Section structure
This article is organized into the following sections: Highlights; Clinical background and unmet need; Study design and methods; Key results; Clinical interpretation; Strengths and limitations; Implications for practice and policy; Conclusion; Funding and trial registration; References.
Highlights
Pigmentary glaucoma (PG) eyes underwent glaucoma procedures more often than primary open-angle glaucoma (POAG) eyes in the IRIS Registry, with a 4-year cumulative incidence of 22.2% versus 19.5% when laser trabeculoplasty (LTP) was included.
More invasive filtering or cyclodestructive procedures represented a greater share of interventions in PG than in POAG, suggesting a heavier interventional burden in PG.
Procedure failure after LTP and minimally invasive glaucoma surgery (MIGS) was higher in PG than in POAG at 1 year, indicating that treatment durability may differ by glaucoma subtype.
Although most patients with PG were non-Hispanic White, severe-stage disease was proportionally more common among non-Hispanic Black and Asian patients, highlighting an equity-sensitive clinical concern.
Clinical background and unmet need
Pigmentary glaucoma is a secondary open-angle glaucoma associated with pigment dispersion from the iris pigment epithelium, with subsequent accumulation of pigment within the trabecular meshwork and impaired aqueous outflow. Clinically, PG often affects younger and more myopic patients than typical POAG populations, and intraocular pressure fluctuations may be pronounced. While both PG and POAG can lead to progressive retinal ganglion cell loss and visual field deterioration, PG has long been considered a somewhat distinct phenotype with different demographics, mechanisms, and possibly treatment responses.
Yet much of the surgical literature and many treatment paradigms in glaucoma are dominated by POAG. Data directly comparing procedural incidence and outcomes between PG and POAG at scale have been limited. This matters because the biological substrate is not identical. In PG, heavily pigmented trabecular meshwork, episodic pigment release, and a younger lens status profile may influence the effectiveness of laser and surgical interventions. Clinicians also need better information on whether commonly used procedures, including LTP and MIGS, perform similarly across glaucoma subtypes.
The present IRIS Registry analysis addresses this gap using a very large real-world dataset. Its scale makes it particularly valuable for understanding relatively less common disease subgroups such as PG, and for exploring differences in procedural patterns, disease severity, and postoperative failure across major intervention categories.
Study design and methods
Fujita, Zebardast, Friedman, and the IRIS Registry Analytic Center Consortium conducted a retrospective cohort study using the IRIS Registry (Intelligent Research in Sight). Eyes with PG and POAG were identified using diagnosis codes from 2013 through 2025.
The study included 49,171 eyes with PG and 2,546,775 eyes with POAG. The main outcome was cumulative incidence of glaucoma-related procedures. The procedures examined were trabeculectomy, tube shunt surgery, MIGS, LTP, and cyclophotocoagulation. Kaplan-Meier methods were used to estimate cumulative incidence over time. For outcome analyses after selected procedures, cumulative failure probability was estimated in matched eyes, allowing a more direct comparison between PG and POAG.
The abstract does not provide the full operational definition of surgical failure, which is important when interpreting comparative results. In large registry-based ophthalmic studies, failure often reflects a composite of inadequate intraocular pressure control, need for repeat intervention, or other clinically meaningful endpoints documented in the record. Readers should therefore interpret failure rates in the context of the full paper’s methodology.
Key results
Population characteristics
The PG cohort differed demographically from the POAG cohort. Non-Hispanic White patients comprised 89.2% of the PG group, compared with 69.0% of the POAG group, a statistically significant difference (P < 0.001). This pattern is broadly consistent with the established epidemiology of pigment dispersion syndrome and PG, which have historically been reported more often in White populations.
However, one of the most clinically important findings concerns severity distribution within PG. Severe-stage disease in the PG group was proportionally highest among non-Hispanic Black patients at 25.1%, followed by Asian patients at 20.2%, Hispanic patients at 19.7%, and non-Hispanic White patients at 14.6%. This does not imply higher prevalence of PG in Black or Asian patients, but it does suggest that when PG occurs in these groups, it may be identified at a more advanced stage or may follow a more aggressive course. Possible explanations include delayed diagnosis, differences in access to subspecialty care, under-recognition of PG in populations where it is perceived as less common, or biological variation in disease expression.
Overall procedural incidence
The 4-year cumulative incidence of glaucoma procedures, including LTP, was 22.2% in PG versus 19.5% in POAG, with a highly significant difference by log-rank testing (P < 0.001). The corresponding 95% confidence intervals were 21.8% to 22.6% for PG and 19.4% to 19.5% for POAG. Although the absolute difference appears modest, at a population level it translates into a substantial excess procedural burden for PG.
The highest incidence of intervention was observed in severe-stage disease, which is clinically intuitive. More advanced damage generally narrows the acceptable target intraocular pressure range and increases the likelihood that medications or watchful monitoring will prove insufficient.
Distribution of procedure types
Filtering or cyclodestructive procedures accounted for 12.8% of procedures in PG and 10.3% in POAG, again a statistically significant difference (P < 0.001). This is notable because these procedures usually reflect more refractory disease, greater pressure-lowering requirements, or failure of prior less invasive treatments. The finding suggests that PG not only leads to more interventions overall, but may more often require escalation to procedures typically reserved for higher-risk or more difficult-to-control glaucoma.
Procedure failure: LTP and MIGS
The cumulative probability of failure following LTP was higher in PG than in POAG: 60.7% versus 58.2% at 1 year (P < 0.001). Failure after MIGS was also higher in PG than in POAG: 66.7% versus 60.8% at 1 year (P < 0.001). These differences, while not enormous in absolute terms for LTP, are clinically meaningful because both LTP and MIGS are often selected for their favorable safety profile and tissue-sparing nature. If durability is lower in PG, clinicians may need to counsel patients more carefully regarding retreatment risk and closer postoperative surveillance.
The higher failure probability after LTP in PG is especially interesting because pigmented trabecular meshwork might theoretically enhance laser energy absorption. Earlier literature has suggested that selective laser trabeculoplasty can be effective in PG, but also raised concern for post-laser pressure spikes in heavily pigmented angles and for waning effect over time. The present registry analysis suggests that, in routine real-world practice, the medium-term durability of LTP may indeed be somewhat worse in PG than in POAG.
For MIGS, the higher failure rate in PG may reflect several possibilities: a younger and more active aqueous dynamics profile, recurrent pigment liberation obstructing outflow pathways, selection of MIGS in eyes that were less ideal candidates than reflected in diagnosis codes alone, or heterogeneity among MIGS procedures grouped together in the registry analysis. Because MIGS encompasses multiple devices and techniques with different mechanisms, granularity in the full paper will be important.
Trabeculectomy with and without cataract surgery
Combined trabeculectomy-cataract surgery had higher 1-year failure rates than standalone trabeculectomy in both diagnostic groups. In PG, failure was 56.4% for combined surgery versus 33.5% for standalone trabeculectomy. In POAG, the corresponding rates were 49.1% versus 34.9%, with both comparisons significant at P < 0.001.
This finding aligns with longstanding surgical experience that phacotrabeculectomy may produce less robust pressure lowering than trabeculectomy alone in some settings, even though combined surgery can reduce total operative burden and address coexisting visually significant cataract. The signal appears particularly strong in PG, where preserving filtration success may be especially important in patients with greater pressure variability or more aggressive disease trajectories.
Clinical interpretation
This study offers several practical messages. First, PG should not be viewed as simply a younger version of POAG. The higher rate of procedural use and the greater share of filtering or cyclodestructive procedures suggest that PG may carry a distinct management burden. In practice, this supports closer monitoring for progression, careful target-pressure setting, and an individualized threshold for escalating treatment.
Second, procedure selection may deserve more subtype-specific thinking. LTP remains a reasonable option in PG, but the elevated failure rate indicates that clinicians should set expectations accordingly and monitor for inadequate response or early recurrence of pressure elevation. The same applies to MIGS. For patients with PG who need durable pressure reduction, especially those with advanced disease, the apparent early failure signal should temper assumptions that MIGS performance in POAG can be directly generalized to PG.
Third, the racial severity findings deserve attention well beyond epidemiology. Because PG is often stereotyped as a disease of White myopic men, clinicians may have a lower index of suspicion in Black, Asian, or Hispanic patients. Under-recognition can delay diagnosis until structural and functional damage is more advanced. This registry analysis supports more deliberate case finding, especially when compatible gonioscopic and iris findings are present.
Fourth, combined cataract-trabeculectomy surgery should be approached thoughtfully in both PG and POAG. The higher failure rate compared with standalone trabeculectomy does not mean combined surgery is inappropriate; cataract burden, patient age, refractive needs, and surgical logistics all matter. But when maximal filtration success is the dominant goal, surgeons may wish to weigh the tradeoff carefully and discuss the risk with patients.
Mechanistic considerations
There is biologic plausibility for the observed differences. In PG, trabecular dysfunction is linked to pigment accumulation, mechanical iris-zonular interactions, and sometimes episodic pigment showers. A procedure that depends on conventional outflow may perform differently in an eye where outflow structures are intermittently obstructed or chronically altered by pigment load. Similarly, postoperative healing responses, angle anatomy, and age-related differences in tissue behavior may vary from typical POAG populations.
For laser therapies, dense trabecular pigmentation can be a double-edged sword: it may improve energy absorption but may also increase the risk of inflammatory response or transient pressure rise. For angle-based MIGS, pigment-related obstruction or ongoing dispersion could theoretically reduce longer-term patency or efficiency, although this remains speculative and requires targeted study.
Strengths and limitations
Strengths
The study’s greatest strength is scale. The IRIS Registry provides a uniquely large real-world cohort, enabling robust comparison between a relatively uncommon glaucoma subtype and the far more prevalent POAG population. The use of time-to-event methods strengthens the evaluation of procedural incidence, and the matched-eye approach for failure analyses improves comparability.
Another strength is clinical relevance. The procedures assessed are common components of modern glaucoma care, and the findings are immediately applicable to everyday decision-making in comprehensive ophthalmology and glaucoma subspecialty practice.
Limitations
As a retrospective registry analysis, the study is inherently limited by coding accuracy, unmeasured confounding, and incomplete capture of clinical nuance. Diagnosis codes may not perfectly distinguish PG from POAG in all cases, particularly when pigment dispersion features are underdocumented.
The abstract does not specify baseline intraocular pressure, medication burden, visual field status beyond stage, lens status, degree of myopia, or detailed procedural subtype information. These variables can strongly influence treatment selection and outcomes. MIGS is especially heterogeneous; combining different MIGS procedures may obscure important differences. Likewise, the exact definition of failure is critical for interpreting the magnitude of risk.
Registry-based studies are also vulnerable to selection bias. Eyes undergoing surgery may differ systematically in ways not fully addressed by matching. Finally, although statistical significance is unsurprising in datasets of this size, clinicians should focus on absolute differences, effect durability, and whether the findings change practice for specific patient subgroups.
Implications for practice and policy
For clinicians, the study supports more proactive surveillance in PG, especially in patients with advanced disease and in racial or ethnic groups that may be diagnosed later. It also argues for more explicit counseling about expected durability after LTP and MIGS.
For health systems and quality programs, the findings suggest that large ophthalmology registries can do more than track volume; they can reveal subtype-specific disparities and real-world effectiveness patterns that are difficult to detect in smaller trials. This is particularly relevant as glaucoma care increasingly incorporates MIGS and other technology-driven interventions.
For researchers, the next step is not simply to repeat these comparisons, but to refine them. Priority questions include whether specific MIGS procedures differ in PG, how lens status modifies outcomes, whether earlier intervention alters the need for filtering surgery, and why severe-stage PG appears more common in some minority groups despite lower overall representation.
Conclusion
This IRIS Registry analysis shows that eyes with pigmentary glaucoma undergo glaucoma procedures more frequently than eyes with primary open-angle glaucoma and are more likely to receive filtering or cyclodestructive interventions. It also suggests that early failure after LTP and MIGS is more common in PG, while combined trabeculectomy-cataract surgery has higher failure than standalone trabeculectomy in both PG and POAG. The study reinforces that PG is a clinically distinct glaucoma subtype requiring tailored monitoring, thoughtful procedure selection, and greater attention to potential disparities in disease severity across racial and ethnic groups.
Funding and trial registration
The abstract provided does not report specific funding information. No ClinicalTrials.gov registration applies to this retrospective registry-based study.
References
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