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Corridor width refers to the horizontal measurement of the middle portion of a progressive addition lens (PAL). This narrow, central channel (the corridor) connects the distance vision zone at the top to the reading zone at the bottom, providing the intermediate power.
read more about corridor width in progressives ...The corridor width is necessary because it controls the functional viewing area for intermediate tasks like computer use. As the power gradually increases down the lens, the clarity is centered in the corridor. The area to the sides of the corridor contains peripheral distortion.
Corridor width affects the lens design significantly. A wide corridor is easier to adapt to but increases the lens thickness and size. A narrow corridor allows for a smaller, thinner lens but makes the sweet spot harder to find, requiring more precise eye movement.
Corridor distortion is the blurriness that occurs on the sides of the corridor. When looking through the correct zone, vision is clear. When moving the eyes horizontally outside the corridor, the distortion can cause a "swimming" sensation or imbalance.
The design of the corridor impacts your backup glasses experience. Since contacts provide seamless vision at all distances, switching to a wide-corridor progressive lens can feel more natural. A stable, comfortable progressive is important for consistent vision when contacts are out.
Yes, the prescription's complexity and the required reading power can influence the size and shape of the corridor.
Yes, many modern lens designs allow the optician to select a wider corridor, which is helpful for computer users, but it may increase peripheral distortion.
The corridors are designed so that when the eyes converge slightly, both eyes are looking through the clearest part of the lens.
If you feel you have a "narrow" field of view in your progressives, ask about "free-form" or digitally surfaced lenses. These offer up to a 30% wider corridor than traditional progressives, significantly reducing the "swaying" sensation in your side vision.
Optical Journal. Evolution of Free-form Technology (opticaljournal.com). 2024.
Review of Optometry. Understanding Progressive Corridors (reviewofoptometry.com). 2023.
ABDO. Spectacle Lens Design (abdo.org.uk). 2024.
AAO. Bifocals and Progressives (aao.org). 2024.