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 Effects of Pneumatic Vitreolysis on Vitreomacular Traction (NCT03647267), a randomized phase 3 study. The primary outcome is Proportion of Eyes With Central Vitreomacular Traction Release Without Rescue Vitrectomy.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03647267 |
| Phase | Phase 3 |
| Condition | Vitreomacular Traction |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 46 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Jaeb Center for Health Research |
| Results posted | Yes |
2. Clinical Question
Population
The trial concerned eyes with idiopathic symptomatic vitreomacular traction (VMT) without a macular hole. The registry record describes the condition and eligibility in those terms; further eligibility details and the characteristics of the enrolled participants are not reported in the registry record.
Intervention
The pneumatic vitreolysis group was assigned a 0.3-mL intraocular injection of C3F8 gas. The registry record calls this intervention pneumatic vitreolysis and identifies the intervention type as a device.
Comparator
The comparison group received a sham injection. The registry record labels the group “Observation,” while the arm description specifies that participants randomized to it received the sham injection. The comparison is therefore active gas injection versus sham, not injection versus no procedure.
Primary question
The primary outcome asks what proportion of eyes had central VMT release without rescue vitrectomy at 24 weeks. It focuses on release while excluding eyes requiring rescue vitrectomy from the success definition. The posted percentages are 78.0 for pneumatic vitreolysis and 9.0 for sham. These are descriptive arm results; a primary between-group estimate, interval, and p-value are not reported in the registry record.
3. Trial Design
The study is registered as a randomized, triple-masked, parallel-group Phase 3 trial of pneumatic vitreolysis for vitreomacular traction. The registry record reports enrollment of 46 and a completed status. The listed start date is 2018-10-16, and primary completion is dated 2020-08-06. The record identifies Jaeb Center for Health Research as the sponsor.
Participants were randomized to pneumatic vitreolysis or sham injection. In the pneumatic vitreolysis arm, the assigned procedure was a 0.3-mL intraocular injection of C3F8 gas. In the observation group, the assigned procedure was a sham injection. Although the group is named “Observation,” the arm description makes clear that it received the sham procedure.
Random allocation is intended to distribute participant characteristics across groups without selecting treatment according to those characteristics. Masking is intended to limit the influence of knowledge of assignment on care, assessment, or reporting. The registry record says the trial was triple-masked but does not identify which roles were masked or describe how masking was maintained. The randomization method and allocation-concealment procedure are not reported in the registry record.
The primary outcome was assessed at 24 weeks. A secondary visual-acuity outcome covers change from baseline to 24 weeks. Other listed secondary outcomes concern rescue treatment, rescue vitrectomy, and central VMT status. The registry record does not provide detailed follow-up schedules or the statistical analysis plan. The completed status describes the registry’s trial status; it does not by itself establish that every planned analysis or every outcome result is available.
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 | Pneumatic Vitreolysis (PVL) | Sham |
|---|---|---|
| STARTED | 24 | 22 |
| COMPLETED | 23 | 22 |
| NOT COMPLETED | 1 | 0 |
Reasons for not completing this period:
| Reason | Pneumatic Vitreolysis (PVL) | Sham |
|---|---|---|
| Lost to Follow-up | 1 | 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 | Pneumatic Vitreolysis (PVL) | Sham | Total |
|---|---|---|---|---|
| Participants analysed | 24 | 22 | 46 | |
| Age, Continuous | years | 70 (SD 10) | 75 (SD 8) | 72 (SD 9) |
| Sex: Female, Male: Female | Participants | 15 | 16 | 31 |
| Sex: Female, Male: Male | Participants | 9 | 6 | 15 |
| Race/Ethnicity, Customized: Non-Hispanic White | Participants | 16 | 17 | 33 |
| Race/Ethnicity, Customized: Hispanic or Latino | Participants | 4 | 5 | 9 |
| Race/Ethnicity, Customized: non-Hispanic Black/African American | Participants | 3 | 0 | 3 |
| Race/Ethnicity, Customized: Unknown or not reported | Participants | 1 | 0 | 1 |
| Diabetes Type: No | Participants | 16 | 12 | 28 |
| Diabetes Type: Type 2 | Participants | 8 | 10 | 18 |
| E-ETDRS visual acuity letter score | units on a scale | 67.8 (SD 10.3) | 69.2 (SD 8.4) | 68.5 (SD 9.4) |
| Intraocular pressure | mmHg | 15 (SD 4) | 14 (SD 3) | 15 (SD 4) |
| Lens status on clinical exam: Phakic (natural lens) | Eyes | 14 | 9 | 23 |
| Lens status on clinical exam: Posterior Chamber intraocular lens | Eyes | 10 | 13 | 23 |
| Epiretinal membrane in central subfield | Eyes | 2 | 1 | 3 |
| Width of vitreomacular attachment that extends within the central subfield | Microns | 480 (315 to 694) | 503 (427 to 646) | 495 (342 to 682) |
| Loss of ellipsoid zone integrity in central subfield | Eyes | 15 | 8 | 23 |
| Loss of ellipsoid zone integrity in foveal center | Eyes | 11 | 8 | 19 |
6. Primary Endpoint
The registry lists the primary outcome as Proportion of Eyes With Central Vitreomacular Traction Release Without Rescue Vitrectomy, measured over at 24 Weeks.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage of eyes |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the proportion of eyes with central vitreomacular traction release without rescue vitrectomy at 24 weeks. It expresses an outcome as a percentage of eyes rather than as a mean score. The wording defines success using both the central VMT release status and the absence of rescue vitrectomy: an eye that had rescue vitrectomy would not meet this endpoint’s stated success condition.
This kind of endpoint can be useful when the research question concerns both a targeted clinical or anatomical status and whether that status was reached without a subsequent rescue procedure. It makes the outcome definition more specific than release status alone. That definition is not interchangeable with visual acuity, rescue treatment considered separately, or other VMT status measures; those address related but distinct aspects of outcome.
The registry lists the assessment time as 24 weeks. It reports values of 78.0 for pneumatic vitreolysis and 9.0 for sham, with arm sizes of 23 and 22, respectively. The posted endpoint values do not include an interval estimate or a primary between-group test. The exact counts underlying the percentages, the handling of missing endpoint assessments, and the analysis population are not reported in the registry record. Consequently, the percentages describe the posted arm results but do not on their own convey the precision of the comparison.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
At 24 weeks, the posted primary outcome is 78.0 for pneumatic vitreolysis and 9.0 for sham. These values describe the reported proportion of eyes meeting the endpoint definition: central VMT release without rescue vitrectomy. They show a marked descriptive separation between the two arm summaries. The registry record does not report a primary comparison estimate, an interval estimate, or a p-value, so the precision and inferential uncertainty for that separation cannot be assessed from the posted primary result alone.
The arm sizes accompanying the primary results are 23 and 22. The record reports enrollment of 46, but does not explain in the posted outcome information how enrollment relates to the denominators used for each endpoint. The counts of eyes underlying the primary percentages are not reported. Without counts and information about endpoint availability, the precision of each percentage cannot be reconstructed from the outcome summary.
The secondary visual-acuity outcome is mean change in E-ETDRS letter score from baseline to 24 weeks. The arm means are 6.7 for pneumatic vitreolysis and 6.1 for observation. A recalculated unadjusted mean difference is 0.6, with an interval from -5.863 to 7.063 and p = 0.856. The interval includes zero, so the posted summary does not pin down a direction for the underlying mean difference. The p-value is not evidence that the groups are equivalent; an equivalence conclusion requires a suitable design and prespecified margin, neither of which is reported in the registry record.
The secondary comparison is a recalculation from posted summary statistics, rather than a reported sponsor analysis. The registry record lists no reported analyses for this outcome. The interval and p-value should therefore be read as an unadjusted summary comparison, not as an adjusted or definitive trial analysis. The sponsor’s own analysis takes precedence if it is available, but a sponsor analysis is not reported in the registry record.
For the primary outcome, the reported percentages are informative as arm-level descriptions, but they are not a substitute for an estimated between-group effect with uncertainty. For the secondary outcome, the mean difference and interval provide a direct comparison, while also indicating substantial uncertainty. Neither result establishes that a treatment works or does not work. Interpretation is limited by the lack of a reported primary inferential analysis, the absence of a reported analysis plan, and the limited set of outcome details in the registry record.
9. Statistical Methods Explained
Different kinds of outcomes call for different summaries. The primary endpoint is a proportion, whereas the visual-acuity outcome is a mean change on a scale. A proportion describes how often a defined outcome was recorded among the eyes counted for that endpoint. A mean summarizes the average change in a numerical measure. These summaries answer related but non-identical questions, so the visual-acuity result should not be treated as a direct statistical test of the primary endpoint.
What does the primary proportion tell us?
The primary outcome is the proportion of eyes with central VMT release without rescue vitrectomy at 24 weeks. The posted percentages are 78.0 for pneumatic vitreolysis and 9.0 for sham. A percentage is an arm-level description of the outcome, not itself an estimate of the uncertainty around the difference between arms. To judge precision, readers generally need an interval for each arm or, preferably, for the between-arm contrast. The registry record does not report such an interval or a primary comparison test.
The outcome is labeled as a count-type measure, but the registry result is presented as percentages. The exact event counts that generated those percentages are not reported. The registry record also does not state how missing or ungradable outcome assessments were treated. Those details matter because a proportion depends on both the outcome count and the denominator used in its calculation.
How should the visual-acuity comparison be read?
The secondary visual-acuity outcome reports mean change from baseline to 24 weeks. The mean change is 6.7 in the pneumatic vitreolysis arm and 6.1 in the observation arm, with standard deviations of 12.4 and 9.6. A standard deviation describes variation among individual observations around an arm mean; it is not the uncertainty interval for the mean difference. The recalculated unadjusted mean difference is 0.6, with an interval from -5.863 to 7.063 and p = 0.856.
An interval gives a range of estimates compatible with the data under the calculation’s assumptions. The confidence level for the posted interval is not reported in the registry record. Because this interval includes zero, the results are compatible with a mean difference in either direction as well as with little or no difference. The interval also spans values away from zero, so the result does not demonstrate that the groups are equivalent. A non-significant p-value is not a test of equivalence or non-inferiority.
The p-value describes how unusual a test statistic at least as extreme as the observed one would be under a specified null model and its assumptions. It does not give the probability that the null hypothesis is true, nor does it measure clinical importance. The reported p-value is unadjusted. The registry record does not describe whether the analysis adjusted for baseline values or other factors, and does not list a sponsor-reported analysis for this outcome. Accordingly, the comparison is a recalculation from the posted means, standard deviations, and arm sizes, not a substitute for a prespecified trial analysis.
What do the planning illustrations mean?
The posted planning illustrations use the observed secondary mean difference as a starting point and consider planning for 100%, 75%, and 50% of that observed effect. For 80% power, the listed participants per arm are 5,393, 9,588, and 21,572, respectively. For 90% power, the corresponding values are 7,220, 12,835, and 28,879. These figures are planning illustrations, not observed power and not a reconstruction of the trial’s original design. The registry record explicitly describes them as based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation.
Planning estimates depend strongly on the effect chosen for detection. A smaller target effect generally requires more information to distinguish it from random variation under a fixed design. The illustrations do not establish that the observed effect is the effect future studies should target. They also do not provide the trial’s sample-size justification: that justification is not reported in the registry record.
Why do the analysis details matter?
Randomization supports a fair comparison by reducing systematic differences in treatment assignment, but the analysis still needs to specify which participants or eyes are included, how missing observations are handled, and which statistical model is used. The registry record does not report these details for the posted primary outcome. It also does not report an interim-analysis plan, multiplicity procedure, or full statistical analysis plan. Without those details, readers should distinguish the directly posted arm summaries from any assumptions needed to make stronger inferential claims.
When a registry result gives no interval or test for a primary proportion, the appropriate reading is descriptive. When an unadjusted secondary comparison is recalculated from summary statistics, it can aid interpretation but should not be mistaken for a prespecified or adjusted analysis. These are general statistical cautions; the specific analysis choices for this trial are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The record lists a primary outcome and multiple secondary outcomes. When a study evaluates multiple endpoints, repeated statistical testing can increase the chance of a nominally unusual result arising by chance. Common approaches include defining one primary test, setting an ordered hierarchy for secondary tests, or adjusting the threshold or estimates for the family of comparisons. These are general statistical approaches; the registry record does not report which, if any, were used for this trial.
The posted visual-acuity comparison is unadjusted and recalculated from summary statistics. The registry record reports no sponsor analyses for that outcome and does not describe a multiplicity correction. The primary result is reported as arm percentages without a between-arm inferential estimate. It is therefore not possible to determine from the registry record how the primary and secondary outcomes were treated in the trial’s inferential analysis, or whether any results were selected for reporting under a prespecified hierarchy.
Important analysis details are also not reported in the registry record. These include the analysis populations, the handling of missing outcome data, the method used to calculate the primary percentages, the statistical model for the primary comparison, and whether any baseline adjustment was planned. The record does not report an interim-analysis plan or the trial’s sample-size justification. Those omissions do not show that a particular method was or was not used; they limit what can be concluded from the registry record.
Missing-data methods can affect both the denominator and the interpretation of an endpoint. For example, an analysis may include only eyes with a recorded assessment or may use another prespecified approach. Without the trial’s stated method and outcome availability information, readers cannot assess whether missing assessments could have influenced the reported percentages or mean change. The posted numbers should be interpreted as the results recorded, not as evidence about unreported analytic choices.
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 |
|---|---|---|---|
| Pneumatic Vitreolysis | 5 | 24 | 20.8% |
| Observation | 0 | 22 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Pneumatic Vitreolysis | 0 of 24 |
| Observation | 0 of 22 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0.01% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Pneumatic Vitreolysis | 10 of 24 |
| Observation | 5 of 22 |
Most frequent serious adverse event terms
| Event term | Organ system | Pneumatic Vitreolysis | Observation |
|---|---|---|---|
| Rhegmatogenous retinal detachment | Eye disorders | 2 of 24 | 0 of 22 |
| Cataract traumatic (ocular injury) | Eye disorders | 1 of 24 | 0 of 22 |
| Endophthalmitis | Eye disorders | 1 of 24 | 0 of 22 |
| Macular hole | Eye disorders | 1 of 24 | 0 of 22 |
| Retinal tear | Eye disorders | 1 of 24 | 0 of 22 |
| Acute respiratory failure | Respiratory, thoracic and mediastinal disorders | 1 of 24 | 0 of 22 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Pneumatic Vitreolysis | Observation |
|---|---|---|---|
| Posterior vitreous detachment | Eye disorders | 3 of 24 | 0 of 22 |
| Cataract | Eye disorders | 2 of 24 | 0 of 22 |
| Ocular hypertension | Eye disorders | 2 of 24 | 0 of 22 |
| Subconjunctival hemorrhage | Eye disorders | 2 of 24 | 0 of 22 |
| Anterior chamber cell | Eye disorders | 1 of 24 | 0 of 22 |
| Anterior chamber flare | Eye disorders | 1 of 24 | 0 of 22 |
| Blurred vision | Eye disorders | 0 of 24 | 1 of 22 |
| Conjunctival hyperemia | Eye disorders | 0 of 24 | 1 of 22 |
| Corneal abrasion | Eye disorders | 0 of 24 | 1 of 22 |
| Corneal edema | Eye disorders | 1 of 24 | 0 of 22 |
Serious events with the highest arm-level rate: rhegmatogenous retinal detachment (8.3%), cataract traumatic (ocular injury) (4.2%), endophthalmitis (4.2%), macular hole (4.2%), retinal tear (4.2%).
The registry reports serious adverse events for the pneumatic vitreolysis group as 5 of 24 at risk and for the observation group as 0 of 22 at risk. Other adverse events are reported for 10 of 24 and 5 of 22, respectively. Deaths are recorded as 0 in both groups. These are descriptive safety counts; the registry record does not provide a comparative statistical analysis or explain how events were judged to be related to the intervention.
The serious-event terms listed include rhegmatogenous retinal detachment at 8.3%, and cataract traumatic (ocular injury), endophthalmitis, macular hole, retinal tear, and acute respiratory failure at 4.2% each. The denominator and event-count basis for these term percentages are not stated in the registry record, so they should not be converted into counts or compared as rates without that context.
Adverse-event figures do not establish causation. They also do not provide a complete account of timing, severity, recurrence, or the relationship of an event to treatment. The values describe the reported safety information, not a conclusion that an intervention caused or prevented an event.
12. What the Result Does, and Does Not, Mean
The posted primary percentages describe how often eyes in each randomized group met the endpoint definition at 24 weeks. The pneumatic vitreolysis arm is reported at 78.0 and the sham arm at 9.0 for central VMT release without rescue vitrectomy. Those arm summaries show a descriptive separation, but the registry record does not include a primary between-group estimate, interval, or p-value. The precision of the primary comparison is therefore not established by the posted percentages alone.
The secondary visual-acuity result addresses a different outcome. Its recalculated unadjusted mean difference is 0.6, with an interval from -5.863 to 7.063 and p = 0.856. The interval spans zero and does not establish a clear direction for the mean difference. It also does not establish equivalence. No medical conclusion should be drawn from this secondary comparison alone, particularly because the registry record does not report a sponsor analysis or the complete statistical plan.
The result does not establish whether the primary finding is robust to alternative analyses, missing outcome data, or adjustments for multiple testing. It also does not provide evidence about outcomes beyond the stated assessment time. The registry record reports the primary endpoint at 24 weeks; longer-term results are not reported in the registry record.
More broadly, trial results describe a study population under its trial conditions. The registry record identifies eyes with idiopathic symptomatic VMT without a macular hole, but does not report detailed participant characteristics or all eligibility criteria. The posted summaries therefore should not be generalized beyond the studied setting without further evidence. The statistical summaries describe the available registry results; they do not constitute medical advice or determine an individual treatment choice.
13. Why This Trial Matters Statistically
This trial illustrates why a registry result needs to be read at the level of the endpoint and analysis actually reported. The primary endpoint is a proportion, and its posted arm values are widely separated descriptively. Yet a percentage alone does not provide an uncertainty interval for the between-group comparison. Without a reported primary inferential analysis, readers cannot gauge its precision from the registry entry.
The record also illustrates the distinction between a primary outcome and a secondary outcome. The secondary visual-acuity comparison is numerical and includes an unadjusted recalculation with an interval and p-value. It answers a different question from whether central VMT release occurred without rescue vitrectomy. Neither result can substitute for the other, and the secondary comparison should not be used to resolve the primary result.
Another statistical lesson is that transparency about analysis choices is part of interpretation. The registry record does not report the analysis population, missing-data methods, multiplicity approach, interim analyses, or full statistical plan. These details help readers understand how results were obtained and how much weight to place on comparisons. Their absence limits independent appraisal; it is not proof that a particular method was omitted from the trial.
Finally, planning values based on an observed effect are not retrospective measures of how well the completed trial was powered. They are illustrations under stated assumptions and should not be mistaken for the original design rationale or observed power. The distinction matters when using a small trial’s results to think about future study planning.
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 main limitation of the posted primary result is that it gives arm percentages without a reported between-group estimate, interval, or p-value. The registry record does not provide the exact counts underlying those percentages or the method used to handle eyes without an assessable outcome. This prevents an independent assessment of primary-result precision and of the role of missing observations.
The numerical secondary comparison is limited to mean visual-acuity change. It is an unadjusted recalculation from summary statistics, and no sponsor-reported analysis is listed in the registry record. Its interval spans zero and is broad relative to the point estimate. The registry entry does not report a confidence level for that interval or whether baseline adjustment was part of the planned analysis.
Several listed secondary outcomes have no numerical results in the registry record. The record also does not report multiplicity methods, analysis populations, interim analyses, or the full statistical analysis plan. These missing details limit assessment of selective emphasis, robustness, and the handling of multiple endpoints. The trial’s sample-size justification is not reported; planning illustrations based on the observed effect do not fill that gap.
The primary assessment is at 24 weeks. Longer-term outcome results are not reported in the registry record, so the posted results do not describe durability beyond that time. Detailed participant characteristics and further eligibility criteria are also not reported, limiting assessment of how broadly the findings may apply. These are limitations of the registry information available for interpretation, not evidence that unreported procedures or analyses were absent from the study.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Effects of Pneumatic Vitreolysis on Vitreomacular Traction — NCT03647267.
- Registry record last updated 2022-09-21; status last verified 2022-09.
- Results first posted 2021-10-28.
- 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
NCT03647267 is a completed randomized, triple-masked, parallel-group Phase 3 trial titled “Effects of Pneumatic Vitreolysis on Vitreomacular Traction.” The registry record reports enrollment of 46 and identifies Jaeb Center for Health Research as sponsor. The study compared a 0.3-mL intraocular C3F8 gas injection with a sham injection in eyes with idiopathic symptomatic vitreomacular traction without a macular hole.
The primary outcome was the proportion of eyes with central VMT release without rescue vitrectomy at 24 weeks. The posted values are 78.0 for pneumatic vitreolysis and 9.0 for sham; a primary inferential comparison is not reported in the registry record. A secondary visual-acuity summary reports mean changes of 6.7 and 6.1, with an unadjusted recalculated mean difference of 0.6, interval -5.863 to 7.063, and p = 0.856.
The registry lists additional secondary outcomes and safety information, but detailed results and analysis methods are not reported for several outcomes. The posted summaries are descriptive and do not replace a complete statistical analysis plan.