Office lenses, also known as computer lenses or near variable focus lenses, are a specialized type of multifocal eyewear designed for individuals experiencing presbyopia, the age-related loss of near focusing ability. Their design is task-specific, providing clear and comfortable vision specifically for intermediate and near working distances, such as viewing a computer screen or reading a document. This specialization makes them a highly effective solution for alleviating the visual strain and discomfort that often accompanies prolonged work at a desk.
The Optical Design for Intermediate Tasks
The technical foundation of office lenses is a “degressive” power design, which means the lens power changes gradually across a vertical corridor, similar to a progressive lens. Unlike single-vision reading glasses that only offer one fixed focal distance, office lenses transition smoothly from a lower power at the top to a higher, full reading power at the bottom. The upper portion of the lens is precisely calibrated for the intermediate zone, which typically corresponds to the distance of a computer monitor, generally 20 to 40 inches away.
The power then increases as the wearer looks downward, reaching the full near-vision prescription in the lower lens area, optimized for reading materials held at a typical 16-inch distance. This gradual power change, or corridor, is engineered to be significantly wider than in a standard progressive lens. The resulting expansive field of view gives the wearer a wide, comfortable zone for viewing a large computer screen without the need for constant, subtle head movements to find the “sweet spot.”
The design minimizes the peripheral distortion common in the edges of general-purpose progressive lenses. By providing a broad, distortion-free area for the most common working distances, the lens promotes a more natural and relaxed head and neck posture. This reduces physical discomfort over long periods of desk work.
Distinguishing Them from Progressive Lenses
The fundamental difference between office lenses and standard Progressive Addition Lenses (PALs) lies in the prioritization of the visual zones. A PAL is designed as an “all-in-one” lens, dedicating the top portion to distance vision, a narrow central corridor to intermediate vision, and the bottom to near vision. The goal of a PAL is versatility for all-day use, including driving and walking.
Office lenses, by contrast, eliminate the distance vision zone entirely or limit it severely to a maximum range of a few meters. This design modification allows the optical laboratory to dedicate the majority of the lens surface area to the intermediate and near zones that are required for desk work. This shift in focus results in a much broader and more accessible corridor for computer and reading distances.
When a person with presbyopia uses a standard PAL for extended computer work, they must often tilt their head back to align their eye gaze with the narrow intermediate corridor in the middle of the lens. Maintaining this unnatural head posture for several hours can quickly lead to neck, shoulder, and back strain. Office lenses solve this ergonomic problem by placing the intermediate power high in the lens, allowing the wearer to view the screen with a natural head position.
The trade-off for this enhanced indoor clarity is that office lenses are not suitable for driving or tasks requiring clear far vision. They function as a dedicated, task-specific pair of glasses, complementing a standard pair of PALs or distance glasses.
Selecting the Appropriate Working Range
Office lenses are available in different designs tailored to the user’s typical working environment and required depth of field. The customization process begins with the eye care professional accurately measuring the individual’s specific working distances, such as the distance from the eye to the computer screen and to any reading material. This data is used to calculate the necessary “degressing” power, which is the reduction in power from the full reading prescription needed to achieve clarity at the intermediate distance.
These lenses are generally categorized by the maximum clear distance they provide. “PC Lenses” or “Computer Lenses” are highly specialized, offering the widest possible intermediate field of view but limiting the maximum clear range to about one to two meters, optimized strictly for a desk and arm’s reach. This type is best for those whose work is confined to a single workstation.
Alternatively, “Room Lenses” or “Extended Range” lenses offer a slightly narrower but still generous intermediate corridor and extend the maximum clear range up to about three or four meters. This design is suitable for people who need to see a computer, read a document, and also clearly view colleagues across a small office or a presentation screen across a conference room.