Evaluation of the Precision of the Microperimetry Function of the Spectral OCT/SLO: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of the Precision of the Microperimetry Function of the Spectral OCT/SLO (NCT01692938), a registered phase not stated study. The primary outcome is Standard Deviation and Mean Test Results of Normal and With Pathology Participants Taken by 3 Different Operator-device Configurations.

2. Clinical Question

3. Trial Design

The registry describes a completed precision study sponsored by Optos, PLC. Its stated purpose was to assess the microperimetry function of the Spectral OCT/SLO. The record gives a start date of 2012-10 and a primary completion date of 2012-11. Enrollment is listed as 32. These registry entries describe the study's timing and enrollment, but do not establish how many people contributed to each analysis.

The primary outcome description reports use of three devices, each operated by a different operator. Each device was used to measure four normal subjects and four subjects with relevant eye pathology. The description states that 24 subject eyes in total—12 normal and 12 with pathology—were measured across all three devices. For each subject, one eye was evaluated using three tests, with repositioning at the start of each test. The relationship between the enrollment figure of 32 and the specified set of 24 measured eyes is not reported in the registry record; the record does not explain whether the figures refer to different study populations or stages.

The record names groups called No Retinal Disease and Retinal Disease, but does not provide descriptions for those arms. Allocation is not stated, and the registry notes that this is not a randomized comparison and that the arms are not a like-for-like control comparison. The design should therefore be understood as a measurement-precision study rather than a randomized comparison of treatments or disease groups.

The primary outcome timeframe is listed as 1 Month. The record describes calculation of overall mean and standard deviation for the two groups, but the numerical values and any analysis results are not reported. It lists two outcome measures and zero analyses. Further details on study sites, participant flow, protocol procedures beyond those described, and the statistical analysis plan 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

Reasons for not completing this period:

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 Standard Deviation and Mean Test Results of Normal and With Pathology Participants Taken by 3 Different Operator-device Configurations, measured over 1 Month.

The primary endpoint concerns the mean and standard deviation of microperimetry test results, measured in decibels, for normal subjects and subjects with pathology. The registry describes measurements from three operator-device configurations, with three tests per subject and repositioning before each test. The stated timeframe is 1 Month.

The mean describes the average recorded test level in a group. It gives a location or central value, but by itself does not describe how consistent repeated measurements are. The standard deviation describes the spread of measurements around their mean. In a precision study, a smaller spread can be consistent with more repeatable measurements under the conditions studied, while a larger spread indicates greater variability. These are general interpretations of the statistics, not findings about this device: the registry record does not report the actual means or standard deviations.

The study description distinguishes several sources of variability: differences across operator-device configurations, differences between subjects within a configuration, and variation within a subject for one configuration. These distinctions matter because a measurement may vary between people even when the procedure is consistent, or vary when the same person is measured repeatedly. The described endpoint provides group-level summaries, but the record does not report component-specific estimates or enough results to determine how much variability came from each source. Nor does it report a threshold for acceptable precision.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The outcome is a continuous measurement reported in decibels. The registry says that an overall mean and standard deviation were calculated for normal subjects and subjects with pathology. These summaries answer different descriptive questions: the mean locates the group’s average result, while the standard deviation describes the spread of results around that average. Neither statistic, by itself, identifies why measurements differ. The numerical summaries are not reported in the registry record.

What does precision mean?

In general, precision concerns the consistency of repeated measurements under specified conditions. A measurement procedure can yield similar results on repeated testing, or it can yield results that vary. Standard deviation is one common way to describe such spread when the data are summarized on a continuous scale. Its interpretation depends on what observations were included and how they were collected. In this study, repositioning before each test is part of the stated procedure, so the repeated results include measurements made after repositioning rather than repeated readings without that step.

Precision is not the same as accuracy. In general, precision concerns repeatability or spread; accuracy concerns closeness to a true or accepted value. A small standard deviation alone would not establish accuracy, and the registry record does not report an external reference standard or an accuracy assessment. The primary endpoint's mean also cannot be treated as evidence of accuracy without a stated target value or comparison standard.

How do the repeated measurements relate?

The description says that each subject had one eye evaluated with three tests. Those tests from the same subject are related observations, not necessarily independent observations. General statistical methods for repeated measurements account for this dependence when estimating uncertainty or partitioning sources of variation. Treating repeated tests as though they came from unrelated subjects can make uncertainty appear too small. The registry record does not state whether an analysis accounted for the repeated-measure structure, and it reports no analysis results from which to evaluate that issue.

The stated precision questions involve variation at more than one level. Measurements can differ within a subject across repeated tests; subjects can differ from one another within an operator-device configuration; and results can differ across configurations. These sources are conceptually distinct. In general, a method that estimates them separately needs to reflect the repeated and grouped structure of the data. The record describes the intended sources of variability but does not report a model, component estimates, or the method used to obtain them.

There is also a design feature that affects interpretation: each of the three devices was used by a different operator. Device and operator are therefore linked in the described measurements. In general, when factors are paired this way, observed differences across configurations cannot automatically be attributed to one factor alone. The record does not describe a design or analysis that separates operator effects from device effects. The results, if reported, would need to be interpreted as differences across the combined operator-device configurations unless the analysis established otherwise.

Why can variability differ across groups?

General statistical interpretation distinguishes variation in average levels from variation in consistency. Two groups could have different means while having similar spreads, or similar means with different spreads. A mean comparison would not answer a precision question on its own, and a standard deviation comparison would not establish that average readings are alike. The registry identifies both normal subjects and subjects with pathology, but does not report their mean or standard deviation values. It also does not report a formal comparison or uncertainty intervals for those summaries.

Decibels are the stated unit for the microperimetry test results. The record does not explain whether the analysis used the original scale or a transformed scale, or describe distributional checks. In general, the suitability of a mean and standard deviation depends partly on the distribution and scale of the measurements. If observations are strongly asymmetric or contain influential values, other summaries or modeling choices may be useful. No such diagnostic information or alternative summary is reported in the registry record.

What do planning calculations represent?

The planning illustration is described as based on the observed effect, not on the trial's own design. Its stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. The illustration is not an observed study result and is not observed power. Sample-size calculations under these assumptions describe a hypothetical future planning scenario, not the precision estimates from this study. Since numerical primary results are not reported, the record does not provide the basis needed to judge the observed effect or reproduce a planning calculation from the study results.

The registry record does not report the statistical model, uncertainty intervals, hypothesis tests, handling of repeated observations, or a prespecified threshold for acceptable precision. Those omissions limit evaluation of how the intended precision questions were analyzed. General explanations of means, standard deviations, and repeated-measure dependence clarify the concepts, but they cannot substitute for the absent numerical results and analysis details.

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("No Retinal Disease", "Retinal Disease")
n   <- c(12, 12)
m   <- c(16.16, 12.23)
sp  <- c(1.735, 3.508)
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  No Retinal Disease  12  16.160  1.735  15.058  17.262
CARM  Retinal Disease  12  12.230  3.508  10.001  14.459

11. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures and zero analyses. The primary outcome is described, but the record does not report numerical results for it. It does not provide details of the other outcome measure sufficient to describe its analysis. The statistical analysis plan, including which outcomes were considered primary or secondary for inference and whether any multiplicity adjustment was planned, is not reported in the registry record.

Multiplicity is a general concern when several outcomes or comparisons are tested: the chance of obtaining at least one apparently notable result can increase as the number of tests grows. Whether adjustment is appropriate depends on the questions and analysis plan. Here, the record does not report inferential results or a plan for managing multiple comparisons, so no claim about adjustment or its absence in the conducted analysis can be made.

Missing-data methods and analysis populations are also not reported in the registry record. The enrollment is 32, while the primary outcome description specifies 24 subject eyes measured across all three devices. The record does not explain how those figures relate, whether all enrolled participants contributed data, or whether any measurements were unavailable. It would not be justified to label the difference as missing data or to assume that every enrolled participant was analyzed.

Participant flow, exclusions, reasons for missing measurements, and any sensitivity analyses are not reported. The record also does not specify whether the analyses were based on all available measurements, a defined subset, or another population. These details are important for assessing whether the reported summaries, if available, represent the intended study population.

12. 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 0% reporting threshold.

The registry reports adverse-event counts in groups named No Retinal Disease and Retinal Disease. In each group, 16 people are listed as at risk for serious adverse events, and zero are listed as affected. The corresponding other-adverse-event counts also list 16 at risk and zero affected in each group. The record lists no top serious adverse-event terms.

These figures mean that the registry records zero affected participants in the listed event categories during the reporting period. They should not be interpreted as proof that no events occurred outside the categories or period covered by the record. The definitions of the event categories, collection procedures, and reporting window are not described in the available registry entries.

Deaths are recorded as null for both groups. Null is not a numerical zero; deaths are therefore not reported in the registry record. The safety counts also do not provide a randomized comparison: allocation is not stated, and the registry says the arms are not a like-for-like control comparison. These data are descriptive registry entries, not evidence for a comparative safety conclusion.

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

The record establishes that a precision study was conducted to assess the microperimetry function of the Spectral OCT/SLO. It describes a measurement procedure involving three operator-device configurations, repeated tests with repositioning, and groups of normal subjects and subjects with pathology. Its stated statistical focus is variation across configurations, between subjects within a configuration, and within a subject for one configuration.

The record does not report the numerical primary outcome values. Mean test results and standard deviations in decibels are named as outcomes, but their values are not reported in the registry record. There is consequently no basis for stating how large the measured means or spreads were, whether one group had greater variability, or whether the measurements met any precision criterion. No such criterion is reported either.

This absence of numerical results is not evidence that the device is precise, nor evidence that it is imprecise. It means the posted registry entries do not answer that empirical question. The study's described setup may be relevant to repeatability, but a design description alone cannot establish the observed degree of consistency.

The record also does not establish a clinical treatment effect. It concerns a measurement function and does not describe a treatment comparison. The groups are not presented as randomized like-for-like controls, and allocation is not stated. The safety counts are descriptive and do not support a comparative conclusion.

Important interpretive details are missing, including the numerical outcome results, the analysis method, uncertainty estimates, participant flow, and the relationship between the enrollment count and the number of eyes specified in the outcome description. Conclusions should therefore be limited to what the record documents: the study purpose, measurement arrangement, and registry entries, without inferring precision, accuracy, or clinical benefit.

14. Why This Trial Matters Statistically

Measurement precision matters in clinical research because conclusions based on a measurement depend partly on how consistently that measurement can be obtained. In general, high variability can make it harder to distinguish real differences from measurement noise, while repeatability supports interpretation of change or differences between groups. Precision studies therefore ask a different question from trials that test whether an intervention changes a health outcome.

This study is statistically interesting because its stated aim distinguishes variation across operator-device configurations, between subjects within a configuration, and within a subject. These are different sources of variability. Separating them can help characterize what a measurement procedure does under specified conditions. The record's description of repeated testing with repositioning makes the within-subject component especially relevant, while the use of different operators with different devices raises the question of whether configuration-level variation can be separated into operator and device contributions.

The registry also illustrates why method descriptions and numerical results are both necessary. Knowing that means and standard deviations were calculated does not reveal their values, uncertainty, or interpretation. Without those results, readers cannot assess the scale of variability or compare groups. Likewise, knowing the enrollment and the number of eyes described for the outcome does not explain who contributed data or how the analysis handled repeated observations.

The value of the record is therefore primarily in its stated measurement objective and procedure. Its limitations also show why complete reporting of estimates, analysis methods, and participant flow is important for a precision study. Those details would be needed to judge repeatability and to understand whether the findings apply to the particular subjects and operator-device configurations studied.

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 main limitation is that the registry record does not report the primary outcome values. It identifies mean and standard deviation as the endpoint summaries, but gives no numerical estimates, uncertainty intervals, or analysis results. Precision therefore cannot be quantified from the posted record, and no comparison between normal subjects and subjects with pathology can be interpreted.

The measurement description links each device to a different operator. Any differences across the three configurations could reflect the device, the operator, or their combination. The record does not report a design or analysis that separates these effects. It also does not report estimates for within-subject, between-subject, or configuration-level variability despite naming these as study objectives.

The enrollment is 32, while the primary outcome description specifies 24 subject eyes measured across the devices. The relationship between these figures, participant flow, and the analysis population are not reported in the registry record. The record does not explain whether all enrolled participants were measured or why the described outcome sample differs from enrollment.

Other relevant methodological details are also absent: the statistical model, handling of repeated measurements, missing-data methods, analysis populations, uncertainty estimation, and any prespecified criterion for acceptable precision. The number and nature of clinical sites are not specified, although the study summary refers to variability across clinical sites. The registry does not provide enough detail to assess how broadly the measurements represent other operators, devices, settings, or patient groups.

Finally, the study is not described as a randomized comparison, allocation is not stated, and the named groups are not like-for-like controls. Its safety counts should not be read as comparative evidence. These limitations constrain interpretation to the described procedure and registry entries.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Evaluation of the Precision of the Microperimetry Function of the Spectral OCT/SLO — NCT01692938.
• Registry record last updated 2017-05-10; status last verified 2017-04.
• Results first posted 2015-11-30.
• 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

NCT01692938 is a completed precision study sponsored by Optos, PLC, evaluating the microperimetry function of the Spectral OCT/SLO. The record lists enrollment of 32, a start date of 2012-10, and a primary completion date of 2012-11.

The primary outcome is described as mean and standard deviation of test results in decibels for normal subjects and subjects with pathology, with a timeframe of 1 Month. The measurement description specifies three devices, each used by a different operator, three tests per subject, and repositioning at the start of each test. It identifies 24 subject eyes measured across the devices: 12 normal and 12 with pathology.

The numerical primary results and analysis details are not reported in the registry record. The relationship between enrollment and the described number of eyes is also not reported. Safety entries list zero affected for serious and other adverse events in each named group; deaths are not reported numerically.