This is a question that is often asked by people who are suffering from age-related macular degeneration (AMD). AMD affects the part of the eye that deals with detail and close-up vision. So very often, poor reading vision is a symptom of this condition.
Younger glasses users
Now, when they are younger, most patients will have traditionally had problems with reading vision corrected by a change in their reading glasses’ prescription. We just give the prescription a “tweak” or “make it a bit stronger” and hey presto! You can read clearly again. This is because the lenses in your reading glasses are correcting a condition called presbyopia (literally “Old Eyes”), where the lens in your eye loses some of its flexibility over time and is unable to focus light on to the retina. The part of your eye that contains all of the cells makes sense of the images coming in. It’s a bit like the film in a camera.
How your eye works
Your retina is made up of lots of very clever, light-sensitive cells that help give depth, colour and detail to the images thrown at them. In particular, there is a large collection of cells in the middle of the retina called the macular and this is the area that deals with detail and, crucially, reading vision.
The reason for sight worsening
This part of the eye requires lots and lots of healthy vitamin production within the body to stay healthy and unfortunately, as we get older, our bodies ability to produce healthy vitamins decreases. This, in turn, can have a degenerative effect on those light-sensitive cells in the macular, hence the name age-related macular degeneration. Unfortunately, any damage done cannot be undone (although it can be slowed down).
As we said earlier, the macular is like the film in a camera. And just like the film in a camera, regardless of how strong the lens is (in this case, the lenses in your reading glasses), if it’s damaged you cannot get a good quality image. Macular degeneration puts a limit on how much improvement is possible through spectacle lenses, and that is why you can’t just make the lenses “a bit stronger”.