Terms and phrases used in the optical industry and on this site:
Frame 'Fit' - The way the glasses fit on different size faces like, Medium Fit for a Medium size face.
Frame 'Size' - The optical size of the glasses, lens, bridge, and temple in millimeters. More below.
Frame 'Lens Size' - The horizontal distance across the center of a lens in millimeters.
Frame 'Bridge Size' - The width of the bridge in millimeters.
Frame 'Temple Length' - The length of the temples in millimeters.
Frame 'Lens Height' - The vertical height of a lens in millimeters.
Frame Materials - The material the eyeglass frames are made of, TR90, Metal, Titanium, etc...
Frame Features - Notable or unique features like "Ultra-light", "Hypoallergenic", "Eco-friendly", etc...
Readers, Cheaters, Pre-made Readers - Over the counter reading glasses pre-made with magnifying lenses.
Reading Glasses - Can be pre-made, custom made, or with prescription lenses.
Learn more about our Frame Sizing
EYEGLASS LENSES MATERIALS AND FEATURES:
Aspheric Lenses - Thinner and flatter than non-aspheric lenses. Especially noticeable in plus power lenses.
CR39 Resin Lenses (1.498 Index) - Traditional, (since 1940), plastic lenses that tend to be heavy and thick especially in moderate to high powers.
High Index or 1.6, 1.7, 1.74 Index Lenses - Thinner, lighter, and higher index than CR39 lens materials.
Polycarbonate Lenses (1.586 Index) - Thin, light weight, very impact resistant lenses.
Scratch Resistant Coating or "SR" - A coating added to a lens surface to make the lens more durable.
UV400 - In CR39 UV400 is an additional treatment to filter UV light to 400nm. Polycarbonate and high index lenses have UV400 built into the material already.
Learn more about Frame Materials
'Reader' Lenses - (Non Prescription) Single vision lenses with basic magnification for reading.
'Rx' or Prescription Single Vision Lenses - Corrective lenses for particular distances, Near Reading, Intermediate, and Distance. Correction for astigmatism and prism can be included. The PD or Pupilarry Distance Measurement is required to line up the optical centers of the lenses with the wearer's pupils.
'Bifocal Reader Lenses' or Lined Bifocals - (Non Prescription) Bifocal Reader Lenses have a line, usually 28mm in length. Below the line is for up close vision and above the line can be for either zero power or for computer/intermediate distance (Computer Bifocal)
'No-Line Bifocal Reader Lenses' - (Non Prescription) Progressive lenses that have no line. The power "progresses" from top to bottom. Like the Bifocal Reader Lenses, the top can be either zero power or for computer.
'Plano' or Zero Power Lenses - Lenses with no magnification or correction.
Progressive Lenses - No-Line multifocal lenses have a channel in the lens. The lens power below the top, progresses in plus power through the channel to the bottom for reading. Modern digital progressive lenses have wide comfortable channels. These lenses can be configured for distance to reading prescriptions as well as computer or office distance to reading. They can be made in any lens material including high index and photochromic lenses.
See our Reading Lens Guide
See our Rx Lens Guide
AR Coating or "AR" - A multi-layer mineral lens coating that "pulls" more light through the lens to your eyes. AR coatings reduce surface reflections dramatically providing better optics and a glare-free look.
Blue Block / BluBlock - A lens or a treatment that prevents a certain amount of blue light (400nm to 500nm) from getting through the lenses.
Blue Block AR Coating - A Anti-reflective coating that selectively reflects away a percentage of HEV blue light. Some lenses provide a level of blue light filtration as well.
Blue Block Tint - A dye absorbed into the lenses that filters a certain level of blue light from (~420nm to 550nm).
Cosmetic Tint - A dye absorbed into the lenses that offers a level of color and cosmetic appeal.
Photochromic Lenses - Lenses that darken based on how much light enters the lens material. These lenses offer the benefit of wearing one pair of glasses for indoors and outside in the sun.
Steve Mower is a licensed Optician and creator of Mojo BluBlock Tints. Steve has over 30 years experience in the optical field. He has been a optical retail manager and has consulted on progressive lens development. Steve has been offering unique reading glasses solutions on-line since 2010.