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Rehabilitation ArticleLow Vision: Practical and Hi-Tech Solutions forVisual Impairment and BlindnessAccess to care of the partiallysighted and blind has been limited,for the most part, to developednations. But that is all beginningto change in our ‘flat-world’ hi-techsociety. 1On December 16, 2004, the WHOreleased new data on the prevalence ofglobal blindness. 2 It was noted that,according to the figures compiled in2002, there were 161 million people whoare visually impaired. 3 Of these, 124 millionare considered to have low vision 4and 37 million are considered to be blind. 5 Of these, 90%of the world’s blind live in developing countries: nine millionin India, six million in China and seven million inAfrica. 6But only four major eye conditions result in almost75% of the world’s individuals having low vision. Theyinclude age-related macular degeneration, glaucoma, diabeticretinopathy, and cataracts.Vision care has become very specialised in developednations. There are anterior segment (corneal, glaucoma,contact lens, and cataract specialists) posterior segment(retinologists), paediatric, sports medicine, neuro, as wellas low vision specialists. The latter are involved in the careof the partially sighted or visually impaired. The lowvision clinicians include optometrists or ophthalmologistsworldwide who have special training in managingindividuals with reduced vision as well as irreversiblevision loss in both eyes.The specialty of low vision is considered to be a tertiaryarea of care in which patients are not only under the careof a low vision clinician but the care of a specialist managingthe eye pathology (eg retinal or glaucoma specialist).The patient, in fact, may be managed in a multi-specialtygroup practice taking care of all the vision relatedproblems. They may also be in a private practice specialisingin low vision, as well as in a vision rehabilitationorganisation, a university or hospital based eye clinic, aswell as veterans administration blind rehabilitation centers(in the US: Chicago, Atlanta, Palo Alto, W. Haven Ct.).Vision rehabilitation services and teamwork are generallyrequired and provided, regardless of whether it is acongenital, early onset, or adventitious aetiology. Thevision rehabilitation team includes the optometrist orophthalmologist specialising in low vision and care of thepartially sighted. It is their primary responsibility to performthe low vision evaluation as well as prescribe anddesign low vision devices. The other members of thevision rehabilitation team include the social worker todeal with issues such as: vision loss, depression, familydynamics, and loss of independence. The team alsoincludes a vision rehabilitation specialist or occupationaltherapist (OT) to instruct patients in the use of the lowvision devices as well as to teach them independent livingskills. Mobility specialists may be called upon, as well, forthe teaching of independent travel, along with educatorsof the visually impaired and job placement specialists.The Clinical Low Vision ExaminationThe specialised low vision evaluation is a functionally orientedexamination to determine patient specific objectivesand needs, to maximise the residual vision with prescriptivelenses, low vision devices, and hi-tech solutions.These objectives may include such diverse demands as,A patient with age-related maculardegeneration using a strong (microscopic)reading lens.reading the label on a prescriptionmedication bottle, reading the dailynewspaper, being able to access thecomputer screen, travelling independentlyand safely in an unfamiliar area,being able to see the Professor’sPowerPoint presentation in college,being able to see the markings on theinsulin gauge, reducing glare in theenvironment, accessing your PIN code,seeing the menu at a fast food restaurant,or using the ATM in the Bank. Thehistory will also investigate comorbidities,such as diabetes or stroke and how they may affect thepatient’s goals and objectives as well.The low vision examination also consists of a specialisedbattery of tests designed to evaluate the patient’svisual function. It includes specially designed visioncharts that measure even the lowest levels of vision. Thepreferred visual acuity chart for testing is the ETDRS(Early Treatment of Diabetic Retinopathy) chart which isalso used for all clinical trials in the United States. 7 Theselogarithmic charts have been statistically validated torecord changes in vision over time as well as to recordvision as low as 1/40 (20/800). Patients with vision of lessthan 2/40 (20/400) may have need of other vision rehabilitationservices such as mobility in order to learn how totravel safely and independently in their environment.Individuals possessing only light perception or no visional all (functionally blind) will also be referred for mobilitytraining in the use of a cane.Contrast sensitivity functional (CSF) testing was addedto the low vision battery of tests by the author and EleanorFaye, MD in 1981. CSF measures the ability to see objects(eg print, road signs), as the contrast decreases. That is,how black does an object have to be, before it can be seen.Contrast sensitivity is becoming an important outcomemeasure in patient management as it relates to quality oflife issues. It is affected by the major pathologies such asmacular degeneration, cataracts, and diabetic retinopathy.Magnification, the usual method of improving performance,may not be as effective as much as enhancing thecontrast by strategies such as increasing the illuminationin all environments.It is important to map out the visual field using automatedperimetry, as well, in eye diseases such as glaucoma,optic nerve disease and systemic conditions such asstroke. Trauma may also lead to significant loss of thevisual field as does retinitis pigmentosa. The latter is aprogressive disease that generally results, not only in a lossof the peripheral vision but night blindness, and significantmobility problems. There is no treatment at this timeto slow the degeneration of the peripheral retina butexciting genetic research (eg ABCR gene) 8 may lead to acessation of progression. Again mobility, or newer hi-techmethods such as use of the GPS, especially when the visualfield is severely compromised, will be essential for independenttravel.The other examination components include a specialisedlow vision refraction test to determine whether aspectacle correction will be beneficial for distance, intermediate,and near tasks, an Amsler grid to evaluate thecentral 20 degrees of the visual field, as well as an ocularhealth analysis.The ability to enhance visual function is one of theobjectives of the evaluation and magnification andDr Bruce P Rosenthal is the Chiefof the Low Vision Clinical Practiceat Lighthouse International inNew York City, Adjunct Professorat Mt Sinai Hospital, DistinguishedProfessor at StateUniversity of New York, and Chairof the Scientific Advisory Board ofthe AMD Alliance International.He lectures throughout the world,has authored of eights books onvisual impairment and maculardegeneration as well as over 100scientific articles.Correspondence to:Email: BROSENTHAL@lighthouse.org16 I ACNR • VOLUME 5 NUMBER 6 • JANUARY/FEBRUARY 2006
Rehabilitation Articleenhancing the CSF are ways of achieving thisobjective. Increasing the magnification can bedone in three ways: relative size, relative distance,and angular magnification. In relativesize magnfication, the object of regard can bephysically enlarged such as the print in a largeprint book. The object of regard can be broughtcloser to the eye, in relative distance magnification,so that the object subtends a larger retinalimage and appears much larger. In angularmagnification the object can be made to appearto be closer to the eye and thus appear larger (egseeing the train or airport departure board).Low vision devices will generally allow theuser to bring an object closer to the eye andthus magnify the retinal image size. Enhancingthe contrast is a different story and may requirea hi-tech device, a filter, as well as techniquessuch as using a bold line pen when writing.In addition to prescriptive lenses for distance(televison, theatre), intermediate (readingmusic, the computer screen), and near tasks(reading) are specialised low vision devices. Thelow vision devices includes strong reading lenses(microscopic lenses), magnifying systems(hand and stand magnifiers), telescopic systems(for use in museums, independent travel or,classroom work), absorptive lenses and filters(for reducing glare as well as increasing thecontrast), and hi-tech devices that are known asclosed-circuit televisions.High plus microscopic lenses are readilyavailable up to 12x (48 diopters – focal distanceof less than 2.03cm) magnification. Opticalmagnification, for all practical purposes is goodup to 6x (24 diopters; focal distance 4.1cm).Most individuals cannot manage the closeworking distance or the restricted depth of fieldin high magnification systems. Illuminatedmagnifiers, especially illuminated stand magnifiersthat sit on the page are available up to 15x(60 diopters). The image stays in focus since themagnifier sits on the page but the field of viewas well as ease in reading significantly decreasesas the magnification increases.That is where the closed circuit televisioncomes into play. As the world moves ahead to ahi-tech age, so will the field of low vision,enabling individuals with the most profoundvision loss access to information on the web.The closed-circuit television, which is a dedicatedsystem that can enlarge print up to over40 times the size of the original print as well asenhance contrast, has been around for 35 years.The ability to reverse polarity, that is changingthe black letters on a white background to whiteon black is perhaps the major feature of theclosed-circuit television. There are brightnessand contrast controls as well as systems thatallow a user to isolate a line. This feature isextremely beneficial when it is difficult to locateor isolate a line of print. It is also helpful in theloss of the visual field from a stoke or tumour.Assistive technology has become much morecommon in the workplace in the United States.Microsoft found that 27% of computer usershave a vision difficulty and have added muchgreater accessibility in their programmeupdates. These include screen enlargers thatmove around the screen like a magnifier, screenreaders that present graphics and text as speech,speech recognition systems that allow for voiceinput commands, screen synthesisers alsoknown as text to speech systems that allowblind users to play back their Word documentincluding the words, numbers, and punctuation.Other programmes for the blind includerefreshable Braille in which a line of print is displayedand then will refresh to play anotherline, a Braille embosser that has the capabilityof transferring computer generated images intoembossed Braille, talking word processors, aswell as large print processors. 9 In additionMicrosoft has included tutorials for the blindand visually impaired for programmes rangingfrom Windows XP to accessing the internet.Accessing the ATM has been difficult if notimpossible for the blind and partially sighted.This has begun to change with the NorthernBank and Clydesdale Banks in Belfast andGlasgow as well as Bank of America in SanFrancisco launching systems that are trulyaccessible. The Northern Bank’s ‘cashpoint’ isused by plugging a set of headphones into ajack, which is fitted to the front of the ATM.The machine uses an automated voice to giveinstructions about the exact location of itemssuch as the numbers on the keypad, the cashdispenser and all other devices on the machine.It also talks through each stage of the process,whether a user wants to check a balance orwithdraw cash. Sighted users can also use themachine by following instructions displayed onscreen. 10,11Even shopping in mega stores such asWalMart in the United States is becoming moreaccessible. WalMart has begun to install stateof-theart point of sale devices in their stores toprotect the privacy and security of shopperswith visual impairments. They explain thatthe 12 new devices have tactile keys arranged likea standard telephone keypad and will allowshoppers who have difficulty reading informationon a touchscreen to privately and independentlyenter their PIN and other confidentialinformation.But the holiday season will also be accessiblethroughout the world with talking catalogues,accessible accounting and cheque writing programmesfor the blind and visually impaired,talking barcode readers, as well as talkingmobile phones and PDAs. 13One of the ways to keep up with innovationsfor the blind and visually impaired is throughthe use of websites such as VisionConnectionfrom Lighthouse International in the UnitedStates. VisionConnection allows for customisationof the screen with the ability to change thefont size as well as enhance the contrast.Additional vision rehabilitation services maybe indicated when the vision is severely compromised.As mentioned mobility may be indicatedwhen the visual field is reduced, especiallywhen it is less that 6 to 8 degrees in diameter.Cane travel is generally taught by individualswho have lost their vision later in life from conditionssuch as macular degeneration. It is generallythe most frequent recommendation byvision rehabilitation organisations in theUnited States. Individuals with congenital andearly childhood loss however, may be taught theuse of guidedogs as well. There is a significantdichotomy in the preferred method of travelamong the different vision rehabilitationorganisations in the US.One of the newer methods of travel is by useof the GPS systems such as Trekker. They haveadapted the system for people who are blind orvisually impaired and allow them access to talkingmenus, talking maps and GPS information.There are other features enabling the user todetermine his or her position, including thestreet address and the surrounding intersections.There are traditional as well as hi-tech strategiesthat will significantly improve the qualityof life, regardless of the extent of vision loss.And accessing those strategies is easy foreveryone through websites such ashttp://www.VisionConnection.org/ 14Access to low vision care, as well as access toreimbursement for low vision devices variestremendously around the world. The Medicareprogramme in the United States, for example,does not cover the cost of a low vision evaluationor low vision devices. Governments as wellas non-governmental organisations have tobegin recognising the low vision health crisisthroughout the world as well as include thevisually impaired in health care programmes.We have the solutions for improving the qualityof life in visually impaired people of all ages.We must now look for the collective strategy aswell as funding to increasing access and availability,regardless of level of vision impairment,as well as socio-economic status.References1. Friedman TL. The World is Flat. A Brief History of theTwenty-first Century Farrar, Straus, and Giroux, NY,2005.2. http://www.worldsightday.ca/facts.htm3. Visual impairment is vision loss involving the loss of anarea of visual function (e.g. Visual acuity, visual field,contrast sensitivity, color vision)4. The definition of low vision used by the WHO: Lowvision is visual acuity less than 6/18 (20/60) and equalto or better than 3/60 (in the better eye with best correction).5. Blindness refers to a total loss or no usable vision.6. http://www.worldsightday.ca/facts.htm7. Ferris Fl3rd, Kassoff A, Bresnick GH, Bailey I. New visualacuity charts for clinical research. Am J Ophthalmol1982;94:91-96.8. Foundation Fighting Blindness;http://www.blindness.org/9. Resource Guide for Individuals with Visual Difficultiesand Impairments;http://www.microsoft.com/enable/guides/vision.aspx10. VisionConnectionhttp://www.visionconnection.org/Content/Technology/News/AnotherBankIntegratesTalkingATMsIntoItsServices.htm11. VisionConnection;http://www.visionconnection.org/Content/Technology/News/EuropesFirstTalkingCashpoint.htm12. VisionConnection;http://www.visionconnection.org/Content/Technology/News/WalMartMakesShoppingMoreAccessible.htm13. VisionConnection;http://www.visionconnection.org/Content/Technology/News/WebSymposiumtoFocusonAccessibleGiftsfortheHolidays.htm14. http://www.visionconnection.org/VisionConnection/default.htmACNR • VOLUME 5 NUMBER 6 • JANUARY/FEBRUARY 2006 I 17
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