Single vision lenses are for correction for one field of vision. Either for distance, intermediate (computer), or near vision (reading).
Instead of having just two or three lens powers like bifocals or trifocals, progressive lenses are true "multifocal" lenses that provide a seamless progression of many lens powers for all viewing distances. With progressive lenses, you can look up to see clearly across the room and in the distance.
Photochromic lenses are eyeglass lenses that darken automatically when exposed to sunlight, then fade back when you return indoors. In most cases, photochromic lenses are clear (or nearly clear) indoors and darken to a medium sun tint outdoors. But there are exceptions.
Protect your eyesight and see clearly outdoors with polarized prescription sunglasses. With polarized lenses, you'll see less glare and more contrast - a combination that results in enhanced, comfortable vision.
Anti-reflective coating reduces glare and halos around lights at night and eliminates unattractive reflections on your lenses.