Many, Many Magnifications
Hi! The last time I wrote I had started to tell you about the great stuff I got from BBVS. I am going to get there, but first I want to do a bit of teaching. Get ready for the educational part of our program!
We talked about scotomata. Singular is scotoma. They are blind spots. If something is in your blind spot totally, you will not see it.
How do we get it so you can see it? Sometimes we use eccentric viewing. We covered that. That is training yourself to use peripheral parts of your retina. Another way is to make the image big enough that it “sticks out” around the edges of your scotoma. Then you can use visual closure to fill in the rest. Visual closure is a perceptual skill. If I would draw a curved line, but not quite close it, visual closure would tell you it was supposed to be a circle.
Many, many magnifications
Now, class, how do we get something to stick out from behind our scotomata? Yep, we magnify it.
There are actually four ways of magnifying an image:
One is relative-size magnification. Bigger things look bigger. This is the concept my colleagues use sometimes if they write me a note. They write REALLY BIG!
The second type of magnification is relative-distance magnification. That is, closer things look bigger. This is the concept I use when I read a text message. I practically hang my phone on the end of my nose! It is also the same concept I use when I watch TV on my tablet.
Oh, by the way, you can get lots of shows on your iPad. The apps are free. While your mother was wrong - sitting inches from the tv does not hurt you - if you sit directly in front of the tv to watch now, your family may hurt you! Holding your iPad inches from your nose and watching that way gets you your shows and avoids the bloodshed!
The third way is angular modification. When I look that term up, I get a lot of gobbledygook that sounds suspiciously like calculus. It has been nearly 50 years since I had calculus! Let us skip the math stuff; shall we?
Angular magnification uses lenses. This was my father’ and my grandfather's answer to AMD and this is where I started before I got my toys.
Let us just say handheld lenses (like magnifying glasses) were better than nothing. Handheld lenses took in very little at any one time. They also had to be held very still. I don’t know about you, but holding something in the same position for a long time? I start to shake. Now THAT was fun. Not!
That does not, however, mean I never use lenses to magnify. I have both monoculars and binoculars. They are good when you cannot, or should not, get too close or when whatever you are looking at cannot be put under your electronic magnifier. I also have a very nerdy looking pair of Max TV glasses I use when I teach and want to see my students.
The fourth way of magnifying is electronic magnification. This is where we came in.
Have you visited our new sister site, ChronicDryEye.net?