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 Optimal Method for Mydriasis in Cataract Surgery (NCT02909140), a randomized na study. The primary outcome is Pupil Size Immediately Prior to Capsulorrhexis.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02909140 |
| Phase | NA |
| Condition | Cataract |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 3 |
| Arms in the primary outcome | 3 |
| Lead sponsor | Johns Hopkins University |
| Results posted | Yes |
2. Clinical Question
Population
People undergoing routine cataract surgery were the intended study population. The registry lists cataract as the condition and describes pupil dilation in the setting of cataract surgery. Although the trial enrollment is recorded as 3, the primary-outcome description says data were analyzed for 1 participant because data were lacking for the other participant in the intracameral arm. The registry does not report additional details about participant eligibility or the characteristics of those enrolled.
Intervention
The intervention options concern how to achieve mydriasis, or pupil dilation, for surgery. The topical regimen is described as phenylephrine 2.5% and cyclopentolate 1%, given as drops in the preoperative area. The intracameral regimen is described as epinephrine 1:10,000 injected into the anterior chamber at the beginning of surgery. A third arm combines topical and intracameral mydriasis. The registry describes intracameral lidocaine 1% in the arm descriptions, but the descriptions are truncated.
Comparator
The randomized parallel-group design assigns participants among topical mydriasis, intracameral mydriasis, and topical plus intracameral mydriasis. The scientific comparison is whether these different approaches produce different pupil sizes during surgery. However, the registry reports a primary-outcome value only for the intracameral arm, so it does not provide the arm-to-arm result needed to evaluate that comparison.
Primary question
The primary endpoint is pupil size, in mm, immediately prior to capsulorrhexis. The study asks whether pupil dilation at that surgical step differs according to the mydriasis approach. The registry reports a value of 8.0 for 1 participant in the intracameral arm and no primary-outcome values for the topical or combined arms. The record therefore describes a measurement, but does not report a comparative estimate of the three approaches.
3. Trial Design
The registry describes a randomized, parallel-group study with three intervention arms: topical mydriasis, intracameral mydriasis, and topical plus intracameral mydriasis. The study title is “Optimal Method for Mydriasis in Cataract Surgery,” and the listed condition is cataract. The registry records enrollment of 3 and trial status as terminated. The listed start is 2016-09, and primary completion is recorded as 2018-08-15. The phase is listed as NA.
The intervention descriptions distinguish topical drops given before surgery from intracameral epinephrine given at the beginning of surgery, with the combined arm using both approaches. The topical description names phenylephrine 2.5% and cyclopentolate 1%; it specifies repeated doses spaced 5 minutes apart in the preoperative area. The intracameral description gives epinephrine 1:10,000 at a volume of 0.2ml to 0.3ml. Descriptions of some arm procedures are incomplete in the registry record, so further procedural details are not reported in the registry record.
Masking is recorded as none. The primary-outcome description separately says that pupil size was measured from digital photography by a researcher masked to intervention. This identifies masking for that measurement, but does not change the overall masking field in the registry. The record does not report the randomization method, allocation concealment, or the reason the study was terminated.
The planned question is comparative, but the posted primary results do not provide a complete comparison. The primary-outcome population note says data were collected only for the intracameral arm and that one participant was analyzed because data for the other participant were lacking. The registry reports no primary value for either of the other arms. Consequently, the randomized design alone cannot establish the treatment contrast: usable results from the relevant arms are also needed.
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.
Before assignment: Although 3 patients were enrolled, no information is available for the 3rd patient. Hence, the discrepancy.
Overall Study
| Stage | Topical Mydriasis | Intracameral Mydriasis | Topical + Intracameral Mydriasis |
|---|---|---|---|
| STARTED | 0 | 2 | 0 |
| COMPLETED | 0 | 2 | 0 |
| NOT COMPLETED | 0 | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Data was only collected for the "Intracameral Mydriasis' arm. We analyzed data for 1 participant only because of lack of data for the other participant.
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.
Population: Absent enrollment
| Characteristic | Unit | Topical Mydriasis | Intracameral Mydriasis | Topical + Intracameral Mydriasis | Total |
|---|---|---|---|---|---|
| Participants analysed | 0 | 2 | 0 | 2 | |
| Age, Categorical: <=18 years | Participants | — | 0 | — | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | — | 0 | — | 0 |
| Age, Categorical: >=65 years | Participants | — | 2 | — | 2 |
| Sex: Female, Male: Female | Participants | — | 1 | — | 1 |
| Sex: Female, Male: Male | Participants | — | 1 | — | 1 |
| Race and Ethnicity Not Collected | Participants | — | — | — | 0 |
| Systolic blood pressure in preoperative area | mmHg | — | 144 (140 to 148) | — | 144 (140 to 148) |
| Heart rate in preoperative area | bpm | — | 75.5 (62 to 89) | — | 75.5 (62 to 89) |
| Systolic blood pressure on entry to OR | mmHg | — | 172 (169 to 176) | — | 172 (169 to 176) |
| Heart rate on entry to OR | bpm | — | 80.5 (72 to 89) | — | 80.5 (72 to 89) |
6. Primary Endpoint
The registry lists the primary outcome as Pupil Size Immediately Prior to Capsulorrhexis, measured over Immediately prior to the capsulorrhexis step of cataract surgery.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | mm |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is pupil size in mm immediately prior to the capsulorrhexis step of cataract surgery. Capsulorrhexis is a defined surgical step, so this endpoint captures pupil size at a specified point rather than at an unspecified time during the procedure. The registry says pupil size was to be recorded by digital photography and measured by a researcher masked to intervention. Using a masked assessor can help limit the possibility that knowledge of the assigned approach influences measurement, although the registry does not report further details about image measurement or quality control.
Pupil size is used as a direct measurement of the degree of dilation at that operative moment. That makes it relevant to the study’s stated aim of comparing approaches to mydriasis. It is not, by itself, a measure of every aspect of the operation, nor does it describe later pupil size, additional use of mydriatic agents, surgical time, or patient experience. The registry lists these and other outcomes separately as secondary outcomes.
The posted primary result is 8.0 mm for 1 participant in the intracameral arm. The primary-outcome note says the analysis included one participant because data for the other participant were lacking, and that data were collected only for the intracameral arm. No primary value is reported for the topical or combined arm. As a result, the endpoint has a reported measurement but no reported between-arm estimate. The registry does not report a spread measure or confidence interval for this result.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The key interpretive feature is the very limited primary-outcome evidence. The registry reports a pupil size of 8.0 mm for 1 participant in the intracameral mydriasis arm. It reports no value for the topical arm and no value for the topical plus intracameral arm. The primary-outcome population note also states that data were collected only for the intracameral arm and that data for another participant were lacking. These results do not support a numerical comparison among the three assigned approaches.
A single recorded value describes that participant’s measurement; it does not establish the typical pupil size in the arm. There is no reported measure of variability, such as a standard deviation or range, and no confidence interval. General statistical explanation: a confidence interval conveys uncertainty around an estimated quantity. With no comparative estimate and no reported measure of uncertainty, the precision of an arm-level average or treatment contrast cannot be assessed from the posted primary result.
The randomized design is relevant to the intended comparison because random assignment can support comparisons between groups when outcomes are adequately observed and analyzed. In this record, however, the available primary result is restricted to one arm and one participant. Randomization cannot supply missing outcome measurements or create an estimate for arms with no posted primary data. The reported result should therefore be read as a descriptive observation, not as evidence that one regimen produced a larger or smaller pupil than another.
The registry marks the study as terminated and records enrollment of 3. It does not report the reason for termination or explain how termination affected data collection. The enrollment total does not resolve the missing primary-outcome information: the record itself says only the intracameral arm contributed primary data, with one participant analyzed. The disposition and outcome data for every enrolled participant are not reported in the registry record.
The registry lists multiple secondary outcomes, including pupil measurements at other surgical times, the need for another mydriatic agent, cumulative energy, phacoemulsification time, and changes in blood pressure or heart rate. However, the record reports no statistical analyses, and no secondary outcome results are included in the registry entries. Those outcomes therefore cannot fill the comparative gap in the primary result. Their listing indicates intended or registered measurement domains, not evidence that results were obtained or that any differences were found.
The appropriate statistical reading is consequently narrow: one primary pupil-size observation is posted for the intracameral arm, while comparative effectiveness and precision are not estimable from the posted primary results. This does not imply that the approaches are equivalent or different. It means the record does not provide the arm-specific results needed to answer the planned comparative question.
9. Statistical Methods Explained
What does a randomized parallel-group design mean?
General statistical explanation: in a randomized study, participants are assigned to interventions by a chance-based process, while a parallel-group design means participants remain in their assigned group for the comparison. These features are intended to make groups comparable at the start and to support interpretation of outcome differences as intervention contrasts. The registry identifies this study as randomized and parallel, but does not report the randomization sequence, allocation concealment, or other implementation details. Those methods cannot be inferred from the design labels alone.
Here, the planned arms are topical mydriasis, intracameral mydriasis, and topical plus intracameral mydriasis. A comparison requires outcome information for the groups being contrasted. The posted primary results include a value for only the intracameral arm, so no contrast between arms is available. This is a limitation of the reported results, not a statistical method that can be repaired by the randomized designation.
What does the primary measurement represent?
The endpoint is pupil size in mm immediately before capsulorrhexis. The registry says this was assessed from digital photography by a researcher masked to intervention. General statistical explanation: defining the measurement time in advance helps make observations more comparable, because measurements taken at different stages may reflect different conditions. Masking a measurement assessor can reduce the opportunity for expectation to influence outcome assessment. The record does not report additional measurement procedures or reliability information.
The posted value, 8.0 mm, is one observation from one participant in the intracameral arm. A participant-level value is not the same as a group average, and one observation cannot describe how much measurements vary within an arm. The registry gives no spread estimate or interval for this endpoint.
Why are uncertainty estimates important?
General statistical explanation: an estimate describes a quantity calculated from observed data; an uncertainty interval communicates how much precision the data provide about that estimate under the analysis model. A narrow interval generally indicates greater precision than a wide one. An interval around a treatment contrast would help show which effects are compatible with the data, while a point estimate alone would not convey that uncertainty.
No confidence interval or comparative estimate is reported for the primary endpoint. With only one posted measurement and no posted values for the other arms, the evidence does not support an estimate of between-arm variation or a treatment contrast. It would not be appropriate to infer an interval, standard error, or p-value from the information in the registry record.
What do the analysis fields indicate?
The registry reports zero analyses and identifies the results as a count-other endpoint that is not reduced to one comparison. It also indicates that values are missing or not estimable for a two-arm comparison. These details align with the absence of a posted arm-to-arm primary analysis. The record does not report a statistical model, an adjustment strategy, a hypothesis-testing procedure, or a prespecified analysis population beyond the primary outcome note about the one participant analyzed.
General statistical explanation: a statistical test evaluates data against a specified null hypothesis and model. A p-value, when reported, describes how incompatible the observed data are with that null model; it is not a measure of the probability that a treatment works. No p-value or test result is posted for this primary outcome, so there is no formal evidence from a reported test to interpret.
How should the sample-size illustrations be understood?
The sample-size assumptions describe planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. The illustrations are not the trial’s own design justification and do not represent observed power. The registry does not report a sample-size justification for the trial. Since the posted primary results do not include a two-arm effect estimate, a planning calculation based on that comparison is not available for this endpoint. Any planning illustration should be understood as a hypothetical design aid, not as an additional result from the trial.
General statistical explanation: planning calculations estimate how many participants might be needed under specified assumptions about the effect to detect, the significance threshold, allocation, and statistical method. Changing the assumed effect changes the planning requirement. Such calculations do not show whether an already completed or terminated study had enough information to answer its question, and they are not a substitute for reported outcome estimates and uncertainty.
Why might a count or rate model matter for other outcomes?
General statistical explanation: outcomes that count events can have variability that exceeds what a basic count model assumes; this is called over-dispersion. When over-dispersion is present, methods that account for it can produce more appropriate uncertainty estimates. The posted primary endpoint is a continuous pupil-size measurement, not an event count, and the record does not report a count-outcome analysis. No conclusion about over-dispersion or any alternative model can be drawn for this trial from the available results.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome and multiple secondary outcomes. The primary endpoint is pupil size immediately prior to capsulorrhexis. Secondary outcomes include pupil size at other points in surgery and on post-operative day 1, whether another mydriatic agent was required, cumulative energy, time for phacoemulsification, and increases in blood pressure or heart rate. The record lists 11 posted secondary outcomes, but does not provide results for them in the registry entries.
Multiplicity arises when several outcomes or comparisons are tested: the more tests considered, the greater the chance that at least one result appears noteworthy by chance if no adjustment or prespecified interpretation is used. General statistical explanation: a statistical plan can specify which outcome is primary, how secondary outcomes will be interpreted, and whether adjustments are used. The registry does not report a multiplicity strategy, an adjustment method, or an analysis plan that would clarify how multiple outcomes were to be handled.
Missing data are central to interpreting the primary result. The registry says primary data were collected only for the intracameral arm and that one participant was analyzed because data for the other participant were lacking. It reports no primary values for the topical or combined arms. The reasons for missing data, the number of missing observations by arm, and any imputation or sensitivity analysis are not reported in the registry record.
The record also does not describe an intention-to-treat population, a per-protocol population, or rules for excluding participants from analyses. The primary-outcome note identifies the analyzed participant count, but does not provide enough information to reconstruct a complete analysis population across all randomized arms. Because there are no posted secondary analyses and no reported missing-data approach, secondary outcomes cannot be used to resolve the missing comparative primary evidence.
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 |
|---|---|---|---|
| Intracameral Mydriasis | 0 | 2 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Topical Mydriasis | 0 of 0 |
| Intracameral Mydriasis | 0 of 2 |
| Topical + Intracameral Mydriasis | 0 of 0 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Topical Mydriasis | 0 of 0 |
| Intracameral Mydriasis | 0 of 2 |
| Topical + Intracameral Mydriasis | 0 of 0 |
The registry reports serious adverse events, other adverse events, and deaths by adverse-event group. For the intracameral mydriasis group, 2 participants are listed as at risk for serious adverse events and 2 as at risk for other adverse events. The registry records 0 serious adverse events, 0 other adverse events, and 0 deaths in that group. For the topical and topical plus intracameral groups, the at-risk counts are 0 and the event counts are also 0.
These figures should be read with the group sizes in mind. A zero event count in a group with 0 participants at risk does not provide safety information about exposure in that group. The intracameral group has a nonzero at-risk count, but the number of participants is very small; the registry’s figures do not establish that the true risk is zero. The record does not report follow-up duration or additional details about how adverse events were collected.
No serious adverse-event terms are listed. General statistical explanation: when no event is observed in a small group, uncertainty about the underlying event rate can remain substantial. A zero count is an observation in the recorded participants, not proof that an event cannot occur. These registry data are therefore descriptive and should not be interpreted as a comparative safety analysis or as a conclusion about safety differences between approaches.
12. What the Result Does, and Does Not, Mean
The posted primary result establishes a limited fact: the registry records pupil size of 8.0 mm immediately prior to capsulorrhexis for 1 participant in the intracameral mydriasis arm. It also says primary data were collected only for that arm and that the analysis included one participant because data were lacking for another participant. No primary result is posted for the topical arm or the topical plus intracameral arm.
The result does not estimate an average pupil size for a group with useful precision, because only one measurement is reported and no measure of variation is given. It does not estimate a difference between the three methods, because the other arms lack primary outcome values. It also does not provide a confidence interval, p-value, or model-based analysis. The registry reports zero analyses, and the available data do not support a comparative statistical conclusion.
The result should not be interpreted as evidence that the three approaches are equivalent, nor as evidence that one approach is superior. A lack of a reported contrast is not the same as a finding of no difference. General statistical explanation: equivalence or non-inferiority conclusions require an appropriate design, a prespecified margin, and an analysis that addresses the relevant contrast. Such a margin and analysis are not reported in the registry record.
The record lists additional outcomes, but no secondary results are present in the registry entries. Their inclusion in the registry does not indicate that the outcomes were measured successfully, analyzed, or found to favor any approach. Similarly, the adverse-event counts are descriptive and limited by the small reported at-risk groups.
Overall, the registry supplies a single primary measurement and incomplete outcome data for the planned comparison. The study question concerns the relative pupil dilation associated with different mydriasis regimens, but the posted results do not answer that comparative question. Conclusions about the size, precision, or direction of an intervention effect are not reported in the registry record.
13. Why This Trial Matters Statistically
This trial matters statistically because its design and its posted results illustrate the difference between a comparative question and a comparative estimate. Randomization and parallel groups describe how the study was intended to compare topical, intracameral, and combined mydriasis. To answer that question, however, outcome data need to be available across the groups. The registry reports a primary pupil-size result only for one participant in the intracameral arm, so the planned contrast cannot be estimated from the posted primary outcomes.
The case also shows why a numerical result needs context. A value of 8.0 mm is precise as a recorded measurement for that participant, but it does not describe the distribution of pupil sizes in an arm or the difference between arms. Statistical interpretation depends not only on the point value, but also on how many observations support it, how complete the outcome data are, and how uncertainty is reported.
There is also a distinction between registration and reporting. The registry identifies a primary endpoint and lists secondary outcome domains, yet does not provide a statistical analysis result for the primary comparison or results for the listed secondary outcomes. That gap limits what readers can learn from the record, regardless of the clinical rationale stated in the summary.
General statistical explanation: transparent reporting of the analysis population, missing outcomes, estimates, and uncertainty helps readers judge how directly results address a study question. In this record, the missing arm-level primary results and the absence of a reported analysis plan leave the comparative interpretation unresolved. The example is useful for distinguishing a planned randomized comparison from evidence capable of quantifying that comparison.
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 primary limitation is that the posted pupil-size data are restricted to the intracameral arm. The registry reports a value for 1 participant and says data were lacking for another participant; it gives no primary values for the topical or combined arms. Without results across arms, the planned comparative endpoint cannot be evaluated. The registry does not explain why data were missing or how missingness was handled.
The recorded enrollment is 3, and the trial status is terminated. The reason for termination, the timing of termination relative to data collection, and the disposition of all enrolled participants are not reported in the registry record. The primary-outcome population note and the adverse-event at-risk counts do not provide a complete account of participant flow across the study.
Precision cannot be assessed because the registry reports no spread measure or confidence interval for the primary endpoint. It also reports zero analyses, and no primary hypothesis test or adjusted estimate is available. The statistical analysis plan, sample-size justification, randomization implementation, and multiplicity strategy are not reported in the registry record.
The masking field is recorded as none, although the primary-outcome description says the researcher measuring the photographs was masked to intervention. This distinction gives some information about outcome assessment but does not clarify whether other study personnel or participants were masked. Several intervention descriptions are truncated, limiting procedural detail. Finally, the registry lists secondary outcomes but provides no corresponding results in the registry entries. These limitations restrict both comparative interpretation and assessment of how completely the registered outcomes were reported.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Optimal Method for Mydriasis in Cataract Surgery — NCT02909140.
- Registry record last updated 2019-09-10; status last verified 2019-08.
- Results first posted 2019-09-10.
- 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.
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18. Record Summary
NCT02909140 is a randomized, parallel-group study of topical, intracameral, and topical plus intracameral mydriasis for cataract surgery. Enrollment is recorded as 3, status as terminated, and masking as none. The primary endpoint is pupil size in mm immediately prior to capsulorrhexis, measured from digital photography by a researcher described as masked to intervention.
The registry reports a primary value of 8.0 mm for 1 participant in the intracameral arm. It states that primary data were collected only for that arm and that one participant was analyzed because data for another participant were lacking. No primary values are posted for the other arms, and the record reports zero analyses. The registry lists secondary outcomes, but their results are not reported in the registry entries. The available results therefore describe one measurement and do not provide an estimate of the planned comparison among mydriasis approaches.