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Computer Vision Syndrome
Presbyopia and Dry Eye

Prescribing Lenses

Single vision lenses
Younger presbyopic computer users can be successfully fitted with single vision lenses designed for the computer distance. This is because they have enough remaining accommodation to see clearly at 40 cm with the intermediate add for the computer distance. In demonstrating the add, it is important to measure the range of clear vision to ensure that it includes their near visual needs. For most younger presbyopes, an add of +0.75 - +1.25 is appropriate. The distance blur through this prescription should be demonstrated to the patient. For many patients, the distance blur is acceptable since their distance visual needs are limited and the amount of blur created by the relatively low add is small. If the distance blur is undesirable, the patient will prefer an occupational lens design.

Single vision lenses can work in the following situations:

  • Early presbyopia
  • When a single power enables clear vision at both intermediate and near
  • When the distance blur is not a problem for the patient

General Wear Bifocal or Progressive addition lenses
Although bifocals and PALS are usually very successful for general wear, they often are not good for a computer worker as discussed earlier.

In some cases the early presbyope will be able to successfully use their general wear bifocals or PALs for computer work. Such a patient will not require the add for the intermediate viewing distance - something which can be determined in the demonstration process. The PAL can be successful in this case because the patient will be able to use the distance portion of their lenses for work at the computer. The computer should not be located too low in these situations.

A bifocal or PAL can also work for the patient who uses the computer infrequently and for relatively short duration � assuming an awkward posture does not cause a problem for short and infrequent periods of time.

General wear bifocal or progressive addition lenses can be successful when:

  • An add is not required for the computer distance
  • The patient works infrequently at the computer

Intermediate/Near Bifocal
If a different add is required for the intermediate and near viewing distances, one way to implement this is to prescribe a bifocal with the intermediate power in the top of the lens and the near power in the segment. This requires writing a prescription that is different from the usual distance/near prescription.

An intermediate/near bifocal can be successful when:

  • Different adds are required for intermediate and near distances
  • The patient wears bifocals for their general visual needs

 

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