September 25, 2005

Descriptions of Low Vision Magnifiers

Posted in: Daily Living


Device

Description

Advantages

Disadvantages
Hand-held magnifier “Sherlock Holmes” type portable magnifying glass. Small and inexpensive. Available in a wide range of powers (1.5X – 8X). Socially-accepted. Leaves only one hand free. Difficult to keep in focus if hand trembles. Clamps with flexible arms are available for attaching to table tops.
Illuminated hand-held magnifier Portable lens with handle and built-in battery-operated light. Small and inexpensive. Available in a wide range of powers (1.5X – 8X). Socially-accepted. Useful for dim subject areas. Leaves only one hand free. Difficult to keep in focus if hand trembles. Clamps with flexible arms are available for attaching to table tops.
Stand magnifier Magnifier on a stand with built-in legs for table tops or books. Maintains steady focal distance. Comes in a wide range of powers (1.7X – 8X). Possible to write beneath and use both hands. Bulkier than hand-held device. Sometimes difficult to get sufficient light between the lens and the subject.
Hand/Stand magnifier Combination of hand-held and stand magnifier. Can be used as either by folding handle and legs, so more portable than a regular stand magnifier. Comes in powers of 2.5X – 3X). None.
Illuminated stand magnifier Illuminated magnifier on a stand with built-in legs for table tops or books. Light source is either a built-in battery-operated bulb, a halogen lamp (A/C), or the more superior LED illumination (D/C). Provides shadowless light close to the subject. Maintains steady focal distance. Comes in a wide range of powers (1.7X – 8X). Difficult to write beneath most models. Even more bulky than an ordinary stand magnifier. Battery-operated models (except LED version) can be expensive to run.
Illuminated bench magnifier Same as above, but mounted on an adjustable arm mounted to a table top or work bench. Good for using both hands for sewing, hobbies, etc. Limited magnification (rarely above 3X). Comparatively expensive.
Dome/Bright Field magnifier Half-spherical magnifier (like a paper weight) that rests directly on the page. Largest dome available is 90mm. Always in focus. Distributes light well onto the surface. Made of heavy glass, rather than plastic.
Bar magnifier Semi-cylendrical lens which rests directly on the page, magnifying one line of print at a time. Makes tracking of a line of text easier. Limited level of magnification power (up to 3X). Reflected light and distortion can be problematic.
Spectacle-mounted magnifier Magnification lenses mounted on spectacles. Leaves both hands free. Short working distance, due to limited level of magnification power of up to 3X. Single magnifying lenses (for one eye only) are available from 4X to 12X.
Clip-on magnifier Magnifying lens which attaches to regular spectacles. Binocular versions available in powers 2X – 4X. Monocular versions available up to 7X. Leaves both hands free. Short working distance, due to limited level of magnification power.
Hand-held or spectacle-mounted telescope Telescopes of low magnification (up to 4X), which can be mounted on spectacles for near intermediate and distance viewing. Good for reading music, viewing TV or plays, reading signs, etc. Restricted field of view. Best for stationary viewing. Focus is fixed, except for the more expensive “Ocutech” model, which mounts on spectacles and features an auto-focus capability.
Field expanders/minifiers Lenses which reduce the apparent size of the subject (like a “peephole” in a door). Useful for people with good central vision, but diminished peripheral vision. None.
Closed circuit television (CCTV)/Video magnifier Device utilizing a camera and monitor to magnify a page or object. The display can be monochrome or full color, and the products are available in a variety of screen sizes and magnification levels. Some models are designed for interconnection with computers. All models allow adjusting contrast and reversing black and white. Books and objects can be placed beneath the camera for viewing. Sufficient room to write. Comparatively expensive. Not portable.
Portable closed circuit television (CCTV)/Video magnifier Portable magnifying device utilizing a camera approximately the size of a computer mouse, plus an interface for connecting to a standard television or head-mounted display. Most models allow changes in magnification, adjusting contrast and reversing black and white. Can be carried in a purse or backpack. Battery power option. Less expensive than stationary CCTV models. Some practice required for smooth operation of the hand-held camera. One-handed operation. Cannot be used for magnification of writing or hand work.
Portable video magnifier Portable magnifying device with a self-contained camera and viewing screen. Some models allow freeze-framing. Most models allow changes in magnification, adjusting contrast and reversing black and white. Can be carried in a purse or backpack, or in its own carrying case. Battery power option. Less expensive than stationary CCTV models, but more expensive than a portable CCTV without a viewing screen. Useful for reading labels or menus, writing checks, and performing other close-up tasks not requiring a wide field of view. Field of view is too small for reading books.

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