Hi, Dr. Ed Huggett here. (I) wanted to answer some questions today about how do we test for low vision?
What actually is done to see if a person is visually impaired, and how can we test for that?
Well, three of the things we look at - one is we look at what's called visual acuity.
How small letter, how small word can we actually make out?
One of the many cards I use is a... we call it the game card and you can obviously see why it's called the game card.
And we've got words that go all the way down into very, very small words.
Top word, there is 2,400, and this typically is tested right at about 16 inches.
So right at the 16 inch distance, we're testing to see how small a word a person could actually make out because you know, it actually, can be a different measure of whether you're testing the letters versus actually words.
And I like to test word acuity. I call this word acuity because that's more to like, more to actual vision.
Other thing that we test for is what's called your field division.
How far can you see to the side, your peripheral vision?
Do you have a problem with your, your central vision? Maybe with macular degeneration, your central vision is impaired and you'll only have peripheral vision.
Or you have a visual field cut like a what's called a Hemianopsia where you may have lost vision due to head trauma.
You could have lost vision to a stroke. And sometimes after surgery that occurs, if you have some type of brain surgery.
So, acuity, your field of vision and one of the things that's rarely ever tested that I test for on a routine basis, and that's called contrast sensitivity.
Contrast sensitivity is how much contrast do you need to be able to see what you want to see.
And you can see on this test here, each letter is slightly less contrast than the previous.
Fades out that looks like almost nothing at the bottom, but then believe it or not, there are letters across, down here.
So contrast sensitivity is very, very critical, and we'll be talking about that in the next video. If you have questions, any comments, please leave them here. Like our video and YouTube channel. And we'll talk to you soon.