Sometime in your early to mid-40s, a condition called “presbyopia” sets in. This process causes blurred vision when trying to read material that is held close to you.

When this happens, a prescription for glasses or contact lenses can be given to provide clear up-close vision. It is, however, a different prescription than a prescription to provide clear distance vision.

Along came computers, and we found we needed a third prescription for intermediate range (closer than the distance but farther out than the average reading material).

The bifocal became a trifocal, and then the progressive (which provides a continuum of foci from distance to near) became the most recent addition in glasses lens options.

With glasses lenses, the eye looks through a different area of the lens depending on the distance you are viewing. The top of the lens contains the distance prescription, the bottom contains the reading prescription, and in between contains the intermediate, if it is a trifocal or progressive lens.

Soft contact lenses always center on the eye, meaning you cannot chose which portion of the lens to look through by moving your eye. A bifocal or multifocal contact lens thus necessitated a much different design.

To create a multifocal contact lens, the engineers came up with something they’ve dubbed “simultaneous viewing.” This is a fancy way of saying you are looking through both distance and near foci at the same time.

These lenses are designed in a concentric ring pattern where the center of the lens is either distance or near and you get the opposite focus as you work your way to the periphery of the lens.

There are pros and cons to this. The biggest pro is that, unlike glasses, the adaptation period to the multifocal contact lens is minimal. You don’t have to learn how to look through the lens in the right spot.

The biggest con is that you don’t get 100 percent pure distance or reading foci. This means that you will sacrifice some of your clarity to have the convenience of distance and reading vision.

No lens is perfect, but the multifocal contact lenses should provide you with good vision for 90 percent of your tasks. There is some “play” with these lenses, meaning we adjust the portion of reading and distance vision to best meet your daily needs.

The first lens we start with often has to be tweaked to land at the right combination for each individual patient. Multifocal contact lenses are a great option for active, busy lifestyles, but don’t meet the needs of everyone.

If you’re sick of glasses, it doesn’t hurt to ask your eye care provider if you are a good candidate for contacts.

Caroline Bundrick, O.D. is an optometrist practicing at Darling Eye Center, with offices in Bluffton and on Hilton Head Island.