Presbyopia gradually becomes more pronounced as we age, until about the age of 65 when we usually have lost all our ability to accommodate. Presby comes from the same word root as Presby terian, and means elder as in church elder. Opia is a Greek root and refers to the eye. Optical Glass Prismatic Lenses Ground and polished to precision optical standards. The hood keeps light from reflecting off the back of the lenses, thus increasing the contrast ratio.
Contrast ratio is the difference between the brightest and darkest point in an image.
Better contrast ratio lets you see details you would miss otherwise. The distance in focus also depends on the amount of illumination - the brighter the field, the more your iris will constrict providing a greater depth of focus. The depth of field is the minimum to maximum distance in focus. Supply limited - get them while they are here. Prices subject to change. .