In neutral eyes the trouble starts between the ages of 45 to 50, sometimes even later. In hyper-far-sighted eyes it begins between the ages of 40 to 45. Near-sighted eyes of minus 3.00 or more, who wear no glasses, have no near vision trouble when they get old.
It is the loss of flexibility in the bending apparatus or ciliary mechanism of your eyes that is the cause of the trouble. You can not bend your eyes for nearer seeing as well as you could when you were younger. To see at 13 inches neutral eyes have to bend 3.00d. and at 20 inches only 2.00d. That is why you can see better holding your newspaper farther away. If you get pair of plus 1.00 glasses, you have to bend your eyes only 2.00d. Again, you can see well at 13 inches. The plus 1.00 glasses make your eyes 1.00d. near-sighted and blur the distant vision.
Between the ages of 50 and 60, you lose more bending ability. Again you have to hold your near work farther away and again it begins to blur. You get a pair of plus 2.00d. glasses and again you can see well at 13 inches. Between the ages of 60 and 70 you may lose all your bending ability and you may have to get a pair of plus 3.00d. glasses to see tiny objects nearby. The distant vision of neutral eyes seldom fails. You are old. You cannot see to read without glasses, but for distant seeing you can see well with your naked eyes.
It is different with hyper or hyper-far-sighted eyes. Signs of trouble begin in the eairly forties and sometimes sooner. First the blur is noticed in near work, but sooner or later, the distant vision also begins to blur. Hyper-far-sighted persons have to bend their eyes even for distant seeing. When a person gets older he loses that bending ability. The vision begins to blur and there is much effort even in distant seeing. A pair of plus 1.00 glasses for distant seeing will, in most cases, make him see well again and also relieve the strain on the eyes. For near-seeing, hyper-sighted eyes have to add more plus to their distant glasses. A pair of bi-focal glasses will make him see both, far and near.
Contents | Lesson 19 | "Has Sight Theory"