Archived posting to the Leica Users Group, 2011/09/19
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Nice work, Herb. My wife and I are slightly younger than you, but not by much. She has been dealing with a different kind of double vision for about 10 years. She has had cataract surgery and lens implants in both eyes, but that had no effect on the double vision. Her lenses are a combination of bi-focals or tri-focals, combined with prisms, both vertical and horizontal. It requires a sharp, up to date, doctor to figure out the proper corrections, and then it is really trial and error. Jim Nichols Tullahoma, TN USA ----- Original Message ----- From: "Herbert Kanner" <kanner at acm.org> To: "Leica Users Group" <lug at leica-users.org> Sent: Monday, September 19, 2011 8:18 PM Subject: [Leica] OT Vision phenomenon > Here is an interesting visual problem that I figured out abut a year ago. > The explanation will have meaning to photographers. > > A year or more ago I noticed a strange double vision in my right eye. It > varied in extent from day to day, but looking at a vertical post, e.g. the > post of a street light, I would see a faint ghost image displaced slightly > to the right. > The ophthalmologist had no explanation. > > Ultimately, I noticed a very interesting effect when looking at traffic > lights from about a block away. A green light expanded into a triangle of > the light and two ghost images below it. A red light was only barely > affected. Hah, wave-length dependent; has to be refraction. > > A lot of thought as to what the hell could it be, and suddenly I had an > aha moment. As you age, the gel in the eye withdraws from the retina. It > had to be a tiny bit of the gel that stuck to the retina. Think about the > micro-prisms that are the focusing aid on the screen of an SLR. > > I confirmed this with my glasses. I wear trifocals. If I shifted my > glasses so that I was looking at the traffic light through the > mid-distance portion, the size of the triangle increased. > > My ophthalmologist was amazed. > > Herb > -- > Herbert Kanner > kanner at acm.org > 650-326-8204 > > Do not meddle in the affairs of cats, > for they are subtle and will pee > on your computer! > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information > >