The current ACUVUE® BIFOCAL Fitting Tips Guide is an excellent tool for problem solving and reconfirmation. The information found in the guide is based on data and opinions gathered from colleagues with a long history of clinical success with ACUVUE® BIFOCAL.
When opportunities exist to improve distance vision with the ACUVUE® BIFOCAL, the clinician is best served by introducing a 0.25 D or 0.50 D hand-held lens in front of the distance (dominant) eye while both eyes are open. If the subjective response reaches the desired goal, the spherical power of the contact lens should be adjusted accordingly. If the subjective response is not sufficient, then reduce the ADD power of the contact lens in the distance (dominant) eye.
Always attempt to keep the contact lens ADD powers as low as possible. The chart below may serve as a reference guide for expected ADD powers based on age.
EXPECTED ACUVUE® BIFOCAL ADD POWERS BY AGE*
Age
ACUVUE® BIFOCAL ADD POWER
40-46
47-52
53-59
60+
+1.00 D
+1.50 D
+2.00 D
+2.50 D
A patient's individual characteristics should be considered as well when the ADD power is determined.
It is recommended that eye care professinals start with the lowest reasonable ADD power. The process for determining the initial ADD power should be:
1. Evaluate the refractive ADD power determined during the examination.
2. Use the following table to determine appropriate ADD power based on age.*
EXPECTED ACUVUE® BIFOCAL ADD POWERS BY AGE*
Age
ACUVUE® BIFOCAL ADD Power
40-46
47-52
53-59
60+
+1.00 D
+1.50 D
+2.00 D
+2.50 D
3. Always round down if the patient is between ADD powers.
Examples:
8 year old with a +1.75 D spec ADD —> start with a
+1.50 D ADD
54 year old with a +1.75 D spec ADD —> start with a
+1.50 D ADD
54 year old with a +2.00 D spec ADD —> start with a
+2.00 D ADD
48 year old with a +2.00 D spec ADD —> start with a
+1.50 D ADD
56 year old with a +2.50 D spec ADD —> start with a
+2.00D ADD
4. A patient's individual characteristics should be considered as well when the ADD power is determined.
Typically, over 40% of patients successfully wearing the ACUVUE® BIFOCAL are using equal ADD powers. Success is maximized by beginning with equal ADD powers. Based on patient response, the
eye care professional
can then modify distance and/or ADD powers in order to optimize the patient's performance.
As distance vision adjustments can be demonstrated without changing the contact lens,
eye care professional
are advised to evaluate distance vision adjustments prior to removing the lens to adjust ADD power.
Clinical studies are currently under way to determine the opportunities and viability of broadening the parameter range for the ACUVUE® BIFOCAL. For now, if you determine that the patient requires additional ADD, be sure to evaluate:
the possibility of having over-minused distance power in one or both eyes
the viability of unequal ADD powers
the possibility that the ADD power (as compared to age) may be too high
the possibility the patient is still adapting to simultaneous vision
For several years, most Eye Care Professionals have taken a scientific approach to this question. Patients are told that the function of a bifocal contact lens was "brain related." In this scientific approach, patients are also told they must "train" their eyes to use the different powers in their lenses or that the brain must "adjust" to the in-focus and out-of-focus images.
An explanation that might be easier for the patient to comprehend might be telling them the adjustment process is similar to looking at a dog playing out in the yard through a screen door. As they look at the dog they are ignoring the screen, but if they focus on the holes in the screen they can still see the dog, but now their focus is on the near image of the holes in the screen.
