Terminology The amount of light emitted by a light source is called the luminous flx and is measured in lumens . The efficacy of a particular light source is the…

There is a plethora of vision tests available, including both tests designed for general clinical use and those specific to low vision. Even within the ‘low vision’ category the tests…

Electronic Vision Enhancement Systems Optical magnifying systems are limited practically to a maximum magnification of about 20×. If using a plus-lens, this would require a +80.00DS lens with a working…

Large Print Increasing the size of the object is most commonly put into practice in the form of ‘large print’, when it may be used alone, or in addition to…

Possible Approaches If the low-vision patient cannot resolve the retinal image, despite the fact that it is optimally focussed onto the retina by their refractive correction, then it is necessary…

Patient-Centred Outcome Measures These are also known as ‘patient-reported outcome measures’ and ‘patient relevant outcome measures’. Patients are not only interested in improvements in clinical data (e.g. visual acuity), but…

The World-Wide Situation The prevalence of visual impairment (VI) is the percentage of the general population who have the condition at a given point in time. Usually, the prevalence of…

Low vision, partial sight and visual impairment are synonyms for the same state: reduced vision, with both eyes open, even with the best optical correction. The definition does not include…