Clinical Comparison of Two Silicone-Hydrogel Contact Lenses: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Comparison of Two Silicone-Hydrogel Contact Lenses (NCT00762385), a randomized na study. The primary outcome is Lens Comfort.

2. Clinical Question

In statistical terms, the key comparison is whether the observed comfort scores differ between lenses, and how precisely that difference is estimated. Because the design is a crossover, sequence and within-participant information could matter to an analysis. The registry record identifies a mixed-model analysis, but does not provide enough detail to reconstruct its model or to determine how it handled period, sequence, or within-participant correlation.

3. Trial Design

The registry record describes a randomized, single-masked crossover study of two silicone-hydrogel contact lenses. The named lenses were galyfilcon A and comfilcon A. Participants entered one of two sequences: galyfilcon A first and comfilcon A second, or comfilcon A first and galyfilcon A second. This design allows the same participant to experience both lenses, so comparisons can potentially account for participant-level differences that would remain between separate treatment groups.

The registry reports 97 enrolled participants and a completed status. The primary outcome population is narrower: only participants who completed the study per protocol were included, with n=78 for each lens outcome. The record does not explain why the per-protocol population is smaller than the enrollment count, whether all participants received both lenses, or how missing observations were handled. It also does not report the planned sample size, the original sample-size justification, or whether enrollment was changed during the study.

The primary outcome timeframe is recorded as “1-week, 2- weeks.” The secondary outcome, overall corneal staining, is recorded at 2 weeks. The registry gives no further schedule details, such as the timing of measurements within each period or the interval between periods. Such details can affect interpretation of a crossover study, but should not be inferred from the sequence descriptions alone.

The study dates are recorded as starting in 2007-08 and reaching primary completion in 2007-10. The record lists phase as NA and status as completed. It does not report the masking identity, the randomization method, allocation concealment, a washout procedure, or a detailed statistical analysis plan. The registry lists three outcome measures and three analyses, while one secondary outcome is posted in the available results. These record entries do not establish that every planned outcome or analysis is represented in the posted results.

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

Reasons for not completing this period:

Second Intervention

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Only participants who completed the study per protocol (n=78)

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 Comfort, measured over 1-week, 2- weeks.

The primary endpoint is lens comfort, expressed as a combined score. The registry describes it as a weighted score derived from individual comfort-related questions. It also states that values greater than zero indicate comfortable and values less than zero indicate uncomfortable. This directional description helps explain the meaning of the score’s sign, but the record does not report the weighting scheme, the individual questions, or a threshold for a difference that participants would consider important.

The posted endpoint statistic is a least-squares mean, with standard error as the measure of dispersion. A least-squares mean is a model-based estimate of an average, rather than necessarily a simple arithmetic average. The record identifies a mixed-model analysis for final values but does not provide the model specification, so the precise adjustment and estimation details are not reported in the registry record.

Comfort is relevant to the stated objective because the study evaluates clinical performance of the lenses and includes comfort-related questions in its endpoint. A combined score can represent information across several questions in one measure, but interpretation depends on how those questions are weighted and how the scale behaves. Those construction details are not reported in the registry record. The primary outcome analysis included participants who completed the study per protocol, n=78, rather than describing an analysis of every enrolled participant.

7. Results Posted in the Registry

• Comfilcon A: mean 0.11 versus 0.15 on control; difference -0.03 (95% CI -0.34 to 0.27), standardized effect d = -0.03; z-test p = 0.839.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Overall Corneal Staining

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard errors.
• Result:
  • Comfilcon A: mean 0.07 versus 0.08 on control; difference -0.01 (95% CI -0.07 to 0.06), standardized effect d = -0.03; z-test p = 0.858.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Comfilcon A and the control. The interval gives the range of effects that remain compatible with the data.

One secondary outcome is posted: overall corneal staining. Its unadjusted recalculation, like the primary comfort comparison, has a confidence interval that includes zero and a p-value that does not indicate a clear difference under that calculation. The posted secondary result therefore follows the same broad statistical pattern as the primary result: neither summary-statistic comparison provides a precise directional distinction between the lenses.

This shared pattern is useful as context, but the secondary outcome does not independently confirm the primary finding. It measures a different aspect of lens performance, and the registry record does not report a threshold for a clinically important change in staining. The primary endpoint remains the study’s comfort measure; the secondary result should be read as additional, not as a replacement for that primary comparison.

Unadjusted secondary results carry less weight when several outcomes or analyses may be considered because the chance of at least one apparently notable result can increase as more comparisons are made. In general, multiplicity procedures can address that issue, but the registry record does not report a multiplicity adjustment or a plan for controlling the overall error rate. The record lists three outcome measures and three analyses, while one secondary outcome is posted. It does not clarify how many comparisons were prespecified, how outcomes were prioritized, or whether any adjustment was used.

The posted secondary result should consequently be interpreted with caution and in the context of the primary outcome and the analysis methods. It does not establish an independent lens advantage, and the absence of a reported adjustment does not mean that an adjustment was definitely omitted from the original analysis. The relevant planning and analysis details are not reported in the registry record.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Overall Corneal Staining

9. Statistical Interpretation

10. Statistical Methods Explained

Several statistical ideas help distinguish the registry’s model-based results from the unadjusted recalculations. The recalculations use posted summary statistics and are not a reproduction of the sponsor’s mixed-model analysis. They are simple comparisons based on the displayed group summaries. In a crossover study, a participant’s measurements under both lenses may be related. An analysis that uses that relationship can differ from an analysis that treats the two sets of summary statistics as independent. The record does not report the within-participant correlation or enough model information to determine how the mixed model handled it.

What does a least-squares mean represent?

A least-squares mean is an estimated mean from a statistical model. Depending on the model, it can account for specified factors or the structure of the data. It is not necessarily identical to the raw average calculated directly from all observations. The registry reports least-squares means for the outcomes and identifies a mixed-model analysis of final values, but does not list the model terms, covariance structure, or any other adjustment details. Therefore, the posted mean values can be described, but the exact model-based interpretation cannot be fully audited from the record.

What does the standard error describe?

The standard error describes the estimated sampling variability of an estimate, such as a mean. It is not the same as the spread of individual participant scores. A smaller standard error generally indicates a more precisely estimated mean, given the assumptions of the analysis. The registry reports standard errors for the outcome means, but does not report the participant-level distributions. The recalculations use those posted standard errors to approximate pooled variability; the approximation is not a substitute for the original participant-level analysis.

Why does the confidence interval matter?

A confidence interval gives a range of estimates compatible with the data under the method’s assumptions. It expresses uncertainty around an estimate and is often more informative than a point estimate alone. If an interval includes zero for a difference, the data and method do not rule out no difference at the stated confidence level. That does not establish equality: the interval may also include differences in either direction. For the recalculated primary and secondary comparisons, each interval includes zero and extends on both sides. The sponsor’s primary mixed-model interval is reported at 98.3%, not 95%, and should be read at its stated level rather than treated as the same interval as the recalculation.

What does the p-value add?

A p-value describes how unusual results at least as extreme as the observed result would be under a specified null hypothesis and analysis model. It is not the probability that the null hypothesis is true, nor does it measure the size or clinical importance of an effect. The recalculated primary comparison has p=0.839, and the recalculated secondary comparison has p=0.858. These are unadjusted values from the summary-statistic recalculations. The registry’s mixed-model entries do not report p-values, so those values should not be attributed to the sponsor’s analysis.

The recalculations are unadjusted comparisons. They do not account for the crossover structure through a paired analysis, and the source record does not provide the participant-level data needed for such a reconstruction. They also do not reproduce any model adjustments that may have been part of the sponsor’s mixed model. The term “unadjusted” here concerns the recalculation method; it does not imply that the sponsor’s model was or was not adjusted in a particular way.

Why can over-dispersion matter?

Over-dispersion occurs when observed variability is greater than a model assumes. In general, ignoring over-dispersion can make standard errors too small and intervals too narrow, giving an overly confident impression of precision. That concern is especially relevant when a model’s assumptions do not match the data structure. The registry record does not report a check for over-dispersion, a variance diagnostic, or the model details needed to assess it. It is therefore a general methodological consideration, not a claim that over-dispersion occurred in this trial.

Because the design is crossover, period effects, sequence effects, carryover, and within-participant dependence are possible issues in general. A suitable analysis may account for factors specified in its protocol and model. The registry record does not report whether these were evaluated or how they were handled. It would be inappropriate to assume a washout period, a particular covariance structure, or a particular test of carryover.

The score is described as a weighted combination of comfort-related questions, but the individual items and weighting are not reported. Composite measures can simplify interpretation, while also making the result dependent on the scale’s construction. Without those details or a stated clinically important difference, statistical estimates can be interpreted in terms of the reported score but not translated into a claim about how noticeable a difference would be to participants.

11. Confidence Intervals and Precision

The recalculated primary comparison is -0.032 for comfilcon A relative to galyfilcon A, with a 95% confidence interval from -0.338 to 0.275. The range includes zero and allows estimates on either side of zero. In general, a confidence interval is a way to express the uncertainty around an estimated difference under the calculation’s assumptions. Its width matters: a point estimate near zero paired with a broad interval is not evidence that every plausible difference is negligible.

The secondary outcome’s recalculated difference is -0.006, with a 95% confidence interval from -0.066 to 0.055. This interval also includes zero and spans both directions. The registry does not report a threshold for a clinically meaningful difference for either outcome, so the intervals cannot be classified as excluding all meaningful effects. That judgment would require a justified threshold that is not reported in the registry record.

The sponsor’s primary mixed-model result has a 98.3% confidence interval from -0.235 to 0.032. A confidence level is the stated coverage level associated with the interval procedure under its assumptions. Because this is not the same confidence level as the recalculated 95% interval, the two should not be compared as if they were generated by an identical method. The registry does not include the model specification needed to assess the sponsor interval’s construction.

Precision is limited not only by interval width but also by what is known about the analysis population and data structure. The primary outcome uses per-protocol completers, n=78, and the record does not explain exclusions or missing observations. Nor does it report participant-level data or the crossover model details needed to independently assess the uncertainty. These limitations make the posted estimates interpretable as reported, while restricting the conclusions that can be drawn about their precision beyond the stated intervals.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total events. They are illustrations calculated from the observed effect, not the trial’s original enrollment plan. The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The planning exercise considers detecting 100%, 75%, or 50% of the observed effect. The registry record does not report the original design assumptions or the trial’s own sample-size justification.

The 80% power column indicates the illustrated number of participants per arm for a design with an 80% chance of detecting the specified effect if that effect is true and the planning assumptions hold. The 90% power column gives the corresponding planning count for a design with a 90% chance under those same conditions. Higher planned power generally requires more participants for a given effect. The figures are not estimates of how likely this completed study was to detect its result.

The rows that plan for a smaller fraction of the observed effect require more participants than rows planning for the full observed effect. This reflects a general principle: smaller differences are harder to distinguish from random variation and therefore require larger studies, all else equal. Because the observed effect is used as the starting point, the illustration should not be treated as an independent estimate of a plausible future effect. These counts are a planning illustration, not observed power.

For a crossover trial, the information available from each participant can depend on the relationship between that participant’s measurements under the two lenses. The listed planning assumptions describe an equal-allocation, two-arm normal-approximation illustration, not a detailed crossover design calculation. The registry record does not report a crossover-specific sample-size method or the assumptions used for the original study design.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -0.032; pooled standard deviation σ = 0.975.
2. n = 2 × (1.96 + 0.842)² × 0.975² / -0.032² = 14,865.0, rounded up to 14,866 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -0.0317                      # observed difference in means
sigma <- 0.97549047663214                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(762385)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 14,866 (80% power), 19,901 (90% power)
 75% of observed effect: n per arm = 26,427 (80% power), 35,378 (90% power)
 50% of observed effect: n per arm = 59,461 (80% power), 79,601 (90% power)
power.t.test: 14866 
Simulated power at n = 14,866 per arm: 0.799 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The registry reports the sponsor’s primary analysis as a mixed-model analysis of final values. It gives a mean difference of 0.032 and a 98.3% confidence interval from -0.235 to 0.032. A p-value is not reported for this analysis. The interval includes zero, but the reported estimate and interval should be quoted as recorded rather than altered to match a separate calculation.

The unadjusted recalculation instead uses the posted means and standard errors. It estimates the difference as -0.032, with a 95% confidence interval from -0.338 to 0.275 and p=0.839. This calculation does not reproduce the mixed model and does not use reported participant-level crossover data. The record does not provide sufficient detail to reconcile the two estimates or explain their differences in direction and interval limits.

The registry’s discrepancy indicator is false. Accordingly, the posted mixed-model analysis is reported as the sponsor’s own analysis, while the recalculation is presented as a separate summary-statistic comparison. Neither result should be silently substituted for the other. The missing model specification and p-value limit further assessment of how the sponsor’s estimate was obtained.

15. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when a study evaluates several outcomes, time points, groups, or statistical comparisons. When many comparisons are examined, the chance of at least one result appearing notable by chance can increase. Methods such as prespecifying a primary outcome or adjusting significance thresholds can help manage that issue. This is a general statistical explanation, not a claim that a particular approach was used in this trial.

The registry identifies Lens Comfort as the primary outcome and lists Overall Corneal Staining as a secondary outcome. It also lists three outcome measures and three analyses, but only one secondary outcome is posted. The registry record does not report the full set of planned comparisons, a multiplicity strategy, or whether adjustment was applied. The unadjusted recalculated p-values should therefore be read as individual comparisons, not as results corrected for the possibility of multiple testing.

The primary analysis population is described as participants who completed the study per protocol, n=78. The record reports 97 enrolled participants but does not explain why the primary outcome population is smaller, describe a flow of participants through the study, or report reasons for missing outcomes. It does not state whether an intention-to-treat analysis was performed, how missing data were handled, or whether the per-protocol population was defined before results were examined. These details are not reported in the registry record.

In a crossover study, analysis populations and missingness can be particularly relevant because observations from each period may contribute to a participant’s comparison. The record does not state whether all participants completed both periods or how incomplete crossover data were treated. It also does not report sensitivity analyses for missing data. No particular missing-data mechanism or bias can be inferred from the enrollment and per-protocol counts alone.

The registry describes the trial as randomized and single-masked, but does not identify who was masked or give details of random sequence generation and concealment. It does not report a complete statistical plan, including interim analyses or stopping rules. Those features should be treated as unreported rather than assumed absent.

16. 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.

The adverse-event record groups participants by the sequence they received. In the galyfilcon A / comfilcon A sequence group, 51 participants were at risk and 0 were recorded as affected by a serious adverse event; 0 were recorded as affected by other adverse events. In the comfilcon A / galyfilcon A sequence group, 46 participants were at risk and 0 were recorded as affected by either category.

These counts are sequence-group summaries, not separate event rates for each lens. Because each sequence includes both lenses, the figures cannot isolate adverse events attributable to one lens or provide a direct lens-by-lens safety comparison. The record lists no serious adverse-event terms. Death counts are not reported in the registry record.

Zero recorded affected participants in these categories means no events were posted for these groups in the registry results; it does not establish that no event could occur or that the lenses have identical safety profiles. The registry record does not give event collection procedures, observation time by participant, or a detailed account of non-serious event types. These summaries should therefore be read narrowly as the posted counts, rather than as comprehensive evidence about safety.

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

The results describe comfort and overall corneal staining scores recorded in a randomized crossover comparison of galyfilcon A and comfilcon A. For both outcomes, the unadjusted recalculated confidence interval includes zero and extends in both directions. The results do not establish a clear difference between the lenses on these posted measures, but neither do they establish exact equality or equivalence.

That distinction matters. A result that does not clearly separate two groups is not automatically evidence that any difference is too small to matter. Equivalence or non-inferiority conclusions generally require a prespecified margin and an analysis designed for that question. The registry record does not report such a margin or identify the study as an equivalence or non-inferiority trial. It also does not report a threshold for a clinically important difference in comfort or staining.

The sponsor’s primary mixed-model result is a separate analysis from the unadjusted recalculation. The record gives its estimate and 98.3% interval but not a p-value or enough model details to reproduce the analysis. The recalculated primary result uses posted summary statistics and does not reconstruct the crossover model. The two results should be interpreted with their methods and limitations in view, rather than merged into a single estimate.

The primary outcome was evaluated among per-protocol completers, n=78. The record does not explain exclusions or missing data, so it is not possible to determine from these results how the included population compares with all enrolled participants. Nor does the registry provide enough detail to generalize beyond the recorded study population, outcome definitions, and timeframes.

Accordingly, the posted data support a cautious statistical description: the observed scores and estimated differences are reported, but uncertainty remains about the size and direction of any underlying difference. They do not, on their own, establish a treatment recommendation or a broader claim about lens performance outside the recorded outcomes and study conditions.

18. Why This Trial Matters Statistically

This study illustrates why a point estimate, confidence interval, and analysis method need to be considered together. The primary recalculated estimate is close to zero, but its interval includes estimates in either direction. Reporting only the point estimate would conceal that uncertainty; reporting only whether a p-value crosses a threshold would also omit information about possible effect sizes.

The crossover design adds an important statistical dimension. Since participants were assigned to sequences involving both lenses, their measurements may be related. A model that uses the within-participant structure can make a different comparison from a simple calculation based on group summary statistics. The registry reports a mixed-model analysis, but does not provide the details needed to assess its assumptions or reproduce it. This makes transparent reporting of the model specification and analysis population especially valuable.

The record also distinguishes enrollment from the per-protocol population used for the primary outcome. Without a participant flow or missing-data account, readers cannot assess how the analysis population was reached. This limits interpretation even when group estimates and uncertainty measures are posted.

Finally, a planning illustration based on the observed effect is not a retrospective measure of the trial’s success. It demonstrates how planning counts depend on the effect size a future study aims to detect and on stated assumptions. It does not reveal the original design rationale, which is not reported in the registry record. These distinctions are central to reading the statistical evidence without overstating what the results establish.

19. 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 main trial-specific limitation is the limited detail available for the crossover analysis. The registry identifies a mixed model but does not report its terms, covariance structure, handling of period or sequence, or treatment of within-participant dependence. The unadjusted recalculations use posted summary statistics and are not a substitute for a participant-level crossover analysis.

The primary outcome is reported for per-protocol completers, n=78, while 97 participants were enrolled. Reasons for the difference, completion by sequence, and missing-data handling are not reported in the registry record. The record does not say whether all participants contributed observations under both lenses or whether an intention-to-treat analysis was conducted.

The comfort score is described as a weighted combination of comfort-related questions, but the individual items, weighting, scale validation, and clinically important difference are not reported. A similar interpretive threshold is not reported for overall corneal staining. Without such thresholds, statistical estimates cannot be translated into a judgment about clinical importance.

The registry lists three outcome measures and three analyses but posts only one secondary outcome. The full outcome and comparison set, prespecification details, and multiplicity approach are not reported. In addition, the record does not describe randomization procedures, identify who was masked, or give details about periods and any interval between them. These omissions limit assessment of potential bias and of how closely the reported analyses match the intended study plan.

The safety results are grouped by sequence rather than by individual lens exposure, and the record does not report deaths. These data do not permit a lens-specific safety comparison. The trial’s original sample-size assumptions and justification are also not reported; the available planning illustration is based on the observed effect and should not be treated as the study’s design calculation.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Clinical Comparison of Two Silicone-Hydrogel Contact Lenses — NCT00762385.
• Registry record last updated 2018-06-19; status last verified 2015-05.
• Results first posted 2010-02-10.
• 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.

23. Record Summary

The registry describes NCT00762385 as a completed randomized, single-masked crossover study comparing galyfilcon A and comfilcon A silicone-hydrogel contact lenses in participants with refractive error. The record reports 97 enrolled participants and identifies Lens Comfort as the primary outcome, measured with a weighted combined score. Its primary outcome results use a per-protocol population of n=78.

The posted results include a sponsor-reported mixed-model analysis of final values and summary statistics that allow unadjusted recalculations. The primary recalculation’s confidence interval includes zero and spans both directions; the record does not provide enough model detail to reconcile it fully with the sponsor analysis. Overall corneal staining is the posted secondary outcome and shows a similar broad pattern in the unadjusted recalculation.

Interpretation is constrained by unreported details about the crossover model, missing data, outcome construction, multiplicity, clinical-importance thresholds, and the original design assumptions. Safety counts are reported by sequence, not separately for each lens.