Product Development And Low Vision Devices

Product Development

Development of Distance Vision Charts in Logmar Notation

LogMAR charts are generally used for precise vision assessment in cases with vision impairment. The centre has developed Logmar charts for the first time in the country, in collaboration with the B & L School. We have high contrast logMAR charts available with letter and tumbling 'E' optotypes. These charts are available for sale.

Low vision assessment kit for eye care professionals in developing countries

This LVA kit is designed for the professionals starting low vision care at secondary level, in developing countries. Kit contents were decided based on our experience and the feedback from eminent professionals working in the area of low vision. The kit comes with an instructional manual explaining the use of each device. For list of kit content click here or write to us at

Vision Stimulation materials

Lack of vision interferes with all other normal developmental processes.  As a result they are often delayed in almost all aspects of growing; acquiring language, motor & interpersonal skills abstract thinking & self care abilities.  Vision is a learned and developed skill that requires stimulation and experience. Like learning to walk and talk, children must learn how to use their vision.   The vision stimulation materials developed at The centre helps children to improve the child’s eyesight, eye movement skills, eye teaming, focusing, depth perception, color vision, peripheral vision, visual perception and processing, and the ability to integrate all of this information with our other senses.

Development of Distance Vision Charts in Logmar Notation

LogMAR charts are generally used for precise vision assessment in cases with vision impairment. The centre has developed Logmar charts for the first time in the country, in collaboration with the B & L School. We have high contrast logMAR charts available with letter and tumbling 'E' optotypes. These charts are available for sale.

Low Vision Devices (LVDs)

A low vision device is any device that enables a person to improve his or her visual performance. Many people confuse low vision devices with standard eyeglasses. But there is a difference - LVDs provide some degree of magnification while standard glasses only focus the image for the eye. The use of magnification may lead to some amount of distortion but the image is enlarged, making it easier to see.

Low vision devices are the tools of trade in low vision care. They help low vision patients to acquire functional vision for practical everyday purposes like reading the newspaper, writing a letter, or cutting vegetables and cooking.

Besides using an optical device to magnify or enlarge the retinal image, actually bringing an object closer or enlarging the print can be of great help to the visually impaired.

Categories of low vision devices


Distance vision telescopes are the only form of optical devices that assist a person with low vision with distance tasks, where conventional glasses are unsuccessful. They improve the resolution of objects by enlarging the image, thus bringing the object closer (angular magnification). 

The closer the telescope is held to the eye, the larger the field of view gets. Therefore, it helps if the user wears the refractive device. However, telescopes are also available as hand-held devices for single eye or monocular use, in powers of 2X, 3x, and 4x magnification. 

These telescopes can be used for the following distance vision tasks:

  • Specific tasks requiring magnification at variable distances, like reading from the black board and recognizing faces at a distance 
  • Spot-distance viewing, like watching television and sports events, or seeing bus numbers and street signs, so that one can travel unassisted.

Although telescopic devices can be of tremendous help in many different situations, they may not always be immediately accepted or incorporated into the daily routine. They may appear clumsy and unattractive, and may be rejected for cosmetic reasons. Moreover, they reduce the field of view; that is, your view of the distance is much narrower through a telescope although it may be much clearer. 

Telescopes can disrupt spatial judgement as the object appears closer than it is. Low vision telescopes can be most useful if accompanied by a concentrated and careful instructional training program which includes localization, fixation, scanning and tracking.


Magnifiers could be either hand-held or mounted on stands and are designed to help low vision patients with short-term spotting tasks. Both the hand-held and the stand-mounted magnifier can be illuminated for better contrast.

The typical uses of magnifiers are:

  • For reading newspapers and books for short periods
  • Checking labels and prices while shopping
  • Reading dials, gauges, and measuring tapes at work
  • Checking mail, phone numbers, and addresses
  • Magnifiers can also be used as a training aid for patients who don't like the close working distance of spectacles.

Various low vision devices are available in India; a list of the manufacturers and their addresses can be accessed from this site.

Varieties of Magnifiers:

Spectacle Magnifiers

Low vision spectacles are monocular or binocular convex reading lenses mounted in standard full diameter or half-eye frame. The convex lens functions to enlarge the images projected on the retina. The lenticular design lenses have less peripheral abrasions. The powers range up to + 24.00Ds. Spectacle magnifiers are used for tasks such as long-term reading, writing, needlework, making invoices and receipts etc. This device is available in India.

The advantages of spectacle magnifiers are:

  • They feel psychologically more comfortable and can be more easily incorporated into one's daily life in comparison to a telescope.
  • Spectacles are particularly useful for prolonged reading.
  • They provide the widest field of view.

Low vision spectacles leave your hands free and make jobs requiring manual adjustments and manipulations easier to perform.

Like telescopes, low vision spectacles also have some disadvantages:

  • They require closer working distances, which may obstruct illumination and make writing difficult if the lens add is stronger than +10 D.
  • They can be inconvenient (because you might need to change glasses) for spot reading tasks, where information is gained from single words or short phrases, such as price tags.
  • They are difficult to use for patients with eccentric viewing that requires eye/head turns as the working distance and optical centre is fixed.

Hand-held Magnifiers

Hand-held magnifiers are convex lenses mounted with a handle so that they may be held in the hand rather than mounted on glasses. The closer the lens is held to the eye, the larger is the field of view. Small pocket magnifiers fit easily into the pocket or purse, and are relatively inexpensive. However, the reading speed and duration are usually slower than with spectacles. The powers range from 10 - 24 diopters. This device is available in India.


  • They are generally inexpensive and readily available.
  • They can be used for reading at more customary distances in the low power range.
  • Mounted magnifiers are familiar devices and are easily assimilated into the normal daily life.
  • They are handy for spot reading tasks, in which information is gained from single words or short phrases, like price tags.
  • They are portable and provide a variable working distance.
  • They can also be used in combination with the patient's spectacle correction. This is important if the patient has a strong cylinder power.


  • They must be held with one hand or, sometimes, with both hands.
  • They are uncomfortable and could cause hand and arm fatigue with extended use. The reduced field of view also slows down reading.
  • They must be held at the correct focal distance for maximum power.
  • They can be difficult to use for patients with limited dexterity or hand tremors.
  • They provide a limited field of view in comparison to spectacles.
  • They are somewhat less effective than spectacle frames with the same power.

Stand Magnifier

A fixed focus stand is a convex lens in a rigid mount that has been set by the manufacturer to focus closer to the page than its focal distance, to reduce peripheral aberration. Most stand magnifiers are designed for use with a standard bifocal add or reading glasses. Powers available : 24 diopters.


  • They can be handy optical devices because the focal distance is stable.
  • They are particularly suitable for patients with hand tremors.
  • They are especially useful for patients who have difficulty in finding or maintaining the correct distance when using spectacles or hand magnifiers.
  • They are useful for patients with a constricted visual field, when held at arm's length.
  • They are also available with a built-in light source, which can be highly effective in enhancing contrast.


  • They have limited mobility, being inconvenient to carry around.
  • They are awkward to use on non-flat surfaces; they require the use of a reading stand.
  • They have a limited field of view.
  • They can cause excess shading and reduce the amount of light on the viewing surface, unless self-illuminated.
  • Most available designs make writing difficult, if not impossible.
  • Prolonged use of these devices may result in poor posture, unless a reading stand is used.

Glare Control Devices

Glare is distracting scattered light, which is a major problem for patients with low vision. Glare can be controlled with devices such as sun-wear or absorptive lenses, tints and ultraviolet coatings, and anti-reflective coatings.

Absorptive Lenses: (for glare control)

  • Tinted sun glasses with side shields: grey, brown and yellow
  • Tinted clip-on sun glasses: grey, green and yellow

Non-optical Devices

  • Reading lamp (long arm adjustable with 60w incandescent or 11w fluorescent bulb) Stellar - Philips
  • Reading stand 
  • Reading guide
  • Writing guide
  • Signature guide
  • Bold line paper
  • Felt-tipped pen (Black ink)
  • Soft lead pencil (3B)
  • Notex (Currency identification)
  • Needle threader

Various low vision devices are available in India; a list of the manufacturers and their addresses can be accessed from this site.

Contact details

National and international manufacturers/dealers of assistive devices

1. Karishma enterprises
132, market tower B, Cuffe Parade,
Mumbai – 400 005
Tel: 022-22181853; Fax: 022-22153291

66/2, D2, MIDC Area, Chinchwad,
Pune – 411 019
Tel: 7474581/7474340
Fax: 020-7470212

614, Jagannath Shankarseth Marg
Dhobi Talao,
Mumbai – 400 002
Tel:   22014906 / 22014923
Fax:  22064363

F-90/3D, Okhla Industrial Area,
Phase - I (Near E.S.I Hospital)
New Delhi - 110 020
Mobile: 9810333853
Tel: 91-11- 42701030, 42701031,          
Fax: 91-11-23844778

111, Anand Dham
10th Road, Khar (W)
Mumbai – 400 052
Tel: 22-2649 7318

6. Barrier Break Technologies
101, Highway Commercial Complex,
IB Patel Road, Goregoan (E),
Mumbai- 400 063,
Phone: +91 (22) 2685 9730/ 2686 0485/6 cell: +91 99202 29081

7. Om Tao Scientific Apparatus
3-2-320/2, Chapal Bazar,
HYDERABAD – 500 027
Tel: 9885054759

8. JUTRON Vision
A-6, NAND Complex Near Aims Oxygen Juna Padra Road,
Phone: +91 –99987-02020
Fax: 91-265-2321323

9. Vision-Aid Charitable Services Society,
16-2-19, Official Colony,
Visakhapatnam – 530002
Tel : 98-49498800
111 East 59th Street
New York, NY 10022 - 1202
Tel (212) 821 - 9200
      (800) 829 - 0500
Fax (212) 821 - 9707
TTY (212) 821 - 9713

2/F, East Wing, Headquarters Building,
248 Nam Cheong Street,
Shamshuipo, Kowloon
Tel: (852) 2778 8332 ext: 397 / 383
Email: /

109 Conner Drive,
Suite 2105,Chapel Hill,
NC – 27514, USA
(800) 326-6460, (919) 967-6460
(919) 967-8146

13. ABISee, INC
141 Parker St, Suite 201, Maynard
MA 01754 800-681-5909

14. Telesensory
520 Almanor Avenue,
Sunnyvale, CA 94085

15. Dolphin Computer Access Ltd.
Technology House,
Blackpole Estate West,
United Kingdom
Tel: +44 (0) 1905 754 577
Fax: +44 (0) 1905 754 559

16. Freedom Scientific’s
11800 31st Court North
St. Petersburg, FL 33716-1805
Tel: 1-727-803-8000 (worldwide)
Fax: 1-727-803-80

L V Prasad Eye Institute
Vision Rehabilitation Centres
L V Prasad Marg, Banjara Hills, 
Hyderabad - 500 034
Tel: +91-40-3061 2821
Fax: +91-40-2354 8271