Safety and Effectiveness of the Sight Sciences VISCO™360 Versus SLT in Primary Open Angle Glaucoma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Effectiveness of the Sight Sciences VISCO™360 Versus SLT in Primary Open Angle Glaucoma (NCT02928289), a randomized na study. The primary outcome is Mean Change From Baseline in Diurnal IOP at 12 Months (Measured in mm Hg).

2. Clinical Question

The study was intended to evaluate both safety and effectiveness, but the posted Month 12 endpoint data cover only participants who had completed that visit before termination for poor enrollment. The primary outcome description notes that one participant in the SLT group underwent a secondary glaucoma procedure at Day 266, and the text describing that participant's Month 12 IOP is incomplete. Consequently, the clinical question is only partially addressed by the registry results: the record gives group-level means and standard deviations for the endpoint subset, but does not report an inferential comparison or a complete account of the endpoint observations.

3. Trial Design

The registry describes a multicenter, prospective, randomized controlled study with a parallel-group model and single masking. The study compared VISCO™360 ab interno canaloplasty surgery with selective laser trabeculoplasty (SLT) in primary open-angle glaucoma. The identity of the person or people masked is not reported in the registry record. The record lists the phase as NA.

The listed enrollment was 29. The study started on 2017-01-23, and its primary completion date was 2019-01-17. Its status is recorded as terminated; the outcome description attributes termination to poor enrollment. At the time of termination, only seven participants—3 in the VISCO360 group and 4 in the SLT group—had completed the Month 12 endpoint visit. These endpoint counts are not the same as the enrollment figure, and the registry does not provide a full accounting of outcomes for everyone enrolled.

The VISCO360 procedure was described as microcatheterization and viscodilation of Schlemm's canal using the VISCO360 Viscosurgical System. The SLT group underwent the SLT procedure. The primary endpoint was mean change from baseline in diurnal IOP at 12 months, measured in mm Hg, following wash-out of glaucoma medication at both time points.

The registry does not report the randomization sequence, allocation concealment, masking procedures, or detailed eligibility criteria. It also does not report a rationale for the planned enrollment, a statistical analysis plan, or whether interim analyses were planned. The available record therefore supports a basic description of the design and observed endpoint subset, but not a detailed assessment of all trial procedures.

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: Subjects provided informed consent at the Screening visit and if the screening eligibility criteria were met, underwent a washout of their intraocular pressure (IOP) lowering medication (generally 4 weeks) before returning for the baseline visit where diurnal IOP was measured. Subjects meeting the diurnall IOP criteria at the baseline visit were than randomized and treated.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Only seven (7) subjects, 3 in the VISCO360 group, and 4 in the SLT group had completed the Month 12 endpoint visit at the time the study was terminated for poor enrollment. One of the 4 subjects in the SLT group underwent a secondary glaucoma procedure (gel stent) at Day 266 so the 12 month DIOP was imputed as the Baseline DIOP (per the protocol analysis plan).

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 Mean Change From Baseline in Diurnal IOP at 12 Months (Measured in mm Hg), measured over 12 months.

The primary endpoint was mean change from baseline in diurnal intraocular pressure (IOP) at 12 months, measured in mm Hg. The registry defines it as the mean of the difference between each participant's baseline diurnal IOP and 12-month diurnal IOP. Measurements at both visits were taken following wash-out of glaucoma medication. The description does not make the subtraction order explicit, so the direction represented by a negative change cannot be established from that wording alone.

As a general statistical concept, a continuous endpoint such as IOP retains information about the measured values rather than reducing each observation to a yes-or-no category. The group mean describes the average observed change, while the standard deviation describes how spread out individual changes are around that average. Neither summary by itself indicates how precisely the group mean is estimated; that assessment ordinarily depends on uncertainty estimates such as confidence intervals, which are not reported for this endpoint in the registry record.

Using measurements at baseline and follow-up makes change over time the stated outcome, while measuring diurnal IOP focuses the endpoint on a measure recorded across the day rather than a single isolated reading. The registry does not give further details about the measurement schedule or how diurnal readings were combined. The endpoint is clinically relevant to the study's stated aim of evaluating IOP reduction, but the incomplete endpoint reporting limits what can be concluded from the posted group summaries.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The posted primary outcome is a continuous measure: mean change in diurnal IOP from baseline to Month 12, expressed in mm Hg. A continuous outcome can take a range of measured values. The reported group mean gives the average of participant-level changes, while the standard deviation describes how variable those changes were around the mean. These summaries answer different questions: the mean describes the center of the observed values, and the standard deviation describes their spread.

What do the mean and standard deviation convey?

The registry reports a mean change of -5.2 mm Hg and standard deviation of 7.6 mm Hg for 3 VISCO360 participants. For 4 SLT participants, it reports a mean change of -3.6 mm Hg and standard deviation of 3.3 mm Hg. Those figures summarize the participants with a completed Month 12 endpoint, not necessarily everyone randomized or enrolled. A standard deviation is not a confidence interval and should not be read as a range containing a specified proportion of the population. It also does not, by itself, quantify the precision of the estimated mean.

General statistical explanation: precision of a mean is commonly conveyed with a confidence interval. A confidence interval reflects uncertainty in an estimate under a specified statistical model and method. The registry does not report confidence intervals for the primary endpoint, so the precision of either group mean cannot be read directly from the posted summaries. The reported standard deviations describe variability in the endpoint observations, not uncertainty in a treatment comparison.

What would a between-group analysis add?

A comparative analysis would estimate the difference in outcome between the randomized groups and describe uncertainty around that comparison. It might use a model or a direct contrast, depending on the prespecified plan and data structure. The registry lists zero analyses and says values are missing or not estimable for a two-arm comparison of this continuous endpoint. Thus, no comparative estimate, confidence interval, or p-value is reported. A reader should not infer a test result from the two group means or compare the means as though that were a formal analysis.

General statistical explanation: an inferential test evaluates how compatible observed data are with a specified null hypothesis, under its assumptions. A p-value does not measure the probability that a treatment works, nor does it describe the magnitude or clinical importance of an effect. A confidence interval can help show both plausible effect sizes and precision. Neither form of comparative inference is available in the registry record for this endpoint.

What do the design assumptions mean?

The registry describes planning illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The assumed effect to detect is described as a stated fraction of the observed effect. These are planning assumptions, not evidence that the trial achieved a particular power or that a treatment effect was established. Any sample-size illustration is a hypothetical planning aid, not observed power. The registry does not report the trial's own sample-size justification or enough detail to establish that the illustration assumptions were the protocol's design assumptions.

General statistical explanation: over-dispersion means that observed variability is greater than a model expects. When a model underestimates variability, its uncertainty estimates can be too narrow and its inferential results may be overly confident. The registry provides standard deviations for the endpoint subset, but does not report a fitted model or a comparison that would permit evaluation of model dispersion. With so few endpoint observations, assumptions about the distribution of participant-level changes would be difficult to assess from group summaries alone.

How should the negative values be read?

The endpoint title calls the outcome a change from baseline, while the description calls it the difference between baseline and 12-month DIOP without stating which value is subtracted from which. That distinction matters because reversing subtraction order reverses the sign. The numerical means should therefore be quoted as recorded, without assigning a direction of IOP change based only on their signs. The registry's stated study purpose concerns reducing IOP, but the incomplete subtraction definition does not resolve this reporting ambiguity.

The endpoint description also states that measurements at baseline and Month 12 followed wash-out of glaucoma medication. This is part of the recorded endpoint definition. The record does not explain the wash-out procedures, provide further measurement details, or describe how missing values were handled. These methods cannot be reconstructed from the posted group summaries.

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("VISCO360 ab interno canaloplasty surgery", "Selective Laser Trabeculoplasty (SLT)")
n   <- c(3, 4)
m   <- c(-5.2, -3.6)
sp  <- c(7.6, 3.3)
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  VISCO360 ab interno canaloplasty surgery  3  -5.200  7.600  -24.079  13.679
CARM  Selective Laser Trabeculoplasty (SLT)  4  -3.600  3.300  -8.851  1.651

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and one secondary outcome: the proportion of participants achieving a ≥ 20% change in mean diurnal IOP at 12 months. Results for that secondary outcome are not reported in the registry record. The record lists two outcome measures and zero analyses. It does not report a multiplicity plan explaining how more than one outcome would be considered in confirmatory inference, or whether the secondary outcome was intended to be exploratory. Without reported analyses or results for the secondary outcome, no conclusion about it can be drawn.

Only seven participants had completed the Month 12 endpoint visit when the study was terminated for poor enrollment: 3 in the VISCO360 group and 4 in the SLT group. The registry does not provide a complete participant flow or describe the endpoint status of everyone enrolled. It does not report whether participants were analyzed according to randomized assignment, whether any other analysis populations were defined, or how missing endpoint data were handled. Imputation, sensitivity analyses, and reasons for non-completion are not reported in the registry record.

The primary outcome description notes that one SLT participant underwent a secondary glaucoma procedure at Day 266 and then ends before stating that participant's 12-month DIOP. The record therefore does not establish how that observation was treated in the endpoint summary or whether the procedure affected the availability or interpretation of the measurement. More generally, the registry does not report an analysis plan addressing intercurrent procedures or incomplete follow-up. These gaps make it difficult to determine how the endpoint subset relates to the randomized comparison the trial was designed to make.

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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: non-ocular (14.3%), ocular adverse event (10.0%).

The registry reports serious adverse events for 1 of 7 participants at risk in the VISCO360 group and 2 of 10 participants at risk in the SLT group. It reports deaths of 1 in the VISCO360 group and 0 in the SLT group. These are safety counts as recorded; they do not establish that an event or death was caused by the assigned procedure. The registry does not provide event narratives or enough detail to assess timing, relatedness, severity beyond the serious classification, or clinical circumstances.

For other adverse events, the record reports 1 affected participant among 7 at risk in the VISCO360 group and 4 among 10 at risk in the SLT group. The record's listed top serious-event terms include “non-ocular” at 14.3% and “Ocular adverse event” at 10.0%. The available information does not explain the event-term coding, whether terms overlap, or the precise basis for those percentages. They should not be interpreted as independent categories or as a full description of safety experience.

The safety denominators differ from the Month 12 endpoint counts. The registry does not explain the relation between the safety populations and the endpoint subset. These figures are descriptive reports from the registry, not a comparative safety analysis, and the record does not report a statistical test of adverse-event differences.

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

The posted results describe mean change in diurnal IOP at Month 12 among a limited endpoint subset: -5.2 mm Hg for 3 participants in the VISCO360 group and -3.6 mm Hg for 4 participants in the SLT group. The reported standard deviations were 7.6 mm Hg and 3.3 mm Hg, respectively. These figures are descriptive summaries, and the registry does not report an inferential comparison or uncertainty interval for the difference between groups.

They do not establish which procedure produced a greater change, how precisely either group mean represents a broader population, or whether an observed difference would be reproducible. The small number of completed Month 12 observations, variation in the summaries, missing comparative analysis, and unclear subtraction order all limit interpretation. The incomplete description of the SLT participant who underwent a secondary procedure adds uncertainty about that endpoint observation.

The record also does not report results for the listed secondary outcome, the proportion with a ≥ 20% change in mean diurnal IOP at 12 months. Nor does it provide enough information to characterize missing outcome data or compare all randomized participants. Enrollment was 29, but only seven participants had completed the Month 12 visit at termination for poor enrollment.

These registry results should therefore be understood as a partial descriptive record, not as definitive evidence for or against either procedure. They do not support medical decisions or claims about treatment effectiveness. The absence of a reported comparison is not proof that the groups were identical, and the difference between the posted group means is not, by itself, evidence of a treatment effect.

14. Why This Trial Matters Statistically

This trial illustrates why reporting the endpoint population and the comparative analysis matters as much as reporting group averages. Randomization is intended to support a fair comparison between assigned groups, but the posted primary endpoint summaries cover only participants who completed Month 12 before the study ended. The registry gives a reason for termination—poor enrollment—but does not provide enough participant-flow or missing-data information to connect the endpoint subset fully to the randomized comparison.

The trial also demonstrates the difference between descriptive and inferential statistics. Means and standard deviations convey the observed group summaries and their variability. They do not give a direct estimate of the between-group effect or its precision. With no reported comparative estimate, confidence interval, or p-value, the numerical summaries alone cannot establish whether the observed pattern is distinguishable from chance variation or how uncertain the comparison is.

Endpoint definitions need to be explicit for interpretation. Here, the registry describes a difference between baseline and Month 12 measurements without specifying subtraction order. That ambiguity matters when interpreting the negative signs. Clear definitions of measurement timing, outcome derivation, and handling of procedures or missing values help readers understand what a numerical change represents.

Finally, the safety counts and efficacy summaries involve different reported denominators. Reading each in its own context prevents mistaken assumptions about who contributed to each analysis. The record is a useful example of how termination, incomplete follow-up, and sparse reporting constrain the conclusions that can be drawn, even when group-level values are available.

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.

Several limitations specific to this trial affect interpretation. The registry reports that the study was terminated for poor enrollment and that only seven participants had completed the Month 12 endpoint visit at that time. Although enrollment is listed as 29, the record does not give a full account of the status or outcome availability of everyone enrolled. Reasons for missing Month 12 measurements beyond the stated termination context are not reported.

The primary endpoint description is incomplete for the SLT participant who underwent a secondary glaucoma procedure at Day 266. It stops after stating that the 12-month DIOP “was,” without reporting the rest of the sentence. The record does not clarify whether that measurement was obtained or included in the group summary. The definition of change also leaves subtraction order unspecified, which prevents confident interpretation of the sign of the reported means.

The registry reports group means and standard deviations but no confidence intervals, comparative effect estimate, p-value, or analysis details. It lists no analyses and indicates that values are missing or not estimable for a two-arm comparison of the continuous endpoint. The record does not report a statistical analysis plan, missing-data methods, analysis populations, or the rationale for the planned enrollment.

Further limitations include the absence of results for the listed secondary outcome and limited detail on masking, eligibility, measurement procedures, and safety-event circumstances. The identity of those masked is not reported. These omissions do not demonstrate that a procedure was ineffective or unsafe; they restrict how much can be learned from the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety and Effectiveness of the Sight Sciences VISCO™360 Versus SLT in Primary Open Angle Glaucoma — NCT02928289.
• Registry record last updated 2025-11-14; status last verified 2025-10.
• Results first posted 2025-09-24.
• 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

NCT02928289 is a multicenter, prospective, randomized, parallel-group study comparing VISCO™360 ab interno canaloplasty surgery with selective laser trabeculoplasty in primary open-angle glaucoma. The registry lists single masking and enrollment of 29. The study started on 2017-01-23, had a primary completion date of 2019-01-17, and is recorded as terminated for poor enrollment.

The primary endpoint was mean change from baseline in diurnal IOP at 12 months following wash-out of glaucoma medication. At termination, 3 VISCO360 participants and 4 SLT participants had completed the Month 12 endpoint visit. Their reported mean changes were -5.2 mm Hg and -3.6 mm Hg, respectively; comparative inference is not reported. The registry also lists one secondary outcome, but its results are not reported. Missing-data methods and the complete status of enrolled participants are not reported in the registry record.