Lecture: The Cerebral Visual Impairments: Diagnosis and the Principles of Management

Most health practitioners when they are confronted with children who have varying degrees of birth asphyxia or any condition leading to neonatal or infantile brain hypoxia or ischemia usually don’t know what to do as each child present with different degrees of damage which make the management onerous. Prof. Dutton explains what each part of the brain does and how each part of the brain responds to injury clearly in an easy to understand way so that we can help these children much more easily.

Lecturer: Prof. Gordon Dutton, Paediatric Ophthalmologist and Emeritus Professor of Visual Science at Glasgow Caledonian University, Scotland
Panelist: Adedayo Adio FWACS, Consultant Pediatric Ophthalmologist
University of Port Harcourt teaching hospital, Nigeria.
Chairperson, Nigerian Pediatric Ophthalmology and Strabismus Society (NIPOSS)


DR ADIO: Everyone, you’re welcome to the fifth edition of the NIPOSS webinars. Today we’re going to be discussing a very important topic, and we have a distinguished guest here with us. But first, I would want to welcome you and wish you good compliments of the joyous season. Who are we? NIPOSS is very important for us to say who the organizers of this is. We’re a society of all pediatric ophthalmologists in Nigeria, who are committed to ensuring the overall eye health of the Nigerian child. And because of this, we don’t really like traveling to have meetings in one particular place. So technology has given us the opportunity to have meetings that we can broadcast to everyone, all over the world. So a study that was done by Aghaji, et al., talking about causes and emerging trends of childhood blindness, concluded that corneal blindness appears to be decreasing, but cortical visual impairment seems to be emerging in the younger age group, and therefore we need to look at appropriate strategies to prevent this sort of childhood blindness. And therefore these patients need to be carefully evaluated. Sometimes you need a multidisciplinary approach. And this might mean examinations by ophthalmologists and neurologists, and even orthopedists, for some of them who may have problems with sitting properly. So today’s topic is cerebral visual impairments. The diagnosis and the principles of management. By no other person than Gordon Dutton. Gordon Dutton is delivering today’s NIPOSS webinar, the fifth one, and we appreciate Cybersight for this collaboration. Professor Gordon is a pediatric ophthalmologist who has worked for over 20 years at the Royal Hospital for Sick Children in Glasgow. He’s retired now, but he’s certainly not tired. This topic is very difficult to understand, for some reason. But today it’s going to be broken down in very simple bites, so that we can understand and be able to help these patients more. Please welcome Professor Gordon Dutton.

DR DUTTON: Hello. I’m now going to share my talk with you. And so this talk is entitled: Assessment and management of the child with cerebral visual impairment, a prior probability or a Bayesian approach. An approach in which you work out what’s happening from your previous experience. As in all diagnostic medicine, the key to identifying each of the many different types of cerebral visual impairment in children is pattern recognition. Whether it is recognition of patterns within the wide range of visual behaviors that parents describe, from taking a good history, or recognition of clinical signs, and the outcome of investigations, it is one’s own practical clinical knowledge of typical patterns that truly helps us to use a prior probability or Bayesian way of thinking, similar to that of Sherlock Holmes, to rapidly reach an accurate diagnosis. It’s not possible to embrace the full panoply of the vast range of cerebral visual impairments in this short time, so my aim is to share some of my own learning experiences, founded upon informed history taking, to make a diagnosis, in the hope of triggering your interest in this fascinating topic. From a detailed review of the world literature, cerebral visual impairment has recently been defined as a verifiable visual dysfunction that cannot be attributed to disorders of the anterior visual pathways or any potentially co-occurring ocular impairment. This definition denotes the wide panoply of visual difficulties, either singly or in the range of combinations that occur as a result of brain injury or dysfunction. It also ensures that the idea that if you have an eye cause of visual impairment, you don’t have a brain cause is not true. One can have both. So impaired vision can be due to, of course, impaired visual acuities. Due to bilateral lesions affecting the striate cortex or its input. Or it may be causing difficulty seeing fast movement, known as dyskinetopsia, whether it’s the flicker of a facial expression or a speeding car. This has been found to be common, for example, in children born before 30 weeks’ gestation. And it relates to pathology affecting the middle temporal lobes, shown in blue. Just in front of the occipital cortex. Homonymous visual field impairments due to unilateral occipital pathology are of course well known. While difficulty handling complex visual scenes often accompanies inaccuracy of using vision to guide motion ,or optic ataxia, resulting in inaccurate reach and apparent clumsiness. This usually relates to bilateral or, less commonly, right sided pathology or dysfunction, affecting the posterior parietal lobes, as shown here in this midcerebellar cut. And their connecting pathway from the occipital lobes, known as the dorsal stream. We diagnosed cerebral visual impairment in this 10-year-old child for the very first time, because nobody had picked up that that destructive pathology can cause such profound difficulties. A history of difficulty recognizing faces, for example, due to the specific inability to do to, or prosopagnosia, which is often associated with problems interpreting the language of facial expression. Does that make you think of a possibility of autism, because people don’t appear to have theory of mind? And for some, there can be difficulties with route finding. To any degree, and in any combination, and these tend to relate to pathology or dysfunction affecting these pink structures, or the fusiform gyrus. For faces, it’s the right temporal lobe. However, a lack of ability to recognize and differentiate shapes and objects tends to relate to pathology affecting the left temporal lobe. However, in children, a combination of both is more common. For example, in children whose hydrocephalus includes the temporal horns of both lateral ventricles, extending into the temporal lobes, who can have profound difficulties recognizing both people and objects, and finding their way about. All of these visual dysfunctions can profoundly affect the quality of life for those affected. As reduced visual acuity or visual field impairment, they can each occur across the full spectrum, from mild to severe. Just as you can have relatively mildly affected acuity or profoundly affected acuity, you can have relatively mild prosopagnosia or profound prosopagnosia. So this applies to all of these issues. As eyecare professionals, I believe we need to be able to suspect, recognize, and identify all of these visual disorders. And that we need to be able to give a precise diagnosis. We then need to arrange for the visual impairments to be well explained and to ensure the best advice is given as to how to manage each person we see who is affected. Otherwise, their lives can be a very lonely journey. From this analysis, you can clearly see that visual acuities and visual fields can be entirely normal in some people with profound visual difficulties, due to cerebral visual impairment. For example, those who have bilateral posterior pathology of the parietal lobes. At this point, it is worth digressing briefly to look at the work of the Hungarian clinician, Balint, who first described the visual outcome of bilateral posterior parietal ischemia in 1909, as well as the papers written by the First World War military neurologist Gordon Holmes, who studied the visual outcome of bilateral pathology in the same location resulting from bilateral posterior parietal shrapnel wounds in six soldiers. Both authors describe that despite entirely normal visual acuities and stereopsis, bilateral extensive pathology in this location is profoundly visually disabling, resulting in inability to see more than one or two items at once, or simultanagnosia, with an inevitable inability to look at something pointed out, which has come to be known as apraxia of gaze, along with profound difficulties using vision to guide movement of the limbs and body, otherwise known as optic ataxia, terminology which should be, but is not used, by paramedical professions or the medical profession. But this is common. This is because this is where we map the surrounding scene with respect to our bodies, so that we can move through this scene. Additional inability to see fast-moving targets and accompanying lower visual field impairment due to the bilateral injury of the adjacent middle temporal lobes and the superior optic radiations was also described by Gordon Holmes in this paper. These features, sometimes severe, but more often less severe, have thus been known about for over 100 years, and many similar descriptions have been published since that time. Such visual difficulties are not uncommon in children, with recent prevalence figures in France and the UK of approaching 4% of all children having a degree of cerebral visual impairment, which is astonishing. This is because the posterior parietal lobes are particularly susceptible to hypoxic ischemic encephalopathy, hypoglycemia, and strokes, as this is the site of the terminal branches of the three cerebral arteries on each side, which create what is known as a triple watershed zone, leading to the risk of watershed infarcts, particularly during the perinatal period. Thinking in reverse, what functions can be retained when the posterior parietal and middle temporal lobes continue to work, and the occipital and temporal lobes have been destroyed by bilateral occipital lobe infarction, due to bilateral posterior cerebral artery occlusion, causing cortical blindness? This was the outcome for our patient MC, whose case has been fully investigated, and has now been published and is described on YouTube. She was a 27-year-old able, right-handed woman, who suffered very low blood pressure, due to severe lung infection in 1999. She was in coma for 59 days, but awoke totally blind, due to bilateral occipital lobe infarction. But now, despite no responses to static perimetry, and no measurable visual acuity, she became able, after a few months, to see water running down a window, as well as to see her daughter’s ponytail moving to and fro, as her daughter walked away. And to walk freely around obstacles, and even catch balls. She has the Riddoch phenomenon, as first described by Captain George Riddoch in the journal Brain, in 1917. Again, in soldiers who had sustained shrapnel wounds. When viewing a moving target in an fMRI scanner, MC’s residual middle temporal lobes showed marked activity, despite her absent occipital and temporal lobes. And these are shown by these little orange patches. So this shows that when in this case the occipital lobes are missing, and the ventral stream is absent, but the posterior parietal lobes are intact, and the middle temporal lobes are functioning, it is possible to move freely through the unseen world. But it is important to note that when I told this patient she would be able to move freely, she did not believe me. But to her great surprise, she found that she was able to do so. I recommended that she should try using a rocking chair to help her to learn to become more conscious of her movement vision, to identify things around the room. And this proved very helpful. How many children with court blindness rock? You’ve probably seen them. This could be facilitating vision by one of the causes of such rocking, because such rocking could actually make their vision better. Having read the book Sight Unseen, which I strong commend to you, by Milner and Goodale, Oxford University Press, in which they describe a very similar case, I recommended to MC that she should try moving her finger to follow the lines of the headlined letters of a newspaper. To her surprise and mine, she found she was able to read the headlines The Times. Remarkably, she was able to guide her forefinger over each letter that she could not consciously see, and after a few months of practice, she became able to imagine moving her finger in this way, and so became able to read large script, by this technique, called Imagined Pantomiming, which Milner and Goodale also described. She eventually became able to read the 6/12 line from half a meter. Since then, I have seen two children with bilateral occipital infarction due to acquired posterior cerebral artery occlusion, as a result of brain swelling, which led to their having no conscious vision. Despite this, they were able to move freely, and they too have subsequently been taught to read successfully in this way. Just as in migraine, where there are very few clinical signs, the key to making a diagnosis starts with history taking. Founded upon one’s knowledge of what experiences or behaviors are pointers to the diagnosis. Children with cerebral visual impairment know that their vision is normal to them, because they know no other way of seeing. They have no way of knowing how those with typical vision see. Just as we may not really know how they see. But measuring the visual functions and taking a history for typical behaviors identifies the causative patterns of disordered vision and leads to the diagnosis. Typical behaviors can be adaptive, to make best use of available vision. Or reactive, when visual experiences are overwhelming, or absent, when there is no response to events they cannot see, while parents adapt to their children’s needs. The key is to recognize the typical clusters of behaviors, some common and others uncommon, seeking out the common ones first. For example, lower visual field impairment is common. Here, in work from Lena Jacobson and colleagues from Sweden, this MRI scans reveal, in A and B, bilateral atrophy and gliosis of the periventricular white matter, mostly posteriorly. Fiber tractography, in C and D, shows a marked reduction in the — sorry — of the fibers of the superior portion of the optic radiations. Fundus photography in E and F shows bilaterally excavated optic discs, due to transsynaptic retrograde degeneration. While perimetry with Humphrey visual field analysis and Goldmann perimetry show paracentrally degraded lower visual fields, while the central 10 degrees are spared in both eyes. These authors have told me that they have since identified evidence of retinal transsynaptic degeneration of perimacular retina using OCT retinal imaging in the same patients. Lower visual field impairment, simulated in the right picture, is common. So what behaviors does this cause? Behavioral adaptations to lower visual field impairment help a child to cope with life. Going downstairs is difficult, and young children go down on their bottoms, or use both hands to hold the banister, while older children may have learned to slide their heel down the riser of the stair to gain tactile guidance. They may carefully feel for floor boundaries. There may be a history of watching television upside down, to use the upper visual field. Young children go down slides head first, to use their upper visual field. Plates may be pushed further away for the same reason, or rotated to find the near food, while a book may be held up to best use the upper visual field to gain access to as much of the page as possible. Reactions to the insecurities of lower visual field impairment include refusing to jump off a bench or refusing to dive into a swimming pool, owing to previous frights or injury. A misplaced low table typically causes a child to become angry when they crash into it. Floor boundaries may not be crossed, while uneven ground and pavements cause tripping and falling. Hockey balls may not be seen, and result in affected children hating the game, partly because they never get chosen for the team. Absent behaviors include not being aware of dropped toys, leaving food on the near side of the plate, inability to find shoes, while excessive scuffing of the shoes shows more objective evidence of lower visual field impairment. Falling off the edge of a pavement, or even down a hole in the pavement is also commonly described in affected children. We have recently described a series of five mainstream school children in India with focal pathology affecting the posterior parietal lobes in four cases, and the posterior splenium in one. These five children had binocular visual acuities ranging from 6/60 to 6/6. From poor to normal. Their delayed diagnoses were made between 7 and 11 years of age. Prior to this, they had been given behavioral labels, such as autistic spectrum disorders. Yes, they had those behaviors, but those are behavioral diagnoses. This is an organic diagnosis. We have found that profoundly affected children tend to gaze at lights, presumably because it’s called competitive simultanagnosia, where an overriding stimulus to stare at stops affected children from looking away. Such children may stare at the floor, while an obvious distant target like a bus cannot be seen. Another feature we have seen is fear of collision. So I apologize. I’ve gone out of touch with my slides. And so these are reactions to posterior parietal pathology. And these are looking at lights. This is the correct slide. Or looking down at the floor. So this can mean — yeah. Such children may stare at the floor, while an obvious distant target like a bus cannot be seen. Another feature we have seen is fear of collision. This can mean that an approaching person may be lashed out at, which could well be due to impaired ability to accurately map moving items, which appear to loom into view, and so are frightening to a baby like this. But we have to be able to imagine and understand these things. Adaptations to simultanagnostic vision that children make in order to focus include getting very close to the TV, if parents will let them. Sitting on the floor behind someone, to see them in their intact upper visual field, and to hear them without having to look at the face. This may well be why affected children do not look at the face of the person talking to them, as they are unable to process both the sights and the sounds at the same time. In our experience, they also choose to place their toys on an unpatterned surface, or to line their toys up, so that they can find them again, due to their simultanagnostic vision, as a consequence of dorsal stream dysfunction. The pathway from the occipital lobes to the posterior parietal lobes, the dorsal stream not working. It is important to recognize that dorsal stream dysfunction is well described as an accompaniment to autistic spectrum disorder. But is this the chicken or the egg? If visual search is impaired because the attentional visual field is limited, people cannot be seen in a crowd. Or if a child has low contrast sensitivity, poor acuity, impaired movement perception, or prosopagnosia, it can of course be argued that this means that friends or family cannot easily be found in crowded places. Or facial expressions may not be recognized. This makes social engagement very difficult, and the affected child may be deemed to have the limited theory of mind characteristic of autism. One can see how these diagnostic labels can overlap. Able parents have often made adaptations themselves to meet their children’s needs. Creating a plain bedroom floor and making floors clear are commonly carried out in response to their children’s needs. And this is advice we need to give, of course. I’ve met some parents who have created high shelves in their children’s bedrooms, so that they can use their upper visual fields to find things, and to reach more accurately. Others have already discovered that bookstands help reading. It is clear that just listening to parents and asking key questions can get to the diagnosis very quickly. Such adaptations are commonly made by parents who are of course teaching us the advice we need to give. This is all part of the probability or Bayesian way of thinking that leads to initial suspicion, and then verification of diagnosis of one form or other of cerebral visual impairment. We have asked adults with acquired cerebral visual impairment what it is like to have vision in which only a small number of items are apparent at any one time. When we showed the picture on the right to one such individual, she said that she was only aware of the face of the man. Sorry. I should have said on the left. She didn’t see the balloons. She saw the face. And when we then blurred the surroundings of the face, she explained that the two pictures looked very similar, if not identical. She herself took this picture at a rugby match, explaining she could only see one person at a time clearly, and agreed that this simulated picture is very close to her experience. Temporal lobe pathology or dysfunction affecting vision is less frequent than occipital and posterior parietal disorders. If the right temporal lobe is disordered, then a left upper quadrantic homonymous visual field defect may ensue, along with inability to recognize faces or prosopagnosia, and a tendency to get lost, due to topographic agnosia, while facial expressions may not be correctly interpreted. Left temporal lobe pathology, on the other hand, tends to cause mirror image visual field loss, along with difficulties recognizing shapes, objects, letters, and numbers, despite sufficient visual acuities. But more often, bilateral pathology limits overall recognition. So what is going on anatomically? A number of MRI tractography studies of people with simultanagnostic vision related to dorsal stream dysfunction associated with periventricular white matter pathology have now been published. In this tractography study of the higher visual pathways, one can see in A the sighted control, the extensive fiber tracts in the occipital lobes running forward in the inferior longitudinal fasciculus, into the temporal lobes, also known as the ventral stream, for recognition and visual learning to take place, and then the superior longitudinal fasciculus or SLF, to the posterior parietal lobes, also known as the dorsal stream, and onward to the frontal lobes, where of course the choices are made as to what to look at. And the saccadic eye movements are generated in the frontal eye fields. In the case of ocular blindness B, there is not much difference, as the tracts are known to be functionally redeployed. But in the case of cerebral visual impairment shown in C, these two tracts are very, very thin, grossly limiting the amount of visual information that can be processed through the dorsal stream, therefore causing simultanagnosia, in turn profoundly limiting visual search and visual guidance of movement. And through the ventral stream, profoundly limiting recognition, as in this case. A nine-year-old boy with partial seizures, born at 36 weeks, presented with lifelong difficulties stepping on or off pavements and going down the stairs. He always tripped over things. He frequently fell and injured himself. He had great difficulty seeing moving objects and identifying objects in a crowded environment. He became subdued and frightened in crowds, and struggled to read crowded text or missed out words. He had visual acuities of 6/9 right and 6/5 left. Normal. And no refractive errors. But he was unable to see from 20 degrees below the midline, due to lower visual field impairment. This description, of course, is very, very similar to that given by Gordon Holmes in 1918 of those six soldiers with posterior bilateral parietal brain injuries. Neuroimaging on him shows bilateral moderate previously undiagnosed periventricular white matter pathology, shown by these red arrows here. And again, it’s the midcerebellar cut in the coronal scan, where you can see the dorsal stream being affected. Given a full explanation and making recommendations such as using walking poles on walks, taking care crossing roads, using a bookstand to cater for the lower visual field, and using a tablet to enlarge print made a huge difference for him, both at home and at school. And when a child understands why he or she has difficulties, and everyone understands the child, everything improves. The child is no longer criticized for mistakes, but praised for effort. And when seen a few months later, he was much more happy and confident. And these are the pictures showing the walking poles, crossing the road, becoming free to navigate with friends, and using a tablet to read with. Quadriplegic children often have marked posterior parietal pathology, and simultanagnosia, profound. Seeing only one thing at a time. With additional poor visual guidance of limb movement and apraxia of gaze, as the eyes can’t move to what is not seen. And this comprises another probable pediatric variant of Balint syndrome, for which the use of a tent to remove all clutter and background sound can slowly wake up affected children, and can be used to enable teaching and learning by eliminating the visual clutter and reducing the background sound, so that things begin to make sense, and they can learn from one thing at a time, naming one thing, naming that experience. You see — I’ll come back to it. Ben was 11 months old when I met him. He had had a difficult delivery, complicated by lack of oxygen to the brain. MRI showed multiple brain injuries, with both posterior parietal lobes being affected. He had a normal physiotherapy report, but had never reached out for a toy or an object. He couldn’t shift his gaze from his mum to me. So we lined his cot with a white sheet. We sat him at one end. We put a single toy at the other, and we waited. 20 minutes later, he had crossed the cot, picked up the toy, and played with it for the very first time in his life, because of its singularity. Ben did not look back. Following a range of measures, he now goes to mainstream school and is doing well. Radio and not TV-centered communication is essential for all children with symptomatic cerebral visual impairment. Close your eyes and listen to the radio. It all makes sense. But close your eyes and listen to the TV. Most of the language does not make sense. Because the words are referring to what you are not seeing. So if one talks about what one sees, but the child does not, then the child cannot learn, because they cannot understand. And of course, they learn that it’s normal to talk with gobbledygook, which is echolalia. We teach it. Vision is needed to access information, whether it is near or distant. To guide movement and to communicate. So when vision is reduced, alternative means are needed to teach effectively. For visual impairment, the medical role stops at diagnosis, which is when we need to work closely in teams to bring about accessible teaching by ensuring that everything taught is learnable. This requires visual assessment teams, who work closely together to assess functional vision with both eyes open. Not limits of vision, but functional vision. Not what people can’t do, but what they can do. And whose role is to teach parents and to teach teachers how to ensure good accessible learning throughout the time they are with the child. Parents spend 85% of the child’s time. Teachers, 15%. So our teaching of parents is totally fundamental. The four textbooks shown in this slide are available online from book depository, which gives free delivery, or Amazon, while the website, CVIScotland, which we have written, provides free online training material for teachers and parents, and can be used with Google Translate. It’s been already translated into 100 languages, and is being watched in 140 countries. So these resources — and by the way, I do apologize. Our three books, the red one, the dark blue one, and the light blue one, are overpriced. But you can read the first three chapters of each book for free on Amazon, and indeed, I commend that to you. Because that introductory material is worthwhile. What and How Does This Child See is by Lea Hyvarinen, and again, is an excellent teaching material. And with that, I’m open to questions. Thank you.

DR ADIO: Thank you very much, Professor Dutton. That was a very stimulating explanation of cortical visual impairment, and we have learned a lot. I wonder whether there are any questions from anyone at this time. Any questions? Questions? We are open to questions at this time. Thank you very much, Dr. Dutton. That was a very interesting explanation of cortical visual impairment. To start off or kick off the questions, I want to ask: You talked about simultanagnosia. Usually parents don’t understand that. But the way you explained it was quite illuminating. That is: Inability to see more than one or two items in a visual scene at once. So could you just go over again how you said we should handle that with the parents? When a patient comes with simultanagnosia?

DR DUTTON: Fine. First, you used the word “cortical”. I use the word “cerebral”. And I think we must internationally use both of these words with an identical meaning. In the United States, the word “cortical” is used. Tending to emphasize more severe pathology. But in fact, we should use them as being identical. So when it comes to — I see a question arrived, but I’ll just address the simultanagnosia bit. The key issue is that this can range from just having difficulty with visual search, maybe probably seeing four or five things at once, to not being able to see more than one thing at once. And one of the weird things about it is that it gets worse when people are stressed. It’s important to recognize that a child that’s in pain or is stressed or anxious or worried — their visual field appears to get narrower and narrower. Adults have told us this. Adults with simultanagnosia that I know well have described in detail. Everything collapses down on them. And then when they’re happy and relaxed, it all opens up. One of the fascinating things is landscapes. On open landscapes, people with simultanagnosia see a wide field, because it’s processed elsewhere. It’s processed in the temporal lobes, and not in the posterior parietal lobes. So one thing is to render — especially to go out into the open, to avoid crowds, to avoid clutter. Diminishing clutter can make an enormous difference. What we do not recognize is that our mental processing of a scene to find something in clutter involves a very active non-conscious process of excluding clutter. So when you exclude clutter for the person, all of a sudden you release the RAM of their mental search brain system that is all non-conscious for us, so that it can be used to find things. So it’s singularity, lack of clutter, when out and about, open landscapes, avoiding busy places, avoiding shopping, going shopping in the evening, going to a party at the very beginning, saying hello to people, enjoying the very beginning, and when it gets crowded, having another engagement to go to, to prevent being overwhelmed, are all examples of advice that we can give to help. I see that the next question is: Please, what is the role of light stimulation in the treatment of cortical visual impairment? That’s a fascinating question. Because you’ve got two elements. On the one side, a light box can help simultanagnosia, if it’s not too illuminated with putting individual separate singular items against a non-crowded background, whereas lights which are focal lights and cause light gazing — which I think it’s very likely to be a manifestation of profound simultanagnosia — is absolutely debilitating, because they just look at that, and they can’t tear their eyes away from it, and it hurts. They hate it. So the other, of course, is the idea of being in a sensory room, where there is only one thing to see. The idea of a sensory room is not to light it all up. Is not light stimulation. It’s to create darkness with a singularity that you put meaningful words to. Not a fluffy ball, but a spoon. So you make sure that a child learns language from an item, so each item that’s introduced — the child experiences and you give it — if they’ve got simultanagnosia, they see one thing, then just say “spoon”, as they feel the spoon. Touch the spoon. And build their language. That is why these children quadriplegic, who are not learning language — we’ve now taught two or three children, totally quadriplegic, who have never had a word to say for the first five or six years of their life, in this way, and they are starting to understand language for the first time. Because we’ve recognized that single words, labeling single experiences, can actually allow them to learn language, to make sense of it for the first time.

DR ADIO: So how long are you going to do that? You’re showing them one thing. So how long do you do that, before you move on to the next thing?

DR DUTTON: It’s intuitively obvious, because you know when they know. Only parents can do this. As soon as the child knows the word, the lady who runs the CVI Scotland website — her child was six years old, before she started to learn, because I taught her how to teach him to speak. And she chose the word “hand”. And she held his hand and said “hand”, “hand”, about 500 times. And then he began to know what the hand was. And when she said “hand”, he put his hand out. Then, of course, she knew that. So she then held his hand and said “hold hand”. And then it was “mummy hand”. And then it was his name, “hand”, and it was “hold hands together”. And then — and gradually you build the sentences, and they grow. And this boy now, two years later, coming up to three years later, now has a vocabulary of over 500 words. More questions. Which is the most appropriate term for cortical visual impairment? Blindness or impairment? It is impairment. Blindness is only the extreme. Blindness is only one in a thousand people. Cortical visual impairment or cerebral visual impairment affects about 3.5% of all children. And so we really need to understand that we are looking at the tip of an iceberg, if we use the term “cortical visual blindness”, and that’s totally inappropriate, unless the child cannot see. He said, passionately.

DR ADIO: Okay.

DR DUTTON: So is it possible for such a patient to recover full vision? The answer is — not the ones with profound difficulties. But I have seen remarkable growth and improvement. Particularly of the dorsal stream, once the dorsal stream problems have been catered for. I’ve seen a girl who had infarcted — who had got Balint syndrome profoundly, and she learned at the age of 32 what her problem was, and she is Mary, on the CVI Scotland website, and she describes how her vision is improving enormously, now she is training herself how to use it. So dorsal stream dysfunction can improve enormously when you take appropriate decluttering approaches and understand people, and don’t say: Can’t you find that? It’s over there. Don’t be stupid! As soon as they understand what’s going on, you can help them, and they can truly improve their own vision, when they come to understand. Moreover, of course, delayed visual maturation in cerebral visual impairment is a very slow process, and I’ve seen acuities improving from being profoundly impaired very slowly for 10, 12 years. It’s a slow, slow process in some people. But you cannot predict who it’s going to be.

DR ADIO: Okay. Now, when a child comes in, a baby is born, maybe six weeks, fixation, nothing is there, three, four months, the child is still below — obviously there’s cerebral visual impairment in this child. So after you do a full evaluation, usually here what we do is we offer them early intervention. The first three years of life. That’s what I do in my practice here.

DR DUTTON: Fantastic.

DR ADIO: So what we do with them is, after we do a full evaluation, then we now categorize — we show them videos of what it means to have cerebral visual impairment. Then we try and study the child, to see which of the impairments — which area is particularly involved. We also ask for an MRI. Okay? To see which area could have maybe hypoxic ischemic encephalopathy, or any of those pathologies that they generally have. So what I’m asking now is: What are the steps — like now, the ones you’ve mentioned are those like five, six years of age. What you’ve mentioned now. Maybe even older ones. But that age from six months to two years, when they’re still a little bit preverbal — what do you suggest that we should do? Let’s talk about neuroplasticity. Okay? I wanted to know what you can offer to these patients, so that we can have better outcomes. Usually they want an instant fix. You know, the parents want an instant fix. They want it to be sorted out immediately. So it’s a very slow process, like you have said. But if you shed more light on what to do actively —

DR DUTTON: Well, I think the first thing is to teach families to have appropriate expectations. To teach them that at diagnosis, medicine stops. We are not being doctors anymore, from their perspective. But we are being habilitationalists. Not rehabilitation. That’s bringing back something you’ve lost.

DR ADIO: Yes. You never had it.

DR DUTTON: But habilitationalists, so we are then using our skill and abilities to actually teach habilitation specialists about the profile. I think the key thing is: The two profiles. You have the profile of limitations, and that is what we focus upon, is what you can’t do with your vision. So if your limit is a visual acuity of — and I’ve used the 6 notation. Or it could be a LOGMAR of 0.5, for example — then you can’t learn from anything smaller than 0.5, and therefore you should always make sure that the pen width that the child uses has a anybody size thicker than that line. And I always prescribed that pen. Because then that is what the child tells the teacher. Everything that’s communicated to them with that line thickness must be that or thicker. Otherwise, they can’t see it. I’ve always told, with that pen, go home for your child and make sure that the eyes and the mouth and the nose of every element of every picture are filled in with that pen. You’ve just measured. They can’t see anything smaller than that. And then you show them a face with eyes that are smaller than that. So that’s an eyeless face. So, in other words, you actually give practical, simple tasks to the parents, to render everything visible to the set of limitations. One technique — and everybody here is going to have dyskinetopsia, because of the frame rate. So here, I’m moving my hand and I’m moving it faster, and you can’t tell how many fingers I’m moving, until I slow down to that. That is an extremely effective way of identifying very simply how fast things have to be, before they disappear. It’s a simple, practical test. So things mustn’t be faster than that. And so then you can — and by the way, you can show YouTube at half rate and a quarter rate. And then they can watch it. It’s easy to find. There’s a little YouTube — so you can watch any films or videos on YouTube at a slow rate, matched to their capacity to see it. In other words, if we profile the visual fields, and we don’t come from the left side of the person that has left inattention, because you don’t exist there, but you always teach from the right, if there is a low acuity — we’ve talked about that. Low speed. If there’s prosopagnosia, and they can’t recognize faces, then you must always use a radio voice. So you can see that in essence you have a set of profiles, and then we recognize that we use vision for three things. We use vision for access to information, we use vision to recognize people, and we use vision to — for social interaction — and we use it to guide our movements. And then you need to focus upon these three elements, as to what it is, being interfered with, by each of those elements of the profile. The other aspect of the profile is what the child can do. What enthuses the child. What makes them happy. What do they want to do? What motivates them? Because neuroplastic development of brain takes place by people who are motivated, active, dynamic, and happy. Only happy children learn. And so it’s the essence of being happy with them too. Obviously I’m condensing into five minutes a week’s session of training.

DR ADIO: Yeah. What do you think of using high plus lenses for children who are not able to look at an object face-on?

DR DUTTON: Well, that’s fascinating. I’ll draw your attention to our paper on the zika virus children. In whom there’s good evidence to show that even at birth — it says here: Can newborn have cortical visual impairment? Yes, they can. For example, with zika virus. And the zika virus babies — so if you look at zika virus, and you put in “zika virus Dutton”, you’ll find it straight away, I guess. Because I’m one of the authors. But the trial of using plus lenses has proved effective, because: How can a brain that cannot see accommodate? So, in other words, poor accommodation is universal in children with low acuity, and therefore they should have near correction. 50% of all children with cerebral palsy cannot accommodate too, and therefore dynamic retinoscopy or empirical use of plus lenses is a very logical and effective additional strategy.

DR ADIO: Fantastic. Great. Okay. If there are no more questions, we come to the end of this. But before you go, I would like to also find out: For those that have problems with finding their way home, some children — yeah. Finding their way home. What are practical steps? That is one. So I don’t have to ask you the second one, I’ll just say that one now. If you have an inferior field defect, many people here don’t like to use a cane guide to be able to — as a third leg, you know. So what are the practical steps we can use to help someone who has an inferior field defect? We have several children — I have several children like that here. So those two questions.

DR DUTTON: Okay. Yeah. I understand that. The first question, which — sorry.

DR ADIO: About finding your way home.

DR DUTTON: Finding your way home. Yeah. One very successful method that is used by a number of children is to actually write a song. Because you want to use alternative linguistic strategies to navigate. So one song that was written by one child was — two lines of it was: I go to lamp post number three, and then I go to the big green tree. And on the way home, it was: I go to the great big green tree, and then I go to lamp post three. And once she had written her songs, she found that she was able to navigate all the way to school and back for the very first time. Because she used an alternative sequenced strategy, and by putting that sequence into song, it’s one of the most effective ways of learning long sequences very quickly and easily. That’s one idea. The other is to look at horizons. It’s on the horizon that there’s least to see. So always as you go, turn back and look where you’re going. Look at the horizon. And look to see what the big landmark is, and think about that landmark, and speak it to yourself, and say it. So you say: Church spire. And then as you go on, you go to the next thing, and you say: Lamp post. Whatever. And so searching the horizon, naming and speaking to yourself the thing, and then sequencing that, and putting them — and imagining them in your own house, or somewhere else. So you can imagine them in a place. It enables you to sequence your route. And many children have benefited from these approaches. When it comes to the lower visual field impairment, first of all, for going downstairs, sliding the heel down the riser of the stair is what blind people do. And it’s very effective. The other thing — because in a sense, you’re blind for the ground. So you need to use the same strategies that blind people utilize under these circumstances. One thing which, for families, in the Western world, is spring-loaded telescopic hiking poles. Spring-loaded, because you don’t know — when it hits the ground, it doesn’t hurt your wrist. And then they find the ground ahead, and as long as all other members of the family, when they go for walks, use those hiking poles too, then you’re not different to anybody else. But in a world in which — or a stick off the ground. Playing with a stick. You know, you can actually play with a stick, and you can run it along the ground, and no one is actually going to think you’re being silly, because you’re just playing with a stick. So you don’t have to have a white stick. Any old stick will do.

DR ADIO: Okay!

DR DUTTON: And then — because you’re wanting to hide this kind of thing from other people — and yet be successful in moving quickly. The other is: Walking on uneven ground, putting the toe down first. And not the heel. It’s toe walking. My friend Daniel Kish, who runs World Vision for the Blind, who is an echolocator, and totally blind, when you watch him carefully, he toe walks on rough ground all the time. Because he probes it before he weight bears. And so he finds a hole in the ground instantly that way, before he weight bears. So toe down. Probe before you weight bear is another technique which can be effective. So there’s some ideas.

DR ADIO: Toe down, probe, and find the way down. Okay. That was very nice. Thank you very much. So we have enjoyed Professor Dutton. He has been speaking to us for the last few 30, 40 minutes on cerebral visual impairment. We have seen how to understand what the features are. So we have to carefully examine our kids, the children who come in, carefully evaluate, ask the parents questions, because the parents spend most of the time with these kids. It’s very important to educate them, and so that they understand also the kinds of issues their own child has. So I have to see them periodically, to gauge their progress. And also offer advice on what to do, step by step. Each milestone that is achieved is also celebrated. So that is a very wonderful discussion we just had. If you have any more questions, you can send them to me. I’ll forward them to him. And I’m sure he would gladly do that and answer them for us. I will send them back all to you. And finally, thank you very much, Professor Gordon.

December 8, 2019

Last Updated: October 31, 2022

2 thoughts on “Lecture: The Cerebral Visual Impairments: Diagnosis and the Principles of Management”

  1. Great insights. Unfortunately very little talk of lenses. I find most of these children have impaired accommodative systems.
    Also with functional or pathological field cuts prisms are helpful. Normally base in the direction of field loss.
    In addition low plus often expands a totally constricted field. Overly sensitive patients may respond to tints especially FL41


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