Last month, we looked at progressive power lenses (PPLs) and their advantages and disadvantages.
There are other lenses we can dispense to presbyopic patients, which can in some cases be a better option than PPLs – or progressive addition lenses (PALs).
These are known as occupational lenses, and include occupational progressive additional lenses (OPALs), enhanced readers, occupational bifocals and single vision intermediate lenses.
So, when should we discuss these options with a presbyopic patient? The short answer is always.
A PAL is a great all-round lens, providing distance, intermediate and near vision, but the intermediate and near areas are not always wide enough, or in the best position for all patients, especially those who use a computer screen for a large part of the day.
Many people are now spending more time in front of screens, and for presbyopic patients, which can cause back, neck and shoulder problems, in addition to not being able to see the screen as clearly as they would like, especially if they are wearing a poor lens choice.
Consider Sally, who works in a call centre five days a week, eight hours a day. Sally is 58 years old, and her prescription is:
RE +1.25/+0.75 X 50
LE +1.50/+0.50 X 140
Near Add +2.25
Intermediate Add +1.25
Sally’s screen is positioned at arm’s length, at eye level, and she needs to read notes on her desk. She also has a second screen next to the first one. She drives to work and has a pair of PALs for general wear but finds them difficult to use at work.
Firstly, why would Sally find her PALs difficult to use at work? As her screen is set at eye level, when she is looking at the screen with her PALs, she is looking through the distance portion, which would cause her to have to raise her chin to look through the intermediate area. This would be very uncomfortable to maintain for eight hours a day.
The other factor here is the second screen, as a PAL would not give a wide enough intermediate area to encompass both screens without having to excessively keep turning her head around. So what is the answer?
The options are occupational PPLs, enhanced readers, intermediate/near bifocals, or single vision intermediate lenses. The single vision intermediate option is often useful for computer users, but in this case, Sally needs to see the notes on her desk.
As her near Add is +1.00D stronger than her intermediate Add, this would probably not be enough for her to clearly see the notes on her desk.
Bifocals could be a good option for Sally, as the top part could be set for intermediate use. This would give a wide field for both screens, and the reading segment would enable her to clearly see the notes on her desk.
The size and position of the bifocal would need to be carefully discussed with the patient, taking the reading area required and the depth of the screen into account.
Next month, we will continue this case study and consider the OPAL and enhanced reading options.
Sue Deal FBDO R is a practising dispensing optician, ABDO College examiner, senior tutor and supervisor for dispensing opticians. She is also a practice visitor and external moderator for ABDO.
Read OA Corner Part 12: PPLs demystified here, where there are also links to past features.