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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® Brand BIFOCAL.
When opportunities exist to improve distance vision with the
ACUVUE® BIFOCAL, the clinician is best served by introducing a
± 0.25 D (±0.50 D) hand-held lens or flipper 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 |
* Nominal ADD powers are matched with material presented on
pages 338-9 and 803-7 in Benjamin WJ (ed): Borish's CR(1998), W.B. Saunders
Company, Philadelphia.
A patient's individual characteristics should be considered
as well when the ADD power is determined.
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It is recommended that practitioners 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:
48 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.
* Nominal add powers are matched with material presented on
pages 338-9 and 803-7 in Benjamin WJ (ed): Borish's CR (1998), W.B. Saunders
Company, Philadelphia.
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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 practitioner 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, clinicians are advised to evaluate distance vision
adjustments prior to removing the lens to adjust ADD power.
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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 power
- the possibility that the ADD power (as compared to age)
may be too high
- the possibility the patient is still adapting to simultaneous
vision
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For several years, most ECP's 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.
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