The ED trifocal is an excellent choice for someone who needs a very wide field of view Vor objects at arm's length and also needs to be able to see clearly both close-up and in the distance This would be a good lens to dispense to a security guard or TV producer who views a large number of VDU screens spread out in front of them and to the sides and who needs to read as well as recognise someone across the room (6) (Figure 2d).
The patient, if a lecturer for example, is able to view reading matter, u se a VDU screen and is able to see to the back of the lecture theatre too.
This allows the patient to work in an office environment and to read, use a VDU screen and look across the office to speak to colleagues.
Decisions as to which lens type to dispense should also be based on t fie patient's working distance, VDU screen height (or other work task), any possible distance vision requirements and the design of any existing PPL being worn.
Understanding how vision problems at near can affect both posture and efficient use of a VDU, should allow optometrists to assist both employees using VDUs and their employers, to make their staff and companies more efficient.
Of all the hazards associated with the use of a visual display unit (VDU), or perhaps more recently termed video display terminal (VDT), visual problems are the most widespread.
* Transient myopia--distance vision blurred after VDU use
The extent to which individual VDU workers are likely to suffer from ocular symptoms will depend upon a number of factors including the state and health of their eyes, the design of the equipment, the design of the workstation and workplace, ambient lighting, glare, screen reflections, the nature of the work and the frequency of breaks.
Though most reports accept the occurrence of transient myopia, they discount the suggestion that viewing a VDU screen for prolonged periods can actually cause myopia.
The blink rate has been found to reduce during VDU use, leading to greater dryness and irritation of the eye.
* Wherever practicable, VDU users should be allowed some discretion as to how they carry out tasks; individual control over the nature and pace of work allows optimal distribution of effort over the working day