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. Author manuscript; available in PMC: 2025 May 1.
Published in final edited form as: Am J Ophthalmol. 2024 Jan 11;261:66–75. doi: 10.1016/j.ajo.2024.01.003

Practice Patterns and Sociodemographic Disparities in the Clinical Care of Anatomical Narrow Angles in the United States

Kristy Yoo 1, Galo Apolo 2, Khristina Lung 3, Brian Toy 2, Benjamin Xu 2
PMCID: PMC11031323  NIHMSID: NIHMS1960006  PMID: 38218513

Abstract

Purpose:

To assess treatment and visit patterns among patients with newly diagnosed anatomical narrow angle (ANA) and identify sociodemographic factors associated with disparities in care.

Design:

Retrospective practice pattern evaluation study.

Methods:

263,422 patients diagnosed with ANA between 2007 to 2019 were identified in the Optum Clinformatics® Data Mart. Inclusion was limited to newly diagnosed ANA, defined as: 1) continuous enrollment during a 2-year lookback period and 1-year study period from first diagnosis, (2) diagnosis by an ophthalmologist or optometrist, (3) no history of pseudophakia, ANA treatments, or prior PACG diagnosis. Outcome measures were treatment with laser peripheral iridotomy (LPI), cataract surgery, or IOP-lowering medications and number of eyecare visits. Logistic and Poisson regression were performed to assess factors associated with treatment and eyecare visits, respectively.

Results:

Among 52,405 eligible cases, 27.7% received LPI, 13.9% received drops, and 15.1% received cataract surgery. Odds of LPI was higher in Asians and Hispanics (OR≥1.16, p<0.001). Non-whites had higher odds of drops (OR≥1.19, p<0.001), but Hispanics had lower odds of cataract surgery (OR=0.79, p<0.001). The mean number of eyecare visits was 2.6±2.1 visits including the day of diagnosis. Older age and treatment were associated with higher rates of eye care visits (RR>1.15, p<0.001).

Conclusion:

More than a quarter of patients with newly diagnosed ANA receive treatment with LPI. Racial minorities are more likely to receive ANA-specific treatments but less likely to receive cataract surgery. These differences may reflect racial differences in disease severity and the need for clearer practice guidelines in ANA care.

Graphical Abstract

This retrospective study assessed 1-year treatment and eyecare visit patterns among patients with newly diagnosed anatomical narrow angles (ANA) using healthcare claims data from 2007 to 2019. Laser peripheral iridotomy (LPI) was utilized in over one-quarter of patients. Non-White patients were more likely to receive LPI and glaucoma drops whereas non-Hispanic White patients were more likely to receive cataract surgery. These findings help identify gaps in knowledge about practice guidelines in ANA care.

Introduction

Primary angle closure glaucoma (PACG) is a leading cause of irreversible vision loss worldwide, currently affecting an estimated 20 million people.1 The prevalence of PACG is projected to rise rapidly over the next two decades due to aging of the world’s population. Any rise in PACG prevalence is problematic as PACG is already responsible for half of glaucoma-related blindness globally despite being only half as common as primary open angle glaucoma (POAG).2,3 Anatomical narrow angle (ANA), a broad term used by practicing clinicians for angle closure prior to development of glaucoma, is the primary risk factor for PACG, in which crowding of the iridocorneal angle can lead to impaired aqueous outflow and elevated intraocular pressure (IOP).4 ANA includes but is not exclusive to cases of primary angle closure suspect (PACS) and primary angle closure (PAC), which together greatly outnumber cases of PACG.5,6 Treatments for ANA include laser peripheral iridotomy (LPI) and cataract surgery, which can alleviate angle crowding and lower IOP and risk of glaucomatous optic neuropathy.7–9 While it is well-established that these treatments modify risk of conversion from ANA to PACG, there is sparse knowledge about real-world treatment patterns among the large number of patients with ANA.9,10

Recent studies have identified consistent disparities in glaucoma care among patients in the United States (US) based on race, insurance, and other socioeconomic factors.11–13 Studies of Black Medicare beneficiaries found higher rates of glaucoma surgery compared to Whites, but after adjusting for race-specific disease prevalence, Blacks actually received glaucoma surgery around 50% below the expected rate.12–14 Disparities in the detection of ANA have also been identified; Blacks are less likely to receive gonioscopy and more likely to be diagnosed with PACG without a prior diagnosis of ANA.11,15 Halawa et al. reported that among Medicare beneficiaries with any subtype of glaucoma, Hispanics and Blacks had fewer outpatient visits but more acute care visits in inpatient and emergency healthcare settings compared to non-Hispanic Whites.12 These findings are concerning and highlight a need for additional insight into current practice patterns among providers caring for patients with ANA.

In this study, we use data from a national healthcare claims database to assess practice patterns and sociodemographic disparities among patients in the US with ANA identified through billing codes. While landmark studies like the EAGLE and ZAP trials recommend dramatic changes in the way angle closure eyes are managed, there is sparse information about current real-world practice patterns.7,9 There is also limited information about disparities in ANA care that could elucidate weaknesses in the general approach to managing this condition. We believe that assessing and interpreting current practice patterns in the context of established disparities in PACG detection and outcomes could provide further insights on how to address their underlying root cause and help standardize the quality of ANA care.

Methods, Intervention, or Testing

The present study is a retrospective practice patterns evaluation study. Optum’s Clinformatics® De-identified Data Mart (CDM) is derived from a de-identified administrative health claims data warehouse of commercial and Medicare Advantage health claims. The database includes approximately 17 to 19 million annual covered lives, for a total of over 65 million unique lives over a 13-year period (1/2007 through 12/2019). Available sociodemographic data included sex, race/ethnicity, education level, income, net worth, insurance product, and census division regions. Available clinical data includes dates of ANA diagnosis, dates of all visits, healthcare provider type, IOP-lowering medications, in-office procedures including gonioscopy and LPI, surgeries including cataract and glaucoma surgery, and first/last date of enrollment in Optum. The University of Southern California Institutional Review Board exempted this study from IRB approval. The study adhered to the tenets of the Declaration of Helsinki and complied with the Health Insurance Portability and Accountability Act.

Study Definitions

Inclusion in the study population required an index diagnosis of ANA based on International Classification of Diseases Ninth Revision (ICD-9) or Tenth Revision (ICD-10) codes and code labels (Supplementary Table 1). The index date of diagnosis was defined as the date of the first claim associated with an ANA diagnosis. Inclusion also required a 3-year (36-month) period of continuous enrollment in Optum, comprised of a 2-year (24-month) lookback period before the index date and a 1-year (12-month) study period after the index date.

Newly diagnosed ANA cases met the following criteria: (1) continuous enrollment during the lookback and study periods, (2) ANA diagnosis provided by an ophthalmologist or optometrist, (3) no history of pseudophakia, IOP-lowering medications, laser treatments, cataract or glaucoma surgery before the index date based on CPT codes (Supplementary Table 1), and (4) no PACG diagnosis prior to or concurrent with the index date of ANA diagnosis. Criterion 2 was implemented to increase the fidelity of ANA diagnoses. Criterion 3 was implemented to ensure patients who received conventional ANA or PACG treatments prior to the index date would not be designated as newly diagnosed ANA. Criterion 4 was implemented as presence of PACG could influence treatment patterns. The primary study outcomes were ANA treatment with LPI, cataract surgery, or IOP-lowering drops within one year after index diagnosis of ANA based on CPT and AHFS classification codes. A secondary outcome was number of visits with eye care providers within the 1-year study period, including the index date of diagnosis. IOP-lowering drops include alpha agonists, beta blockers, carbonic anhydrase inhibitors, miotics, prostaglandin analogs, and miscellaneous antiglaucoma agents (Supplementary Table 1). Treatments initiated or visits occurring after the 1-year window were not considered. Patients with multiple treatments within one year were represented in all applicable treatment categories without special consideration. By nature of healthcare claims data, clinical factors, including gonioscopy findings and IOP measurements, needed to conform patients to strict epidemiological definitions of primary angle closure disease (PACD) were not available for analysis.

Statistical Analysis

The proportion of ANA with treatment within one year was calculated and stratified by sex, age, race/ethnicity, and insurance product type. The proportion of the total cohort and each treatment group was also stratified by number of eyecare visits. Analyses were conducted on the patient level rather than eye level due to lack of laterality data in ICD-9. Continuous data were expressed as means and standard deviations while categorical data were expressed as proportions and percentages. Correlation between treatments was assessed by Kendall correlation coefficients. Univariable logistic regression models were developed with sociodemographic and treatment variables to determine odds ratios (OR) for treatment of ANA. A multivariable logistic regression model was developed using variables significant at p < 0.15 in univariable analysis. Age, sex, and race/ethnicity were included in the multivariable model regardless of significance. The same variables were then used in a univariable and multivariable Poisson regression to determine rate ratios (RR) of eyecare visits. From the multivariable models, clinically and statistically significant variables were defined as having an OR or RR greater than 1.15 or less than 0.85 and a p-value < 0.05. Sensitivity analyses to assess the durability of the primary findings was performed by repeating logistic regression analyses using data from the subset of patients with record of gonioscopy before or on the date of ANA diagnosis based on CPT codes. Statistical analysis was completed with R version 4.2.1.

Results

A total of 263,422 patients diagnosed with ANA were identified in the Optum database (Supplemental Figure 1), and 52,405 (19.9%) patients met the eligibility criteria for newly diagnosed ANA (Figure 1). The mean ± standard deviation age of study patients at index date was 66.4 ± 12.2 years. There were 34,084 (65.0%) females and 18,309 (34.9%) males, and there were 22,262 (42.5%) with commercial insurance and 30,143 (57.5%) with Medicare insurance.

Figure 1.

Figure 1.

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Attrition diagram of eligible patients with newly-diagnosed anatomical narrow angle (ANA).

Within the 1-year period after index diagnosis of ANA, 23,575 (45.0%) patients received some form of treatment. Among these patients, 14,526 (27.7%) received LPI, 7,302 (13.9%) received IOP-lowering drops, and 7,916 (15.1%) received cataract surgery (Table 1). Asians and Hispanics had higher rates of LPI (31.0% and 30.2%, respectively) compared to Whites and Blacks (27.3% and 25.1%, respectively) (Table 2). Asians, Hispanics, and Blacks received IOP-lowering drops at a higher rate (>15.4%) compared to Whites (12.5%), but Whites and Blacks received cataract surgery at a higher rate (>15.3%) compared to Asians and Hispanics (<13.7%). Correlation between all 3 treatments was low (r = −0.01 to 0.14).

Table 1.

Proportion of anatomical narrow angle (ANA) cases receiving treatment within 1 year stratified by age and sex.

Age Range Male Female Overall
N n % N n % N n %
LPI <40 430 48 11.2% 830 143 17.2% 1260 191 15.2%
40–49 1269 251 19.8% 2721 724 26.6% 3990 975 24.4%
50–59 2812 747 26.6% 5904 1792 30.4% 8717 2539 29.1%
60–69 4532 1301 28.7% 8960 2796 31.2% 13498 4099 30.4%
70–79 6719 1930 28.7% 11555 3176 27.5% 18279 5108 27.9%
80+ 2547 669 26.3% 4114 945 23.0% 6661 1614 24.2%
Overall 18309 4946 27.0% 34084 9576 28.1% 52405 14526 27.7%
IOP-lowering Drops <40 430 20 4.7% 830 38 4.6% 1260 58 4.6%
40–49 1269 111 8.7% 2721 168 6.2% 3990 279 7.0%
50–59 2812 313 11.1% 5904 541 9.2% 8717 854 9.8%
60–69 4532 724 16.0% 8960 1112 12.4% 13498 1837 13.6%
70–79 6719 1186 17.7% 11555 1781 15.4% 18279 2967 16.2%
80+ 2547 505 19.8% 4114 802 19.5% 6661 1307 19.6%
Overall 18309 2859 15.6% 34084 4442 13.0% 52405 7302 13.9%
Cataract Surgery <40 430 2 0.5% 830 5 0.6% 1260 7 0.6%
40–49 1269 16 1.3% 2721 24 0.9% 3990 40 1.0%
50–59 2812 121 4.3% 5904 197 3.3% 8717 318 3.6%
60–69 4532 452 10.0% 8960 1050 11.7% 13498 1504 11.1%
70–79 6719 1387 20.6% 11555 2679 23.2% 18279 4068 22.3%
80+ 2547 775 30.4% 4114 1204 29.3% 6661 1979 29.7%
Overall 18309 2753 15.0% 34084 5159 15.1% 52405 7916 15.1%
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Abbreviations: N = Newly-diagnosed anatomical narrow angle; n = number receiving treatment.

Table 2.

Proportion of anatomical narrow angle (ANA) cases receiving treatment within 1 year stratified by age and race.

Age Range Asian Black Hispanic White
N n % N n % N n % N n %
LPI <40 136 11 8.1% 139 16 11.5% 186 36 19.4% 743 121 16.3%
40–49 434 110 25.3% 328 64 19.5% 579 150 25.9% 2458 602 24.5%
50–59 556 153 27.5% 734 189 25.7% 1129 355 31.4% 5873 1729 29.4%
60–69 808 291 36.0% 1239 355 28.7% 1629 533 32.7% 8757 2587 29.5%
70–79 1324 444 33.5% 1587 404 25.5% 2410 741 30.7% 11331 3073 27.1%
80+ 413 127 30.8% 639 145 22.7% 756 205 27.1% 4416 1045 23.7%
Overall 3671 1136 30.9% 4666 1173 25.1% 6689 2020 30.2% 33578 9157 27.3%
IOP-lowering Drops <40 136 8 5.9% 139 2 1.4% 186 3 1.6% 743 43 5.8%
40–49 434 39 9.0% 328 32 9.8% 579 39 6.7% 2458 156 6.3%
50–59 556 57 10.3% 734 121 16.5% 1129 116 10.3% 5873 522 8.9%
60–69 808 139 17.2% 1239 256 20.7% 1629 228 14.0% 8757 1057 12.1%
70–79 1324 269 20.3% 1587 396 25.0% 2410 459 19.0% 11331 1603 14.1%
80+ 413 84 20.3% 639 169 26.4% 756 186 24.6% 4416 808 18.3%
Overall 3671 596 16.2% 4666 976 20.9% 6689 1031 15.4% 33578 4189 12.5%
Cataract Surgery <40 136 0 0.0% 139 1 0.7% 186 0 0.0% 743 5 0.7%
40–49 434 3 0.7% 328 4 1.2% 579 5 0.9% 2458 26 1.1%
50–59 556 17 3.1% 734 40 5.4% 1129 40 3.5% 5873 208 3.5%
60–69 808 72 8.9% 1239 140 11.3% 1629 191 11.7% 8757 961 11.0%
70–79 1324 279 21.1% 1587 367 23.1% 2410 473 19.6% 11331 2586 22.8%
80+ 413 108 26.2% 639 190 29.7% 756 209 27.6% 4416 1349 30.5%
Overall 3671 479 13.0% 4666 742 15.9% 6689 918 13.7% 33578 5135 15.3%
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Abbreviations: N = Newly-diagnosed anatomical narrow angle; n = number receiving treatment.

All variables were included in the multivariable logistic regression model as every variable had at least one level that was significant at p < 0.05 (Table 3). On multivariable analysis, treatment with LPI was associated with Asian and Hispanic race (OR ≥ 1.16; p < 0.001), residence outside the Northeast (OR ≥ 1.23; p < 0.001), record of gonioscopy (OR = 1.84; p < 0.001), and Medicare preferred provider organization (PPO) (OR = 1.29, p = 0.03). Age under 40 years had lower odds of LPI (OR = 0.57; p < 0.001) while age 50–79 had higher odds of LPI (OR ≥ 1.21; p < 0.001). Treatment with IOP-lowering drops was associated with male sex (OR = 1.25; p < 0.001), older age (OR ≥ 1.44; p < 0.001), non-White race (OR ≥ 1.19; p < 0.001), residence outside the Northeast and Midwest (OR > 1.32; p < 0.001), and gonioscopy (OR = 1.46; p < 0.001). Odds of receiving cataract surgery increased with each decade of life, and those aged over 80 years had the highest odds by far (OR = 29.91; p < 0.001). Residence outside the Northeast and gonioscopy (OR > 1.16; p ≤ 0.003) were associated with increased odds of cataract surgery while Hispanic ethnicity, college graduation, and annual income above $100,000 were associated with decreased odds of cataract surgery (OR ≤ 0.83, p < 0.001). Medicare insurance was associated with cataract surgery (OR > 1.54; p < 0.001), and this pattern persisted when applied to subset of patients over age 65 (OR ≥ 1.32, p ≤ 0.05). Education did not exhibit any durable effects on any treatment.

Table 3.

Univariable and multivariable logistic regression analysis of factors associated with receiving treatment within one year.

LPI IOP-lowering Drops Cataract Surgery
Univariable Analysis Multivariable Analysis Univariable Analysis Multivariable Analysis Univariable Analysis Multivariable Analysis
P value OR (95% CI) P value P value OR (95% CI) P value P value OR (95% CI) P value
Sex
 Female REF REF REF REF REF REF
 Male 0.008 0.94 (0.90–0.98) 0.008 <0.001 1.25 (1.18–1.32) <0.001 0.761 0.96 (0.90–1.01) 0.139
Age
 <40 <0.001 0.57 (0.47–0.69) <0.001 0.003 0.60 (0.43–0.83) 0.003 0.148 0.60 (0.23–1.33) 0.250
 40–49 REF REF REF REF REF REF
 50–59 <0.001 1.29 (1.17–1.42) <0.001 <0.001 1.44 (1.24–1.69) <0.001 <0.001 3.53 (2.50–5.14) <0.001
 60–69 <0.001 1.35 (1.23–1.48) <0.001 <0.001 2.03 (1.75–2.35) <0.001 <0.001 9.46 (6.81–13.62) <0.001
 70–79 <0.001 1.21 (1.09–1.34) <0.001 <0.001 2.60 (2.23–3.05) <0.001 <0.001 18.83 (13.51–27.17) <0.001
 80+ 0.811 1.08 (0.97–1.22) 0.170 <0.001 3.47 (2.95–4.11) <0.001 <0.001 29.91 (21.40–43.28) <0.001
Race
 Asian <0.001 1.38 (1.27–1.50) <0.001 <0.001 1.54 (1.39–1.71) <0.001 <0.001 0.92 (0.82–1.03) 0.142
 White REF REF REF REF REF REF
 Black 0.002 0.88 (0.81–0.95) 0.002 <0.001 1.71 (1.57–1.87) <0.001 0.279 0.87 (0.79–0.96) 0.005
 Hispanic <0.001 1.16 (1.09–1.24) <0.001 <0.001 1.19 (1.10–1.30) <0.001 <0.001 0.79 (0.72–0.86) <0.001
Education
 High school or less REF REF REF REF REF REF
 Some college 0.258 1.02 (0.97–1.08) 0.484 <0.001 0.90 (0.84–0.96) 0.002 <0.001 0.90 (0.84–0.97) 0.003
 College graduate <0.001 0.86 (0.80–0.93) <0.001 <0.001 0.89 (0.80–0.98) 0.014 <0.001 0.83 (0.75–0.92) <0.001
Income
 <$40K REF REF REF REF REF REF
 $40K-49K 0.237 1.07 (0.98–1.17) 0.131 0.552 1.07 (0.96–1.20) 0.196 0.371 1.03 (0.92–1.14) 0.611
 $50K-59K 0.104 1.06 (0.98–1.16) 0.163 0.240 0.97 (0.87–1.08) 0.604 <0.001 0.88 (0.79–0.97) 0.013
 $60K-74K 0.438 1.03 (0.95–1.11) 0.521 <0.001 0.90 (0.81–0.99) 0.028 <0.001 0.86 (0.78–0.94) <0.001
 $75K-99K 0.004 1.11 (1.03–1.19) 0.005 <0.001 0.91 (0.83–1.00) 0.043 <0.001 0.89 (0.81–0.97) 0.007
 $100K+ 0.009 0.99 (0.93–1.06) 0.845 <0.001 0.85 (0.77–0.93) <0.001 <0.001 0.74 (0.68–0.81) <0.001
Location
 Northeast REF REF REF REF REF REF
 South <0.001 1.30 (1.23–1.38) <0.001 <0.001 1.45 (1.34–1.56) <0.001 <0.001 1.42 (1.32–1.53) <0.001
 Midwest <0.001 1.49 (1.39–1.59) <0.001 0.403 1.11 (1.01–1.21) 0.025 <0.001 1.38 (1.27–1.50) <0.001
 Mountain <0.001 1.73 (1.56–1.92) <0.001 <0.001 1.93 (1.69–2.20) <0.001 <0.001 1.35 (1.18–1.55) <0.001
 Pacific <0.001 1.23 (1.12–1.34) <0.001 <0.001 1.32 (1.18–1.48) <0.001 <0.001 1.19 (1.06–1.34) 0.003
Gonioscopy
 No REF REF REF REF REF REF
 Yes <0.001 1.84 (1.76–1.93) <0.001 <0.001 1.46 (1.37–1.55) <0.001 <0.001 1.16 (1.09–1.22) <0.001
Insurance
 COM HMO/EPO REF REF REF REF REF REF
 COM Other 0.130 0.97 (0.89–1.05) 0.430 0.078 1.01 (0.90–1.13) 0.895 0.038 1.14 (0.97–1.34) 0.111
 COM PPO 0.013 0.89 (0.74–1.07) 0.233 0.483 1.10 (0.86–1.39) 0.450 <0.001 1.24 (0.91–1.66) 0.166
 MCR HMO/EPO 0.300 1.04 (0.94–1.16) 0.411 <0.001 0.93 (0.81–1.07) 0.291 <0.001 1.56 (1.32–1.85) <0.001
 MCR Other <0.001 0.90 (0.82–0.99) 0.029 <0.001 0.92 (0.81–1.05) 0.219 <0.001 1.56 (1.33–1.84) <0.001
 MCR PPO 0.042 1.20 (1.07–1.35) 0.002 <0.001 1.03 (0.88–1.20) 0.722 <0.001 1.54 (1.29–1.85) <0.001
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Statistically significant p-values and odds ratios are bolded.

Abbreviations: OR = odds ratio; CI = confidence interval; REF = reference group; COM = commercial health insurance; MCR = Medicare health insurance; HMO = health maintenance organization; EPO = exclusive provider organization; PPO = preferred provider organization.

A total of 32,533 (62.1%) patients with record of gonioscopy were included in the sensitivity analyses. Results were similar to the primary findings except for the following: odds of LPI among Hispanics compared to non-Hispanic Whites no longer met the cutoff for clinical significance (OR = 1.11, p = 0.009), and highly educated patients now had significantly lower odds of IOP-lowering drops (OR = 0.85, p = 0.007). Cataract surgery analysis expanded on the primary findings with all non-Whites, instead of only Hispanics, having lower odds of cataract surgery (OR ≤ 0.85, p ≤ 0.007) and more levels of higher income having lower odds of cataract surgery (OR ≤ 0.84, p = 0.004).

Overall, patients had 2.6 ± 2.1 visits with an eyecare provider within one year of diagnosis, including any visit on the day of diagnosis (Supplementary Table 2). 35.2% of patients received only one office visit, comprising 14.5% of those treated with LPI, IOP-lowering drops, or cataract surgery and 52.2% of those untreated within one year. In the multivariable Poisson regression analysis of eye care visits (Table 4), older age (RR ≥ 1.15, p < 0.001) and treatment by LPI (RR = 1.38, p < 0.001), IOP-lowering drops (RR = 1.73, p < 0.001), or cataract surgery (RR = 1.41, p < 0.001) were associated with increased rate of eyecare visits. Sex, race, education, income, location, gonioscopy, and insurance type were not associated with number of eyecare visits.

Table 4.

Univariable and multivariable Poisson regression analysis of factors associated with eyecare visits within 1 year.

Univariable Analysis Multivariable Analysis
P value RR (95% CI) P value
Sex
 Female REF REF
 Male 0.452 0.98 (0.96–0.99) < 0.001
Age
 <40 0.003 0.99 (0.95–1.05) 0.816
 40–49 REF REF
 50–59 <0.001 1.06 (1.03–1.09) < 0.001
 60–69 <0.001 1.13 (1.10–1.16) < 0.001
 70–79 <0.001 1.15 (1.12–1.19) < 0.001
 80+ <0.001 1.19 (1.15–1.23) < 0.001
Race
 Asian 0.003 0.98 (0.96–1.00) 0.068
 White REF REF
 Black <0.001 1.03 (1.00–1.05) 0.019
 Hispanic 0.005 1.01 (0.99–1.03) 0.413
Education
 High school or less REF REF
 Some college 0.018 1.01 (1.00–1.03) 0.149
 College graduate <0.001 1.04 (1.01–1.06) 0.001
Income
 <$40K REF REF
 $40K-49K 0.758 1.00 (0.97–1.02) 0.912
 $50K-59K 0.493 1.02 (1.00–1.04) 0.118
 $60K-74K 0.033 1.01 (0.99–1.04) 0.212
 $75K-99K 0.036 1.03 (1.01–1.05) 0.013
 $100K+ <0.001 1.03 (1.01–1.05) 0.001
Location
 Northeast REF REF
 South 0.244 0.98 (0.96–1.00) 0.012
 Midwest <0.001 0.94 (0.92–0.95) < 0.001
 Mountain 0.976 0.95 (0.93–0.98) 0.002
 Pacific 0.760 1.00 (0.98–1.03) 0.685
Gonioscopy
 No REF REF
 Yes <0.001 1.01 (1.00–1.02) 0.240
Insurance
 COM HMO/EPO REF REF
 COM Other 0.068 0.99 (0.97–1.01) 0.371
 COM PPO 0.360 0.95 (0.91–1.00) 0.077
 MCR HMO/EPO <0.001 0.93 (0.90–0.95) < 0.001
 MCR Other <0.001 0.98 (0.96–1.01) 0.230
 MCR PPO <0.001 1.02 (0.99–1.06) 0.191
LPI Treatment
 No REF REF
 Yes <0.001 1.38 (1.37–1.40) < 0.001
IOP-lowering Drops
 No REF REF
 Yes <0.001 1.73 (1.71–1.76) < 0.001
Cataract Surgery Treatment
 No REF REF
 Yes <0.001 1.41 (1.39–1.43) < 0.001
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Statistically significant p-values and odds ratios are bolded.

Abbreviations: RR = rate ratio; CI = confidence interval; REF = reference group; COM = commercial health insurance; MCR = Medicare health insurance; HMO = health maintenance organization; EPO = exclusive provider organization; PPO = preferred provider organization.

Discussion

In this study, we used healthcare claims data to assess the rates of treatment with LPI, IOP-lowering drops, and cataract surgery within one year of ANA diagnosis. Overall, 27.8 % of patients received LPI, 13.9% of patients received IOP-lowering drops, and 15.1% of patients received cataract surgery. Although there were racial differences in ANA treatment patterns, with Asians and Hispanics receiving significantly more LPI and drops and non-Hispanic Whites receiving significantly more cataract surgery, adjusted visit utilization in multivariable models was similar between races. These findings suggest that treatment type differs by race and ethnicity and racial minorities with ANA are more likely to receive ANA-specific treatments like LPI and IOP-lowering drops, possibly due to higher severity of angle closure.

Over a quarter of newly diagnosed ANA cases in our study cohort received LPI in at least one eye, which appears quite high in the context of previous practice guidelines and recent landmark studies advocating for fewer LPIs in angle closure eyes.9,16,17 The World Glaucoma Association (WGA) and American Academy of Ophthalmology (AAO) both recommend that eyes with primary angle closure (PAC), along with PACG, should receive LPI treatment due to its angle widening and IOP lowering effects.16,18 While we are unable to calculate the exact ratio of PAC to primary angle closure suspects (PACS) due to a lack of clinical data in the Optum database, it seems reasonable to assume that the majority of our study cohort had PACS or even milder angle closure based on proportions from epidemiological studies.19,20 Given this assumption, the proportion of ANA patients receiving LPI appears quite high based on concerns raised by the WGA in 2006 and AAO in 2016 within the time period from which our study data were derived regarding the lack of evidence supporting LPI in mild cases of angle closure.16 The high LPI rate is also concerning in the context of the EAGLE and ZAP trials, two landmark studies on angle closure promoting earlier lens extraction over LPI in some PAC eyes or fewer LPIs overall in PACS eyes, respectively.7,9 However, as these studies were published in 2016 and 2019, respectively, it is unlikely that their influence would be directly observable in our dataset, which spanned from 2007 to 2019. Nevertheless, LPI rates among ANA patients were higher than expected given WGA and AAO guidelines at the time.

Our study reveals clear racial disparities in ANA treatment patterns. Asians, Blacks, and Hispanics all receive IOP-lowering drops at a significantly higher rate than non-Hispanic Whites, and Asians and Hispanics are more likely to receive LPI than non-Hispanic Whites. Racial minorities in the United States appear to receive more ANA-specific treatments compared to non-Hispanic Whites, which supports previous findings that they also experience more severe angle closure disease. Blacks and Hispanics with PACG are at higher risk of blindness, more likely to need glaucoma surgery at initial diagnosis, and more likely to need additional treatment after LPI compared to non-Hispanic Whites.12,21–23 Possible sources for this disparity in disease severity are systemic (e.g. cost-related barriers to medication adherence and utilization of eye care services),22,24 patient-level (e.g. mistrust of medical institutions leading to higher rates of loss to follow up),25,26 and provider-level (e.g. latent biases leading to higher rates of glaucoma testing and surgical treatment).27 The higher rates of LPI and IOP-lowering drops among racial minorities may also be related to unseen differences in ocular biometrics or other clinical factors that influence disease detection and management.11 The need to speculate broadly regarding our findings highlights the lack of knowledge about racial differences in anterior segment anatomy and angle closure pathogenesis that could explain observed differences in treatment patterns.

Non-Hispanic Whites in our study had the highest rate of cataract surgery despite having the lowest rates of IOP-lowering drops and LPI, which at first appears contradictory to speculation regarding racial differences in angle closure severity. Cataract surgery, while a potent treatment for angle closure, is more commonly performed for visually significant cataract than ANA.28 However, the benefit of lens extraction in angle closure eyes had been promoted in statements by the WGA in 2006 and AAO in 2016.7,16 Prior studies have reported racial differences in cataract prevalence in the United States, with non-Hispanic Whites having a higher prevalence compared to Blacks and Hispanics.29–31 One study reported that the cataract surgery rate among older Black Medicare beneficiaries was 30% lower than their non-Hispanic White counterparts.32,33 Our finding that racial minorities receive less cataract surgery than non-Hispanic Whites but more treatments specific to ANA suggests that angle status was unlikely to have been the primary determinant of who received cataract surgery.12

The oldest age group (>80 years) was associated with lower odds of LPI compared to age groups 50 to 79 years, which initially appears concerning given the importance of older age as a risk factor for incident and prevalent PACG.10,22 However, age >80 years was also strongly positively associated with cataract surgery, which likely helps offset its negative association with LPI from an ANA treatment perspective. Female sex, higher income, location in the Northeast geographic region, and commercial health insurance product also conferred lower odds of receiving some form of ANA treatment. Men are more likely than females to have late-detected PACG, which may explain the higher treatment levels of males seen in our study.34 Higher income was associated with lower odds of drops and cataract surgery, which is in line with prior cross-sectional studies and reviews finding lower socioeconomic status (SES) associated with higher odds of more severe glaucoma and cataracts.35,36 Possible explanations for this pattern include wealthier patients affording more eyecare visits and healthier lifestyles with less common glaucoma comorbidities, such as hyperlipidemia and diabetes.37 Medicare beneficiaries appeared to have significantly higher odds of cataract surgery, which supports prior work reporting higher rates of cataract surgery and worse visual acuity at time of cataract surgery in Medicare beneficiaries compared to commercial insurance beneficiaries.38,39 However, without clinical data, we are unable to conclude a reason for the insurance-related disparity in our study, and future work should utilize different databases for more precise information on insurance treatment patterns.

Although the AAO recommends all patients suspected of narrow angles receive gonioscopy,18 only 62.1% of our study cohort had record of gonioscopy before ANA diagnosis. This is similar to previous reports that around half of patients undergoing glaucoma evaluations or surgery received gonioscopy.40 One explanation for low rates of gonioscopy in our study is that some patients are receiving gonioscopy prior to the lookback period, making it impossible to distinguish between newly diagnosed ANA and previously-diagnosed PACD that did not follow up for over two years. However, this would not explain low rates reported by other studies. One explanation proposed by Coleman et al. for low rates of gonioscopy is the undercoding and miscoding of gonioscopy, which would affect all claims-based analyses like the present study. Underperformance of gonioscopy may result in misclassification of glaucoma subtype, and it remains an area where disease course can be improved.

Short-term (one-year) utilization of office visits was influenced by several factors among patients with newly diagnosed ANA. Although there are no clear guidelines for frequency of ANA follow-up, around half of untreated patients received only a single visit up to a year after ANA diagnosis, whereas the large majority (85%) of treated patients received more than one eyecare visit, which makes sense given that treatment with LPI and cataract surgery often entails multiple visits for the procedure and subsequent follow ups. Older age was also associated with more visits, which is expected as older age is associated with increased prevalence of most eye diseases, including cataracts.2,30 Race, education, and income were not significant in the multivariable model for eyecare visits after accounting for ANA treatments. This result was somewhat surprising as previous work reported racial minorities and patients of low SES are less likely to see an eyecare provider than non-Hispanic Whites and high SES patients.41 In our cohort of patients newly diagnosed ANA, this effect may be attenuated by increased angle closure severity associated with low SES and racial minorities and the relatively short duration of the study period. However, it is important to acknowledge that the prior work was conducted in the general population while our study was conducted in a subpopulation with a specific eye-related diagnosis. These populations are distinct and may have different patterns of healthcare utilization; therefore, direct comparisons should be made with caution.

Our study has several limitations. First, ANA is a broad term for narrow angles without glaucomatous change, and there is insufficient information in the Optum database (e.g. gonioscopy findings) to categorize patients based on standard definitions of angle closure severity (e.g. PACD). Similarly, there is no information on motivating factors used to decide whether a patient should be treated or not (e.g. IOP). Nevertheless, this database is one of the few data sources that allows us to investigate real-world practice patterns in a diverse, multi-racial cohort of patients. Second, patients in a claims-based database may represent higher disease severity than the normal population, who are less likely to manifest symptoms that would motivate an eye evaluation. This limitation may inflate the true treatment rate compared to the rate in a population-based sample. Finally, the Optum database only contains data on insured patients, which means uninsured and undocumented patients are unrepresented within our dataset. These vulnerable patient populations are often neglected, even in disparities research, and future research may benefit from additional efforts to represent them.31

Our findings on the treatment patterns of newly diagnosed ANA may help guide future directions of research in the field of angle closure. The observed differences in treatment patterns highlights the need for additional studies on the anatomical basis of racial differences in angle closure detection. There is also a need for standardized, objective guidelines to detect and manage patients with ANA prior to conversion to PACG to address identified disparities and conserve healthcare resources. In addition, it is unclear how treatment rates will be affected by recent recommendations by the ZAP and EAGLE trials to consider performing fewer LPI in PACS and PAC eyes. Therefore, further work is needed to assess changes in practice patterns over time, establish clearer practice guidelines based on longitudinal data, and ultimately address prevailing disparities in angle closure care.

In summary, a high proportion of ANA patients received treatment with LPI, IOP-lowering drops, or cataract surgery. While racial minorities were at higher risk of receiving treatment with LPI or drops, there was no difference in eyecare visits. These findings are largely consistent with prior disparities identified among ANA and PACG patients and may be related to anatomical or disease factors that are unobservable given limitations of claims-based data. However, the lack of understanding about causative factors highlights the need for longitudinal and multi-racial data on anatomical mechanisms of angle closure and risk factors for progression.

Supplementary Material

1

Supplementary Table 1. Diagnosis, procedure, and treatment codes used in the study.

2

Supplementary Table 2. Proportion of anatomical narrow angle (ANA) cases stratified by number of eyecare visits and treatment.

Acknowledgments

This work was supported by grants K23 EY029763 from the National Eye Institute, National Institute of Health, Bethesda, Maryland and an unrestricted grant to the Department of Ophthalmology from Research to Prevent Blindness, New York, NY.

Footnotes

Disclosures

No financial disclosures.

Declaration of interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Supplemental Material available at AJO.com.

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

1

Supplementary Table 1. Diagnosis, procedure, and treatment codes used in the study.

NIHMS1960006-supplement-1.docx (15.2KB, docx)
2

Supplementary Table 2. Proportion of anatomical narrow angle (ANA) cases stratified by number of eyecare visits and treatment.

NIHMS1960006-supplement-2.docx (16.1KB, docx)

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