A Comparison of
Patient Preference and Lens
Performance in a small Frame:
VAR CF vs. AO Compact
Drew J. Brooks, OD
Rod L. Tahran, OD, FAAO
Over the past several years, small frame styles have increased in popularity and resulted in more patients being fit in PALs with fitting heights below the traditional 22 to 24 mm minimum recommended height. The American Optical Compact is a new PAL design that is being marketed as a lens that can be used in small B measurement frames, allowing fitting heights at 17mm.
To determine wearer acceptance of PALs in smaller frames, a clinical study was conducted to compare patient preference and to evaluate lens performance between VAR CF and AO compact when used in small frames with short B. measurement.
Clinical findings indicated clear overall preference of VAR CF to AO Compact in every criterion is measured, including near vision.
The design of this study was to fit 20 patients in a small frame that would result in a fitting height of 17mm (+/- 1mm). Twenty patients compared the AO Compact lens with VAR CF lens.
Each patient selected a frame that would allow 17mm fitting height. To avoid order bias, brands were rotated so half of the patients would wear VAR CF first and half would wear AO Compact first. Therefore, each patient was assigned to one of two groups that determined which lens was worn first. The first lens brand was worn for two weeks and then removed from the frame. The second lens was inserted into the same frame, having the same Rx and fitting height as the first, and worn for two weeks.
Each patient filled out four survey questionnaires. The first questionnaire was given prior to wearing either test lens, and was directed at the patients current glasses. The second questionnaire was given after wearing the test lens for two weeks and was directed at the first test lens. The third questionnaire was given after wearing the second test lens for two weeks and was directed at the second test lend. A final questionnaire was given immediately after the third questionnaire and was directed at the patients preference of the two test lenses.
Ten patients wore VAR CF lens first and the AO Compact lens second. Ten patients wore the AO Compact first and the VAR CF second. A list of each patients sex, age, occupation, previous Rx, brand fitting height of the test lenses, add power of the test lenses and preferred test lens was tabulated.
A significant difference in dynamic vision, or vision while moving, was also identified in the patient responses. This is less of a surprise due to the softer peripheral design of VAR CF compared with AO Compact . Eighty five percent of respondents rated dynamic vision with VAR CF as above average to very good compared with only half of respondents with AO Compact. Half of the patients rated dynamic vision with AO Compact as below average to very poor.
Eighty five percent of patients adapted rather easily to very easily to VAR CF. Fifteen percent of patients found it difficult to very difficult to adapt to VAR CF. Thirty five percent of patients found it difficult to very difficult to adapt to AO Compact; half of the AO Compact patients thought it was rather easy to very easy to adapt to the lens.
Eighty five percent of patients were rather satisfied with VAR CF® compared with half of respondents for AO Compact™. While only 15% of VAR CF patients were dissatisfied to very dissatisfied, more than twice as many patients were dissatisfied to very dissatisfied with AO Compact.
Preference: VAR CF vs. AO Compact
The average results of the final questionnaire comparing VAR CF to AO Compact indicated a clear overall preference for VAR CF over AO Compact. In fact, 65% of patients preferred VAR CF to AO Compact.
The mean patient age was 54 years old with the youngest patient being 44 and the oldest being 67. Seventy five percent of the patients were female. Patients were randomly selected for the clinical test and as a result, previous lenses included signal vision reading, bifocals, trifocals, and PALs. Add powers range from 1.50 diopters to 2.75 diopters.
Patients were asked to rate their lenses on a variety of criteria, including adaptation, satisfaction, distance, intermediate and near vision. VAR CF ® rated higher than AO Compact ™ in all criteria tested. Near vision, which is the primary design emphasis of AO Compact, was also rated higher for VAR CF than for AO Compact. Mean satisfaction rating for VAR CF was 7.0 compared with 4.9 for AO Compact.
The following radar graph illustrates the average ratings for VAR CF and AO Compact for each of the primary questions. The radar graph utilizes a rating scale of 1 to 10 being the highest. For instance, the mean rating for near vision is 6.5 for VAR CF and 5.0 for AO Compact.
Ninety-five percent of patients rated distance vision with VAR CF as above average. Seventy-five percent of patients rated AO Compact as above average with 25% rating it as below average to poor.
A wider dispersion between the two lenses was identified in near vision. Three quarters of patients rated near vision with VAR CF as being above average to very good with one quarter of patients rating it below average to very poor. In comparison, only slightly more than half of the patients rated near vision with AO Compact as above average to very good. Forty-five percent of patients rated near vision with AO Compact as being below average to very poor. This is somewhat surprising since it was the primary marketing claim for the AO Compact.
In the final questionnaire, when patients were asked to rate which lens they preferred for near vision, 60% chose VAR CF, 20 % chose AO Compact and 20% had no preference.
This study compared the use of VAR CF® and AO Compact™ in a small B size frame with a 17mm fitting height. It showed that although a PAL can be used in a small frame with less than a recommended 22mm fitting height, there are limitations in ease of use and lens performance.
The AO Compact was not preferred over VAR CF and did not perform nearly as well in all areas studied. Patients more often reported significant discomfort when wearing the AO Compact. Overall visual CF and patient satisfaction were lacking in the AO Compact.
Patients clearly preferred the VAR CF when fit in a small B size frame over the AO Compact. CF and ease of use with VAR CF was superior to AO Compact, while the near reading area was functional and as good as AO Compact.
Although a small frame can be used when prescribing a PAL, one would anticipate higher patient ratings if a deeper frame were used that maximizes the near-vision zone.
These final conclusions from this study can be made:
· Whenever possible, recommend a frame that will allow a 20mm fitting height to provide the best possible near field of a view.
· When a small B size frame is desired, even at a 17mm fitting height, patients prefer and have better success with VAR CF than AO Compact.
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