Performance of Toric Silicone Hydrogel Contact Lenses Following One Month of Daily Wear: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Performance of Toric Silicone Hydrogel Contact Lenses Following One Month of Daily Wear (NCT03418064), a randomized na study. The primary outcome is Lens Centration.

2. Clinical Question

Other listed outcomes include average hours of wear per day and average comfortable wearing time. Each appears more than once in the registry’s secondary-outcome list, but the record does not explain the repeated entries or provide their results. The clinical question is therefore clear at the level of the intended comparison, while the outcome data needed to assess the comparison are not reported in the registry record.

3. Trial Design

The registry describes a prospective, randomized, double-masked crossover study sponsored by CooperVision, Inc. The study status is completed. The listed enrollment is 42. The study began on 2018-02-10, and primary completion is recorded as 2018-05-16. The phase is listed as NA.

The two devices were fanfilcon A toric and lotrafilcon B toric contact lenses. In a crossover design, participants receive the study conditions in different periods, allowing comparisons to be made within participants when the protocol and analysis support that approach. The record says participants wore each lens either as the first or second lens in the crossover study. It does not report how treatment sequences were assigned, the length or conduct of each period beyond the one-month wear described in the study aim, or whether any washout interval was used.

Randomization and double masking are recorded, but the method used to generate or conceal the allocation is not reported in the registry record. The record also does not describe who was masked, how masking was maintained, or whether the crossover sequence could affect the assessment. These design details matter because sequence, period, and carryover effects can influence comparisons in crossover studies.

The primary outcome was assessed at dispense and measured lens centration. The registry lists 15 outcome measures, but it does not provide a set of reported analysis results for the primary outcome in the material described by the record. It also lists no analyses. The record does not report the statistical plan, analysis population, or treatment of incomplete observations. Consequently, the design features can be described, but the methods used to turn the collected measurements into an inferential comparison cannot be reconstructed from 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.

First Intervention (1 Month)

Second Intervention (1 Month)

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 Lens Centration, measured over Dispense.

The primary endpoint is lens centration, recorded as a count of participants and assessed at dispense. The description defines centration as the position of the lens on the eye in primary gaze, using a 1-3 scale: 1 is optimal centration, 2 is acceptable slight decentration, and 3 is unacceptable decentration. These categories represent clinically distinct descriptions of lens position rather than a single continuous measurement.

Centration is relevant to a contact-lens performance assessment because it records whether the lens sits in an intended position on the eye. The endpoint can distinguish optimal positioning from acceptable or unacceptable decentration. That makes the categories interpretable as descriptions of performance, while preserving distinctions that could be lost if all categories were collapsed into one binary outcome.

The registry record does not report the number of participants in each centration category for either lens, nor does it provide a statistical comparison of those categories. It also does not explain whether centration was evaluated separately at multiple observations or how the crossover structure was handled for this endpoint. The record notes that the primary outcome has several categories or time points and was not reduced to one comparison. Without those outcome details, the endpoint definition can be explained, but the relative centration results cannot be determined from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The study is described as randomized, double-masked, and crossover. These terms describe distinct aspects of design. Randomization assigns treatment order by chance, which can reduce systematic differences between sequences when properly implemented. Masking limits knowledge of treatment assignment and may reduce bias in care or assessment. A crossover design exposes participants to conditions in different periods, so each participant can contribute observations under more than one condition. The registry record does not report the randomization procedure, who was masked, the period structure, or the analysis method.

What does the crossover design change?

In general, crossover data are not automatically equivalent to data from independent parallel groups. Measurements from the same participant may be correlated. A suitable analysis can account for that within-participant relationship and may also consider period or sequence effects. Carryover is another general concern: an effect from one period could persist into a later period. Whether these issues were assessed or adjusted for is not reported in the registry record. The description of the design alone is not enough to establish how the analysis handled them.

How should the centration scale be understood?

The primary outcome uses three categories, ranging from optimal centration to acceptable slight decentration and unacceptable decentration. In general, a categorical outcome is described by the number of observations in each category. An ordinal analysis may use the ordering of categories, whereas a nominal analysis treats categories without assuming an ordering. Combining categories into a binary result may answer a narrower question, but can discard information. The registry record says the primary outcome has several categories or time points and was not reduced to one comparison. It does not report the category counts or specify an analysis that preserves the scale.

What can an estimate and confidence interval tell a reader?

In general, an effect estimate describes the observed contrast under a defined analysis, and a confidence interval communicates uncertainty around that estimate. A narrow interval indicates greater precision under the model assumptions; a wide interval indicates less precision. Intervals do not by themselves establish clinical importance, and they depend on the design and analysis being appropriate. No effect estimate or confidence interval for lens centration is reported in the registry record, so precision cannot be assessed.

Why is the analysis method important?

General statistical methods should match the outcome type and design. For a categorical endpoint, the method should make clear whether the comparison concerns category distributions, a particular category, or a contrast formed by combining categories. For crossover data, the method should account for repeated observations from participants where appropriate. If the distribution is more variable than a model assumes, standard errors may be too small; general methods that account for over-dispersion can help avoid overstating precision. There is no indication in the registry record that over-dispersion was relevant here, and no statistical model is reported.

The record lists zero analyses. It does not report whether the primary analysis was adjusted, whether a model was fitted, or what significance threshold or confidence level was used. General statistical interpretation cannot fill in those missing design and analysis choices. In particular, no p-value or interval should be inferred from a descriptive endpoint definition or from enrollment alone.

What do planning calculations mean?

In general, sample-size calculations describe the amount of information a proposed study might need under specified assumptions. The registry’s planning assumptions describe a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation; the effect to detect is stated as a fraction of the observed effect. The record characterizes these as planning illustrations based on the observed effect, not as the trial’s own design. Such illustrations are hypothetical planning aids, not observed power and not evidence that a comparison was statistically significant. The numeric planning results and their relevance to the trial’s actual design are not reported in the registry record.

For time-to-event outcomes, a general planning approach may focus on the number of events; for other outcomes, planning may be expressed as participants per arm. The registry’s assumption text makes that distinction. It does not establish that this primary endpoint was analyzed as a time-to-event outcome, and no such interpretation is warranted from the endpoint description.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 15 outcome measures. It names average hours of wear per day and average comfortable wearing time among the secondary outcomes, with each label repeated. It does not explain the repeated entries, identify which outcomes were treated as confirmatory, or report a multiplicity adjustment. The primary outcome itself has multiple categories or time points and was not reduced to one comparison. Without a defined family of tests and a stated analysis plan, the effect of multiple comparisons on interpretation cannot be assessed.

In general, evaluating many outcomes or comparisons can increase the chance of finding an apparently notable result by chance. Methods for handling multiplicity depend on which comparisons were planned and which were considered primary. No correction method, hierarchy, or prespecified testing sequence is reported in the registry record. The record also lists no analyses, so it is not possible to determine which tests, if any, were conducted or how multiplicity was addressed.

Missing-data procedures and analysis populations are also not reported in the registry record. The record does not say whether all enrolled participants were included in outcome analyses, how incomplete or unavailable observations were handled, or whether the analysis followed assigned sequence or actual lens wear. These choices can affect estimates and uncertainty, particularly in crossover studies where outcomes may be observed in more than one period.

The record’s enrollment and safety counts do not answer these questions. They do not establish the number of observations available for the primary endpoint or the population used in any efficacy analysis. Accordingly, neither missing-data bias nor the handling of multiple outcomes can be evaluated from the registry record.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry lists safety figures separately for Fanfilcon A Toric and Lotrafilcon B Toric. For each lens group, 42 participants are listed as at risk for serious events and 42 as at risk for other events. The recorded numbers affected are zero for serious events and zero for other events in each group; deaths are also recorded as zero in each group. No serious-event terms are listed.

These are the counts recorded in the registry, not a comparison adjusted for the crossover design. Because the study is described as a crossover, the group entries should not be added or interpreted as separate, independent participant populations. The record does not explain the event-collection window, definitions used for other events, or whether safety was assessed across each treatment period or for the study as a whole.

Zero recorded events in these entries means that no affected participants are listed for the specified categories in the posted figures. It does not prove that the underlying risk is zero, establish that the lenses have identical safety, or rule out events that were not captured or reported. The record does not provide an analysis of comparative safety or uncertainty around these counts. The figures should therefore be read as descriptive registry counts, with the reporting limitations in mind.

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

The registry record establishes that the study was designed to compare fanfilcon A toric and lotrafilcon B toric contact lenses after one month of wear in a randomized, double-masked crossover study. It also defines lens centration as the primary outcome and identifies several secondary outcomes related to hours of wear and comfortable wearing time. These details clarify what the study set out to assess.

They do not establish the comparative result. The primary endpoint is categorical, but category-specific findings and a statistical comparison are not reported in the registry record. The secondary outcome results are also not reported. As a result, the record does not show whether one lens had better centration, longer wear, or greater comfortable wearing time, nor does it quantify uncertainty around any such contrast.

In general, a lack of a reported difference is not the same as evidence of equivalence. Demonstrating similarity or non-inferiority requires a defined margin and an analysis designed to evaluate it. Such a margin and analysis are not reported in the registry record. Similarly, the zero event counts in the listed safety groups describe the posted figures but cannot establish that risk is absent or that the lenses are equally safe.

The record’s status as completed and its enrollment of 42 do not substitute for outcome estimates. Enrollment alone cannot indicate the precision of a comparison, particularly when the analysis population, missing observations, and crossover-specific modeling are not described. The appropriate interpretation is therefore limited: the record documents the intended study and its outcome definitions, while the comparative clinical findings are not reported in the registry record.

13. Why This Trial Matters Statistically

This study is statistically informative as an example of why design details and outcome reporting need to be read together. A crossover design can support within-participant comparisons, but interpretation depends on the period structure, treatment sequence, possible carryover, and analysis of repeated measurements. The registry identifies the design but does not report how these features were addressed analytically.

The primary outcome also illustrates the importance of retaining the structure of categorical data. Lens centration is described using three ordered categories, each with a distinct interpretation. A single summary can obscure how observations are distributed across those categories. The record itself notes that the outcome has several categories or time points and was not reduced to one comparison, leaving no single result to interpret.

For biostatisticians and clinical researchers, the distinction between a planned question and an assessable result is central. This record identifies the comparison, endpoint, and broad design, but does not report the category counts, effect estimate, uncertainty interval, or analysis details necessary to judge the result. Its listed safety counts are descriptive and similarly do not provide an adjusted comparative analysis.

The case also shows why completed status and enrollment should not be mistaken for evidence of a finding. Outcome-specific estimates and transparent methods are needed to evaluate direction, magnitude, and precision. Without them, conclusions about relative lens performance would go beyond what the registry record reports.

14. 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 limitations specific to this record constrain interpretation. Most importantly, the primary endpoint is defined but its results are not reported as category counts or as a comparison. The registry notes that the outcome has several categories or time points and was not reduced to one comparison. Consequently, no observed distribution or effect estimate can be assessed.

The registry lists 15 outcome measures, while the named secondary outcomes include repeated entries for average hours of wear per day and average comfortable wearing time. The reason for these repeated entries is not reported in the registry record. The record also does not identify a multiplicity strategy, so the relationship between the primary and secondary outcomes is unclear.

Although randomization, double masking, and a crossover model are recorded, important operational and analytic details are absent. The allocation method, masking procedures, period and sequence details, washout procedures, handling of carryover, and statistical model are not reported. The record does not specify analysis populations or how missing observations were handled. These gaps limit assessment of bias, precision, and suitability of the analysis for the design.

The safety figures are limited to the listed counts and do not include event definitions, collection periods, or comparative uncertainty. Finally, the registry’s enrollment figure does not by itself establish the amount of information available for each outcome. Taken together, these limitations mean the record supports a description of the trial but not a reliable assessment of comparative outcome effects.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Performance of Toric Silicone Hydrogel Contact Lenses Following One Month of Daily Wear — NCT03418064.
• Registry record last updated 2019-11-13; status last verified 2019-10.
• Results first posted 2019-11-13.
• 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.

18. Record Summary

NCT03418064 is a completed, prospective, randomized, double-masked crossover study sponsored by CooperVision, Inc. It enrolled 42 and compared fanfilcon A toric with lotrafilcon B toric contact lenses after one month of wear. Astigmatism is listed as the condition. The recorded start date is 2018-02-10, and primary completion is 2018-05-16; phase is listed as NA.

The primary outcome is lens centration in primary gaze, described on a 1-3 scale from optimal through acceptable slight decentration to unacceptable decentration. The registry record indicates that the outcome has several categories or time points and was not reduced to one comparison. It lists 15 outcome measures and no analyses. Primary and secondary outcome results, analysis populations, missing-data procedures, and the statistical plan are not reported in the registry record.

For each lens group, the safety entries list 42 at risk, zero serious events, zero other events, and zero deaths. These figures are descriptive and should be interpreted in light of the crossover design and the missing reporting details.