Refitting Somofilcon A Sphere Contact Lens Wearers Into Fanfilcon A Sphere Lenses for 4-Weeks of Wear: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Refitting Somofilcon A Sphere Contact Lens Wearers Into Fanfilcon A Sphere Lenses for 4-Weeks of Wear (NCT03974802), a na na study. The primary outcome is Lens Centration for Somofilcon A (Habitual) Lens.

2. Clinical Question

In practical terms, the study was intended to evaluate clinical performance after habitual somofilcon A wearers changed to fanfilcon A lenses. The registry summary describes the study as prospective and subject-masked, while the masking field says none; the record does not resolve this difference. The primary endpoint metadata concern the habitual lens at baseline, rather than a stated post-refit comparison. Although daily and comfortable wearing time outcomes are listed as secondary outcomes, their results are not reported in the registry record. The record also does not report a statistical analysis relating baseline centration to later wear experience.

3. Trial Design

The registry describes a completed prospective study with a single group and enrollment of 41 participants. Its arm description says participants habitually wore somofilcon A lenses and were refitted with fanfilcon A lenses. The study title specifies 4-weeks of wear. The recorded start date is 2019-05-14, and the primary completion date is 2019-07-24.

This is not a randomized, parallel-group trial. Allocation is recorded as NA, and the registry explicitly cautions that the lens groups are not a like-for-like control comparison. The lens sequence described is habitual somofilcon A followed by fanfilcon A. Observations under each lens, if made in the same people, would be paired or sequential rather than independent evidence from randomized groups. However, the record does not describe the timing of outcome assessments beyond identifying baseline for the primary outcome, nor does it detail any washout or other study procedures.

Masking information is internally inconsistent: the brief summary calls the study subject-masked, whereas the masking field is NONE. The registry does not explain the discrepancy, so the masking status cannot be resolved from the record. The study is marked completed. The record lists CooperVision, Inc. as sponsor, and NA for phase.

The study lists 31 outcome measures and zero analyses. That distinction matters: outcome listings describe what was planned or registered for assessment, while an analysis result requires reported data and a stated method. Neither an analysis population nor a protocol-level statistical plan is reported in the registry record. The enrollment figure alone does not establish how many participants contributed data to each outcome. The record does not report withdrawals, missing observations, or outcome-specific denominators.

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.

Overall Study

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 for Somofilcon A (Habitual) Lens, measured over Baseline.

The registered primary endpoint is lens centration for the somofilcon A habitual lens at baseline. The description says centration was measured on a 3-point scale: 1 indicates optimal centration, 2 indicates acceptable decentration, and 3 indicates unacceptable decentration. The outcome unit is described as percentage of participants, while the parameter is recorded as NUMBER. The registry record does not explain how the scale categories were summarized into a number or percentage.

Centration is a lens-position characteristic. In general, measuring a defined feature of lens fit can help describe how a lens sits on the eye and can provide a structured clinical observation rather than an unstandardized impression. The 3-point scale also distinguishes acceptable from unacceptable decentration, which may be useful when describing the distribution of fit assessments. These are general reasons such a measure may be used; they do not establish the value of this endpoint in this study.

The timeframe is baseline, and the endpoint names the habitual lens, not the fanfilcon A test lens. No category counts, percentage, summary value, uncertainty interval, or test of a lens difference is reported in the registry record. Thus, the endpoint definition clarifies what was to be assessed, but does not reveal the observed centration status of participants or whether centration changed after refitting.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record does not report an analysis method for the primary endpoint. The following concepts are general explanations of how data of this type might be approached; they should not be read as methods used in this study.

Describing a three-category measure

A 3-point centration scale is ordinal: its categories have an order, but the distance between adjacent categories is not necessarily equal. A transparent summary could report the count or proportion of participants in each category, retaining the distinction between optimal, acceptable, and unacceptable centration. Treating the scale as a continuous score would require an explicit rationale, because assigning numbers to ordered categories does not by itself establish equal spacing between them.

The registry describes the primary outcome as a percentage of participants, but also labels its parameter as NUMBER. It does not say whether the intended summary was a percentage in one category, a percentage meeting a threshold, or another statistic. Without that definition and the observed category counts, it is not possible to reconstruct the endpoint or check its calculation. Any interpretation of a percentage would also depend on the denominator: the record does not report an outcome-specific number assessed.

Within-person measurements

In general, a before-and-after or sequential refitting study may collect observations from the same participants under each lens. When the same person contributes both measurements, the observations are related; methods that account for pairing can be more appropriate than methods that treat the two sets as independent. The registry's single-group description and lens sequence are consistent with a sequential design, but it does not report whether the same endpoint was measured under both lenses or how any paired data were analyzed. The primary endpoint listed is specifically baseline centration for the habitual lens.

Because the lens sequence is not randomized, any change observed over time could have multiple explanations. General considerations include time, learning, changes in assessment, and the order in which conditions are experienced. The record does not report methods to address such possibilities. This limits causal interpretation even if a numerical difference were available.

Uncertainty and statistical tests

In general, a confidence interval describes a range of values compatible with the data and a stated method, and communicates precision as well as the direction and size of an estimate. A p-value, when calculated under a specified statistical model, describes how unusual data at least as extreme as those observed would be under a null hypothesis. Neither measure alone establishes clinical importance, and both depend on the analysis being appropriate to the design and data. The registry record reports no confidence intervals, p-values, or model specification for the primary endpoint.

For a proportion, precision depends in part on the number of observations and the distribution of outcomes. A sample of 41 enrolled participants does not automatically mean that all 41 contributed an observed value to every outcome. General reporting should identify the denominator used for each estimate and address unavailable observations. The registry record does not report outcome-specific denominators or missing-data methods.

Planning calculations

A planning illustration is described using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; its target effect is expressed as a fraction of an observed effect. These are assumptions for a planning illustration, not evidence about the trial's own design. The record describes this study as single-group and non-randomized, so the equal-allocation two-arm setup does not mirror its stated structure. Planning sample sizes are not observed power, and they do not show how likely a result from the completed study was to be statistically significant.

In general, a sample-size calculation depends on the outcome, target effect, variability or event rate, significance threshold, desired power, and analysis design. If an observed effect is used as the planning reference, the illustration inherits uncertainty in that estimate; it should not be interpreted as an independently established effect. The registry record does not report a trial-specific sample-size justification, target power, or protocol calculation. The actual planning outputs and a primary endpoint result are not reported in the registry record, so no study-specific precision or adequacy assessment can be made from the available details.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 31 outcome measures, including several daily wearing time and comfortable wearing time entries, with repeated titles among the secondary outcomes. It reports zero analyses. The record does not describe which outcomes were designated for formal hypothesis testing, how many comparisons were planned, or whether any adjustment for multiple testing was specified. A multiplicity strategy is therefore not reported in the registry record.

In general, testing many outcomes or contrasts can increase the chance of obtaining at least one apparently notable result by chance. Methods for handling multiplicity depend on the goals and hierarchy of the analyses. Without a stated analysis plan and reported results, it is not possible to determine whether multiplicity was addressed or how it would affect interpretation.

Missing-data information is also not reported. The registry does not say whether participants withdrew, whether any outcome observations were unavailable, how missing values were handled, or whether sensitivity analyses were conducted. Enrollment of 41 participants is not equivalent to an outcome-specific analysis population of the same size.

The record does not report an intention-to-treat, per-protocol, or other named analysis population. It also does not provide an estimand describing the target effect, such as how discontinuation or incomplete wear would be treated. These omissions prevent assessment of how the analysis population was selected and how its results would relate to all enrolled participants. None of these missing details can be inferred from the outcome list or the completed status.

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 41 participants at risk in the somofilcon A habitual lens group and 41 in the fanfilcon A test lens group. It records zero serious events and zero deaths in each group. The figures for other adverse events also list zero participants affected in each group.

These counts describe what is recorded, not a comparison demonstrating equivalent safety. The record describes one group moving from habitual to test lenses, not randomized parallel groups, and it does not report a statistical safety comparison. It also does not provide event definitions, individual event details, or information about how long each participant contributed to safety follow-up beyond the study's stated 4-weeks of wear.

In general, a zero count in a study does not establish that an event cannot occur; precision depends on the amount and duration of observation and on how events are identified and recorded. The registry does not provide enough detail to quantify uncertainty around the safety figures. The listed counts should therefore be read as the reported event totals for this study, not as proof that risk is absent.

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

The registry record establishes that a completed, prospective, single-group refitting study enrolled 41 habitual somofilcon A sphere lens wearers and described refitting them with fanfilcon A sphere lenses for 4-weeks of wear. It also defines a baseline lens centration measure for the habitual lens and lists wearing-time outcomes. Those details clarify the study question and its general structure.

The record does not report the primary endpoint result, the secondary outcome results, or statistical analyses. Consequently, it cannot establish from the registry information whether centration was optimal, acceptable, or unacceptable for participants, nor whether daily or comfortable wearing time differed between the lenses. A study design and outcome definition are not substitutes for observed estimates and uncertainty.

The single-group sequence also matters. Even if comparative numerical results were available, a non-randomized sequence would not provide the same basis for causal interpretation as a randomized comparison. Differences could be associated with lens, time, order, or measurement conditions, and the registry does not report an analysis addressing these factors. The record itself cautions that the groups are not a like-for-like control comparison.

The reported safety entries list zero serious events and zero deaths in both lens groups, as well as zero participants affected by other adverse events. These entries describe the registry's counts; they do not establish that no risk exists or that the study can rule out uncommon outcomes. No formal safety comparison or uncertainty estimate is reported.

Overall, the registry supports a description of study design, registered endpoints, and recorded safety counts, but not a conclusion about the size, precision, or clinical importance of an effect. Such an interpretation would require outcome results and the analysis methods, population, and missing-data information, none of which are reported in the registry record.

13. Why This Trial Matters Statistically

This trial is statistically notable because its registered lens groups can be mistaken for a conventional treatment-versus-control comparison. The registry describes habitual somofilcon A wearers being refitted with fanfilcon A, and explicitly warns that the groups are not a like-for-like control comparison. Recognizing the sequential, single-group structure is essential: it shapes what comparisons can mean and what causal claims the design can support.

The primary outcome also illustrates why an endpoint definition needs to be paired with a clear summary rule. The centration assessment uses three ordered categories, while its metadata describe the unit as percentage of participants and the parameter as NUMBER. Without a stated summary definition or results, the record does not clarify exactly how the scale was to be reduced for reporting. Clear outcome definitions help readers distinguish a category distribution from a threshold-based percentage or a numerical score.

Another statistical issue is the difference between registering outcomes and reporting analyses. The record lists 31 outcome measures but zero analyses. An outcome list does not tell readers which hypotheses were tested, how uncertainty was assessed, or whether multiple comparisons were considered. Similarly, enrollment does not show how many observations contributed to each analysis.

Finally, the safety counts require calibrated interpretation. Zero recorded events are a factual result in the registry, but without uncertainty estimates and fuller follow-up details, they cannot establish absence of risk. These are general lessons in reading clinical trial records: design, endpoint definition, analysis, and precision all contribute to interpretation, and no single element can stand in for the others.

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 trial-specific limitations follow from the registry record. First, the design is listed as single-group, with participants moving from habitual somofilcon A lenses to fanfilcon A test lenses. Allocation is NA, and the record says the groups are not a like-for-like control comparison. This makes a simple between-lens contrast difficult to interpret causally, especially because the registry does not report a method for accounting for the sequence.

Second, the primary outcome is defined for the habitual lens at baseline, not as an explicit comparison of centration under both lenses. The record gives a 3-point scale but does not clarify how its categories correspond to the listed percentage unit and NUMBER parameter. The primary result itself is not reported in the registry record.

Third, the brief summary describes the study as subject-masked, but the masking field says NONE. The record does not explain this difference. The actual masking procedures therefore cannot be determined from the registry entries. The record also does not report further information on eligibility, participant characteristics, outcome-specific denominators, missing observations, or analysis populations.

Although 31 outcomes are listed, zero analyses are reported. No statistical plan, multiplicity handling, sample-size justification, or analysis method is reported in the registry record. Repeated secondary outcome titles add uncertainty about how the listed measures were organized. These limitations concern what can be learned from the registry record; they do not establish that corresponding information was absent from study conduct or other documents.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Refitting Somofilcon A Sphere Contact Lens Wearers Into Fanfilcon A Sphere Lenses for 4-Weeks of Wear — NCT03974802.
• Registry record last updated 2020-08-18; status last verified 2020-08.
• Results first posted 2020-08-18.
• 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

The registry describes a completed prospective, single-group study of habitual somofilcon A sphere lens wearers refitted with fanfilcon A sphere lenses for 4-weeks of wear. Enrollment was 41; the recorded start date was 2019-05-14, and primary completion was 2019-07-24. Myopia is listed as the condition, and CooperVision, Inc. as sponsor.

The primary outcome is baseline centration for the habitual lens, described on a 3-point scale. The record lists 31 outcome measures and zero analyses, but does not report primary or secondary outcome results. The masking descriptions conflict: the summary says subject-masked, while the masking field says NONE. Safety listings show zero serious events and deaths in each lens group, with 41 at risk per group. The registry cautions that the groups are not a like-for-like control comparison.