Evaluation of the Cosmetic Performance of AIR OPTIX® COLORS: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of the Cosmetic Performance of AIR OPTIX® COLORS (NCT01398787), a randomized na study. The primary outcome is Overall Preference.

2. Clinical Question

This is a question about reported cosmetic preference in the study population and at the stated assessment time. It is not a question about longer-term wearing experience or clinical outcomes. The result describes how often participants preferred each lens under the study assessment, rather than how strongly they preferred it or why. Because both lenses were worn by each participant, the comparison is based on contralateral wear, not on assigning one group of participants to wear only AIR OPTIX® COLORS and another group to wear only FRESHLOOK® COLORBLENDS. The registry record identifies the study population and endpoint, but further details about the setting and participant characteristics are not reported in the registry record.

3. Trial Design

The study is listed as completed and randomized, with single masking and a single-group model in the registry record. It enrolled 198 participants. The study ran from 2011-07, with primary completion in 2011-12. The phase is listed as NA. The sponsor is CIBA VISION, and the condition is Cosmetic Appearance.

Participants wore both colored contact lens types, one in each eye. For the AIR OPTIX® COLORS assignment, the lotrafilcon B lens was randomly assigned to one eye and the phemfilcon A lens was worn in the fellow eye. The corresponding FRESHLOOK® COLORBLENDS assignment describes the phemfilcon A lens randomized to one eye and the lotrafilcon B lens in the fellow eye. Thus, although the registry uses a single-group model label, the lens comparison is a randomized, within-participant contralateral-wear assessment. The registry does not report the randomization sequence or how allocation concealment was handled.

The primary assessment was made on Day 1, 2-10 minutes after insertion. The endpoint description identifies Pair 1 study lenses and says each lens was assessed separately. The primary outcome was pre-specified for AP1. AP1 included enrolled and exposed participants minus discontinuations, missing responses, and protocol violations as determined by masked review. The primary result is based on 168 participants for each lens. The relationship between the full enrolled count and the final endpoint population is not further described in the registry record.

The registry lists six outcome measures and no analysis entries. It does not report the identity of the masked party or parties, details of the assessment setting, planned follow-up beyond the stated endpoint, or the original statistical design assumptions.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: Of the 198 enrolled participants, 1 was exited as a screen failure prior to study product exposure. This reporting group includes all enrolled and exposed participants (197).

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The analysis population includes all enrolled and exposed participants in AP1, minus any discontinuations, missing responses, or protocol violations as determined by masked review.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: The analysis population includes all enrolled and exposed participants.

6. Primary Endpoint

The registry lists the primary outcome as Overall Preference, measured over Day 1, 2-10 minutes after lens insertion.

The primary endpoint is Overall Preference, reported as the percentage of participants who preferred the study lens. Each lens was assessed separately. Participants compared the Pair 1 lenses worn in their eyes and selected one of four responses: preference for the left-eye lens, preference for the right-eye lens, no preference, or both eyes equal. The endpoint description does not treat the response as a graded measure of preference intensity; it reports the proportion preferring a given study lens.

Preference is used to capture a participant-reported cosmetic comparison between the two colored lenses. The measure is suited to the stated study question because participants directly experienced both lenses and were asked to express an overall choice shortly after insertion. The reported percentages are 49.1% for AIR OPTIX® COLORS and 24.6% for FRESHLOOK® COLORBLENDS, each among 168 participants. Those figures describe the recorded preference outcome at the specified assessment, not all aspects of lens performance.

The endpoint does not establish whether participants would maintain the same preference over longer wear, nor does it measure comfort, vision, sustained use, or other outcomes unless separately reported. Although the registry lists six outcome measures, the primary result concerns the Day 1 preference assessment. Details of the other outcome measures are not reported in the registry record.

7. Results Posted in the Registry

• FRESHLOOK® COLORBLENDS: 24.4% (41/168) versus 48.8% (82/168) on control; risk difference -24.4 percentage points (95% CI -34.4 to -14.4), risk ratio 0.50 (0.37–0.68); unadjusted two-proportion z-test p = <0.001.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is binary at the level of each lens-specific preference: a participant either preferred the lens or did not register a preference for it under the response definition. The registry describes four possible responses, but the outcome is reported as the percentage who preferred each study lens. A percentage makes the result interpretable as a proportion of the endpoint population. For AIR OPTIX® COLORS, the reported value is 49.1%; for FRESHLOOK® COLORBLENDS, it is 24.6%. The denominator for each is 168 participants.

How to read a risk difference

A risk difference subtracts one event proportion from another. In this setting, the “event” is preference for a particular lens, not a medical event. The reported contrast is for FRESHLOOK® COLORBLENDS relative to AIR OPTIX® COLORS and is -0.244. A negative value indicates that the proportion preferring the comparison lens was lower than the proportion preferring the reference lens. The interval is -0.344 to -0.144. Because this is a difference in proportions, its scale is additive; it is not a percentage change or a ratio.

How to read ratios

The risk ratio compares the two preference proportions by division, while the odds ratio compares the odds of the preference outcome. The reported risk ratio is 0.5, with an interval from 0.367 to 0.680; the reported odds ratio is 0.339, with an interval from 0.213 to 0.539. These relative measures describe the same comparison using different scales. An odds ratio should not be read as though it were a risk ratio, particularly when the outcome is not rare. For a reader focused on the absolute contrast, the risk difference is the most direct of the three reported measures.

What the p-value says

The posted unadjusted p-value is <0.001. As a general statistical explanation, a p-value measures how unusual data at least as discrepant as the observed data would be under a specified null hypothesis and statistical model. It is not the probability that the null hypothesis is true, and it does not measure the size of the observed preference contrast. “Unadjusted” indicates that the reported value is not presented as adjusted for multiple comparisons. A multiplicity plan is not reported in the registry record.

Why the paired design matters

Participants wore both study lenses, one in each eye, and the eye receiving each lens was randomized. This contralateral arrangement differs from a parallel-group design in which each participant wears only one assigned lens. Paired observations can be related because responses from the same participant share personal characteristics. As a general statistical point, methods that account for within-participant pairing can use that relationship; treating paired observations as independent can misstate uncertainty. The registry record does not describe the method used to account for the paired design, so the details of that modeling cannot be confirmed from the record.

The primary endpoint population, AP1, includes enrolled and exposed participants except for discontinuations, missing responses, and protocol violations identified through masked review. This defines who was intended to contribute to the primary analysis, but the registry does not report the counts excluded for each reason or how missing responses were handled beyond their exclusion from AP1. Each posted lens result has a denominator of 168.

As a general statistical point, a confidence interval represents a range of values reasonably compatible with the data and the method used to calculate it. Its width reflects the precision of the estimate, which is influenced by the amount of information and the variability in the data. The registry record does not state the confidence level or the precise calculation method for the reported intervals. The interval values should therefore be read as reported, without assuming an unreported procedure.

The comparison also includes a p-value and relative measures, but the registry lists zero analysis entries. The underlying analysis specification, including any model details, adjustment variables, and handling of dependence between eyes, is not reported in the registry record. These omissions do not change the posted numerical estimates, but they limit independent assessment of how the comparison was conducted.

10. Confidence Intervals and Precision

The reported risk difference is -0.244, with an interval from -0.344 to -0.144. The interval lies below zero, matching the negative direction of the estimated contrast: the preference proportion for FRESHLOOK® COLORBLENDS was lower than that for AIR OPTIX® COLORS in the posted comparison. The interval conveys uncertainty around the estimate; it is not a range containing a fixed proportion of individual participant responses.

The reported ratio estimates provide additional scales for the same contrast. The risk ratio is 0.5, with an interval from 0.367 to 0.680. The odds ratio is 0.339, with an interval from 0.213 to 0.539. Their intervals do not include the null value of 1, just as the risk-difference interval does not include the null value of 0. These are conventional reference points for interpreting ratio and difference intervals, respectively. The confidence level and interval calculation method are not reported in the registry record.

The endpoint proportions are based on 168 participants for each lens, and the study enrolled 198 participants. The analysis population definition excludes discontinuations, missing responses, and protocol violations, but the counts for those exclusions are not reported in the registry record. Precision should therefore be considered alongside the available denominator and the limited information about exclusions and analysis methods. The interval gives more information about uncertainty than the point estimate alone, but it does not resolve uncertainty about generalizability, possible effects of the measurement context, or the unreported handling of paired observations.

The interval is also distinct from the p-value. The p-value summarizes compatibility with a null model under the analysis assumptions; the interval shows a range of plausible contrast values under its calculation method. Neither alone establishes the practical importance of the preference difference, and the registry record does not report a threshold for interpreting a difference as important.

11. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total events. They are illustrations based on the observed effect rather than the trial’s own design. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect set to a stated fraction of the observed effect. These are planning assumptions for interpreting the illustration; the original trial design assumptions are not reported in the registry record.

The 80% power column gives the planned number of participants per arm for an analysis to have an 80% probability of detecting the specified effect under the stated assumptions, if that effect and the other assumptions hold. The 90% power column describes the corresponding planning target at 90% probability. These are design probabilities under a hypothetical repeated-sampling model, not guarantees for a particular study. The displayed figures are not observed power.

Rows that plan for smaller fractions of the observed effect require more participants per arm than rows that plan for the full observed effect. This is expected: smaller differences are harder to distinguish from random variation, so more information is needed to detect them at the same significance level and power target. The curve should be read as the same general relationship across effect sizes: as the effect targeted for detection becomes smaller, the required sample size increases. The illustration is based on this study’s observed preference contrast and should not be treated as the original enrollment rationale or as evidence that the trial was designed to detect that contrast.

12. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.488; treatment proportion p₁ = 0.244; average p̄ = 0.366.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6813 = 1.3353.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6590 = 0.5547.
4. n = (1.3353 + 0.5547)² / (-0.2440)² = 60.0, rounded up to 60 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.488095238095238                          # control proportion
p1 <- 0.244047619047619                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(1398787)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 60 (80% power), 80 (90% power)
 75% of observed effect: n per arm = 111 (80% power), 149 (90% power)
 50% of observed effect: n per arm = 257 (80% power), 344 (90% power)
power.prop.test: 60 
Simulated power at n = 60 per arm: 0.805 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

13. Multiplicity, Missing Data and Analysis Populations

The registry lists six outcome measures and identifies Overall Preference as the primary outcome, pre-specified for AP1. It lists no secondary posted results and no analysis entries. The record therefore does not provide a complete account of the outcome hierarchy, the number of planned comparisons, or how the analysis treated multiple outcomes or repeated assessments. A multiplicity procedure is not reported in the registry record.

The posted comparison reports an unadjusted p-value of <0.001. It should be understood as unadjusted, rather than interpreted as a value corrected for the possibility of testing multiple outcomes or comparisons. The record does not state whether any adjustment was planned or performed elsewhere. Since the primary description says each lens was assessed separately, the registry record alone does not establish the full set of tests contributing to the reported result.

AP1 is defined as all enrolled and exposed participants minus discontinuations, missing responses, and protocol violations as determined by masked review. This makes clear that the primary population was not simply every enrolled participant. However, the registry record does not report the number of participants excluded for each reason, the count with missing responses, or the detailed rules used to classify protocol violations. It also does not report an imputation method or sensitivity analyses for missing data.

Randomized eye assignment and contralateral wear create paired observations within participants. The registry record does not describe the statistical method used to account for that dependence. It also does not identify who was masked or explain how masking was maintained during review. These gaps limit evaluation of the analysis process, even though the endpoint definition and the AP1 population are described.

14. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

The adverse-event record lists 197 participants at risk in each lens group for serious events and 197 at risk in each group for other events. It reports zero serious events judged related and zero other events judged related for AIR OPTIX® COLORS, and the same reported counts for FRESHLOOK® COLORBLENDS. No serious-event terms are listed.

These figures concern events judged related, as reflected in the registry fields, rather than all events of any cause. The record does not provide event descriptions or counts for unrelated events in this summary. The denominator of 197 differs from the primary endpoint denominator of 168; the registry record does not explain the difference between these populations. The death fields are null, so deaths are not reported in the registry record. A zero in the related-event fields should be read as no related events recorded for that category and group, not as proof that no event of any kind occurred or that an event could not occur in another population or setting.

15. What the Result Does, and Does Not, Mean

The posted results show that AIR OPTIX® COLORS was preferred by 49.1% of participants, compared with 24.6% for FRESHLOOK® COLORBLENDS, in the Day 1 assessment of habitual FRESHLOOK® wearers. The reported comparison is consistent with a lower preference proportion for FRESHLOOK® COLORBLENDS. The risk-difference interval lies below zero, and the posted unadjusted p-value is <0.001. These results describe the measured preference response under the study conditions.

The result does not establish that a preference would persist with longer wear or at other visits. The assessment took place 2-10 minutes after insertion on Day 1. It also does not establish what participants would prefer outside this study population, or under different conditions of lens use. The registry record does not provide additional population characteristics needed to evaluate how broadly the finding might apply.

Preference is a subjective cosmetic outcome. It is not a direct measure of comfort, visual performance, duration of use, or a clinical outcome. The result therefore cannot answer questions that the endpoint did not measure. Nor does the preference contrast by itself establish a complete performance comparison between the lenses.

The registry reports zero serious and zero other adverse events judged related in each lens group, with 197 participants at risk for each event category. These safety figures are limited to the recorded related-event counts and do not establish the absence of all possible harms. The death fields are not reported in the registry record.

In statistical terms, the posted point estimate and interval communicate the direction and uncertainty of the observed preference contrast. They do not remove uncertainty arising from unreported analysis details, missing-response handling, or the applicability of the study population and assessment conditions. The record supports a description of preference at the stated time; broader conclusions are not established by this endpoint alone.

16. Why This Trial Matters Statistically

This study illustrates how the design and the endpoint need to be read together. The registry labels the model as single group, but the lens assessment is randomized at the eye level and both lenses are worn by each participant. That contralateral setup is important: the two lens-specific preference results are not independent summaries from separate participant groups. The registry record does not state the analysis method used to account for the paired observations, making the design particularly relevant when interpreting the precision estimates.

The endpoint also demonstrates the difference between a participant-reported preference and a broader performance claim. A four-point response is reduced to the percentage preferring each lens, which is a direct and understandable summary of the stated cosmetic question. But that summary does not describe preference strength, reasons for preference, or other dimensions of contact lens use. Keeping the inference tied to the endpoint prevents a narrow result from being read as a general assessment of every lens attribute.

The comparison offers several statistical scales: a risk difference, risk ratio, odds ratio, and an unadjusted p-value. Each conveys a different aspect of the same contrast. The risk difference gives the contrast on the proportion scale; the ratios express relative comparisons; and the p-value addresses compatibility with a null model under the analysis assumptions. The intervals add information about uncertainty that a p-value alone cannot provide.

Finally, the registry distinguishes the enrolled total from the endpoint denominator and provides a defined analysis population, but it does not report the exclusion counts or missing-data procedures. Together with the absent multiplicity and model details, this shows why transparent reporting of analysis populations and statistical methods matters even when the primary result is straightforward to state.

17. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
• Participant counts were reconstructed from posted percentages and arm sizes, so small rounding differences are possible.

The endpoint is an early assessment: Day 1, 2-10 minutes after lens insertion. It does not describe preference after longer wear or at later assessments. The registry record does not report whether participants were assessed again for this outcome or provide details of any later preference results.

The study population consisted of habitual FRESHLOOK® COLORBLENDS wearers. The registry record does not provide further participant characteristics, so the extent to which the findings apply to other groups cannot be evaluated from the record alone. The study assesses a cosmetic preference question and does not, through this primary endpoint, evaluate every aspect of lens performance.

Although eye assignment was randomized and each participant wore both lenses, the analysis method for the paired observations is not reported in the registry record. The identity of the masked party or parties and the randomization procedures are also not reported. These omissions make it difficult to independently assess the analysis assumptions and safeguards against bias.

The primary analysis population excludes discontinuations, missing responses, and protocol violations identified through masked review. The counts excluded for these reasons, the handling of missing responses, and sensitivity analyses are not reported in the registry record. The enrolled total is 198, whereas each lens-specific endpoint denominator is 168; the reasons for this difference are not detailed.

The registry lists six outcome measures but no secondary posted results or analysis entries. It does not report a multiplicity plan, the original sample-size justification, or the confidence-interval calculation method and confidence level. These limitations concern reporting and interpretation; they do not change the values reported for the primary comparison.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Evaluation of the Cosmetic Performance of AIR OPTIX® COLORS — NCT01398787.
• Registry record last updated 2014-03-28; status last verified 2014-02.
• Results first posted 2014-03-28.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

21. Record Summary

The registry record describes a completed randomized, single-masked study of AIR OPTIX® COLORS and FRESHLOOK® COLORBLENDS in habitual FRESHLOOK® wearers. Both lenses were worn by each participant, with the eye receiving each lens randomly assigned. The primary outcome was the percentage preferring each lens on Day 1, 2-10 minutes after insertion.

Among 168 participants for each lens, 49.1% preferred AIR OPTIX® COLORS and 24.6% preferred FRESHLOOK® COLORBLENDS. The reported risk difference for FRESHLOOK® COLORBLENDS relative to AIR OPTIX® COLORS is -0.244, with an interval from -0.344 to -0.144; the unadjusted p-value is <0.001. The registry record reports zero serious and zero other events judged related in each group, with 197 participants at risk for each category. Analysis details, multiplicity methods, and the reasons for the difference between enrollment and endpoint denominators are not reported in the registry record.