User Manual

Part Number: PFG01017 Page 11 of 17
Revision A Revision Date: July 2016
3. Special Fitting Considerations
Unilateral Lens Correction
There are circumstances where only one contact lens is required. As an example, an emmetropic presbyopic
patient would only require a near lens while a bilateral myope may require only a distance lens.
Example:
A presbyopic emmetropic patient who requires a +1.75 diopter add would have a +1.75 lens on the near eye and
the other without a lens.
A presbyopic patient requiring a +1.50 diopter add who is –2.50 diopters myopic in the right eye and –1.50
diopters myopic in the left eye may have the right eye corrected for distance and the left eye uncorrected for near.
4. Near Add Determination
Always prescribe the lens power for the near eye that provides the optimal near acuity at the midpoint of the
patient’s habitual reading distance. However, when more than one power provides optimal reading performance,
prescribe the least plus (most minus) of the powers.
5. Trial Lens Fitting
A trial fitting is performed in the office to allow the patient to experience monovision correction. Lenses are fit
according to the directions in the general Fitting Procedures described earlier in this guide.
Case history and standard clinical evaluation procedures should be used to determine the prognosis. Determine
which eye is to be corrected for distance and which eye is to be corrected for near. Next determine the near add.
With trial lenses of the proper power in place, observe the reaction to this mode of correction.
Immediately after the correct power lenses are in place, walk across the room and have the patient look at you.
Assess the patient’s reaction to distance vision under these circumstances. Then have the patient look at familiar
near objects such as a watch face or fingernails. Again assess the reaction. As the patient continues to look
around the room at both near and distance objects, observe the reactions. Only after these vision tasks are
completed, should the patient be asked to read print. Evaluate the patient’s reaction to large print (e.g. typewritten
copy) at first and then graduate to new print and finally smaller type sizes.
After the patient’s performance under the above conditions are completed, tests of visual acuity and reading
ability under conditions of moderately dim illumination should be attempted.
An initial unfavorable response in the office, while indicative of a guarded prognosis, should not immediately rule
out a more extensive trial under the usual conditions in which a patient functions.
6. Adaptation
Visually demanding situations should be avoided during the initial wearing period. A patient may at first
experience some mild blurred vision, dizziness, headaches, and a feeling of slight imbalance. You should explain