Low vision Totally Explained

Everything about Low Vision totally explained

| }} Low vision is a subspecialty within the professions of optometry and ophthalmology and opticianry dealing with individuals who have less than normal vision even with the most accurate conventional prescription available. It can be a result of either congenital or acquired factors. An example of the former is Leber's congenital amaurosis and of the latter age-related macular degeneration.

Classifying Low Vision

Anyone with noncorrectable reduced vision is considered to be visually impaired, and can have a wide range of causes. The World Health Organization uses the following classifications of visual impairment. When the vision in the better eye with best possible glasses correction is:

20/30 to 20/60 : is considered mild vision loss, or near-normal vision
20/70 to 20/160 : is considered moderate visual impairment, or moderate low vision
20/200 to 20/400 : is considered severe visual impairment, or severe low vision
20/500 to 20/1,000 : is considered profound visual impairment, or profound low vision
less than 20/1,000 : is considered near-total visual impairment, or near total blindness
No Light Perception : is considered total visual impairment, or total blindness
There are also levels of visual impairment based on visual field loss (loss of peripheral vision).

Go to Visual acuity to consult an international visual acuity expression chart.
In the United States, any person with vision that can't be corrected to better than 20/200 in the best eye, or who has 20 degrees (diameter) or less of visual field remaining, is considered to be "legally blind" or eligible for disability classification and possible inclusion in certain government sponsored programs.

Magnitude of visual impairment

Globally, in 2002 more than 161 million people were visually impaired, of whom 124 million people had low vision and 37 million were blind. However, refractive error as a cause of visual impairment wasn't included, which implies that the actual global magnitude of visual impairment is greater.

Worldwide for each blind person, an average of 3.4 people have low vision, with country and regional variation ranging from 2.4 to 5.5.

Pathologies which may cause vision acuity loss

Cataracts

Glaucoma

Uveitis

Macular degeneration

Corneal opacity

Trachoma

Diabetic retinopathy

Myopia magna

Stargardt's disease

Albinism

Retinitis pigmentosa Since the estimates of the 1990s, new data based on the 2002 global population show a reduction in the number of people who are blind or visually impaired, and those who are blind from the effects of infectious diseases, but an increase in the number of people who are blind from conditions related to longer life spans. This new information underscores the need to modify the health care agenda to include the management of the diseases that are now becoming prevalent.
According to the Catalan Association for the Blind and Visually Impaired (ACCDV), experience tells that seeking the support of other people affected is a good therapy to overcome the disability, not only for the individual affected but for their families as well. There are associations that give this kind of support and can put the person in touch with professionals specialized in the collective's problems.

The Low Vision Examination

It is critical that all patients be examined by an optometrist or ophthalmologist specializing in Low Vision Care prior to other rehabilitation training to rule out potential medical or surgical correction for the problem and to establish a careful baseline refraction and prescription of both normal and low vision glasses and optical aids. Only a doctor is qualified to evaluate visual functioning of a compromised visual syetem effectively. American Optometric Association web site

Types of help available

The ACCDV

states that medical help aside, the main ones are, in first place, information; secondly, what help the administration offers; and finally the ones which facilitate personal rehabilitation, education, and work and social integration.
Information is fundamental: doctors and sanitary personnel must have this information to offer the patient when the moment is right. The desolation that doctors experience when they must tell a patient they can't do anything more is only surpassed by the loneliness and isolation the patient, who doesn't know where to go or what to do for help. Administrative aids are valuable allies, though sometimes they may lie hidden under a legal mess. Adaptation to the disability and psychological help are priority-one issues and must be confronted from the start. Not least =important and almost as urgent is the education of the patient and their family to confront the new situation. The adaptation of the work place (the one the person currently has or a different one) is regulated by laws and norms and there are interesting subventions for companies that make the necessary modifications to allow a person with disabilities into their work force; therefore the reluctance to hire visually handicapped people is an anti-economic prejudice, for the company and society. Lastly, social integration aids facilitate adapted leisure and cultural activities, and private and public initiatives tending to improve mobility and better access to information for everybody, including the visually impaired.

Optical Aids

The vast majority of patients with low vision can be helped to function at a higher level with the use of low vision devices. Low vision specialists recommend appropriate low vision devices and counsel patients on how better to deal with their reduced vision in general. Many government and private organizations exist to aid the visually impaired.
In an article, Augusto Bruix Bayés mentions that the main principle behind low vision is to magnify the image using various tools. Improving Far sight: works best with static objects

Theater

Cinema

Contemplating scenery

Seeing the bus number Improving Near sight: the person must work closer to the object

Reading

Writing

Crafts Improving sensitivity to contrast: the person must use special optical filters Other tools:

Book stands

Special lights

Grid paper

Magnified games

Watches, audio thermometers, special phones, etc.

Effectivity of optical aids

In a study performed by this specialist on 1,000 patients, all subjects with a visual acuity above 0.02 decimal (20/1000 feet) significantly improved their vision. From this group, 48% were very satisfied with their visual aids, 44% were satisfied, 5% little satisfied and 3% unsatisfied. Adaptation process to visual aids In the patient's first visit, the most adequate options for their particular case are studied, taking into consideration their psychological, cultural, social and work factors, and the degree of improvement experienced with the selected aids, advising the patient on which aids will yield a better quality of life. After the specific adaptation, there's a follow up to ensure the patient is correctly using and taking the best advantage of the visual aids. In some cases (approx. 4%), the initial visual aids must be changed. Once the patient is released, a report on their first visit and follow up is given to their eye doctor or the professional who made the referral. We believe that low vision, as a complementary technique to ophthalmology, has a great future, due to the progress of science, the increase of life expectancy, and the increasing need people have to access information.

Other aids

For the totally blind, there are books in braille, audio-books, machines and computer programs which transform text files into sound. low vision people can, of course, make use of these tools as well.
Computers are, precisely, fundamental tools of integration for the visually impaired person. They allow, using standard or specific programs, screen magnification and conversion of text into sound or touch (Braille line), and are useful for all levels of visual handicap. OCR scanners can, in conjunction with text-to-speech software, read the contents of books and documents aloud via computer. Vendors also build closed-circuit televisions that electronically magnify paper, and even change its contrast and color, for visually impaired users. For more information, consult Assistive technology.

Conclusions

An ever-increasing number of people are at risk of visual impairment as populations grow and demographic shifts move towards the predominance of older age groups. Potentially blinding eye conditions such as age-related macular degeneration (AMD), diabetic retinopathy and glaucoma are increasing as the number of people affected grows. These are non-communicable chronic eye diseases to which the principles of long-term care including issues of cost of treatment and compliance (adherence) apply. Additionally, more programmes for those with low vision will need to be made available.Further Information

Get more info on 'Low Vision'.

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