Clinical Evaluation of Two Daily Wear Silicon Hydrogel Contact Lens: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Evaluation of Two Daily Wear Silicon Hydrogel Contact Lens (NCT02354924), a randomized na study. The primary outcome is Visual Acuity.

2. Clinical Question

3. Trial Design

The registry describes a prospective randomized controlled study with a double-masked, parallel-group design. It lists 60 participants as enrolled and identifies Visco Soft Contact Lens and Biofinity Soft Contact Lens as the two device interventions. The reported group sizes are 40 for Visco and 20 for Biofinity. Randomization is reported, but its sequence-generation method, allocation concealment, and implementation are not described in the registry record. The specific people masked, and the procedures used to maintain masking, are also not reported.

The condition is myopia. Both lenses are described as daily-wear, monthly disposable soft contact lenses; the Visco lens is Olifilcon A and the Biofinity lens is Comfilcon A. The registry lists the study start as 2013-06 and primary completion as 2013-11, with status COMPLETED. The study is listed as phase NA. These record entries do not provide additional information about participant flow, actual follow-up for each participant, or protocol adherence.

The primary endpoint is visual acuity, defined as a count of eyes with acuity correctable to Snellen 20/25 or better, assessed at 3 months. Two secondary outcomes are listed: slit-lamp findings, and symptoms, problems and complaints and incidence rate. The registry reports 3 outcome measures and 0 analyses. It does not describe a statistical analysis plan, a sample-size justification for the trial, interim analyses, or specified analysis populations. The planning assumptions recorded for a separate sample-size illustration should not be read as evidence about how the trial itself was designed.

The sponsor is Visco Vision Inc. The registry record supports a description of the design and listed outcomes, but it does not give enough detail to reconstruct the conduct of randomization, masking, follow-up, or the analysis. Those omissions matter when considering how closely the posted endpoint results represent the intended randomized comparison.

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 Visual Acuity, measured over 3 months.

The primary endpoint is the count of eyes with visual acuity correctable to Snellen 20/25 or better at 3 months. It is a threshold-based outcome: each eye is classified according to whether its acuity meets the stated criterion, and the endpoint is expressed as a count. The unit is an eye, rather than a participant-level score. The registry does not clarify whether both eyes could contribute for an individual participant, how eye-level observations were handled, or how the count relates to the participant enrollment total.

Visual acuity is a clinical measurement relevant to vision, while the stated threshold turns that measurement into a countable endpoint. A threshold can make a result easier to describe, but it also discards information about how far measurements fall above or below the threshold. General statistical interpretation therefore depends on knowing the measurement procedures, the rules for selecting or combining eyes, and the analysis method. Those details are not reported in the registry record.

The record reports an assessment timeframe of 3 months. It does not give additional assessment visits or indicate whether the endpoint refers to a particular visit window. The posted outcome values are 80 for Visco and 40 for Biofinity, with arm sizes listed as 40 and 20, respectively. Because the record identifies the count outcome as missing or not estimable for a two-arm comparison, those values cannot by themselves be treated as a valid between-group effect estimate. No confidence interval or inferential comparison is reported.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a randomized comparison aim to estimate?

In general, random allocation is intended to make treatment groups comparable at the start of a study, apart from chance variation. A comparison between groups can then estimate an effect of assignment, subject to how the study is conducted, how outcomes are measured, and how missing observations are handled. Randomization does not guarantee that groups are identical, and it does not replace a clearly specified analysis. The registry identifies this study as randomized, but further details about sequence generation and concealment are not reported in the registry record.

A parallel-group design assigns participants to one group for comparison with another group. The registry lists Visco and Biofinity arms. The record reports group sizes of 40 and 20, and does not explain the allocation ratio or why the reported groups have those sizes. A double-masked label indicates that masking was intended, but does not identify who was masked or how. These design details can affect the interpretation of measurements and reports of symptoms, but they cannot be inferred from the label alone.

How should a count endpoint be analyzed?

General statistical methods for count outcomes depend on what is counted and on the relationship between the count and its denominator. A count of events, a count of people meeting a criterion, and a count of eyes meeting a criterion can require different interpretations. If individuals contribute multiple eyes, observations from the same individual may be related rather than independent. An analysis should account for the unit of randomization and the structure of the outcome. The registry calls the unit an eye, but does not report how multiple eyes per participant were handled.

Counts are often modeled with methods suited to nonnegative discrete outcomes. The appropriate approach depends on the data distribution, exposure or denominator, and design. Over-dispersion is a general concern when count variability exceeds what a simple count model assumes; ignoring it can make uncertainty estimates too optimistic. That general issue cannot be evaluated from arm-level counts alone. No distributional information, model, variance estimate, or analysis method for the visual-acuity endpoint is reported in the registry record.

For a threshold endpoint, the denominator is important. A count can be interpreted as a proportion only when the relevant number of observed units is known and the units have been defined consistently. The registry gives arm sizes as 40 and 20, but does not explain the relationship between those sizes and the eye-level counts of 80 and 40. It would therefore be inappropriate to derive a proportion or comparative effect from these entries. The record itself notes that a two-arm comparison for this count outcome is missing or not estimable.

What do an effect estimate and confidence interval convey?

In general, an effect estimate expresses the contrast between groups on a chosen scale, such as a difference in means, a ratio, or a difference in proportions. The scale should match the outcome and the scientific question. A confidence interval communicates uncertainty about that estimate under the analysis assumptions. A narrow interval indicates greater precision than a wide interval, but precision is not the same as clinical importance. A p-value, when reported, addresses compatibility with a specified null hypothesis under the analysis model; it does not measure the size or practical importance of an effect.

For this trial, no primary-outcome effect estimate, confidence interval, or p-value is reported. The arm counts cannot substitute for those quantities because the registry marks the comparison as not estimable. No recalculated estimate is available in the record. There is therefore no numerical basis for assessing the magnitude, direction, or precision of the treatment contrast.

How should planning illustrations be understood?

In general, a sample-size calculation asks how many participants may be needed under specified assumptions about the effect to detect, variability, significance level, power, and allocation. It is a planning exercise, not an outcome of the trial. The record's stated planning assumptions use a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is expressed as a fraction of the observed effect. For non-time-to-event outcomes, the stated convention is participants per arm for a specified power. The record does not report a trial-specific sample-size justification, so these assumptions must not be interpreted as the study's design rationale.

A planning illustration based on an observed effect is especially dependent on that effect being estimable and clearly defined. Here, the primary count comparison is marked as missing or not estimable. Any planning exercise should therefore be read only according to the assumptions stated for it, not as evidence that the trial had a particular achieved power. Power is not a measure of the probability that a result is true, and a post hoc calculation does not repair an unestimable comparison.

What can the registry's analysis count tell us?

The registry lists 0 analyses. That entry does not explain whether no statistical analyses were performed, whether analyses were not entered into the record, or whether the record contains other reporting limitations. It does mean that a reader cannot identify a posted model, adjustment strategy, or inferential test from the analysis entry. The statistical plan, including any interim analyses, is not reported in the registry record. No analysis method should be attributed to the investigators without a record of it.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures, including the primary visual-acuity endpoint and 2 secondary outcomes: slit-lamp findings, and symptoms, problems and complaints and incidence rate. It reports 0 analyses. The statistical plan is not reported in the registry record, so it is not possible to determine whether outcomes were prespecified in this form, how the primary and secondary outcomes were prioritized, or how multiple comparisons were handled.

Multiplicity is a general issue when several outcomes or comparisons are tested. Conducting many tests can increase the chance of finding at least one apparently notable result by chance. Methods such as prespecifying a primary outcome or adjusting inference can address particular multiplicity concerns, but no such approach should be assumed. The record does not report an adjustment method, a hierarchy of outcomes, or a testing strategy.

The primary count outcome is identified as not estimable for a two-arm comparison. The record does not report missing-data counts, reasons for missingness, imputation methods, or sensitivity analyses. It also does not state an intention-to-treat, per-protocol, or other analysis population for the endpoint. The primary population field is empty. These omissions prevent assessment of whether participants were analyzed as randomized, how incomplete observations were treated, and whether the endpoint analysis included the full randomized population.

These details are consequential because exclusions and missing observations can affect the comparability created by randomization. Without participant flow and analysis-population definitions, the reported arm sizes cannot be confirmed as endpoint denominators. The registry record does not provide enough information to assess that issue.

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 0% reporting threshold.

The registry lists zero serious adverse events and zero other adverse events in the Visco group, with 40 participants at risk. It lists zero serious adverse events and zero other adverse events in the Biofinity group, with 20 participants at risk. Deaths are listed as zero in each group. These are recorded event counts for the groups shown; they are not estimates of comparative risk.

A zero count does not establish that the underlying risk is zero. In general, the interpretation of adverse-event counts depends on how events were defined and collected, how long participants were observed, whether follow-up was complete, and how repeated events were counted. Those details are not reported in the registry record. The record also does not describe the severity or nature of any non-serious events, and lists no top serious-event terms.

The groups differ in their reported sizes, and the record does not provide an inferential safety comparison or uncertainty interval. The figures should therefore be read as descriptive registry entries, not as proof that the lenses have equal safety or that no adverse event could occur.

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

The registry record establishes that a completed, randomized, double-masked, parallel-group study evaluated Visco and Biofinity soft contact lenses in people with myopia. It identifies an eye-level visual-acuity count at 3 months as the primary outcome and lists two secondary outcomes. It also reports arm sizes and arm-level endpoint values. These details describe the recorded study and its posted outcomes.

The primary result cannot be interpreted as a comparative treatment effect. The record explicitly identifies the count outcome as missing or not estimable for a two-arm comparison. It does not provide an effect estimate, confidence interval, or p-value. The eye-level count definition and its relation to the reported group sizes are not sufficiently explained to support deriving a rate or contrast. As a result, the direction, size, and precision of any difference between groups remain undetermined in the registry results.

This is not evidence that the groups had the same outcome, and it is not evidence that one group had a better outcome. It is a limitation of what can be concluded from the posted statistical results. The same caution applies to the secondary outcomes: they are listed, but their results and analyses are not reported in the registry record for interpretation.

The adverse-event entries report zero serious events, zero other events, and zero deaths in both groups. Those counts are descriptive. Without additional information about event collection and follow-up, they do not demonstrate absence of risk or equivalence between groups.

In general, a randomized design can support a causal comparison when outcomes, analysis populations, missing data, and statistical methods are adequately reported and the analysis is appropriate. The registry record supplies the design labels but not those analytic details. Its entries therefore support a cautious account of what was registered, not a conclusion about comparative clinical benefit or harm.

13. Why This Trial Matters Statistically

This trial illustrates an important distinction between a study design and an interpretable statistical result. Randomization and masking are meaningful design features, but they do not by themselves produce an effect estimate. To evaluate a randomized comparison, readers need a clearly defined outcome, denominators or analysis populations, an analysis method, and an account of uncertainty. The registry identifies the primary endpoint and design, but the primary count comparison is marked as missing or not estimable.

The endpoint is recorded in eyes, whereas enrollment and arm sizes are reported in participants or group counts without further explanation of how the units connect. That difference highlights why the unit of analysis must be explicit. When multiple observations can arise from one participant, treating them as independent can misstate uncertainty. The registry does not explain the handling of eyes within participants, so the issue cannot be resolved from the posted record.

The entry also demonstrates why outcome listings are not equivalent to outcome analyses. Three outcome measures are reported, but 0 analyses are listed, and the two secondary outcomes have no results in the record available for interpretation. Without a statistical plan, readers cannot check how multiplicity, missing observations, or analysis populations were addressed.

Finally, the sample-size assumptions describe a planning illustration, not the trial's own justification or an observed measure of power. Separating planning assumptions from trial results helps prevent a numerical illustration from being mistaken for evidence about the strength or certainty of the clinical comparison. The statistical lesson is that careful interpretation depends as much on transparency about units, denominators, and analysis as on the presence of randomized design features.

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 details needed to interpret the endpoint are not reported in the registry record. The primary measure counts eyes, but the record does not explain whether one or both eyes could contribute per participant, how the eye-level observations were selected or combined, or how the reported counts relate to group sizes. The endpoint values are marked as not estimable for a two-arm comparison, and no inferential result accompanies them.

The registry does not report participant characteristics, eligibility criteria beyond the condition of myopia, participant flow, reasons for withdrawal, or the number with an observed primary outcome. The reported arm sizes do not establish how many participants contributed endpoint data. The analysis population and missing-data approach are also not reported, so the extent and handling of incomplete follow-up cannot be assessed.

Although the trial is described as randomized and double-masked, the record does not give details of sequence generation, allocation concealment, who was masked, or how masking was maintained. It does not report a statistical analysis plan, a trial-specific sample-size justification, or interim analyses. No model or inferential procedure is listed for the primary endpoint.

The registry lists two secondary outcomes but does not report their results. It also lists zero analyses, so there is no posted analysis strategy against which to evaluate the outcomes. Safety entries lack further information about event definitions and observation completeness. Together, these omissions limit assessment of both the comparative visual-acuity result and the completeness of safety reporting. They do not establish that unreported procedures or analyses did not occur; they mean those details are not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Clinical Evaluation of Two Daily Wear Silicon Hydrogel Contact Lens — NCT02354924.
• Registry record last updated 2017-04-14; status last verified 2017-03.
• Results first posted 2017-04-14.
• 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

NCT02354924 is a completed randomized, double-masked, parallel-group study of Visco and Biofinity soft contact lenses for people with myopia. Enrollment is listed as 60; the reported group sizes are 40 for Visco and 20 for Biofinity. Both lenses are described as daily-wear, monthly disposable devices. The study start is listed as 2013-06 and primary completion as 2013-11. The sponsor is Visco Vision Inc.

The primary outcome is a count of eyes with visual acuity correctable to Snellen 20/25 or better at 3 months. The posted values are 80 and 40, respectively, but the record marks the two-arm comparison as missing or not estimable. It reports 2 secondary outcomes, 3 outcome measures, and 0 analyses. No inferential comparison, analysis population, missing-data method, or trial-specific statistical plan is reported in the registry record.

Zero serious adverse events, zero other adverse events, and zero deaths are listed in each group. These entries are descriptive and do not establish comparative safety.