Assessment of Alcon's Ocular Image Quantification System: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Assessment of Alcon's Ocular Image Quantification System (NCT01282138), a randomized phase 4 study. The primary outcome is Change From Baseline in Patient-Assessed Ocular Itching, Environmental Exposure Chamber (EEC), at 3 Hours.

2. Clinical Question

3. Trial Design

This was a phase 4, randomized, double-masked, parallel-group study sponsored by Alcon Research. The registry lists allergic conjunctivitis as the condition and reports enrollment of 13. The study started in 2010-12, had primary completion in 2011-03, and is marked completed. These dates describe the registry record; they do not establish how long each participant was followed.

The two groups received Patanol or Tears Naturale II. For both groups, the described schedule was one drop in each eye twice daily for five days before allergen provocation testing, with an additional drop in each eye approximately 15 minutes before testing. The registry gives the products and schedules but does not describe the randomization procedure, allocation concealment, or which people were masked.

The study title and official title refer to assessment of an ocular image quantification system using conjunctival allergen provocation testing and natural allergen exposure in an environmental exposure chamber. The primary outcome reported in the registry concerns patient-assessed itching after exposure in the chamber. A primary outcome for the conjunctival provocation method is not listed in the posted results.

The posted endpoint values are group means with standard errors. Patanol has 6 participants in the endpoint record and Tears Naturale II has 7. Although the registry identifies the study as randomized, it does not report the methods used to analyze the endpoint or a between-group estimate. Details of any protocol deviations, adherence, or participant flow are not reported in the registry record.

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.

EEC

CAPT

Analysis population for the primary outcome, as defined in the registry: All enrolled participants

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.

6. Primary Endpoint

The registry lists the primary outcome as Change From Baseline in Patient-Assessed Ocular Itching, Environmental Exposure Chamber (EEC), at 3 Hours, measured over Baseline, 3 hours.

The primary endpoint is change from baseline in patient-assessed ocular itching after 3 hours in the environmental exposure chamber. Itching was scored on a 0-4 scale: 0 means none; 1 is a tickling sensation involving one or more corners of the eye; 2 is an all-over tickling sensation; 3 is moderate continuous itching with a desire to rub; and 4 is severe itching with an irresistible urge to rub. The registry describes the endpoint as a mean, with standard error as the measure of uncertainty.

A change score expresses how a participant's score at the specified assessment differs from baseline. A negative mean change indicates that the average score at the assessment was lower than baseline, on the scale as recorded. The endpoint is patient-assessed, so it reflects participants' reports rather than an objective measure of eye appearance or an image-based score. The registry does not explain how the ocular image quantification system relates to this particular endpoint.

Patient-reported itching can capture a symptom directly experienced by participants during allergen exposure. The selected assessment time anchors the measurement to 3 hours in the chamber. The registry does not report why that time was selected, whether other assessments contributed to a summary, or whether the score was collected at additional time points.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The endpoint is continuous in the registry’s statistical classification and is summarized by a mean. A mean combines participant measurements into a single measure of the group’s central level. For a change endpoint, each recorded value represents change from baseline, and the group mean summarizes those changes. A mean is useful for describing the average direction and size of observed changes, but it cannot show the full pattern of participant responses.

The standard error is a measure of the precision of an estimated mean. In general, it reflects how much an estimate might vary across repeated samples drawn under the same conditions. It is not the same as the standard deviation, which describes variability among individual measurements. The registry reports standard errors of 0.6 for Patanol and 0.2 for Tears Naturale II. Individual-level variability is not reported, so the amount of variation in participants’ change scores cannot be read directly from these figures.

A confidence interval is a range of values generated by a statistical procedure to express uncertainty around an estimate. In general, a narrower interval indicates greater precision under the assumptions of that procedure. Confidence intervals for the primary group means or for a treatment contrast are not reported in the registry record. The standard errors alone do not establish the interval that would result from an analysis, because the calculation and assumptions must also be specified.

A treatment comparison would ordinarily focus on a contrast between the groups, rather than on whether each group’s change differs from baseline in isolation. Such a contrast needs an estimate and an uncertainty measure, and typically a defined analysis method. The registry posts neither a comparative estimate nor a comparative confidence interval or p-value for this endpoint. It reports 0 analyses and indicates that values for a two-arm comparison of the continuous endpoint are missing or not estimable. Therefore, the available summaries do not support a formal test of the difference between treatments.

The outcome uses a 0-4 symptom scale. Although the registry treats the endpoint as a continuous measure and reports means, the scale itself has ordered response categories and fixed lower and upper limits. In general, a mean can summarize such scores, but readers should remember that it does not show the category frequencies or participant-level transitions. Whether a different summary or model was considered is not reported in the registry record.

The registry’s planning assumptions describe an illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. The illustration considers detecting a stated fraction of the observed effect. These assumptions describe planning calculations, not the design justification for this completed trial. The trial’s own sample-size justification, target effect, and chosen power are not reported in the registry record. Any planning illustration based on an observed effect is not observed power and does not establish that the trial was adequately sized for its intended question.

Normal approximations are general statistical tools that can be used to estimate uncertainty or plan sample sizes when their assumptions are reasonable. With small groups or bounded scores, the adequacy of an approximation depends on the data and analysis details. The registry does not identify a primary statistical test, model, or variance assumption, so it is not possible to assess which inferential method was intended or whether its assumptions were checked.

Over-dispersion is a general concern when the observed variability is greater than a model assumes; if ignored, uncertainty may be understated. It is not possible to determine whether over-dispersion is relevant because the registry does not report the individual outcomes, a fitted model, or a dispersion assessment. Likewise, adjustments for baseline values or other participant characteristics are not described. No adjusted analysis should be presumed from the posted group summaries.

Randomization is intended, in general, to make treatment groups comparable on average, including for factors that may not have been measured. It does not guarantee balance in a small study, and the registry does not show baseline characteristics or describe the randomization method. Double masking can reduce some risks of bias, but the registry does not say who was masked, how masking was maintained, or whether it was assessed. These design labels alone do not establish that all sources of bias were avoided.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Patanol", "Tears Naturale II")
n   <- c(6, 7)
m   <- c(-1.63, -1.11)
sp  <- c(0.6, 0.2)
sd  <- sp * sqrt(n)      # standard errors converted to SDs
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Patanol  6  -1.630  1.470  -3.172  -0.088
CARM  Tears Naturale II  7  -1.110  0.529  -1.599  -0.621

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures, but no secondary outcomes are posted. The primary endpoint described in the results is patient-assessed itching after 3 hours in the environmental exposure chamber. It is not reported whether the study protocol specified additional outcomes, repeated assessments, or multiple comparisons that were not included among the posted results.

Multiplicity arises in general when several outcomes, time points, or treatment comparisons are tested. Without a plan to account for multiple testing, the chance of at least one apparently unusual result can increase. The registry does not report a multiplicity adjustment, an outcome hierarchy beyond the designated primary endpoint, or an analysis plan. It is therefore not possible to determine how multiplicity was handled. The absence of posted secondary results should not be interpreted as evidence that no secondary measurements were collected.

Missing-data handling is also not reported in the registry record. The primary outcome identifies all enrolled participants as its population, and the endpoint group counts are 6 for Patanol and 7 for Tears Naturale II. The record does not explain whether all randomized participants contributed data, how missing endpoint measurements were handled, or whether any sensitivity analyses were performed. It does not report reasons for missing observations or participant-level follow-up.

The analysis population is described as all enrolled participants for the primary outcome, but further details about whether this corresponds to all randomized participants or another analysis set are not reported. The registry gives no protocol deviations, exclusions, or analysis-population definitions. Accordingly, the posted summaries cannot establish how missingness, exclusions, or multiple testing may affect the interpretation.

12. 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.

Most frequent non-serious adverse event terms

The registry reports serious adverse events for 0 of 6 participants at risk in the Patanol group and 0 of 7 participants at risk in the Tears Naturale II group. These figures describe the serious adverse event counts recorded for the groups; they do not demonstrate that the risk of serious events is identical between treatments. With small groups, the absence of recorded events does not rule out events that could occur in a larger population.

For other, non-serious adverse events, the record reports 0 of 6 participants affected in the Patanol group and 2 of 7 affected in the Tears Naturale II group. The registry does not provide the specific terms for these events in the posted summary. It also does not provide an analysis comparing adverse-event rates, or enough information to interpret event severity, timing, or relationship to treatment.

Deaths are not reported in the registry record. The adverse-event counts are descriptive and should be read separately from the symptom endpoint. They do not provide a general safety conclusion or establish that one treatment has a different safety profile from the other.

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

The record documents a randomized, double-masked comparison of Patanol and Tears Naturale II in a small study of allergic conjunctivitis. Its posted primary outcome concerns the mean change in patient-assessed ocular itching after 3 hours in an environmental exposure chamber. The reported mean changes are negative in both groups, and the record provides a standard error for each group mean.

Those descriptive statistics do not establish which treatment produced a larger change, or whether any numerical difference between groups is statistically distinguishable from chance. The registry contains no comparative estimate, confidence interval, or p-value for the endpoint. Nor does it report a result evaluating the accuracy or performance of the ocular image quantification system. The study title and stated purpose should not be mistaken for evidence that those questions were answered by the posted endpoint.

The findings are limited to the recorded group summaries and the specified chamber assessment. They do not show how symptoms changed for each participant, how scores were distributed across the response scale, or whether the same pattern would occur in other settings. The registry does not provide results for natural allergen exposure or a comparison between allergen provocation methods in the posted outcome data.

The absence of a reported comparative analysis is important: a descriptive mean in each arm is not a substitute for a treatment contrast. Similarly, the absence of reported serious adverse events in these groups cannot establish that serious events cannot occur. The record supports a restrained reading of what was measured and posted, while leaving key inferential and design questions unresolved.

14. Why This Trial Matters Statistically

This study illustrates a distinction central to clinical trial interpretation: a randomized design and arm-level outcome summaries do not automatically yield a reported estimate of the treatment contrast. The registry identifies Patanol and Tears Naturale II as randomized parallel groups, and it reports a mean change and standard error for each. Yet it does not include a comparative analysis for the continuous primary endpoint. Readers therefore have descriptive information but not the inferential result needed to quantify a between-group effect.

The endpoint also highlights why the summary statistic matters. A mean change condenses a participant-assessed symptom score into one average, while the standard error communicates uncertainty about that average. Neither statistic shows the range of individual changes or the distribution of responses across the 0-4 scale. Participant-level data or additional distributional summaries would answer different questions, but they are not reported in the registry record.

The trial’s small treatment groups also make precision especially relevant. The posted standard errors differ, and no confidence intervals or comparative uncertainty estimates are available. Without an analysis plan and a treatment contrast, the apparent separation between group means cannot be interpreted as evidence of a difference. This is a useful reminder to distinguish observed summaries from conclusions supported by a formal analysis.

Finally, the record’s stated focus on an ocular image quantification system and allergen provocation methods is broader than the primary outcome result that is posted. Connecting an assessment tool to a clinical endpoint requires information about how the tool was evaluated and how its measurements relate to participant experience. Those details and results are not reported. The study thus underscores the importance of matching the claim of interest to the endpoint and analysis actually available.

15. 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.

Several trial-specific details needed to interpret the results are not reported in the registry record. The randomization procedure, allocation concealment, identities of the people masked, and assessment of masking are not described. Baseline characteristics are also absent from the posted results, so comparability of the small groups on measured characteristics cannot be assessed.

The primary outcome is patient-assessed itching, while the study title refers to an ocular image quantification system. The record does not explain how the imaging system was used, what image-derived measures were evaluated, or how they relate to the symptom endpoint. The posted results also do not include an outcome for conjunctival allergen provocation testing or natural allergen exposure as a separate method. Thus the relationship between the study’s stated purpose and its reported primary result remains unclear.

No statistical analysis plan, test, model, or adjustment strategy is reported. The record does not provide a treatment contrast, confidence interval, or p-value for the primary endpoint. It also does not describe missing-data handling, participant flow, protocol deviations, adherence, or the reasons for any unavailable measurements. These omissions limit assessment of bias and precision.

The small group counts and absence of participant-level results restrict what can be learned from the mean changes. The registry does not report the distribution of scores, individual changes, or subgroup results. The trial’s own sample-size justification and intended power are not reported. These limitations mean the posted information is best interpreted as brief descriptive evidence for this endpoint and these participants, rather than a complete account of the trial’s statistical findings.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Assessment of Alcon's Ocular Image Quantification System — NCT01282138.
• Registry record last updated 2012-12-18; status last verified 2012-07.
• Results first posted 2012-07-25.
• 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.

19. Record Summary

The completed phase 4 study randomized participants with allergic conjunctivitis to Patanol or Tears Naturale II under double masking and a parallel-group design. Enrollment was 13. Both groups followed the described dosing schedule before allergen provocation testing.

The primary outcome was mean change from baseline in patient-assessed ocular itching after 3 hours in an environmental exposure chamber. The registry reports -1.63 with a standard error of 0.6 for Patanol among 6 participants, and -1.11 with a standard error of 0.2 for Tears Naturale II among 7 participants. No comparative analysis is posted for this continuous endpoint.

The record reports no serious adverse events in either group; other adverse events affected 0 participants in the Patanol group and 2 in the Tears Naturale II group. Deaths are not reported in the registry record. Details of the statistical plan, missing-data handling, and the ocular image quantification system’s performance are not reported.