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Editorial

Low vision aids

A boon

Natarajan, Sundaram

Author Information
Indian Journal of Ophthalmology: May 2013 - Volume 61 - Issue 5 - p 191-192
doi: 10.4103/0301-4738.113314
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Dear Friends,

It gives me great pleasure to write the last summer editorial of this Diamond Jubilee year of Indian Journal of Ophthalmology (IJO).

We live in an era when technology in every field is growing exponentially. High tech gadgets have given us innumerable ways to improve our quality of life. Here, I write to you about an important but underutilized modality of vision rehabilitation using currently available options.

A person with low vision is one who has permanent visual impairment with best corrected visual acuity (BCVA) less than 6/18 to perception of light or central visual field <10° because of an untreatable cause in both eyes, but who uses, or is potentially able to use, vision for the planning and/or execution of a task.[1] As it does not include patients with treatable causes (refractive errors, cataract, posterior capsular opacification, and corneal scars, clinically judged to be treatable by penetrating keratoplasty), it identifies patients who will benefit from low vision services.

The leading causes of noncurable visual impairment include retinal disease (age-related macular degeneration, diabetic retinopathy, hereditary dystrophies, myopic degeneration, etc.), glaucoma, other forms of optic atrophy, amblyopia, corneal disease, endophthalmitis, congenital eye anomalies, and higher visual pathway defects. As noted above, most causes are related to the aging process; hence, the numbers with visual impairment will only rise, as the trend is toward increasing life expectancy. This brings us to focus on the need to rehabilitate the ‘rehabilitative services’.

According to a study, percentage of patients regaining near vision to N8 were from the age related macular degeneration (ARMD) group, followed by glaucoma, diabetic retinopathy, and myopic degeneration.[2]

There are numerous ways to help the patient with low vision remain independent, including making things brighter (by improving illumination, controlling glare, and increasing contrast), bigger, and bolder. Using audio books, e-book reader, and text-to-speech computer software are few available technologies.

Various products are available to magnify reading fonts, which includes optical (telescopes and magnifiers) and electronic devices.

Optical devices, like telescopes, are used for refining distant tasks like reading blackboard, street signs, bus numbers, recognizing faces. These are available as refractive devices to be fitted on to glasses, and as hand held for monocular magnification, which, however, severely restricts the field of view.

Telescopes may be rejected by many patients for cosmetic purposes and problems with spatial judgment as it makes the objects appear nearer. While others may be very happy for the clarity it offers.

Magnifiers are another form of optical devices (hand held, bar, dome, fixed or variable focus stand, spectacle binoculars). These may have inbuilt illumination function. Its prime use is for near tasks like reading newspapers or books, writing and signing, viewing mobile texts, checking price tags, and much more.

Spectacle magnifiers in particular provide widest field of view. Hand held magnifiers are cumbersome, as they are not hands free like their counterparts, making it difficult for patients with tremors and while doing tasks that require use of hands, like writing, etc.

Electronic video magnifiers like closed-circuit TVs (CCTVs) provide distortion free viewing, a large field of view, and a very large range of magnification levels (from 2 to 70 times). Video magnifiers have an advantage over the conventional optical magnifier in being flexible in its larger field of view and greater magnification. However, it may be limited by its display size and power requirements.

E-book readers

E-book readers, for example, the Kindle®, the iPad®, and other electronic readers are used to read the print off the screen and also to listen to audio books. They have longer battery lives and are specially designed such that, the font size may be enlarged and the contrast may be corrected. These make them better readable than the tablet devices. Adding to their advantage, they are easily portable and more affordable than their counterparts like the CCTVs.

Both have text-to-speech functionality and can read aloud to the user. E-readers do not offer the same level of magnification as CCTVs. Some, which emit their own light like the iPad, also offer reversed-polarity (white letters on black background) displays, which helps to reduce glare and makes it easier to read.

Smartphones and tablets

Smartphones and tablets offer a range of apps and built-in functions to help people with low vision: iRead, iLoupe, Tap Magnify, Magnify, iCan See, and iMagnify use the device's camera and light source to magnify and illuminate text. While these apps cannot rival the power of a CCTV, they are portable, cost effective alternatives for those who need some level of magnification. Of course, efficient use of either hand held magnifiers or smartphones requires steady hands.

MapQuest, Ariadne GPS: Available for Apple and Android phones, these apps use global positioning system (GPS) services to track directions and present the same voice-guided instructions. If you make a wrong turn, MapQuest will reroute you automatically.

Voice interface: Voice recognition software on the iPhone 4S, called the Siri allows the user to check the weather, email, or their calendar and also call contacts from the phonebook without having to visually navigate a series of icons.

Color ID: Identifies colors, though not so accurately and uses a text to speech software to speak the color name loud.

In a study, 9 out of every 10 patients improved reading ability by enlarging the font size using the iPad compared with using only their spectacles.[3]

These devices do not use rocket science and are available freely, improve quality of life and foster independence.

Young people are motivated to make the best use of low vision aids (LVA) devices. Children and patients with lesser impairment prefer to use spectacle magnifiers. In contrast, older patients with severe impairment bank on hand held magnifiers.[4]

This issue gives an insight into some of the rare case scenarios including Welder's maculopathy and electrical injury resulting in retinal thermal coagulation. These case reports are investigated with the use of OCT, thus providing a hope to their further research and management. Also, a fresh look at a very interesting and novel concept of coculture of limbal and conjunctival epithelial cells. As noted in the article, this single step technique is particularly useful when conjunctival, in addition to the corneal surface is affected.

1. . World Health Organization. The Management of Low Vision in Children Report of a WHO Consultation (Bangkok, July 1992). 1993 Geneva World Health Organization WHO/PBL/93.27
2. Margrain TH. Helping blind and partially sighted people to read: The effectiveness of low vision aids Br J Ophthalmol. 2000;84:919–21
3. Chalam KV, Gupta SK, Grover S. Evaluation of the impact of the iPad (as low visual aid) on reading ability and quality of life of low vision patients Poster presentation. 2011 Orlando, FL American Academy of Ophthalmology (AAO)
4. Dada VK, Acharjee SC. Low vision aids developed by intermediate technology and its specific role in the management of macular diseases Indian J Ophthalmol. 1983;31:124–8
© 2013 Indian Journal of Ophthalmology | Published by Wolters Kluwer – Medknow