after the first year of life, then perhaps the most appropriate term would be cortical or cerebral vision impairment. One could argue that. In fact, unlike 20 years ago, where delayed visual maturation was a term that extended well beyond the first year of age, I think more and more eyecare practitioners are comfortable diagnosing the unexplained vision impairment from the LGN forward, or the chiasm forward, as cortical or cerebral visual impairment, rather than delayed maturation. I believe it’s a more active diagnosis and would expedite care for that birth to 3 child with appropriate trained people to maximize the visual development of that child. AAPOS, the American Association of Pediatric Ophthalmologists, changed their definition in 2015 of what CVI is. They call it cortical visual impairment, yet they say it’s a decreased visual response due to a neurological problem affecting the visual part of the brain. Typically a child with CVI has a normal eye exam or has an eye condition that cannot account for the abnormal visual behavior. They go on to reiterate that it’s one of the most frequent causes of visual impairment in children. So here for the first time an eyecare group acknowledges the fact that you can have not only issues in the anterior part of the visual pathway, but also in the posterior part of the visual pathway. But the issues at the anterior portion of the visual pathway do not adequately explain how they’re using the vision they have. I’d like to call your attention to the definition at the bottom, the functional definition. Vision impairment due to damage or disorder of pathways and visual centers in the brain, including the pathways serving visual perception, cognition, and visual guidance of movement. This was a definition that was put forth by Gordon Dutton, an esteemed pediatric ophthalmologist, and Amanda Lueck, an esteemed vision educator, both of whom have lectured nationally and internationally. They published a book in 2015 called Impairment Of Vision due to Damage to the Brain. It’s useful for all aspects of identification individuals with CVI, as well as possible rehabilitation strategies, and the logic for them. And this is a wonderful definition, in that it is not structurally based. It is completely functionally based. It allows and understands that MRIs are not available everywhere in the world for a diagnosis. It also understands that structure doesn’t always equal function, in spite of having a potentially normal MRI that’s typically obtained, it still does not mean that there isn’t an issue with function. And that brings up the concept of vision function versus functional vision. Gus Colenbrander in Dutton and Bax’s book on CVI talked about this concept. And so vision function, quite simply, is any of the data that you collect in an eye exam. Acuity, contrast, intraocular pressure — numbers. Functional vision is how they use what they have. And in fact, that’s often the chief complaint from the parents or the caregivers or the actively involved educators with these children. It’s like… How do they use what they have? I don’t understand it. The acuity is pretty good, but yet Johnny can’t read or doesn’t understand the letters. I don’t understand what’s going on. So Dr. Colenbrander would say that in your exam room is not a place to measure functional vision, because you’re not looking and observing the child in their typical environment. However, I feel it’s critical that we try to approximate or we use what we can in the exam room to get a sense of their functional vision, so that we can best advocate for their needs, and write in our reports recommendations surrounding what we found in our environmental modifications in the exam room, and how that impacted performance. For example, if I’m collecting grating acuity on a patient, and I can do that with my interns walking around, having a conversation with the parent, going card after card and getting to a comprehensive threshold, that tells me one thing. If, on the other hand, I need to have the room visually and auditorily quiet, and just highlight the cards themselves, and there’s significant latency for the child to be attracted to that card, that I might need to use some auditory stimulus like tapping on the center of the card to gain their visual attention to the task by using auditory stimuli that are proximal to the task, and then how sustained is their fixation, how many cards can I go through before they need to take a break — all of that becomes important when trying to determine some idea about how that child might use vision in a classroom, whether it’s significantly adapted for them or not. Other vision function findings that we need to collect, obviously, are acuity and contrast. The two do not always go together, and I think it’s critical that we do collect contrast on our patients, as well as acuity findings. And, of course, with periventricular leukomalacia, you have to be concerned about an inferior field defect, whether it’s relative or absolute or a quadrant or complete. And others with brain damage in areas of the brain that impact the visual cortex — there could be associated field deficits. And of course, we need to distinguish that from visual neglect. Finally, one other piece to look at is the optic nerve. And here there’s been great debate and much change over time. Looking at an optic nerve, if you saw a large cup and a pale nerve, you would automatically in a newborn — one of the things to be thinking about is: Does the child have glaucoma? Another thing to add to your differential here is the possibility of retrograde axonal degeneration that occurs from the LGN forward, as a result of brain damage further back in the visual system. It’s a brain lesion that occurs between the 24th and 35th gestational week, and that is before the optic nerve is fully developed. And Dr. Jacobson feels very strongly that, rather than term it atrophy, which it looks like for all of us who are used to looking at adult nerves that were once completely healthy and then become atrophic, she feels it should be termed optic nerve hypoplasia, as it has not been fully formed, and therefore it’s not appropriate to call it atrophic. Believe it or not, I’ve had parents come into my office and say… My three-year-old… One doctor says atrophy. One says hypoplasia. What is it? I don’t understand the difference. This is a subtle point, but I think it’s an important point, and we as an eyecare profession probably need to get on the same page about this, to provide less confusion for patients and their families. And of course, there are higher order visual processing issues that can impact children who have cerebral vision impairment. And in fact this may be the significant area that’s impacted, rather than acuity or contrast or color. And here you see — many of you might be familiar with the Dutton picture on the left of the various centers of the occipital cortex and the temporal lobe and the parietal cortex for the dorsal stream, posterior temporal lobe for the ventral stream, and the connections to the frontal lobe. Here this speaker then came up with this color-coded system here, which matches the boxes in this screen, to provide some additional information for the viewer trying to understand this slide. Dr. Dutton instead created a tree of vision for parents and anyone to consider, regarding the areas of the brain that can be impacted with cerebral vision impairment. So here we have the ocular structures, going back, the nerves, the chiasm, the tracts, subcortical vision, LGN, and then the occipital lobes, and here branching upwards for the dorsal and ventral stream. And you can see the components that are involved in the dorsal stream, vision for action. And you can see this wide area here where there’s some overlap of responsibility between the visual library of the brain, the temporal lobes, involved in naming colors, recognizing words, numbers, objects, shapes, animals, recognizing people, facial expressions, finding people within a group. So you can see there are some shared areas of responsibility, and some relatively separate ones. It’s believed that more people have dorsal stream impairment than have ventral stream impairment, but we’ll show you a case where perhaps there are times where we might be underestimating that. As I mentioned before, delayed visual maturation is really appropriately defined within the first year of life when visual function returns to normal. It almost seems that you can’t make that diagnosis until the vision has improved. So I think that goes towards why I am more likely to give a diagnosis of CVI rather than delayed visual impairment. And perhaps after year one, if not only vision function but functional vision has improved dramatically would I consider then reclassifying it as delayed visual maturation. So we’ll have a section here now on what we think about, as we see a patient who might have CVI. And I think this is the most challenging, one of the more challenging aspects, of this. And makes it so much more interesting and exciting than routine eye exams. Here we need to collect a significant amount of information about the child, analyze it, and not trying to be too visual system-oriented in our views, but still, are there some underlying visual reasons, visual pathway reasons, regardless of where that lies — anterior or posterior visual pathway — are there some reasons that have been not diagnosed yet, or understood, that can be contributing to the presentation of this patient? And in fact, that is often the chief complaint by the family. How does my child use their vision? What does it mean? Where is the problem? And so we review — either with the patient or ahead of time, and usually some combination of both — the maternal health, the birth history, the medical history, the developmental history, any CVI surveys or inventories that might have been done, ahead of the appointment, by either vision educators, using their assessment tools — one of the assessment tools that are commonly used in North America — as well as reviewing reports from all the players that you see here in the list on the right. All of them are important. They all have something to offer. The neuropsych reports, looking at overall intellectual functioning, looking at the difference between performance and verbal, looking at the visual perception tests that are done, and understanding and trying to figure out… Well, why is it poor? If it’s not poor, why wasn’t it poor? Were they using other skills to accomplish that task? How do I explain all of this, and how do I probe during the exam, in order to get answers to these questions? Or who else can I bring in to help us understand how this child is using what they have? Often other issues that the parents might express is: How can we improve the use of vision for things like activities of daily living, communication, learning, or other aspects? What should the print size or symbol size be? Knowing their acuity, you want to go a little larger than that. Just like we don’t read 20/20 text. We read text that’s closer to 20/50. The salient features of their symbols need to be a few times larger than threshold as well. How many symbols do I fit on a screen, or in their notebook, in their symbol notebook? Should there be contrast between them? How close should they be next to each other? Well, if the child has issues around complexity, then simplifying the symbols and putting fewer on a page probably is the best way to go. I have here a picture of a toddler looking at himself in the mirror, to remind me that we do in fact use a mirror, a portable mirror, a small mirror, in our office. Maybe 30 centimeters square or a little larger. Where I would hold it up and look and see if that patient is in fact — recognizes him or herself in the mirror. Do they get a smile? Do they reach out and point to the person? Can I use it and move it slowly and see if the child is able to follow themselves or sustain visual attention? Or do they only sustain it when it is still? And how long do they sustain it? Those are things I might look at with the mirror. I find surveys helpful as part of a history tool. Not as a diagnostic tool. There is not one author of a survey that suggests in any way, shape, or form that the survey is the be all and end all to a diagnosis of CVI. It is part of doing a structured history. And in fact, Gordon Dutton’s survey — he finds from his approximately 50 questions, there are five that appear to be most salient when he interviews families. And the next slide will enumerate those. Dr. Ortibus in her surveys also will suggest this very strongly, and if you go to the http://teachcvi.net/screening-tools page, you’ll see there are a number of them there for different ages, each with increasing numbers of questions, and she’ll point out to her colleagues that these are used for referral, and not for diagnostic purposes. The Israeli survey is a wonderful survey for individuals who are low functionally. Are functionally, developmentally very delayed. It’s a wonderful survey for them. Short and easy to give. Here are the directed history questions. And there may be some here that, depending upon the culture and the child’s understanding of the environment, that may need to be adjusted appropriately, but these five questions resonate most strongly in the work that Dr. Dutton has done. And we often ask questions similar to these, during our history taking as well. All right. So you’ve collected a bunch of information during the history. You have, ahead of the patient, reviewed perhaps lots of reports, and now it’s like the rubber meets the road here. How do I manage this patient? Many of you are familiar with working with kids and infants, and many of you are probably also familiar with working with kids with multiple impairments. However, in my experience, I see that there needs to be an adjustment for how we think about the exam. I often see reports where it says: Untestable and uncooperative. And I don’t think that that’s an appropriate onus to place on the patient. We are in a sense the host for that patient, for this exam, just like you’re a host at a dinner party or a party you’re having with friends and family. And your job as the host is to make sure everyone has a good time. Your job as the doctor is to provide the environment through which you can collect the information that you need in a way that the patient feels comfortable and therefore you can be successful. As a caveat to that, it’s not only how one introduces — and importantly models and adapts the technique, modeling it with a loved one and enlisting their help for how to model it, so that you can be successful — but also when one performs the technique during the exam. That will ultimately determine your success in acquiring that information. Succinctly, it’s performing the right test at the right time in the right way. The exam doesn’t have to begin with covering the right eye and reading the lowest line of letters you can see. In fact, if you’re gonna start with acuity at all, it’s always with both eyes open first, not one eye or the other. You might do motilities from a distance first, and slowly approach the child with a toy of interest, and gain their comfort as you approach their personal space. We are strong believers in collecting any form of data we can, both functionally — vision function and functional vision data. So we do collect acuity. I know there are some who feel that grating card or using Lea paddles are not appropriate ways to assess vision function. We agree and explain to parents that this is a detection test and not a recognition test, and it might overestimate vision or symbol acuity. But it gives us some significant functional information, and it gives us numbers to compare over time, as we’re watching the development of that child. We do not have the time to go through how to explain to use the cards. But just be aware that at good-lite there are instructions and videos that you can get or search for online. The doctor here prefers cycles per degree of acuity. We record the cycles per degree in our chart and put an acuity notation that is more understandable to the general public, with a caveat that it might be — in some cases, significantly, but in most cases slightly overestimating Snellen or symbol acuity. So the cards or the paddles are labeled in cycles per centimeter, but keep in mind that’s the physical measurement of the card, regardless of where you hold it, versus here — this would be cycles per degree. If the card were further away, then you see that the angular subtense of it is different, and it is what could be translated to an actual acuity measure. And you can see, as we all know, that acuity develops pretty rapidly over the first year or so of life, and even the first year and a half to two years of life, and then starts to plateau. And here are Lea’s norms for acuity. The Teller card acuities that are also available have their own sets of norms, both with both eyes open and monocular. I say both eyes open rather than binocularly, because many of our patients are pretty educated, and most of our patients do have a strabismus. So binocular acuity doesn’t resonate with them. I’ve had many parents say: What do you mean binocular? My child has this large eye turn. They’re not binocular. We know as eye doctors that that’s shorthand for both eyes open, but they don’t. Rather than getting into that conversation, I’ve become accustomed to saying both eyes open. Of course we assess occlusion on a patient. What is their order like? There’s the sense of central, steady, maintains fixation, but how do they react to that patch? If the better eye obviously — the better-seeing eye is being patched, are there more behavior problems than when the other eye is patched? And what does that mean? And if there’s a subtle difference, is it that there’s maybe an amblyopia, or is it that… What’s the test order? And perhaps then the next time you see the child, you switch the order of which eye you patch first. You also need to be creative when you assess this population. And that goes from having some appropriate toys that are gonna engage patients, be looking at hand-eye coordination, visually guided motor stuff, with things like form board puzzles, of which I include the Lea puzzle, both the black and white side and the colored side. And look how it’s very simplified. Very simple colors, lots of space between, and there’s actually an image of each of these shapes below. Compare that with this here, where there are these farm animals, and if you don’t… On a quick look, you don’t even see the outline of where those shapes fit in. So if you have varying levels of complexity of puzzles, you can assess how that child might be operating in their near space, and perhaps even how they deal with complexity out in the world beyond. This is sort of a down and dirty way of confirming some things that were noted, perhaps, in the visual perceptual testing that was done as part of a neuropsych exam or the school-based assessments. Lea also has contrast cards that are a nice screening set. She also has a device to assess visual fields. We use a different device that’s homemade, that are wands. We have two wands that are similar. So we use it like a confrontation. So we’re holding both of them, but only illuminating one at a time, and trying to assess a field. We also need to look at the impact of correction of refractive error. Some might say that if you have acuity of… For example, 20/500, and you find +2 as the refraction, should you prescribe it? It doesn’t make sense. The acuity doesn’t match, and that’s even out of, say, their better-seeing eye. The acuity doesn’t match their function. On the one hand, why bother? On the other hand, maybe providing that little bit of impetus, providing some of that focusing for that patient can then stimulate at least some increased visualization, visual attention, at near, that then could grow on itself. And it might be that the patient doesn’t need glasses for the rest of their lives, but it could be something to help stimulate visual attention. And one way of assessing that is through the use of dynamic retinoscopy, which we really don’t have time to go into. But it’s something that is underutilized in this population, and should be considered. Dr. Lawrence and her colleagues, the clinic that she works with, has a case series of patients who very definitely benefited from the use of plus at near to stimulate the use of visual attention and accommodation. My only caveat for using dynamic retinoscopy with this population — even though some of your diagnostic kits came with MEM cards, Monocular Estimate Method cards that have even pediatric-appropriate shapes on them… Even though we think they are appropriate for a given patient, they might not be. So you might want to consider using something that’s clinically relevant, rather than maybe something that’s scientifically prudent. So even a somewhat large toy of interest, held in the relative plane of the retinoscopy, retinoscope, as you’re using it to assess whether there’s significant width or not, or if they’re accommodating to the right of the target, in which you would see a nice bright reflex, but if there’s significant lag, even with a toy of attention, I would consider the use of an add or underlying hyperopic correction, in order to generate some sort of positive utilization of their vision. So after you collect all the data, and the hard numbers — vision function plus functional vision findings — you need to sort of roll that back in your brain, think about everything that that child came to you with, with their reports, and figure out if there are places where you can plug in or even come up with a diagnosis, to explain what’s going on. So it could be as simple as making an environmental accommodation, prescribing spectacles, either prescribing some low vision devices, depending upon the age of the child, or some pre-low vision devices, in a way to get them used to things, or even just enlarging print or symbol size, providing key things, issues around complexity, advocating for vision professionals to be involved — vision educators to be involved in the care of that child. Or there could be a referral to an educational team for further evaluation, with a strong emphasis on making sure that that child feels part of the educational community and the community at large. It’s not that — yes, they don’t see the world the same way everyone else does, and the goal of the accommodations, whether it be glasses or low vision devices or enlarged print is to level the playing field, to make it so that they too can participate in learning the same way as their fully sighted peers, or as close as possible to that goal. We might be seeing someone who’s transitioning from early intervention, the birth to 3 programs, to preschool, and with that patient potentially, when I discussed having to turn off the lights and just wait a significant amount of time for them to make a visual response, that’s someone who’s going to need a visually quiet and auditorily quiet room or area to engage vision, if that’s in fact the goal of that particular task at that time. And certainly they’ll need frequent visual breaks. We also are seeing people who are transitioning from one school to another, or people who are increasingly mobile, and being able to do it — they can’t do it independently when, on an age-appropriate level, they should be. We also might be seeing someone who is non-verbal and has a sense of cause and effect, so we may need to be making recommendations regarding how they should use their vision for their particular communication system, whether it’s computer-based, auditory output, partner-assisted with auditory output, or symbols, and whether they should be simple symbols, colored symbols, what kind of background, et cetera. So here’s a case of a preschooler, two and a half years old, with periventricular leukomalacia, cerebral palsy, and they came in for an assessment of visual field. The patient is walking with their head down, and the question is are they walking with their head down because of cerebral palsy, or is it CVI? He was premature, he had PVL diagnosed via ultrasound, he has spastic triplegia, he has healthy eyes with right intermittent exotropia, and you can see his grating card acuity. Our colleague, Dr. Mayer, developed a bowl perimeter, and I know there’s more of a tent-like structure that’s being developed at LV Prasad at Hyderabad, that shows some promise, and hopefully will become commercially available in the near future. But that’s an awesome device. This is a one-of-a-kind device at this point. We used — Dr. Mayer attempted to collect field information on this child. You can see the sort of free space. And she sees the patient’s space in her monitor, and she can present the stimuli wherever, and there’s some reinforcement for the child to fixate, and some lights are presented anywhere in the periphery, and she assesses whether or not the child sees it, either by the eye movement or the head movement or pointing towards those stripes upon which there is positive reinforcement or reward given in the form of flickering or movement. Here you can see a visual field defect as a result of PVL. So the reason this child walks with his head down is to in fact see the world in front of him. And when we collected acuity, we also needed to have just the cards illuminated. So even though those numbers are what they are, functionally they’re probably much lower. Also, when he went to reach for something, he kind of looked away before grasping, a classic sign of an issue with visually guided motor behavior. And all of these, along with the PVL and the history, are strong indications that this child has in fact cerebral visual impairment and needs proper recommendations and support in the school system. At the other extreme, here’s a school-aged female, about to graduate from high school, who was born prematurely, had retinopathy of prematurity, and comes to us from several states away, wondering about visual function versus functional vision. So how much vision, centrally and peripherally, does she have, is the question, and how does she use her vision? She has difficulty walking with changes of terrain or steps, she has a slow reaction time, and they’re wondering about a second opinion about her proficiency in driving. Her eyes ache and tire easily with demanding near tasks. Her eye doctor felt that her visual acuity and visual fields were… Excuse me. Were adequate for school work and driving. Prior vision teacher and orientation mobility specialist evaluations felt that services were not needed for her. In fact, she was told she was lazy by both her eye doctor and when the mother would go to team meetings about this, that was reiterated to her as well. They just felt that this patient was using her acuity as an excuse for not performing. When I mean not performing, she was still a B/A student, getting good grades, but worked really hard to do so. I met her — she was sitting in the waiting area, and we had a short conversation, and she was very verbal, very articulate, very engaging, completely right on. She and her mother — we went into the exam room, we had the history… And here you see again premature, twin to twin transfusion syndrome, she had bilateral germinal matrix hemorrhages, irregularly shaped brain, and hypotonia of trunk and extremities. Her ocular history was positive for retinopathy of prematurity, she had high myopia and anisometropia, and a staphyloma that was more pronounced in the right eye, and she also had some refractive and strabismic error in that eye. So we had this wonderful conversation, and then we went to collect acuity. And it took easily 15 minutes to collect acuity, with both eyes open and with each eye separately. And as it went on, her voice became fainter, her skin became paler, and she literally went from sitting erect and comfortably in the chair to almost twisting and curling up onto her side and turning her head to see the screen on the far end of the room. Everything changed about her. This was fatiguing. And clearly was not an act. Here is a bright person. You would not have expected this at all. This is something beyond the anterior visual pathway. Here are her fields, that were done by the ophthalmologist. The red or the outer circle — for those who might be color-deficient — is the normal field or an approximation of it, and the field inside is what was found on the 1 isopter assessment of her gross visual field. A neuropsych eval revealed normal IQ, but there were processing speed delays and anxiety. A driving evaluation was felt that she was unable to manage and figure out what to do in a complex situation. And in a driving simulator, even had great difficulty planning and successfully completing a lane change. To quote the findings of the driving evaluation, she currently does not have the life skills necessary to cross a busy street, manage herself independently at home, or in the community. This is an occupational therapist, performing this evaluation of driving, and came to the succinct conclusion that she cannot safely cross a street or be independent. And here she is, about ready to go off to college, and hopefully get a driver’s license, and at the same time — well, previously the vision educators and the eye doctor taking care of her didn’t really consider what else might be going on. So there was a recent MRI that was done, that was requested, but in realtime I also had the mother and daughter independently complete a Dutton survey. Here we see the MRI findings that are positive for mild parietal and occipital area volume loss and asymmetric ventricles. So the Dutton survey says: Not applicable, rarely, sometimes, often, always — are the bins that you can select, as you tick off and move down and answer each item. And there are categories of things that are assessed. And there are a series of questions, regarding visual field and visual attention, a series of questions, 11 of them on visually guided movements. There are 5 questions on impairment perception of movement, et cetera. As you can see. And mother and the patient scored always or often on 26 of the dorsal stream items. On the ventral stream, mother and daughter disagreed on six of seven. That is, the patient reported an inability to recognize close relatives in real life and in photos and confuses strangers for familiar people. Yet she was able to hide that from her mother her entire life. She’s very social. She smiles. She says hi. And when she hears the person’s voice, she can then greet them. She came up with a very neat adaptive strategy. So the question I posed to you with the patients that we see, that are non-verbal: How many of them might also have a ventral stream problem that we’re not able to completely diagnose, because we don’t have the feedback specifically from the patient? In any event, what we concluded was that she does in fact have an ocular visual impairment, if you will, and I know there are some that hate that term, so an anterior visual pathway problem, but it’s not the primary cause of the way that she’s using the vision that she has. The Ed team and the eye doctor unfortunately did not identify these signs consistent with cerebral vision impairment. The MRI in this case, plus the exam observations, plus the Dutton inventory, revealed quite strongly that this patient has cerebral vision impairment, and we provided a host of recommendations and resources and strongly advocated for their implementation to allow this person to maximize her potential within her community and her life. So instead of going to a four-year school, she went to a community college, and we had vision educators working with her, to make sure she had access to that environment, and that she was able to move forward. The final couple of pieces of our presentation is to look at setting up a CVI clinic, and then resources. Resources that might be helpful for you setting up the clinic, resources helpful for patients learning more about CVI, and resources helpful for you to learn more. Fortunately, there’s this wonderful article that’s been recently published and is available — you can download it for free — that talks about what they went through to set up their clinic in their setting, and some of the pros and cons and the work yet still to be done, in order to maximize their impact on children with cerebral vision impairment. And I encourage you all to look at it. Their goal was to develop a holistic approach in the clinic and in the community. Their clinic team included a pediatrician, a neurologist, a psychiatrist, an occupational therapist, a pedi ophthalmologist, an optometrist, and a pediatric orthoptist. And the issues were that they needed to develop a good team within their own setting, but they also needed to find and develop and/or recruit agencies to provide the services in the community. Importantly, they and others have pointed out the extraordinary important role parents play in the habilitation of a child with cerebral vision impairment. They must be engaged and involved, and whatever we are recommending needs to be recommended in a way that is perfectly understandable by them and in a way that they can execute, empower themselves to best enable their child. So the recommendations that they provide need to be structured and achievable, and, of course, in many rural settings and in many developing countries, the equipment needs to be affordable, and there needs to be an effective and constructive feedback loop. Resources. I am employed by the New England College of Optometry, but our clinic is at Perkins, where it’s been for over 30 years, and I contacted the Perkins International program, and they got back to me with some resources, since they do trainings of vision educators from around the world. And here are some resources that you can utilize, that they then may be able to direct you to services in your area. And I imagine these slides will be available for you to look at on your own time as well, to get this, if you can’t grab it right now. And then here are some other agencies that, through their network, they sent out a mailing, and Numida Jacobs was helpful in telling me about one of these associations. One of these organizations here as well. And so here they are. So here are agencies that are up and running, and not from all over the world, unfortunately, but this is an opportunity for the future, to put together a resource list, where people can get services in their communities, from throughout the world. And having said that, I know one site that’s trying to do that, and connect doctors and parents and vision educators. It’s the http://cviscotland.org site. It’s an awesome site, a growing site. Other links I include often in reports are the ones that follow here. And then finally, here are some textbook resources for cerebral vision impairment. A vision educator who lectures around the world and very often in North America is Christine Roman-Lantzy, and she has a second edition of her book that was recently published, but there’s another book that is about to come out that has even more information. The first and second edition — there are some changes, but perhaps the other book is something else that you might want to potentially look at. So some key points. Approach to care needs to be patient-centric and parental-centric. There is a significant diversity of presentation of individuals with cerebral vision impairment. The presence of an anterior visual pathway condition does not rule out of the possibility of CVI. Providing a diagnosis of CVI requires a review of medical and behavioral information. You need to learn about resources in your country or community. If few exist, consider some combination of developing them at your setting and then beyond your community, partnering if possible with agencies and regional institutions for the blind, seeking help of others internationally, and figuring out ways of engaging parents to aid in maximizing the child’s potential. All right. And here is the last poll question. Please check any that apply, relative to this presentation. Okay, yeah. And I apologize for not having more useful resources. I actually spent about two months trying to collect those resources that I was able to provide for you today. And that was the best I could come up with. So it’s obviously a goal for all of us involved in the care of these patients, to come up with resources all around the world. Finally, I would like to thank you again for having me speak, and I hope you all walked away with something important to think about. My knowledge came as a result of the 18 years I’ve been at the Perkins — the New England Eye — Perkins low vision clinic, and working with my colleague, Derek Wright, who for the past few years has been working elsewhere, but for the past several years he was instrumental in attuning me to the tremendous role they can play in assessment and in treatment and habilitation of individuals with visual impairment. And Dr. Luisa Mayer, PhD, vision scientist, who is just a wonderful person, and is brilliant and inclusive, and her former experience as a special education teacher has been invaluable. And currently at Perkins I have a colleague who is awesome. Nicole Ross. And liaisons to our respective schools at Perkins, who have taught me a lot over the years about how to work with this population. Thank you, and I do have — I know I’ve run maybe just a speck over. I do have time for just a couple of questions.
>> You can go ahead and stop sharing your screen, and we have two questions so far, if you want to open up the Q and A box.
DR KRAN: There they are. Why specifically — so the first question is: Why specifically inferior field defect commonly occurs in CVI children? Okay, so… When you think about where the periventricular leukomalacia is, it impacts the optic radiations. So it grabs those radiations, that bundle of fibers. It can hit them bilaterally or just on one side. And if it’s bilateral, you’ll have a complete inferior field constriction, and if it’s just on one side, then you’ll have that side, that quadrant, will be impaired. So it’s those fibers going back that’s the problem. Does VEP have a role in diagnosing CVI? That’s a good question. One issue is: How many centers throughout the world? Well, centers might, but… Does the diagnosis of CVI need to be something that can only occur at a tertiary care center? And the answer to that question is… I don’t think so. I think we essentially have a primary care practice, but we see tertiary care patients. And we’re often challenged by the tertiary care ophthalmologist. We’re actually referred patients to make that diagnosis. So I think VEP is helpful, perhaps, in distinguishing a behavioral acuity from what the brain potentially might be able to process. I know that there have been several studies published regarding change and acuity and VEP over time, and there was one by Fulton and colleagues that showed that they seem to change in step over time. So I don’t know. I think if you have it, great. If you don’t have it, it’s not the end of the world. The visual neglect from a visual field defect… I’m gonna refer you… So the question is how you differentiate visual neglect from a visual field defect. That is a long and complex answer, and I’m gonna refer you to the book I mentioned. But as a quick answer, just moving the head and body towards that area, all of a sudden they see a person they didn’t see before — should give rise to the thought that maybe there is neglect. There are also these cancellation tests for older children who might be able to do them, and where you can see in fact strong neglect. And where they’ll miss things that they should be finding, like there’s a line bisection task, or searching for certain things within a piece of paper, and they miss them only in one area. So things like that. You can differentiate a normal field, yet they have neglect. Does vision stimulation work for CVI? Well, I think that’s a loaded term. Not intentionally, obviously. Visual stimulation. So there used to be a thought… You know, vision teachers used to be involved in what’s called “vision stim”. And that’s fallen out of favor, the use of that term or what they thought they were accomplishing. I think the broader question to ask — or maybe what you were trying to ask — are there ways of improving the individual’s use of their vision? And the answer is yes. And I think looking at Christine Roman-Lantzy’s book for some of her thoughts, looking at some of Gordon’s books, especially Gordon and Amanda’s books, with their thoughts — and it’s not just their thoughts; they had people writing chapters from around the world who are leading edge with respect to the care and management of individuals with cerebral vision impairment… So creating a space where they can use their vision, and then slowly making those changes to perhaps adapt them to more typical settings is helpful. Giving them alternative ways to process that information, using a multisensory approach, if pertinent, for that person, for travel and learning, should be employed. So tools that are currently in a vision educator’s tool box as part of a functional vision assessment, which include a learning media assessment with sensory channel component, is really helpful. To work with. Within your own clinic, again, I would just — for the interests of time — I think Gordon and Amanda’s book is a really great place to start. All right, and then, finally, what is the LVD that can enhance visual field defect in CVI children? I’m not sure what LVD means. I know there’s some work in Germany… Oh, low vision device? What is the low vision device that can enhance the visual field defect of CVI children? That’s a good question. So we had someone else with an inferior field defect who was unaware of that space below, and we tried using, for example, yoked prisms, to bring that visual world up into his field, and it was no successful. And it was not successful. I think it was not successful because even though we were able to bring it up into his awareness, the vision orientation specialist was unable to get him to integrate that visual information into his world. When you think about a Peli prism or other prisms to make somebody aware of their field deficit, by bringing stuff from that field, an image of it, into their seeing field can be helpful, in that it causes better scanning, I think that’s the goal of that prism, is to remind the patient to look into that seeing field, become a better scanner. Some of our patients do become extraordinarily good scanners, which makes assessing the visual field quite difficult, because now you’re telling them: I don’t want you to use the adaptation you made on your own in order for me to collect the information to find your visual field deficit. And there sometimes we need to advocate for unified or improved scanning skills if their scanning skills are insufficient, but in terms of other low vision devices, I haven’t… For acuity, you can certainly prescribe monoculars. For distance, for spotting, you can certainly prescribe handheld or stand magnifiers at near. We have access to a lot of electronic magnification devices. Obviously smartphones with their cameras are awesome. Other ways of enlarging print. So there are a whole host… You should be thinking about using your tool box that you use for traditional low vision patients, for this patient population as well. All right.>> So thank you, Dr. Kran. I think that’s a good place to stop, since there are no more questions. Thanks, everyone. Have a good day.


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April 16, 2018

Last Updated: October 31, 2022

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