Low Vision Assessment
Both distance and near visual acuities are measured, as well as refraction to the most appropriate correction of refractive errors. Most low vision devices are used in conjunction with refractive correctives. For many older people, their low vision devices will be bifocal glasses with a "high plus" reading.
• Contrast sensitivity tests measure the ability to detect objects at low contrast
• Visual field tests examine a patient's peripheral vision
• Light adaptation tests measure vision in reduced lighting
• External and internal eye examinations ensure the whole eye is examined.
Prescription of Low Vision Devices
Low vision devices (LVD) help low vision patients to maximise their remaining vision and live independently.
LVDs are either optical or non optical. Optical devices have one or more lenses to modify or enlarge an image and they need to be prescribed by an eye care worker. They include High Add bifocal, stand magnifiers, illuminated magnifiers, telescopes and low vision CCTV.
Non optical devices do not have a lens system but can make it easier to see objects. They are usually large print books, talking clocks, talking calculators, and low vision playing cards.
The combination of both optical and non-optical devices is usually necessary for different tasks in daily living. Training in LVDs is usually discussed with the patient and family as most are difficult to use due to the limited field of view.