Low vision (LV) can be described as the suboptimal level of vision, which is detrimental to the patient and his daily tasks, and at the same time common glasses cannot provide aid.
Vision specialists prefer to describe low vision with such functional terms, as a single number of visual skill may not be enough to describe the daily difficulties that the patient encounters. Thus, low vision is more than the inability to read characters of certain size at the chart.
Low vision may also caused by loss of visual field, metamorphopsia, photophobia, color vision defects, and binocular confusion. Many eye diseases can reuslt in low vision. Wet and dry forms of macular degeneration, glaucoma, and diabetic retinopathy are just some of them.
Other significant diseases are the hereditary ones, such as the congenital optic atrophy, the retinal dystrophies and the congenital cataract.
In the latest years there is an increase in the demand for low vision services. Some of the reasons may be the increase in life expectancy, which on turn causes an increase in the prevalence of age related diseases, and the high visual demands of life nowadays.
The low vision specialist has an ample selection of tools to use, both visual and non visual ones. Visual aids may be high powered reading glasses, telescopic aids, colored filters, electronic or table top aids. Many of them require some training to benefit from them. Once the patient grasps their function however, they are very efficient to help him maintain his daily function.
Visual low vision aids employ three different strategies:
- The first one is magnification, as the object of interest is magnified to the level that is discernible by the patient.
- The second one is the use of colors and contrast.
- The third is the utilization of healthier parts of retina for vision.
Another category are the non visual aids, usually auditory.