Thanks to eye medications containing benzalconium chloride to which I appear to be allergic, I have a deterioration of vision due to scarring. The visual effect is similar to that caused by keratoconus (see Wikipedia http://en.wikipedia.org/wiki/File:Kc_simulation.jpg) and for point of light, I see about 5 degraded images (again see Wikipedia http://upload.wikimedia.org/wikipedia/en/thumb/d/d7/Kc_simulation2.png/220px-Kc_simulation2.png). When travelling in the car, I have difficulty identifying speed limit signs showing anything from 30, 50, 60, 80,90 since they all look like a blurred 80 until I am about 5 yards from them which is not satisfactory for driving purposes. When I saw the ophthalmologist last I complained about my visual deterioration and he said it was due to the scarring and nothing could be done. Looking at keratoconus and other corneal defects and the treatments for them, I wonder of either a corneal implant or a contact lens could counter the effects of the scarring. Your advice would be most welcome.