Sociodemographic and Geographic Variation in Access to Neuro-Ophthalmologists in the United States

Neuro-ophthalmologists have expertise in rare and complex disorders, but the ability of patients to access neuro-ophthalmic care has not been examined at a nation-wide level.

Clinical Research: Epidemiology Meets Neuro-Ophthalmology Section Editors: Heather E. Moss, MD, PhD Stacy L. Pineles, MD Sociodemographic and Geographic Variation in Access to Neuro-Ophthalmologists in the United States Katie Xue, BA, Yilin Feng, MD, Vicky Tam, MA, Chun Chieh Lin, PhD, MBA, Lindsey B. De Lott, MD, MS, Ali G. Hamedani, MD, MHS Background: Neuro-ophthalmologists have expertise in rare and complex disorders, but the ability of patients to access neuro-ophthalmic care has not been examined at a nationwide level. Methods: Using the 2020 directory of all 502 members of the North American Neuro-Ophthalmology Society as a reference, we found the practice locations of 461 confirmed practicing members and converted each street address to latitude and longitude coordinates. We calculated the travel distance and time from each census tract to the nearest practice location and calculated population-weighted averages by state, region, and other prespecified factors. Choropleth maps were used to visualize the distribution of travel distances and times across the United States. Results: California had the most practicing neuroophthalmologists out of any state (50), whereas 4 states (DE, MT, SD, and WY) had none. Washington, DC and MA had the most neuro-ophthalmologists per capita. The average travel distance and time to the nearest neuroophthalmologists were found to be 40.90 miles and 46.50 minutes, respectively, although a large portion of western plains and mountain regions had travel times of over 120 minutes. Patients in rural areas had longer travel times than those in urban areas, and Native American patients had the longest travel times of any racial or ethnic group. Conclusion: The travel time to see a neuro-ophthalmologist varies widely by state, region, and rurality, with Native American patients and rural patients being disproportionDepartments of Neurology and Ophthalmology (KX, AGH), Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Ophthalmology (YF), Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts; Department of Biomedical and Health Informatics (VT), Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania; Department of Neurology (CCL, LBDL), University of Michigan Medical School, Ann Arbor, Michigan; Department of Ophthalmology and Visual Sciences (LBDL), Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan; Leonard Davis Institute for Health Economics (AGH), University of Pennsylvania, Philadelphia, Pennsylvania The authors report no conflicts of interest. Address correspondence to Ali G. Hamedani, MD, MHS, 423 Guardian Drive. Blockley 829, Philadelphia, PA 19104: E-mail: [e-mail] Xue et al: J Neuro-Ophthalmol 2023; 43: 149-152 ately affected. By identifying the areas with the greatest travel burdens, future policies can work to alleviate these potential barriers to care. Journal of Neuro-Ophthalmology 2023;43:149–152 doi: 10.1097/WNO.0000000000001821 © 2023 by North American Neuro-Ophthalmology Society N euro-ophthalmologists specialize in diseases that comprehensive ophthalmologists or neurologists may be uncomfortable diagnosing and managing. Some neuroophthalmic conditions may lead to irreversible vision loss if not promptly diagnosed and treated, and others may be the initial manifestation of a potentially disabling or lifethreatening neurologic or systemic illness. However, studies show that although neuro-ophthalmologic consultation is associated with meaningful changes in diagnosis and management (1–3), it may take months before a patient is able to see a neuro-ophthalmologist, and delays in care have the potential to lead to adverse health outcomes (4). In addition to the limited number of neuro-ophthalmologists in the United States, their concentration within urban academic centers may contribute to prolonged travel times and access limitations. In other ophthalmic subspecialties such as glaucoma, long commutes have been identified as a significant barrier to care (5), and patients living in “service deserts” are more likely to face other socioeconomic disparities such as reduced income and lack of health insurance (6). In neurology, local availability of neurologists is also associated with receipt of neurologic care, but this varies considerably by diagnosis (7). The density and geographic distribution of neuroophthalmologists relative to the general population have not been examined. Given that low provider density and prolonged travel times can impact patient care and neuro-ophthalmologists play an important role in diagnosing and treating specific conditions, it is important to determine which communities have the greatest limitations in access to a neuro149 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Research: Epidemiology Meets Neuro-Ophthalmology ophthalmologist. This study aims to analyze the national distribution of neuro-ophthalmologists in the United States and identify populations that face greater access barriers. METHODS Standard Protocol Approvals, Registrations, and Patient Consents This study did not qualify as human subjects research and was exempt from approval by the University of Pennsylvania Institutional Review Board. Identification of Neuro-Ophthalmologists in the United States We obtained a complete directory of all members of the North American Neuro-Ophthalmology Society (NANOS) on June 1, 2020. A member of the research team (K.X.) performed a Google search of each NANOS member in October 2021 to obtain their current office street addresses. When a neuro-ophthalmologist had multiple practice locations listed, we randomly selected one for analysis. We excluded NANOS members who did not have an active clinical practice (e.g., students, nonclinician researchers, and retirees). Travel Calculations Using the Texas A&M University Geoservices Program, we converted each neuro-ophthalmologist’s street address to latitude and longitude coordinates (8). Next, we calculated travel distance and time to the nearest neuroophthalmologist for each census tract in the United States using the Network Analyst extension in ArcGIS Desktop 106.1 (Environmental Systems Research Institute, Redlands, CA). We used the geographic centroid of each census tract as the starting point and defined the nearest neuro-ophthalmologist as the one with the shortest driving time. Data Visualization and Statistical Analysis We produced choropleth maps to visualize the distribution of travel distances and times across the United States. Using publicly available 2010 US Census data (9), we calculated the number of neuro-ophthalmologists per capita in the United States overall and by state and census division. We also calculated weighted averages of travel distance and time to the nearest neuro-ophthalmologist using census tract population as analytic weights. Our travel distance and time calculations were made at the census tract level, but some census tracts have a higher population than others. A simple arithmetic mean does not consider these differences in population, which may lead to biased national estimates. By weighting the average relative to census tract population, we allow more highly populated census tracts to “count” 150 more in the average then less populated ones, ensuring that the nationwide average is broadly reflective of the general population. For example, if census tract A has a population of 30,000 and a travel time of 30 minutes and census tract B has a population of 5,000 and a travel time of 60 minutes, then a weighted average would be (30,000 · 30 + 5,000 · 60)/35,000 = 34.29 minutes. We calculated weighted averages for the entire US population as well as for prespecified strata according to race and ethnicity. We also compared average travel distance and time and the proportion of individuals who were 60 or more minutes away from the nearest neuro-ophthalmologist for low-income vs non–low-income census tracts and rural vs urban census tracts. Low-income census tracts are defined as census tracts where the poverty rate exceeds 20% or the tract’s median family income is less than or equal to 80% of citywide or statewide median family income. Maps were produced using Maptitude 2021 (Caliper Corporation, Newton, MA), and statistical analyses were performed using STATA/IC 15.1 (College Station, TX). RESULTS Of 502 NANOS members in 2020, 461 were confirmed to be practicing neuro-ophthalmologists and were included in the analysis. There were 50 practicing neuroophthalmologists in California, the most of any US state. There were no practicing NANOS members located in DE, MT, SD, or WY. After Washington, DC, MA had the largest number of neuro-ophthalmologists per capita (3.56 per million inhabitants). Travel calculations were available for 73,414 of 73,642 (99.69%) census tracts in the United States. The average travel distance and time to the nearest neuroophthalmologist in the United States are 40.90 miles and 46.50 minutes, respectively. As shown in Figure 1, most neuro-ophthalmologists are located in major cities along the East coast, Midwest, and West coast, resulting in pockets of shortened travel time within these regions. By contrast, the western plains and mountain regions are characterized prolonged travel times of 120 minutes or longer throughout much of the region. Travel times were longer in rural census tracts (79.78 minutes) than urban ones (36.62 minutes) but similar for low-income (49.68 minutes) and non–lowincome census tracts (44.94 minutes). Travel times were also longer for Native Americans (86.52 minutes) than other racial or ethnic groups (Table 1). CONCLUSIONS In this study, we examined the nationwide distribution and accessibility of neuro-ophthalmologists in the United States. We found that individuals need to travel an average of 40.90 miles and 46.50 minutes to reach the nearest neuroophthalmologist, but this is considerably greater for those in Xue et al: J Neuro-Ophthalmol 2023; 43: 149-152 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Research: Epidemiology Meets Neuro-Ophthalmology TABLE 1. Mean travel distance and time to the nearest neuro-ophthalmologist stratified by demographic and census tract characteristics Low-income census tracts Non–low-income census tracts Urban census tracts Rural census tracts White Black Asian Native American Hispanic Mean Travel Time (Minutes) Mean Travel Distance (Miles) 49.68 44.94 36.62 79.78 50.54 33.29 24.71 86.52 41.93 44.45 39.16 31.40 72.90 44.90 27.91 18.92 80.69 37.18 the western plains and mountain regions, and there are 4 states (DE, MT, SD, and WY) with no practicing neuroophthalmologists. Travel times were even greater for patients in rural areas and for Native Americans, potentially compounding existing health care disparities for these groups (10). Given that previous studies have demonstrated that the local availability of eye care providers is associated with improved patient awareness of disease, screening frequency, and visual outcomes, it is important to recognize and address these barriers to access. To improve access and reduce travel times, the number of neuro-ophthalmologists in the United States would need to increase, particularly in rural and underserved geographic regions. These areas may not have enough patient volume to sustain a purely neuro-ophthalmic practice, so policies that encourage the creation of hybrid comprehensive/neuroophthalmology or mixed specialization practices would be ideal for these areas. As an alternative or addition to neuro- ophthalmology recruitment incentives, the growing use of tele-neuro-ophthalmology services, delivered either directly to patients or through consultation with local ophthalmologists or neurologists, could also improve access and alleviate the burden of lengthy travel times (11–13). Because most neuro-ophthalmologists are concentrated in academic medical centers or large metropolitan areas, our findings also highlight potential limitations in the neuroophthalmology research literature. Specifically, patients who live in areas with few or no neuro-ophthalmologists are likely to be managed by comprehensive ophthalmologists or neurologists rather than neuro-ophthalmologists and are therefore inaccessible to observational or interventional research studies in neuro-ophthalmology. Excluding these communities may limit the generalizability of these research studies. The epidemiology, health care utilization, and outcomes for diseases such as idiopathic intracranial hypertension may also differ across different geographic FIG. 1. Choropleth map of travel time to the nearest neuro-ophthalmologist in the United States. Xue et al: J Neuro-Ophthalmol 2023; 43: 149-152 151 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Research: Epidemiology Meets Neuro-Ophthalmology regions, so research samples from tertiary academic centers may not be generalizable to the entire population. We used geographic proximity as a marker of accessibility to the nearest neuro-ophthalmologist, but it is important to note that this is not a direct measure of health care access, as patients may face prolonged wait times or difficulty establishing care because of insurance issues regardless of travel distance. This is particularly true of minoritized populations and low-income individuals, who had lower estimated travel times because of their concentration within large cities but may nevertheless face considerable access barriers. Furthermore, the NANOS membership directory may not have captured every practicing neuro-ophthalmologist in the United States, and our calculations are unable to incorporate provider volume and appointment availability. In conclusion, neuro-ophthalmologists are unevenly distributed across the United States, with patients in rural areas and Native American patients facing the greatest travel burden. By identifying areas that are underserved with regards to neuro-ophthalmologist availability, efforts can be made to improve access in these areas and better understand the effects of neuro-ophthalmic consultation on research and health outcomes. REFERENCES 1. Fisayo A, Bruce BB, Newman NJ, Biousse V. Overdiagnosis of idiopathic intracranial hypertension. Neurology. 2016;86:341– 350. 152 2. Kahraman-Koytak P, Bruce BB, Peragallo JH, Newman NJ, Biousse V. Diagnostic errors in initial misdiagnosis of optic nerve sheath meningiomas. JAMA Neurol. 2019;76:326–332. 3. Stunkel L, Kung NH, Wilson B, McClelland CM, Van Stavern GP. Incidence and causes of overdiagnosis of optic neuritis. JAMA Ophthalmol. 2018;136:76–81. 4. Stunkel L, Mackay DD, Bruce BB, Newman NJ, Biousse V. Referral patterns in neuro-ophthalmology. J Neuroophthalmol. 2020;40:485–493. 5. Rothman AL, Stoler JB, Vu DM, Chang TC. A geodemographic service coverage analysis of travel time to glaucoma specialists in Florida. J Glaucoma. 2020;29:1147–1151. 6. Vu DM, Stoler J, Rothman AL, Chang TC. A service coverage analysis of primary congenital glaucoma care across the United States. Am J Ophthalmol. 2021;224:112–119. 7. Lin CC, Callaghan BC, Burke JF, Skolarus LE, Hill CE, Magliocco B, Esper GJ, Kerber KA. Geographic variation in neurologist density and neurologic care in the United States. Neurology. 2021;96:e309–e321. 8. Texas A&M University. TAMU GeoServices. Available from: https://geoservices.tamu.edu/. Accessed February 22, 2022. 9. U.S Census Bureau. QuickFacts. Available from: https://www. census.gov/quickfacts/fact/table/US/PST045218. Accessed September 30, 2020. 10. Woodward MA, Hughes K, Ballouz D, Hirth RA, Errickson J, Newman-Casey PA. Assessing eye health and eye care needs among North American native individuals. JAMA Ophthalmol. 2022;140:134–142. 11. Ko MW, Busis NA. Tele-neuro-ophthalmology: vision for 20/20 and beyond. J Neuroophthalmol. 2020;40:378–384. 12. Lai KE, Ko MW, Rucker JC, Odel JG, Sun LD, Winges KM, Ghosh A, Bindiganavile SH, Bhat N, Wendt SP, Scharf JM, Dinkin MJ, Rasool N, Galetta SL, Lee AG. Tele-neuro-ophthalmology during the age of COVID-19. J Neuroophthalmol. 2020;40:292–304. 13. Moss HE, Lai KE, Ko MW. Tele-neuro-ophthalmology utilization, availability, and attitudes: update 1 year into the COVID-19 public health emergency. J Neuroophthalmol. 2022. (epub ahead of print). Xue et al: J Neuro-Ophthalmol 2023; 43: 149-152 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.