2011-10-21-Understanding Cortical Visual Impairment
Seminars@Hadley
Understanding Cortical Visual Impairment (CVI)
Presented by
Dr. Kia Eldred
Moderated by
Billy Brookshire
October 21, 2011
Billy Brookshire
Welcome to name is Billy Brookshire and I’ll be your Moderator today.And today we’re going to be talking about cortical visual impairment.Your presenter today is an incredible presenter on this topic, Dr. Kia Eldred, who has been presenting on cortical visual impairment for some time and is one of those experts in the field who knows a lot about it.
Kia and I worked for years; well I shouldn’t say that Kia should I?Worked for a few years on a medical program down in Houston and I always enjoyed her presentations as I know you are too.So that I don’t take any more of her time I’m going to go ahead and relinquish this microphone.So Kia, I’m turning the microphone over to you.
Dr. Kia Eldred
Good morning everyone.This is pretty exciting.I’ve never done anything like this on the internet, so new for me.I have known Billy a long time and I’m not embarrassed to say that; he’s a great guy and I’m getting older and I’m okay with that.So I’m going to talk about cortical visual impairment and blindness; talk about functional implications and rehabilitation.
I am an optometrist and I worked at the University of Houston for 20 years.And I’ve worked in the field of brain injury and acquired brain injury and worked with multiply handicapped kids all that time.I’m currently at the Michael E DeBakay VA Medical center in Houston.And there I work with low vision patients as well as the gentleman coming back from the most recent conflicts with concussive blast injuries and with stroke (inaudible 0:01:42) and a researcher.
Okay, so the course objectives that we’re going to be discussing are that you’ll be able to define cortical blindness and visual impairment and identify different types to recognize clinical findings and functional implications of cortical vision loss as well as strategies to enhance their vision.And you’ll understand less commonly seen cortical visual changes and the importance of rehabilitation and education will be emphasized.
Just a little, I have a slide up of my dad’s art work.His name was Dale Eldred.He worked in Kansas City for a long time so hey those of you in Kansas City.And just like to touch on his beautiful art work with rainbows.
The next slide I have up is the definition of cortical blindness and visual impairment; both congenital and acquired.And I know those of you that are taking this as CE, I wanted to tell you it can occur both congenitally and it can be acquired with many fewer cases that are acquired.
As far as vision loss in the United States, cortical visual impairment makes up 22% of children with vision loss in the US.Now that’s the majority of children who have visual impairment.There is 14% of kids that have retinopathy of prematurity, which is actually sort of related. And then optic nerve hypoplasia is 10% and coloboma is 7% and cataract is 6%, Albinism is 5% and optic atrophy is 2%.
Cortical visual impairment is now the leading cause of visual impairment and blindness in children in the United States.And that’s probably related to the fact that we are able to see more and more kids that are being born quite early and with other types of issues and neurological and developmental difficulties.So it is associated with cerebral palsy, and that might be something that you want to remember if you’re taking attest in the near future.
General CVI diagnosis and evaluation – the way this diagnosis is come to is that we’re looking at it as a diagnosis of exclusion; it’s based on medical history information often.As an optometrist I don’t tend to be the one to give the very first diagnosis of this but I may do that because it may be that this has never been brought up but we’re seeing all the signs and no one’s put this label, if you will, on the child.
But it is a helpful label because it’s going to allow them to be looked at in a particular way and rehabilitated in a particular way.So it is a diagnosis of exclusion.I think that we’re going to find, as far as history would be, there would be a history of perinatal hypoxia and ischemia.There would be perhaps traumatic brain injury; encephalitis, meningitis.And about 75% have accompanying neurological deficits as has been noted in a recent study, which makes sense.
So, hypoxic ischemic encephalopathy would be an infant that would be a term infant that perhaps at birth had this difficulty.Periventricular leukomalacia, or PVL, would be a pre-term infant who has had an episode of lack of oxygen.And then TBI, or traumatic brain injury, would be a child that perhaps had “shaken baby”, accidental head injury, meningitis, shunt failure, seizures, cardiac arrest or development delay.
So all these children would be people that we’d be really concerned that may have a cortical visual impairment and we’re going to be looking at that as we examine them.
So, the demographics of congenital CVI are were going to find it more commonly in wealthier nations; although a friend, an ophthalmologist I know Linda Lawrence in [Filana, Kansas] does travel extensively and really has found so many kids out there that have this diagnosis besides the US.But probably more predominantly in the wealthy nations due to our ability to medically intervene early in their lives.
And it’s considered to constitute between .07% and .22% of the total school population in the US.I think this is something that you’ll already probably acknowledge, but just kind of review this and to think about it because this is the area I know a lot of teachers and books that work with kids as far as mobility.
These are the things you start wondering about when you’re working with a child.And they may not have the label CVI, but you’re definitely seeing some of these signs.And do kind of ask about that and perhaps they need further evaluation to determine that because it will help you work with them if you have that knowledge.
So this would be a child that perhaps has a unwanted or avoided social gaze; they just don’t look in your eyes as you speak with them.They have very brief fixations; an intermittent following of any objects.They often have, most of them will have reduced visual acuity but also there are some folks that have 20/20 vision and cortical visual problems.
And I really think; I have a child that was premature, I have triplets that are 13 and they were born at 29 weeks and one of my kiddos is pretty brilliant but has a really hard time with object finding and just some different issues that really are CVI related.
Visual field block is not uncommon with generalized constriction commonly.They may have an altitudinal defect, meaning they can’t see on the inferior or maybe the superior part of the visual field, or hemianopsia, meaning to the right or the left, or field cut is what our medical colleagues often call this.This can be very difficult to test for if the child has cerebral palsy and is non-verbal.
But I work in the Nova clinic at the University of Houston and there are several other clinics like this in the US.We look at the child.We examine from fairly objective means what their vision is like.And over the years we’ve had pretty good success in determining what a vision field looks like based on just confrontation responses and we’ll talk about that.
These children have decreased responses to visual stimuli when there’s music, noise and sounds present and often when they’re touched; so they just can’t have simultaneous stimuli.They have to concentrate to use their vision.So there’s two different sorts of areas of vision that are disrupted with cortical visual impairment.There’s a dorsal stream, which is the “where is it” pathway.And that’s associated with the posterior parietal occipital lobe.And then there’s the visual motor disturbances that are occurring with that.So there’s two – visual motor and visual spatial disturbances.
There’s deficits in fixing direct visual attention to objects.This is why you also see that straight ahead gaze.They can often shift fixation and gaze to a new stimulus quickly and they have hard times with fine motor tasks like copying and drawing.And they may also have visual spatial disturbances such as finding objects, judging direction and distance objects, and orienting their body to the physical world.So they’re often standing too close to someone or can’t find (inaudible 0:09:34).
Then there’s the ventral visual system which is also disrupted, which can be disrupted with CVI.So it might be one or the other or both.So the ventral system is the “what is it” pathway.And this occurs in the inferior temporal lobe of the brain.These folks are going to have trouble with discrimination, recognizing objects and integrating visual images and objects.
So the team players for rehabilitation are going to be this list I have on the screen, which includes a physical medicine rehabilitation, physician.If the child doesn’t have any physical deficits, this person probably won’t be coming into play, but if they have spasticity or other issues with motor movement then they’re going to be on the team.There might also be an orthopedic person.
The pediatrician, neurologist, physical therapist, occupational therapist, speech therapist, artificial therapist, if the patient is visually impaired an optometrist, orientation mobility specialist; these will all be folks working with the child as well as probably a recreational therapist.
Here’s a picture of a young lady, probably three or four.I think I lifted this from somewhere; it’s not actually my patient.But this is pretty commonly what we’ll see our kiddos look like.She’s in a wheelchair with a table on the front of it and she has a push button for probably yes or no answers.She is strapped in pretty well so she can be sitting upright.So they have a lot of motor problems and difficulties as well as communication difficulties.And they even have a fan up by her to maybe regulate her temperature, that may be a problem for this little girl.
So I’m going to talk about a case next and kind of apply what we’re talking about to the case.So, this is the case of a young man, one of my more favorite patients frankly, those are the ones you always remember well of course.And he is now 12; I started to see him when he was like I think five or six.And he was a 28 week old premature infant.When he was born he weighed about 1 pound 15 ounces; so he was a little bitty tike.He’s a twin and I sort have this multiple thing.
So he had central apnea, meaning he was having a difficult time with breathing but it wasn’t physical it was a central neurological deficit.He had autotoxicity from gentamicin, an antibiotic, as a preemie, which can happen.Se he has hearing loss, total hearing loss.He had cochlear implants at age three.He’s currently in good health.He is wheelchair bound like our little girl I showed in the picture.
He has a headrest because he cannot sustain erect head posture, which starts coming into play with a lot of these guys.He is a special education student, but it includes inclusion classes in sixth grade.He has also some resource and life skills that his parents are very adamant about him being in inclusion; it’s been great for him.
He has occupational and physical and speech therapy at school as well as the visual imperative (inaudible 0:13:04) mobility services.He uses a DynaBox for communication and a Smart Board.And probably a lot of seeing this on your iPad and that’s become a really great thing for communication and it will be interesting to see if when he comes back in if that’s what he starts to use.He is not verbal, aside from the speaking with the DynaBox, but a very with it, interactive child.
So we utilize something called Cardiff Cards.Many of you are familiar with [Color Cards], which are cards that have stripes on one side and not on the other.The stripes change in width and they’re black and white.They start very large.You hold the cards up for the child to view and we see which side they’ll look; to the right or the left.The stripes fade into gray.
So after a while the stripes become too narrow for the child to discern the difference between the side with the gray and the side with the black and white.So we’re able to measure the visual acuity by measuring the distance between the black and white stripe and the distance they are from the card.Just like on (inaudible 00:14:14), with the big E and our eye can see the separations; that’s what the [Color]Card does.It’s looking for the separation or the resolution of our eyes and our brain.
So this fellow, with preferential viewing is what we call it, because we were having the child look towards one side or the other of the target and show us with their eyes what they’re seeing.He got 20/40 acuity, which is about two lines from the bottom of the eye chart, three; so really quite good vision.His previous exams spanning the seven year time I was seeing him, he went from 21/30 all the way down to 20/40.And he is pretty accurate with his responses.
He has a 30^ alternating exotropia, meaning his eye turns out one at a time.He uses one eye at a time to view information in front of him.He has a vertical gait palsy, meaning his eyes do not move up and down.They’re only straight ahead.So he had a deficit near the time of his birth where he had some kind of interruption in that track in his brain and his eyes only move horizontally.
He has pretty full visual skills, and I’m going to talk about that in a minute.There’s a picture of Cardiff Cards.Now what the Cardiff Cards look like, I don’t see it on my screen either, is that they are cards which have pictures, one on the top and one on the bottom.And what you’re doing is you’re looking at the separation of the black and the white.So there’s a picture of a fish on the top of one card and on the bottom of another and it’s black and white outline.
That one actually shrinks so that it’s harder to see and discern against the background of the gray as the visual acuity increases.But you’re just looking at the kiddo looking up and down.And for this guy, although he has this vertical gait palsy, we held the fish side to side and we would talk about the picture on the card.So these are a little more fun for kids than looking at stripes.
The next picture should be I think some toys.What we do with the toys, and I’ll just keep talking, is that we use these as targets for peripheral vision.We’ll stand in front of the patient and the other person or examiner will stand behind them and bring the targets in from the side.We use lights, we use toys, we look for the kiddos to move their eyes to the position where the object is coming.
Now with this fellow, the guy I was seeing, the one I’m discussing, he actually would smile.So he was able to communicate well enough and understand what we were requesting of him.That whenever he saw the target coming he would smile. And so you can do that, you can do eye blink, but a lot of our kiddos we just look for responses usually.
So as far as assessment of this child, he had normal color vision, which we’re going to show a picture of in a minute.And again, it’s a preferential viewing path.He had good contrast sensitivity with the Hiding Heidi cards, which are the pictures of one side has a face and one side is blank; and the side with the face gets more faded as we go further into the cards.He had a normal focusing or accommodated response.And that’s a really important thing for these kiddos for us to look at is, their focusing for up close.Some of them have difficulty because of seizure medications and other problems and so we want to look at that closely.
He has a really small refractive error.He has a little bit of far-sightedness and some stigmatism in his eye, but his visual acuity is quite good and the command of his neuro work is quite high because he’s in these inclusion classes.So we want to take that into account and not just think about the refractive error.
People with cortical vision impairment can still benefit from glasses in optimizing the image on their retina.So we always want to think about correcting them with the best correction.In some cases the vision is so poor, as light perception or very poorly defined form perception, then we don’t want to mislead our parents and we’ll talk to them about it.There may be some reason to go ahead and put them into glasses even as a protective device.
So we did evaluate the ocular health and it was passed and everything looked fine.This is a Pease Allen viewing plate, which are not readily available, and this is what we used though.And there are some other preferential viewing tests available for color, not many really.These are just colors embedded in the background and that’s how we determine color, by him just looking at the little square on the purple background.There’s a green square on a purple background and a blue square on a purple background.