Evaluating Low Vision Services
Optometrists may find it unusual to consider the concept of ‘success’ in relation to one of their prescribing strategies, because the supply of spectacles for the correction of refractive error…
Rehabilitation Techniques for Nystagmus
Nystagmus is an involuntary ocular oscillation which includes a slow phase eye movement as part of each cycle. Visual impairment can result, either from the oscillation itself, or from an…
Prescribing Magnification
Once it has been concluded that refractive correction alone will not be sufficient to improve vision to the required level, magnification will be needed. This may be combined with other…
The Eye Examination
There are a number of tests which could be carried out at this stage to confirm what the patient has told you about their ocular condition, or what you have…
Contrast and Glare
Improving Visibility of the Retinal Image Into this category come a wide range of very simple strategies which are designed to aid vision, but do not affect the vergence or…
Illumination and Lighting
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…
Clinical Measures of Visual Performance
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…
Transverse Magnification
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…
Relative Size Magnification: Increasing the Object Size
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…
Magnification
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…
