Geographic Distribution of Access to Glaucoma Surgery: An IRIS® Registry (Intelligent Research in Sight) Analysis

We evaluated access to glaucoma surgical care by quantifying the geographic distribution of glaucoma surgeries across the United States.

Retrospective cohort study.

Using the IRIS® Registry (Intelligent Research in Sight), we extracted patient information associated with all glaucoma procedures from January 1, 2013, to December 31, 2019.

Descriptive statistics were used to evaluate physician, patient travel, and practice patterns. The US Department of Agriculture's Rural-Urban Commuting Area Codes were used to define urban and nonurban zip codes. Multivariate logistic regression analyses were performed to determine which types of glaucoma surgeries were more likely to occur in urban areas. According to US Postal Service definitions, districts were defined as aggregates of zip codes sharing the same first 3 digits; regions shared the same initial digit.

The primary outcomes were the likelihood of each procedure type occurring in urban areas. The secondary outcomes were procedure characteristics (e.g., type, location) and the proportion of procedures requiring inter-region or inter-district travel.

The most performed glaucoma procedures were trabecular microbypass (iStent and Hydrus) (207 451 cases, 39%) and trabeculectomy (115 302 cases, 22%). Urban practice locations accounted for most surgeries (91%), with 96% of glaucoma subspecialists and 88% of nonglaucoma ophthalmologists performing surgeries exclusively in urban areas. Among 281 271 surgeries requiring inter-district travel (47%), most were performed in urban, rather than nonurban, practices (93%). A smaller subset of 42 667 surgeries involved inter-region travel (8% across all procedure types). Trabeculectomy (11%) and glaucoma drainage device (GDD) implantation (10%) were the procedures with their highest proportion of cases involving inter-region travel. We found higher odds of nearly all types of glaucoma surgeries occurring in urban practice locations: goniotomy/canaloplasty (odds ratio [OR], 1.66; confidence interval [CI], 1.59-1.74), XEN ab interno (OR, 1.54; CI, 1.38-1.72), endocyclophotocoagulation (OR, 1.46; CI, 1.39-1.53), GDD (OR, 1.70; CI, 1.62-1.77), and trabeculectomy (OR, 1.24; CI, 1.17-1.32). Only trabecular microbypass was less likely to be performed in urban areas (OR, 0.49; CI, 0.47-0.51).

Patients are more likely to receive most types of glaucoma surgeries in urban practice locations. Trabeculectomy or GDD implantation involved inter-regional travel in approximately 10% of cases.

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