Geographic Distribution of Access to Glaucoma Surgery: An IRIS® Registry Analysis.

Abstract

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

Design: Retrospective cohort study PARTICIPANTS: 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.

Methods: Descriptive statistics were employed to evaluate physician, patient travel, and practice patterns. The United States Department of Agriculture's Rural-Urban Commuting Area Codes were utilized to define urban and non-urban 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 United States Postal Service definitions, districts were defined as aggregates of zip codes sharing the same first three digits; regions shared the same initial digit.

Main outcome measures: 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.

Results: The most performed glaucoma procedures were trabecular microbypass (iStent and Hydrus) (207,451 cases, 34%) and trabeculectomy (64,931 cases, 23%). Urban practice locations accounted for most surgeries (91%), with 96% of glaucoma subspecialists and 88% of non-glaucoma ophthalmologists performing surgeries exclusively in urban areas. Among 281,271 surgeries requiring inter-district travel (47%), most were performed in urban, rather than non-urban, 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 (OR=1.66, 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).

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