User Manual

Part Number: PFG01017 Page 10 of 17
Revision A Revision Date: July 2016
Occupational and environmental visual demands should be considered. If the patient requires critical vision
(visual acuity and stereopis) it must be determined by trial whether this patient can function adequately with
monovision. Monovision contact lens wear may not be optimal for such activities as:
• Visually demanding situations such as operating potentially dangerous machinery or performing other
potentially hazardous activities; and driving automobiles (e.g., driving at night). Patients who cannot pass
their state drivers license requirements with monovision correction should be advised not to drive with this
correction, OR may require that additional over-correction (spectacles) be prescribed.
B. Patient Education
All patients do not function equally well with monovision correction. Patients may not perform as well for
certain tasks with this correction as they have with bifocals, trifocals or reading glasses. Each patient must
understand that monovision, as well as other presbyopic contact lenses, or other alternatives, can create a
vision compromise that may reduce visual acuity and depth perception for distance and near tasks. During
the fitting process it is necessary that the patient understands the disadvantages as well as the advantages
of clear near vision in straight ahead and upward gaze that monovision contact lenses provide.
2. Eye Selection
Generally, the non-dominant eye is corrected for near vision. The following test for eye dominance can be used.
A. Ocular Preference Determination Methods
Method 1
Determine which eye is the “sight eye”. Have the patient point to an object at the far end of the room. Cover one
eye. If the patient is still pointing directly at the object, the eye being used is the dominant (sighting) eye.
Method 2
Determine which eye will accept the added power with the least reduction in vision. Place a trial spectacle near
add lens in front of one eye and then the other while the distance refractive error correction is in place for both
eyes. Determine whether the patient functions best with the near add lens over the right or left eye.
B. Refractive Error Method
For the anisometropic corrections, it is generally best to fit the more hyperopic (less myopic) eye for distance
and the more myopic (less hyperopic) eye for near.
C. Visual Demands Method
Consider the patient’s occupation during the eye selection process to determine the critical vision requirements.
If a patient’s gaze for near tasks is usually in one direction, correct the eye on that side for near.
Example:
A secretary who places copy to the left side of the desk will usually function best with the near lens on the left
eye.