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with Lynne McAlister and Sara Kitchen, Certified Teachers of the Visually Impaired.

Lynne: Hi, I'm Lynne McAlister.

Sara: And I'm Sara Kitchen.  And today, we're gonna talk about cortical visual impairment.  Give you an introduction to it, what's it all about, because not everybody is familiar with it.  And so we wanted to just kind of give you a starting point.

Lynne: So, this is CVI 101.

Sara: Yes.

Lynne: And I'm gonna start with the definition of cortical visual impairment. This is diagnosed to recognize when there's an obvious visual impairment that's unexplained by any damaged to the eye itself.  Usually, it's coupled with red flags, and we're gonna get into those a little later.  CVI is a relatively new area of research.  It wasn't until the mid-'80s that it was even considered a visual impairment.  Before that, it was just kind of lumped in to the MR brain damaged group.  It's the fastest growing visual impairment in developed countries.  This is probably because with our kind of Western medicine, we're able to keep people alive after serious injury that in the past would not have survived.

Sara: Uh-hmm. And preemies.

Lynne: Yes.  So, since CVI is, um, you know...since visual impairments are diagnosed by an eye doctor, some doctors maybe reluctant to diagnose a visual impairment when there is no obvious damaged to the eye that is visible to the eye doctor.  And so we have found that CVI maybe underreported.  You may have a student that has really obvious characteristics of CVI and functions as an individual with a cortical visual impairment.  Yet on the eye report, the diagnosis is just something totally off.  I think we have a student with a muscle imbalance, I think.  It's the reason for her visual impairment on the eye report.

Sara: And it really does makes sense that the doctor wouldn't feel comfortable with diagnosing that because their training is in the eyeball and it's not in the brain.  That's a different area. . .

Lynne: Right.

Sara: ...completely. So...

Lynne: So, you can't rely on the eye report to know if you are working with a student with CVI.  Well, tests such as MRIs, you know, can be somewhat useful and that you can see the areas at the brain that are damaged.  They're not gonna give you a lot of information about what the student's vision is like.  Even the same part of the brain damaged in two different individuals could give you two wildly different visual characteristics.  So, when you are working with the individual that has characteristics of cortical visual impairment, the first thing you're gonna wanna do is go back and look at the medical history of the student.  And what we're gonna be looking for is really obvious red flags.  Asphyxia is a big red flag, that's a lack of oxygen at any point during birth, prebirth, really anything that would restrict air to the brain, strokes...

Sara: Uh-hmm.

Lynne: ...drowning...

Sara: And when the blood flow is restricted, that's another thing.

Lynne: Uh-hmm.

Sara: Mainly, all of these things have to do with blood flow or oxygen to the brain.

Lynne: Right.

Sara: And also, any head trauma could cause CVI.

Lynne: Right.

Sara: Or an infection, an infection that causes swelling will restrict the blood flow.

Lynne: Right. Cytomegalovirus, I think, is a big one.

Sara: Uh-hmm.

Lynne: And any kind of trauma, like Sara said, gun shot wound, car accident, bike accident and things like that.  So, when you now, if you have a student with some of these characteristics, and then you have the red flag in the medical background, that's a really good indication that you should start looking at CVI.  And thinking about trying to figure out now what exactly this student can see.  So, here's a picture of the brain I'd like to use.  It shows how visual information comes in through the eye.  It travels down the optic nerve to the back of the brain.  And then, it is diverted into two streams.  The ventral stream goes to the temporal lobe there toward the bottom of the brain.  And this is where visual object perception and recognition takes place.  So, this is where you recognize your mother.  The other stream travels up toward the top of the brain to the parietal lobe. And this area of your brain allows your body to act upon what you're seeing.  And so, this is the part of the brain that allows you to give your mother a kiss.

Sara: Oh.

Lynne: So, anytime there's damage to any of this whole system or any part of the brain in between these systems, so they can't communicate with each other, there is, you know, a chance that your vision will not function correctly.  You know, we're gonna talk more about specific characteristics of CVI.  But one of them is, you know, the inability in a lot of kids to look at something and act upon it at the same time.  And so, that might be explained, you know, through this picture that those two areas of the brain aren't communicating with each other.  Okay. I found it really interesting when I did my research on CVI to kind of wrap my brain around the notion that, um, we...humans perceive vision as an external events, so that we tend to think, um, things are out there, and I'm looking at them because they're out there.

When actually, nothing is out there.  Your brain is using chemical processes to make a form of picture based on information that's coming into it. And so, vision actually is an internal event.  And so when we think about it that way and when we think about students, people with CVI, they're seeing everything that you and I are seeing. But, you know, with the lack of any other damage to the eye itself, all the information is going in to their brain.  They can see everything.  They're just not making that picture.  Their brain is not putting it together.  And that is the cause of the visual impairment.  Not that they can’t see.

Sara: Right. And that is the same with the other senses as well.  I mean, all of our senses happen inside of our heads and we only know the things we know about...We know where things are in space from previous experiences and integrating our senses.  And that's really something to think about, too, when you're thinking about kids with CVI because it's not...Sometimes it's not just the vision that isn't integrated, sometimes it's the whole slew of things that are not integrated, so...Not only that they have to integrate-their vision’s, not working so well with their other senses, but they may have to, you know, their other senses might a little scrambled as well.

Lynne: Right.  So, the old theory was that your brain was hard-wired.  And certain parts of your brain have certain function.  And if there's damage to any of those parts, then you lost that function forever.  You would never get it back.  However, recent research shows really clearly that the brain is not hard-wired at all.  There's a lot of, lot of research out there now about brain plasticity and how plastic your brain is.  Different parts of your brain take over really easily for other parts that used to do, you know, used to have a function.  In my research, I've read an article about an experiment where they did PET scans on people who just recently lost their vision and were learning Braille.  And it was almost instantaneous that these people's occipital lobe, that traditionally processes visual input was processing the tactile input when they were reading Braille.

Sara: Oh, that's neat.

Lynne; Yes. And they said the speed that which that part of the brain took over the tactile processing was so fast, that it was just like it was wired to do that.

Sara: Wow! That's cool.

Lynne: Yeah, it was really interesting.

There is a little video that we found on PBS.

Is that where it is?  Called Wired Science.  Based on the experience of Paul Bach-y-Rita back in the '80s, which is kind of goes on this very topic.  We're not gonna take time right now to show it to you, but...

Sara: But you can click on the link in your notes and you can look at that video.

Lynne: Right. It's very, very interesting.  And it goes along with this whole subject.

Sara: One of things, though, in that video that I don't want anybody to misled by is that there is, um, there is...  All of the examples given are for people who have previously had vision, I think.  And they had some visual knowledge, so it's...  We're not advocating that you put electrodes in your students' mouths.  Mostly, what we really want you to know and if you watch the video, you'll know what I'm talking about.  What we really wanted to emphasize is that the brain is plastic.  And that's what this video does.  Even though it does deal with some visual rewiring.  So, I just want you to really quickly look at this drawing.  And it was done by an eight-year-old who has cortical visual impairment.  And what's really interesting in this drawing is that the eyes and the hair are on the bottom and the mouth is on the top.  Can you see those two circles, kind of half circles on the side?

Those are the ears.  This child has drawn a face, but it's upside down.

It was right-side up to the child...  This is how the child drew it.  And the child described it and said that the eyes and the hair were down here. And so, this is the way a child who has CVI and can communicate through drawing and, you know, describing it, sees.  So, it's just really interesting because things can be really scrambled and, you know, their perception will be really different.