Pseudophakic Astigmatic Reduction With Verion-LenSx Arcuate Incisions: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pseudophakic Astigmatic Reduction With Verion-LenSx Arcuate Incisions (NCT02763124), a na na study. The primary outcome is Uncorrected Monocular Distance Visual Acuity.

2. Clinical Question

The study’s stated aim is to assess the effectiveness of the Verion-LenSx guided arcuate incision technique to reduce astigmatism in a pseudophakic population. The primary outcome is visual acuity, while the listed secondary outcomes concern change in corneal astigmatism, change in refractive cylinder, and spectacle independence at distance. These outcomes address related but distinct aspects of vision and refractive status. The record does not report numerical results for them, so the clinical question can be described, but the results cannot be judged from this registry record.

3. Trial Design

The study, titled Pseudophakic Astigmatic Reduction With Verion-LenSx Arcuate Incisions, is registered as NCT02763124. It is described as a single-group study with enrollment of 18 participants. The listed intervention is the Verion-LenSx procedure, using a femtosecond laser system to perform one or two corneal arcuate incisions. The condition listed is astigmatism, and the sponsor is Gainesville Eye Associates.

The registry record lists the study start as 2016-05, primary completion as 2016-10, and status as completed. The phase is recorded as NA. Masking is listed as none, and allocation is listed as NA. There is no control group described. Consequently, the design does not provide a concurrent comparison for separating changes associated with the procedure from changes that might occur over time or from other influences.

The primary outcome is uncorrected monocular distance visual acuity in logMAR, measured at 60 days (+/- 10 days) after laser treatment. The secondary outcomes listed are change in corneal astigmatism, change in refractive cylinder, and spectacle independence at distance. Although the registry record states that there are four outcome measures, numerical results are not reported for the listed outcomes. It records zero analyses.

The record does not report detailed eligibility criteria, baseline participant characteristics, the method of selecting participants, or a statistical analysis plan. It also does not report a protocol-based sample-size justification. Any planning illustration based on the observed effect is not evidence that the study was designed around that illustration or that a prespecified design target was met.

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 Uncorrected Monocular Distance Visual Acuity, measured over 60 days (+/- 10 days) after laser treatment.

The primary endpoint is uncorrected monocular distance visual acuity measured on the logMAR scale at 60 days (+/- 10 days) after laser treatment. It assesses distance vision in an individual eye without correction, according to the registry description. The record explains that logMAR values are ordered so that smaller values indicate better visual acuity. The endpoint is recorded as a continuous measure, with the mean and standard deviation specified as its summary statistics.

Visual acuity is used as an outcome because it describes a functional aspect of vision. In this study it is distinct from the listed refractive outcomes: a change in corneal astigmatism or refractive cylinder describes refractive status, whereas uncorrected visual acuity describes measured visual performance without correction. The record does not report how visual acuity was measured beyond its monocular, distance, uncorrected, and logMAR descriptors, nor does it report details of the measurement procedure or assessor.

The scheduled assessment window is 60 days (+/- 10 days) after treatment. The record does not report the numerical mean, standard deviation, participant-level observations, or a confidence interval for this endpoint. Therefore, it defines what was intended to be measured and when, but it does not establish the observed visual acuity or its precision.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a continuous measurement, and the record specifies a mean and standard deviation. As a general statistical explanation, a mean describes the center of a set of measurements, while a standard deviation describes how spread out individual measurements are around that center. These summaries answer different questions: the mean gives a typical level under the chosen summary, and the standard deviation describes variability among observations. Neither is reported numerically for this endpoint in the registry record.

The outcome uses the logMAR scale, for which the registry states that smaller values indicate better visual acuity. Interpreting a numerical estimate therefore requires attention to the scale’s direction as well as its size. A change score would also require a defined baseline measurement and a clear convention for subtraction. The registry record does not report a numerical result or enough detail to establish how a change analysis was conducted.

In general, a confidence interval is an uncertainty summary for an estimated quantity. A narrower interval indicates greater precision under the method’s assumptions; a wider interval indicates less precision. It does not describe the range of individual participant values, and it does not guarantee that the true value lies within the calculated interval. No confidence interval for the primary endpoint is reported in the registry record. A p-value, when reported, addresses compatibility of data with a specified null model under statistical assumptions; it is not a measure of effect size or clinical importance. No primary-outcome p-value is reported.

What does the single-group design allow?

A single-group study can describe measurements in the treated group and may describe changes over time if repeated measurements and appropriate results are reported. It does not directly compare outcomes with a concurrent untreated or alternative-treatment group. As a general principle, the absence of a control group makes it difficult to distinguish a procedure-associated change from natural variation, measurement variation, or other changes occurring during follow-up. The record lists allocation as NA and identifies a single-group model; it does not describe randomization or a comparator.

Why can dispersion matter?

Continuous outcomes can vary substantially among participants. The standard deviation summarizes that variation, while the standard error and confidence interval, when calculated, address uncertainty in an estimated group mean. These are not interchangeable quantities. General statistical methods may also need to account for skewness, outliers, or other departures from assumptions. No distributional diagnostics or alternative summaries are reported in the registry record, so the suitability of any particular model cannot be assessed from it.

What do the planning assumptions mean?

The record describes a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes the effect to detect as a stated fraction of the observed effect. The illustration is not the trial’s own design justification, and the record does not report the numerical observed effect or the resulting planning values. Because this study is single-group, an equal-allocation, two-arm illustration should not be mistaken for the design that was conducted. Any sample-size figures derived from such assumptions are planning illustrations, not observed power. A post hoc calculation using an observed effect does not establish the probability that the completed study detected a real effect.

For a general two-group planning calculation, the assumed effect, variability, significance level, allocation, and statistical model all influence the required sample size. Planning for a smaller fraction of an effect generally requires a larger study than planning for a larger effect, all else being equal. This is a general relationship, not a numerical conclusion about this study. The registry record does not report a prespecified clinically important difference, a protocol-based sample-size justification, or a comparison design for the completed study.

Over-dispersion is a general issue for count outcomes when variability exceeds what a simple probability model assumes. It can make standard errors too small and statistical tests too optimistic if not addressed. The primary endpoint is continuous rather than a count outcome, so count-model over-dispersion is not the central issue for its stated analysis. The registry record does not provide enough outcome analysis detail to evaluate model assumptions for the continuous endpoint.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Verion-LenSx")
n   <- c(18)
m   <- c(0.14)
sp  <- c(0.11)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Verion-LenSx  18  0.140  0.110  0.085  0.195

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists a primary outcome and three secondary outcomes, and states that there are four outcome measures. It does not report numerical results for these outcomes and records zero analyses. The statistical plan, including whether the outcomes were analyzed in a prespecified order or whether any multiplicity adjustment was planned, is not reported in the registry record.

Multiplicity is a general concern when several outcomes or statistical tests are considered. As the number of tests grows, the chance of at least one apparently notable result can increase if each test is judged separately without accounting for the broader set. Approaches to multiplicity can include prespecifying a primary outcome, controlling an error rate, or treating secondary outcomes as exploratory. The registry identifies a primary outcome, but the planned testing strategy and interpretation of secondary outcomes are not reported. No claim about adjustment or lack of adjustment can be made from this record.

The analysis population is not reported in the registry record. Although enrollment is listed as 18, endpoint-specific denominators, exclusions from analysis, and the number with measurements at the scheduled assessment are not reported. Missing-data frequency, reasons for missingness, and methods for handling missing observations are also not reported. These omissions matter because the analyzed participants may not represent everyone enrolled if outcome measurements are unavailable, and missing-data methods can affect estimates and their uncertainty.

The record does not report whether analyses were adjusted for baseline measurements or other participant characteristics, or whether repeated measurements were modeled. Those details are necessary to reproduce or fully assess an analysis. With no reported numerical estimates or analysis descriptions, neither multiplicity handling nor the effect of missing data can be evaluated.

12. 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.

Most frequent non-serious adverse event terms

The registry record lists the Verion-LenSx group with 18 participants at risk for serious adverse events and zero affected. It lists one participant affected by other adverse events among 18 at risk, and zero deaths. The record does not list any serious adverse event terms.

These entries describe the safety figures recorded in the registry; they do not establish that no unrecorded events occurred, nor do they explain how events were defined, collected, or adjudicated. The reporting period and the specific events included under the other-adverse-event category are not reported in the registry record. The record also does not describe the severity, timing, relatedness to the procedure, or outcomes of the other adverse event. The figures should therefore be read as registry entries, not as a complete account of every potential safety consideration.

In general, zero recorded serious events in a study group does not prove that an event is impossible or that a procedure has no safety risks. Safety interpretation depends on event definitions, follow-up, completeness of reporting, and the amount of information available. Those details are not reported in the registry record.

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

The registry record establishes that a study was conducted to assess Verion-LenSx guided arcuate incisions in a pseudophakic population with astigmatism. It identifies the primary endpoint, its measurement scale, and its assessment window, and it lists three secondary outcomes. It also records enrollment of 18 participants and completed status. These details describe the study question and design, but they are not numerical evidence of an outcome.

The primary outcome’s scale has a stated direction: smaller logMAR values indicate better visual acuity. However, without the observed mean, standard deviation, or a comparison over time, the record does not show the direction or magnitude of the outcome. It likewise does not report numerical results for the astigmatism, refractive cylinder, or spectacle-independence outcomes. Thus, no estimate of effect or its precision can be drawn from this record.

The study’s single-group design also limits causal interpretation. If a within-group change were available, it would describe the group’s observed course, but without a comparator it would not isolate the procedure’s contribution from other possible explanations. This is a general design limitation, not evidence that any particular alternative explanation occurred.

The registry safety entries report zero serious adverse events, one other adverse event, and zero deaths in the listed group. These figures should be interpreted in light of the event and follow-up details that are not reported in the registry record.

Overall, the record is informative about the intended question, intervention, outcome definitions, and broad design. It does not report the result values needed to determine what was observed, how precisely it was estimated, or how the secondary outcomes behaved. It therefore supports description of the study, not a conclusion about the size or certainty of an effect.

14. Why This Trial Matters Statistically

This study is statistically notable for the way its design and outcome definitions frame the evidence that can be obtained. A single-group design can document outcomes after a procedure, but it cannot provide a direct concurrent treatment comparison. That distinction is important whenever a result is interpreted as evidence of change: observed change and a causal treatment effect are not equivalent concepts.

The primary endpoint is a continuous visual-acuity measure, summarized in the registry plan using a mean and standard deviation. Its logMAR direction is explicitly stated, which is essential for reading any numerical estimate correctly. The secondary outcomes focus on refractive changes and spectacle independence, so a complete interpretation would need to distinguish visual acuity from those related outcomes rather than treating them as interchangeable.

The record also illustrates why registration details and outcome results serve different purposes. It records the study’s aim, intervention, timing, and outcomes, but it does not report the numerical endpoint findings or analysis methods. Without estimates and uncertainty measures, statistical precision cannot be judged. Without analysis details, reproducibility and the handling of missing data or multiple outcomes cannot be assessed.

The planning illustration is another reason to keep design assumptions separate from study findings. It is described as based on an observed effect and a hypothetical two-arm allocation, while the completed study is recorded as single-group. Such an illustration is not evidence that the study was planned or conducted as a two-arm trial, and it is not observed power. Careful separation of design, analysis, and outcome reporting helps prevent stronger conclusions than the record can support.

15. 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 central limitation for interpreting this trial from the registry record is that numerical results for the primary and secondary outcomes are not reported. The primary endpoint is defined, but its mean, standard deviation, and any estimate of change or uncertainty are absent. The record also lists zero analyses. As a result, the study’s observed outcome magnitude and precision cannot be assessed.

The single-group design has no comparator, and masking is listed as none. These features limit comparative and causal interpretation. The record does not report detailed eligibility criteria, baseline characteristics, the participant selection process, or the measurement procedures beyond the primary endpoint’s broad description. It is therefore not possible to assess how the enrolled population compares with other populations or how consistently outcomes were measured.

Although enrollment is listed as 18, the record does not state endpoint-specific analysis counts, whether all enrolled participants completed the scheduled assessment, or how missing observations were handled. It also does not report a statistical analysis plan, multiplicity strategy, or protocol-based sample-size justification. These omissions prevent assessment of whether analyses followed prespecified methods and whether the available data were sufficient for the intended comparisons.

For safety, the registry entries list adverse-event counts, but event definitions, timing, ascertainment methods, and the details of the other adverse event are not reported. These limitations are specific to the information in the registry record; they do not establish that additional methods or data do not exist elsewhere.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Pseudophakic Astigmatic Reduction With Verion-LenSx Arcuate Incisions — NCT02763124.
• Registry record last updated 2019-11-01; status last verified 2019-10.
• Results first posted 2019-11-01.
• 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.

19. Record Summary

NCT02763124 is a completed, single-group study sponsored by Gainesville Eye Associates. The registry record lists enrollment of 18 participants and the Verion-LenSx procedure, using one or two corneal arcuate incisions. The study aim is to assess reduction of astigmatism in a pseudophakic population.

The primary outcome is uncorrected monocular distance visual acuity in logMAR at 60 days (+/- 10 days) after treatment. Three secondary outcomes are listed: change in corneal astigmatism, change in refractive cylinder, and spectacle independence at distance. Numerical results and analysis details are not reported in the registry record, which records zero analyses.

The safety entries list zero serious adverse events, one other adverse event, and zero deaths in the Verion-LenSx group. The study has no comparator, and the record lists no masking.