This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Two Phase Clinical Study of the Impact of Contact Lenses and Solutions on Corneal Structure (NCT00804999), a randomized na study. The primary outcome is HRT Corneal Scan.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00804999 |
| Phase | NA |
| Condition | Normal Contact Lens Wear |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 51 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Christine Sindt |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns people with contact-lens use histories described in the registry record. Its arm descriptions distinguish subjects who had never worn contacts and had no ocular problems from subjects who had worn contacts for at least two weeks without incident. The registry does not give a complete description of the primary endpoint population, so the population used for that outcome is not reported in the registry record.
Intervention
The study examined contact lenses soaked in named solutions, including Clear Care, ReNu, and OPTI-FREE. The arm descriptions refer to an overnight soaking period of 10 hours before the subject returned. Those descriptions are incomplete in the registry record, so details beyond the text recorded for each arm are not available.
Comparator
The registry identifies a randomized, parallel-group design, but it does not report the precise primary-outcome comparison or explain how each participant was assigned to a comparison. The listed safety groups include non-contact wearers using Clear Care and groups with overnight soaking in ReNu or Optifree. The relationship between those safety groups and the primary endpoint comparisons is not reported in the registry record.
Primary question
The primary endpoint is an HRT corneal scan measuring cell density, expressed as a mean in cells/mm^3, at baseline and 2 hours. The stated aim is to assess confocal microscopy for examining corneal structural changes and identifying potential consequences of contact lens wear and solution use. The registry does not report whether cell density changed, the size or direction of any change, or a statistical comparison between groups.
In general, a study question about a measured change asks whether the recorded value differs across time, groups, or both. The registry record does not specify the exact contrast used to answer that question, and the posted results do not provide an outcome estimate. Therefore, the clinical question can be described from the stated measurement and study aim, but the size and precision of any observed difference cannot be assessed.
3. Trial Design
The registry describes a completed, randomized, triple-masked, parallel-group study. It records an enrollment of 51 and lists the phase as NA. The study dates are recorded as starting 2008-11-01, with primary completion on 2009-03-01. The sponsor is Christine Sindt. The condition listed is Normal Contact Lens Wear. These registry entries identify the general framework, but they do not supply a full protocol or a complete account of how the study was conducted.
In a randomized study, assignment to study groups is intended to reduce systematic differences between groups; the registry does not report the sequence-generation method, allocation concealment, or implementation details. Triple masking indicates that the record classifies the study as triple-masked, but it does not identify which roles were masked or how masking was maintained. A parallel design means groups are followed in their assigned study paths rather than described as a crossover. The record does not give further design details about the schedule or the planned comparisons.
The listed interventions are Clear Care, ReNu, and OPTI-FREE, each classified as a drug in the registry. The arm descriptions refer to contact lenses soaked in solution for 10 hours and mention baseline HRT before the subject returned. They also distinguish people who had never worn contacts from people who had worn them for at least two weeks without incident. The descriptions end mid-sentence, so further procedural details are not reported in the registry record.
The registry lists 51 enrolled participants, but does not report how many were assigned to each primary-outcome group, how many completed each assessment, or how many contributed to the analysis. The four safety groups have their own at-risk counts, but those counts should not be treated as the primary endpoint sample sizes. The registry does not explain their relationship to the enrolled population or to the primary analysis. A formal sample-size justification, recruitment details, and the analysis population 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.
Overall Study
| Stage | Non Contact Wearer Using Clear Care | Overnight Soaking With Renu | Overnight Soak in Optifree | Overnight Soak in Optifree Replnish |
|---|---|---|---|---|
| STARTED | 15 | 12 | 14 | 10 |
| COMPLETED | 15 | 12 | 14 | 10 |
| NOT COMPLETED | 0 | 0 | 0 | 0 |
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.
| Characteristic | Unit | Non Contact Lens Wearers Using Clear Care | Overnight Soaking With Renu | Overnight Soaking in Optifree | Overnight Soaking in Optifree Replinish | Total |
|---|---|---|---|---|---|---|
| Participants analysed | 15 | 12 | 14 | 10 | 51 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 15 | 12 | 14 | 10 | 51 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 13 | 11 | 13 | 9 | 46 |
| Sex: Female, Male: Male | Participants | 2 | 1 | 1 | 1 | 5 |
| Region of Enrollment: United States | Participants | 15 | 12 | 14 | 10 | 51 |
6. Primary Endpoint
The registry lists the primary outcome as HRT Corneal Scan, measured over baseline and 2 hours.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | cells/mm^3 |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is titled HRT Corneal Scan. Its stated purpose is to look for cell density, reported as a mean with standard deviation, with units of cells/mm^3. The recorded timeframe is baseline and 2 hours. The study summary describes an interest in using confocal microscopy to examine changes in corneal structure and identify potential consequences of contact lens wear and/or solution use.
In general, cell density is a quantitative measure: a mean describes the average recorded value in a group, while a standard deviation describes how dispersed individual measurements are around that average. These summaries answer different questions. The mean describes the group’s central value; the standard deviation describes variation among measurements. Neither one alone establishes whether groups differ or whether an observed change is precise.
The registry does not report the mean cell-density values, standard deviations, changes from baseline, group contrasts, or confidence intervals. It also does not describe the measurement protocol, the specific corneal locations assessed, or rules for handling scan quality. Those details are not reported in the registry record. Consequently, the endpoint’s intended measurement can be identified, but its observed magnitude and reliability cannot be evaluated from the posted results.
Baseline and 2 hours indicate the stated assessment times, but the registry does not specify a primary contrast between those time points or whether the main analysis compared changes between groups. Without that definition and the outcome results, there is no basis for describing a direction or size of an endpoint effect.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a trial intended to examine corneal cell density after contact lenses were exposed to different solutions. It identifies a mean HRT corneal scan at baseline and 2 hours as the primary endpoint. However, it does not report numerical results for that endpoint. There is no posted mean, standard deviation, estimated change, between-group contrast, confidence interval, or p-value to interpret. The registry record therefore does not establish the magnitude, direction, or precision of any difference in cell density.
This distinction matters because the existence of a defined endpoint is not itself evidence of a result. A study can specify what it plans to measure while leaving the findings unavailable in the registry. The enrollment of 51 is a design and recruitment figure; it does not reveal how many participants contributed usable scans or how much information the endpoint analysis contained. The primary-outcome analysis population and group-specific participant counts are not reported in the registry record.
The registry classifies the study as randomized, triple-masked, and parallel. Those design labels are relevant to how results would ordinarily be interpreted, but they cannot substitute for outcome data. The record does not explain the randomization procedure, identify the masked roles, or state the exact primary comparison. It is therefore not possible to determine from this record whether a particular analysis accounted for baseline values, compared changes over time, or used another approach.
In general, an effect estimate describes the observed difference or change, and a confidence interval conveys the range of values compatible with the data under the method used. A p-value, when reported, addresses compatibility with a specified null model; it does not describe the size or practical importance of an effect. None of these inferential quantities is reported for the primary endpoint. No conclusion about a difference in cell density can be drawn from the registry information alone.
The record includes adverse-event counts, with zero serious events, zero other adverse events, and zero deaths reported in each of the four listed safety groups. These counts describe the safety entries as recorded, not the primary endpoint. They should be read with their group-specific at-risk counts and with the limitations of registry reporting in mind. The registry does not describe event definitions, collection procedures, or analysis methods, so these entries do not provide a complete account of safety monitoring.
The study summary states an objective of assessing confocal microscopy and examining potential consequences of contact lens wear and/or solution use. That objective is not a reported finding. In the absence of primary endpoint results, the record supports a description of the study’s question and structure, but not a determination about whether corneal cell density differed or how precisely it was measured.
9. Statistical Methods Explained
What does the endpoint summary represent?
The registry identifies a continuous outcome: HRT corneal cell density, summarized as a mean and standard deviation in cells/mm^3. In general, a continuous measure can take different values across a range. The mean is a measure of the group’s center, while the standard deviation describes the spread of observations around that center. Both can help characterize a distribution, but neither is an estimate of the difference between study groups by itself.
The endpoint is recorded at baseline and 2 hours. A comparison across those times might describe within-person change, while a comparison between groups might examine whether changes differ by solution or study arm. These are general examples of possible questions, not descriptions of the analysis used in this study. The precise primary contrast and statistical method are not reported in the registry record. Nor are endpoint means, standard deviations, or participant counts available, so no estimate can be reconstructed from the record.
Why do estimates and uncertainty matter?
In general, an effect estimate gives the magnitude and direction of a contrast defined by the study question. A confidence interval describes uncertainty around that estimate under the assumptions of the analysis. A narrower interval indicates greater precision than a wider interval, but precision does not by itself establish importance. A p-value addresses how compatible observed data are with a specified null hypothesis and statistical model; it does not measure the size of an effect or the probability that a hypothesis is true.
The registry record does not report an effect estimate, confidence interval, or p-value for the primary endpoint. Without these, readers cannot assess how large a cell-density difference might have been or how precisely it was estimated. The absence of those results should not be interpreted as evidence that the groups were equivalent, nor as evidence of a difference.
What can the design labels tell us?
The study is classified as randomized, triple-masked, and parallel. In general, random assignment is intended to limit systematic differences between groups, and masking is intended to limit the influence of knowledge of assignments on study conduct or assessment. A parallel design follows groups in distinct study paths. These general features can inform how results are considered, but the labels alone do not establish that the procedures were implemented successfully or that bias was absent.
The registry does not report how the random sequence was generated, how assignment was concealed, which people were masked, or whether masking remained intact. It does not describe protocol deviations or the analysis population. Those implementation details are not reported in the registry record. The study’s phase is listed as NA, which does not provide further design or analysis information.
What do the planning assumptions mean?
The registry’s sample-size assumptions describe a planning illustration based on an observed effect, rather than the trial’s own design justification. The assumptions specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. These are planning assumptions, not evidence about what the trial observed.
In general, a sample-size calculation estimates the number of participants needed under stated assumptions about an effect, variability, significance threshold, and power. A planning illustration is conditional on its inputs and should not be read as a result of the study or as observed power. The registry record does not report a protocol-based sample-size justification, the observed effect used for the illustration, or calculated participant requirements in the registry record for interpretation. No planning requirement can therefore be stated from this record.
For this continuous outcome, a normal approximation is a statistical approach that relies on assumptions about the sampling distribution. The registry does not report whether the assumptions were checked or whether an alternative analysis was used. General statistical guidance cannot fill in those missing study-specific details.
Why is over-dispersion relevant in general?
Over-dispersion describes variation greater than a model expects. In general, when data are more variable than assumed, standard errors can be understated and confidence intervals can be too narrow if the model does not account for the extra variation. This concept is relevant to some statistical models, especially when outcomes are counts. The primary endpoint recorded is a continuous mean, and no model or dispersion assessment is reported. It would therefore be inappropriate to claim that over-dispersion was present or that a particular adjustment was used.
What does the available analysis information establish?
The registry records one outcome measure and no analyses. Its note indicates that the primary outcome has several categories or time points and was not reduced to one comparison. As a result, the posted record does not identify a single outcome contrast that can be interpreted as the primary statistical result. The number and nature of any additional planned or completed analyses are not reported in the registry record.
In general, a transparent analysis description would identify the population analyzed, outcome definition, comparison, treatment of baseline measurements, handling of missing observations, and model or test used. These items help readers judge whether an estimate answers the stated question and how robust it may be. The registry does not give those details for the primary endpoint. No adjusted or unadjusted statistical result is posted, and there is no sponsor analysis result against which a recalculation could be compared.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies one primary outcome measure, but notes that it has several categories or time points and was not reduced to one comparison. The record therefore does not define a single primary statistical contrast for interpretation. It does not state whether multiple comparisons were planned, which contrasts were considered primary or secondary, or whether any multiplicity adjustment was used. Those analysis details are not reported in the registry record.
In general, multiplicity arises when several outcomes, groups, time points, or contrasts are examined. With more opportunities to declare a finding, the chance of at least one apparently notable result can increase unless the analysis accounts for the number and structure of comparisons. This general concern does not show that a particular error occurred in this study. Without the analysis plan and results, the scale of any multiplicity issue cannot be assessed.
The registry does not report the number of participants with an HRT scan at each assessment, reasons for missing scans, or the method used to handle missing measurements. It also does not describe whether all randomized participants were included, whether the analysis was limited to participants who completed assessments, or how protocol deviations were treated. Missing-data handling and analysis populations are not reported in the registry record.
In general, missing outcomes can affect interpretation when the reasons for missingness relate to participants’ characteristics or measurements. The impact depends on the amount and pattern of missing information and on the assumptions used in analysis. None of those study-specific details is available, so the consequences of missing data cannot be evaluated.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Non Contact Wearing Using Clear Care | 0 | 15 | 0.0% |
| Overnight Soaking With Renu | 0 | 12 | 0.0% |
| Overnight Soaking in Optifree | 0 | 14 | 0.0% |
| Overnight Soaking in Optifree Replinish | 0 | 10 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Non Contact Wearing Using Clear Care | 0 of 15 |
| Overnight Soaking With Renu | 0 of 12 |
| Overnight Soaking in Optifree | 0 of 14 |
| Overnight Soaking in Optifree Replinish | 0 of 10 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Non Contact Wearing Using Clear Care | 0 of 15 |
| Overnight Soaking With Renu | 0 of 12 |
| Overnight Soaking in Optifree | 0 of 14 |
| Overnight Soaking in Optifree Replinish | 0 of 10 |
The registry lists four safety groups. For Non Contact Wearing Using Clear Care, 15 were at risk for serious events and 15 for other adverse events; the reported affected counts were 0 for each, with 0 deaths. For Overnight Soaking With Renu, the corresponding at-risk counts were 12 and 12, with 0 affected by serious events, 0 affected by other adverse events, and 0 deaths. For Overnight Soaking in Optifree, the at-risk counts were 14 and 14, with the same reported affected counts of 0 and 0 deaths. For Overnight Soaking in Optifree Replinish, the at-risk counts were 10 and 10, with 0 serious events, 0 other adverse events, and 0 deaths.
These entries report no affected participants in the listed categories among the stated group-specific at-risk counts. They do not describe the primary endpoint, and the safety groups should not be assumed to be the primary analysis groups. The registry does not report event definitions, ascertainment procedures, follow-up details for safety, or the relationship between these groups and the full enrolled population. The absence of recorded events is not a complete description of possible risks, and it does not establish that no events occurred outside the registry’s reported categories.
12. What the Result Does, and Does Not, Mean
The registry establishes that a completed, randomized, triple-masked, parallel study was registered with a stated interest in corneal structure, contact lenses, and solutions. Its primary measure is an HRT corneal scan focused on cell density, expressed as a mean in cells/mm^3 at baseline and 2 hours. The record also lists an enrollment of 51 and describes solution-soaking procedures in incomplete arm descriptions.
What the record does not establish is whether cell density changed, whether any change differed between groups, or how precise any estimate was. There are no primary endpoint values, effect estimates, confidence intervals, or p-values reported. The registry does not define the exact primary comparison or identify the number of participants contributing to the endpoint analysis. Consequently, neither the direction nor the size of an outcome can be inferred from the study description alone.
In general, absence of a reported result is not evidence that there was no effect, and it is not evidence that an effect occurred. A null conclusion would require results and an analysis capable of evaluating the relevant contrast with adequate precision. A positive conclusion would likewise require reported estimates and uncertainty. Those elements are not reported in the registry record.
The adverse-event entries report zero serious events, zero other adverse events, and zero deaths in the four listed groups, alongside their at-risk counts. Those entries are limited to the categories and groups recorded. They cannot answer the study’s primary cell-density question, and the record does not describe the completeness or procedures of safety collection.
Accordingly, this registry record is useful for identifying the study’s intended measurement and broad design, but it does not support a conclusion about the observed primary outcome or its statistical significance. The distinction between a registered objective and a reported result is essential when interpreting the available information.
13. Why This Trial Matters Statistically
Statistically, this study illustrates why a stated outcome and a study design are not enough to interpret a trial. The registry identifies a continuous primary endpoint, a measurement timeframe, and a randomized, triple-masked, parallel design. Yet without the endpoint values, analysis population, defined comparison, and uncertainty estimates, the central statistical question remains unanswered in the record.
That gap is particularly important when an outcome is described across more than one time point. In general, baseline and follow-up measurements can be compared in several ways, and each comparison answers a distinct question. A within-group change is not the same as a difference in change between groups. The registry notes that the outcome has several categories or time points and was not reduced to one comparison. This prevents readers from identifying a single contrast as the primary result.
The record also distinguishes study planning from observed evidence. Its sample-size assumptions describe a planning illustration, not the trial’s own design rationale or a finding. In general, a planning calculation depends on assumptions and does not establish that the resulting study was adequately powered for its actual outcome or that an effect was observed. The registry does not report the protocol’s sample-size justification.
Finally, the safety entries show how counts can be informative but limited. Group-specific at-risk counts and zero reported events give a concise account of the recorded categories, while missing definitions and collection details limit broader interpretation. The study therefore matters statistically as an example of the need to connect the question, analysis, estimate, and uncertainty before drawing conclusions from a clinical trial record.
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.
The most important limitation for interpreting the primary outcome is that no endpoint results are reported. The registry gives the outcome name, unit, summary measure, and assessment times, but not the cell-density observations or any comparison. Without an estimate and its uncertainty, the effect’s direction, magnitude, and precision cannot be evaluated.
The study’s primary comparison is also unclear. The registry notes that the outcome has several categories or time points and was not reduced to one comparison. It does not specify which group contrast or time-based contrast was intended as primary. The statistical analysis method, treatment of baseline values, and handling of repeated observations are not reported in the registry record.
Although enrollment is recorded as 51, the record does not state the number assigned to each primary-outcome group or the number with usable measurements at each assessment. The analysis population and missing-data procedures are not reported. The four safety groups have separate at-risk counts, but their relationship to the primary endpoint population is not explained.
The descriptions of the arms are incomplete, ending mid-sentence, and the record does not give the method for random sequence generation, allocation concealment, or the roles included in triple masking. It also does not report a protocol-based sample-size justification, a complete statistical plan, or the specific measurement procedures for the HRT scan. These omissions restrict assessment of design implementation, bias, and reproducibility.
The registry reports zero serious events, zero other adverse events, and zero deaths in the listed groups, but does not provide event definitions or collection methods. These entries should therefore be treated as limited registry reports rather than a complete safety characterization.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Two Phase Clinical Study of the Impact of Contact Lenses and Solutions on Corneal Structure — NCT00804999.
- Registry record last updated 2018-01-23; status last verified 2017-12.
- Results first posted 2018-01-23.
- 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.
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18. Record Summary
The registry describes a completed randomized, triple-masked, parallel study with enrollment of 51 and phase listed as NA. It records the study dates as 2008-11-01 to primary completion on 2009-03-01 and identifies Christine Sindt as sponsor. The stated aim concerns confocal microscopy and potential corneal structural consequences of contact lens wear and solution use.
The primary measure is mean HRT corneal cell density in cells/mm^3 at baseline and 2 hours. Clear Care, ReNu, and OPTI-FREE are listed as interventions, and the arm descriptions refer to lenses soaked for 10 hours. The record does not report primary endpoint results, a defined primary comparison, or the analysis population. It lists four safety groups with zero reported serious events, zero other adverse events, and zero deaths in each group.