Choosing the Correct Lens
Single Vision
Single-vision lenses correct your vision for just one distance - either close up or far away. In other words, the entire lens is correcting one vision problem. In contrast, multifocal lenses, such as progressives or bifocals, correct vision for two or more distances at the same time.
Lined Bifocal
A two power lens known for the distinct lined separation between corrective distant vision, and close reading vision. Benefits to this style of lens is that it has a larger viewing area for reading, and the transition from distance to close up reading is easy for most.
Lined Trifocal
A three power lens known for the distinct lined separation between corrective distant, intermediate, and close reading vision. Benefits to this lens style is that it corrects for intermediate distance, which includes computer distance along with distant and close-up correction. The separation of the distances is distinct, and easy to transition to for most.
Progressive or No-Line Lenses
Progressive lenses are no-line multifocal lenses that look exactly the same as single vision lenses. In other words, progressive lenses will help you see clearly at all distancese without those annoying (and age-defining) "bifocal lines" that are visible in regular bifocals and trifocals.
Task Specific Lenses
Your everyday eyeglasses and lenses may not be the best choice of eyewear when you are doing repetitive tasks or tasks done at a specific distance from a piece of equipment or object. Your regular glasses are just fine for everyday tasks, but when you spend more than an hour in front of a computer or a specific distance from work equipment, then you have a specific task or specific vision issue that can be corrected with "task specific" eyeglasses. Ask your optician for more details.