Potentially Missed Opportunities in Prevention of Acute Angle-Closure Crisis

Abstract

Importance

If an anatomic narrow angle is not appropriately diagnosed and treated, it can result in acute angle-closure crisis (AACC) and lead to substantial vision loss.

Objective

To identify patients who presented with AACC and assess for factors that may have been associated with risk of developing it.

Design, Setting, and Participants

This population-based retrospective cohort study conducted from January 1, 2001, to December 31, 2015, included a 20% nationwide sample of 1179 Medicare beneficiaries. Patients aged 40 years or older with AACC were identified with billing codes. A 2-year lookback period from the date of initial presentation of AACC was used to identify patients who had at least 1 eye care visit, received a diagnosis of open-angle glaucoma (OAG) or suspected OAG, or received at least 1 medication associated with risk of AACC. Of the patients who had at least 1 eye care visit, those who underwent gonioscopy, received a diagnosis of an anatomic narrow angle before developing AACC, or both were identified.

Main Outcomes and Measures

Proportions of patients who had at least 1 eye care visit, had OAG or suspected OAG, received at least 1 medication associated with risk of AACC, underwent gonioscopy, or received a diagnosis of an anatomic narrow angle before development of AACC.

Results

A total of 1179 patients had a confirmed diagnosis of AACC. The mean (SD) age of patients with AACC was 66.7 (11.8) years (range, 40-96 years), 766 were women (65.0%), 57 were Asian (4.8%), 109 were Black (9.2%), 126 were Latino (10.7%), 791 were White (67.1%), and 96 were other race and ethnicity (8.1%). Of these patients, only 796 (67.5%) consulted an optometrist or ophthalmologist at least once during the 2-year lookback period. A total of 464 individuals (39.4%) had OAG or suspected OAG, and 414 (35.1%) had received at least 1 medication associated with increased risk of AACC before developing it. Of the 796 patients who consulted an optometrist or ophthalmologist in the lookback period, less than one-third underwent gonioscopy in the 2 years before developing AACC (n = 264 [33.2%]), and less than one-half of all patients undergoing gonioscopy received a diagnosis of an anatomic narrow angle (n = 113 [42.8%]). Most patients underwent gonioscopy in the 1 to 4 weeks preceding the AACC.

Conclusions and Relevance

In this group of Medicare patients, there appear to have been multiple opportunities for interventions that may have averted AACC. Interventions aimed at addressing risk factors associated with AACC and improving performance of gonioscopy might be associated with reduced risk for ocular morbidity.

Key Points

Question

What opportunities to diagnose and treat an anatomic narrow angle may be missed in the care of patients at risk for acute angle-closure crisis?

Findings

In this cohort study of 1179 Medicare patients with acute angle-closure crisis, only 22.7% underwent gonioscopy, and 42.8% of those who underwent gonioscopy had a diagnosis of an anatomic narrow angle in the 2-year period preceding presentation.

Meaning

These results suggest that interventions aimed at improving access to optometrists and ophthalmologists should be considered and that the proper use of gonioscopy to diagnose an anatomic narrow angle and avert acute angle-closure crisis should be increased.

This cohort study assesses the presence or absence of interventions for Medicare patients with acute angle-closure crisis that may avert its occurrence and associated vision loss.

Introduction

Acute angle-closure crisis (AACC) is characterized by abrupt obstruction of aqueous outflow by appositional closure of the anterior chamber angle.¹ Family history of angle closure, older age, female sex, Asian descent, hyperopia, and short axial length are risk factors for AACC.^2,3,4,5 Characteristic clinical signs and symptoms of an acute attack include a mid-dilated pupil, elevated intraocular pressure, pressure-induced corneal edema, closed angles detected using gonioscopy, vascular congestion, eye pain, headache, nausea, and/or vomiting. If left untreated, AACC can lead to corneal endothelial injury, iris atrophy, cataract, retinal vascular occlusion, and/or glaucomatous optic neuropathy.^6,7,8,9 Up to 50% of individuals with AACC subsequently develop angle-closure glaucoma, a condition that accounts for a substantial proportion of irreversible blindness worldwide, with a global prevalence of 0.5%.^7,10

The identification of patients with eyes at risk of AACC and the performance of prophylactic laser peripheral iridotomy (LPI) or lensectomy can prevent serious ocular morbidity.^1,11,12 Gonioscopy is the criterion standard for an accurate evaluation of anterior chamber angle status, and the American Academy of Ophthalmology recommends that gonioscopy be performed in the initial evaluation of all patients with suspected glaucoma, along with repeated gonioscopy at least every 5 years for those who receive a diagnosis of glaucoma.^1,13 Multiple studies have found that the rates of gonioscopy are low, even among patients with a diagnosis of glaucoma.^14,15,16 The aim of this retrospective study was to identify patients who presented with AACC and retrospectively assess for the presence or absence of key factors before the angle-closure event that may have helped prevent its occurrence, including eye care use, receipt of gonioscopy and/or anterior segment imaging, and use of medications that may have predisposed to angle closure.

Methods

Data Source

Data for Medicare beneficiaries were obtained from a nationally representative 20% sample of beneficiaries with Medicare Parts A and B coverage who were enrolled in fee-for-service Medicare from January 1, 2001, to December 31, 2015. This database captures all ocular and systemic diagnoses based on International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) billing codes and information regarding diagnostic and therapeutic procedures performed based on Current Procedural Terminology and Healthcare Common Procedure Coding System codes. Use of this data set has been described for the study of health care resource use and outcomes among patients with ophthalmic and nonophthalmic conditions.^17,18 This cohort study adhered to the tenets of the Declaration of Helsinki¹⁹ and was approved by the University of Michigan institutional review board. Informed consent was waived by the University of Michigan institutional review board owing to deidentification of patient records in this retrospective study. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for cohort studies was followed in this study.

Inclusion and Exclusion Criteria

Patients aged 40 years or older with AACC identified by ICD-9-CM code 365.22 were included in the study. They were required to have 2 diagnoses on separate visits for disease confirmation. To further substantiate the diagnosis, patients were required to have undergone LPI, cataract extraction, or incisional glaucoma surgery within 1 week of initial diagnosis, as identified by Current Procedural Terminology and Healthcare Common Procedure Coding System codes. We used a 2-year lookback period from the date of initial presentation of AACC to screen for prior LPI, cataract extraction, or incisional glaucoma surgery and excluded patients with any of these prior procedures.

Statistical Analysis

Statistical analyses were performed with SAS, version 9.3 (SAS Institute). The study included a 20% nationwide sample of Medicare records from January 1, 2001, to December 31, 2015. The characteristics of the participants were summarized for the entire sample with mean (SD) values for continuous variables and frequencies and percentages for categorical variables.

Patients with AACC were identified, and baseline demographic characteristics were obtained, including patient age as well as self-reported sex and race and ethnicity. A 2-year lookback period preceding initial presentation of AACC was used to identify patients who received at least 1 eye care visit, had open-angle glaucoma or suspected open-angle glaucoma, or received at least 1 medication associated with risk of AACC (selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, antihistamines, carbonic anhydrase inhibitors, and topiramate) before developing AACC. Patients who underwent gonioscopy or anterior segment imaging (anterior segment optical coherence tomography or ultrasonographic biomicroscopy) within the 2-year lookback period were identified. Among the patients who had at least 1 eye care visit in the lookback period, we identified those who underwent gonioscopy, received a diagnosis of anatomic narrow angle, or both. Among the patients who underwent gonioscopy, we determined the interval between the performance of gonioscopy and the development of AACC.

Results

A total of 1179 patients had a confirmed diagnosis of AACC. The mean (SD) age of patients with AACC was 66.7 (11.8) years (range, 40-96 years), 766 were women (65.0%), 57 were Asian (4.8%), 109 were Black (9.2%), 126 were Latino (10.7%), 791 were White (67.1%), and 96 were other races and ethnicities (8.1%), a category assigned to patients whose race was not provided as any of the aforementioned race categories within the database (Table 1). Of all patients with AACC, only 796 (67.5%) consulted an ophthalmologist or optometrist at least once during the 2-year lookback period; the remaining 383 patients (32.5%) had received no eye care in the 2 years preceding the AACC (Table 2). A total of 464 patients (39.4%) had open-angle glaucoma or suspected open-angle glaucoma, 268 (22.7%) underwent gonioscopy, and 414 (35.1%) had received at least 1 medication associated with increased risk of AACC before developing the disease (medications with increased AACC risk included selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, antihistamines, carbonic anhydrase inhibitors, and topiramate) (Table 2).

Table 1. Demographic Characteristics of All Patients With Confirmed Diagnosis of Acute Angle-Closure Crisis.

Characteristic	Patients, No. (%) (N = 1179)
Age, mean (SD), y	66.7 (11.8)
Sex
Male	413 (35.0)
Female	766 (65.0)
Race
Asian	57 (4.8)
Black	109 (9.2)
Latino	126 (10.7)
White	791 (67.1)
Othera	96 (8.1)

^a Patients whose race was not provided as any of the aforementioned race categories within the database were designated as other.

Table 2. Characteristics of All Patients With Confirmed Diagnosis of AACC.

Characteristic	Patients, No. (%) (N = 1179)
≥1 Eye care visit
Yes	796 (67.5)
No	383 (32.5)
OAG or suspected OAG
Yes	464 (39.4)
No	715 (60.6)
Received ≥1 medication associated with risk of AACCa
Yes	414 (35.1)
No	765 (64.9)
Underwent gonioscopy
Yes	268 (22.7)
No	911 (77.3)
Underwent anterior segment imagingb
Yes	66 (5.6)
No	1113 (94.4)

Abbreviations: AACC, acute angle-closure crisis; OAG, open-angle glaucoma.

^a Includes selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, antihistamines, carbonic anhydrase inhibitors, and topiramate.

^b Anterior segment optical coherence tomography or ultrasonographic biomicroscopy in the 2 years before AACC.

Of the 796 patients who consulted an optometrist or ophthalmologist during the lookback period, 264 (33.2%) underwent gonioscopy in the 2 years before developing AACC, of whom 113 (42.8%) received a diagnosis of an anatomic narrow angle (Table 3). Most patients underwent gonioscopy 1 to 4 weeks before the AACC (n = 91 [34.5%]) (Table 4). Of the 1179 patients in the cohort, 66 (5.6%) underwent anterior segment imaging (defined as anterior segment optical coherence tomography or ultrasonographic biomicroscopy) during the 2-year lookback period; of these patients, 23 (34.8%) also underwent gonioscopy (Table 2).

Table 3. Patients With Confirmed Acute Angle-Closure Crisis and 1 or More Eye Care Visits Who Underwent Gonioscopy vs Those Who Did Not.

Variable	Patients, No. (%) (N = 796)
	Received gonioscopy	Did not receive gonioscopy
No. of patients	264 (33.2)	532 (66.8)
Diagnosis of an anatomic narrow angle
Yes	113 (42.8)	64 (12.0)
No	151 (57.2)	468 (88.0)

Table 4. Interval Before Onset of AACC Among Patients With 1 or More Eye Care Visits Undergoing Gonioscopy During Lookback Period.

Interval before AACC	Patients, No. (%) (N = 264)
1-2 y	47 (17.8)
6-12 mo	18 (6.8)
1-6 mo	63 (23.9)
1-4 wk	91 (34.5)
2-7 d	40 (15.2)
1 d	5 (1.9)

Abbreviation: AACC, acute angle-closure crisis.

Discussion

Our study highlights missed opportunities to diagnose and treat patients with eyes at risk for AACC. Recognition of risk factors and appropriate eye care use with accurate characterization of the anterior chamber drainage angle are necessary steps for preventing AACC and the potential for progression to angle-closure glaucoma with substantial ocular morbidity.

Eye care underuse is 1 factor that may contribute to the underdiagnosis and undertreatment of AACC in eyes at risk. We found that approximately one-third of patients received no eye care in the 2 years preceding AACC (Table 2). The American Academy of Ophthalmology recommends that all patients undergo a baseline comprehensive eye evaluation at aged 40 years, followed by an examination every 2 to 4 years for those aged 40 to 54 years, and every 1 to 3 years for those aged 55 to 64 years who are without risk factors.²⁰ Individuals aged 65 years or older should receive an examination every 1 to 2 years given that the incidence of ocular disease increases with age.²⁰ The ages of the patients in our study ranged from 40 to 96 years, with a mean age of 66.7 years. Given that all these patients developed AACC and had certain risk factors for angle closure, arguably they all should have been receiving eye examinations at least as frequently as the recommended schedule for patients with no risk factors (eg, at least every 1-2 years). Lower socioeconomic status, male sex, younger age, non-White race, lack of insurance, and lack of trust in the physician have previously been associated with suboptimal use of eye care.^21,22,23,24 Interventions targeted at addressing these risk factors and increasing eye care use among high-risk groups may allow for better identification and treatment of patients at risk for AACC.

Even among patients who had had an eye care visit in the 2 years before receiving a diagnosis of AACC, most did not undergo gonioscopy. Although alternate techniques, such as estimation of limbal chamber depth by slitlamp examination, have been used to estimate anterior angle narrowing, gonioscopy remains the preferred method for an accurate assessment of the anterior chamber drainage angle.^13,25,26,27 Prior studies have found similar low rates of gonioscopy, even among patients with a diagnosis of glaucoma. Coleman and colleagues¹⁴ found that among Medicare beneficiaries undergoing glaucoma surgery, gonioscopy was performed in only 49% of patients in the 4 to 5 years preceding glaucoma surgery. Similarly, Hertzog and colleagues¹⁵ found that in a retrospective medical record review of patients with open-angle glaucoma, only 51.3% underwent gonioscopy as part of the initial ophthalmic examination.

The potential reasons for the suboptimal rates of gonioscopy include prioritization of other components of the ophthalmic examination, use of alternate methods to characterize anterior chamber angle depth, patient’s refusal to undergo the examination owing to need for topical anesthesia and potential for ocular discomfort, or financial barriers (such as lack of insurance or costs associated with copayments).^14,15 Educational initiatives aimed at cultivating awareness among optometrists, ophthalmologists, and trainees on the importance of gonioscopy as a diagnostic tool may help address the underuse of the technique. The electronic health record could be used to trigger reminders for gonioscopy to be performed on schedule for patients with glaucoma, according to American Academy of Ophthalmology guidelines, and to screen patients with known risk factors for angle closure (eg, family history, hyperopia, or use of medications known to precipitate AACC). Our study population included all patients covered under the same insurance provider. Therefore, lack of insurance was not a barrier to care. However, prior studies have shown that even among patients with insurance, copayments as low as $5 were associated with reduced rates of preventive screening tests.²⁸ Initiatives aimed at reducing financial barriers to gonioscopy may be associated with increased patient willingness to undergo this important component of an eye examination.

We found that even among the 264 patients who underwent gonioscopy, 151 (57.2%) did not receive a diagnosis of an anatomic narrow angle (Table 3). Underperformance or suboptimal performance of gonioscopy may lead to missed diagnoses. Varma and colleagues¹⁶ found that 1 of 11 patients who were referred to a tertiary glaucoma center with a diagnosis of open-angle glaucoma (some of whom had undergone gonioscopy by the referring physician) was subsequently found to have angle closure after undergoing gonioscopy by a glaucoma specialist. The American Academy of Ophthalmology guidelines recommend that gonioscopy be performed in a dark room with a short (1-mm), bright slit beam that does not pass through the pupil to allow for an accurate assessment of angle morphology.¹ This investigation suggests that increased attention to education on proper gonioscopy technique among ophthalmology residents and optometry students may be needed to ensure accurate characterization of angle morphology with gonioscopy.

Anterior segment imaging techniques have been proposed as an adjunct to gonioscopy for assessing anterior chamber morphology given that high-quality gonioscopy requires patient cooperation as well as examiner expertise. Anterior segment optical coherence tomography and ultrasonographic biomicroscopy have been found to reliably assess angle morphology and, in some cases, to be more sensitive than gonioscopy for identifying an anatomic narrow angle.^29,30 In our study, 66 of 1179 patients (5.6%) underwent anterior segment optical coherence tomography or ultrasonographic biomicroscopy in the 2 years before AACC diagnosis, with 23 (34.8%) having also undergone gonioscopy (Table 2). Although gonioscopy is often used for the assessment of anterior chamber morphology, given anterior segment imaging’s relative lower cost and greater availability, it may be considered as an adjunct for screening for an anatomic narrow angle when gonioscopy is not feasible, such as in cases of corneal opacities or when corneal contact is undesirable (eg, in the setting of trauma, during the perioperative period, or when there is a history of corneal transplant).

Approximately half of all patients (113 of 264; 43%) who underwent gonioscopy in our study received a diagnosis of an anatomic narrow angle but did not undergo prophylactic LPI, which produces substantial deepening of the anterior chamber angle and is effective at preventing AACC.^12,31,32 In cases of unilateral AACC, approximately 40% of patients will develop AACC in the fellow eye within 5 years if untreated.³³ The American Academy of Ophthalmology recommends that patients with unilateral AACC promptly undergo prophylactic LPI in the fellow eye; in addition, patients with occludable angles found by routine gonioscopy may wish to undergo prophylactic LPI before completion of the dilated fundus examination because dilation rarely precipitates AACC.^1,34 However, clinical circumstances may exist in which the risk of precipitating AACC may be outweighed by the diagnostic value of a dilated fundus examination.

In addition, patients should be counseled on signs and symptoms of AACC should they develop the condition before receiving prophylactic LPI. Certain commonly prescribed drugs, such as selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, and antihistamines, have been associated with a high risk of precipitating AACC because of their mydriatic effects.³⁵ We found that more than one-third of patients who developed AACC had received at least 1 medication associated with precipitating AACC in the preceding 2 years and may have benefited from prophylactic LPI (Table 2). To identify those at risk and recommend prophylactic LPI when indicated, the electronic health record could be used to trigger reminders for primary care physicians to refer for ophthalmic evaluation or for optometrists and ophthalmologists to perform gonioscopy at routine eye care visits for patients receiving medications that predispose to AACC.

Newer prospective clinical trials^36,37 have demonstrated a relatively low rate of progression from suspected primary angle closure status to more substantial forms of chronic angle-closure spectrum disease, such as primary angle closure or primary angle-closure glaucoma. The incidence of AACC in these studies was extremely low, and although risk reduction was observed with iridotomy placement, the difference in outcomes may not be clinically significant in all situations. These studies were conducted for primarily Chinese patients and may not be generalizable to a US-based cohort. Ultimately, the utility of LPI placement for patients at risk should be determined on a case-by-case basis.

Limitations

This study is not without limitations. This was a retrospective review of data from a health care claims database, and limitations inherent to this type of study include lack of certain clinical information (eg, best-corrected visual acuity, intraocular pressure, and gonioscopic findings). In addition, errors in diagnosis coding could bias study results; gonioscopy may not have been billed in all visits despite having been performed. Our study was not designed to identify patients who were correctly identified and treated or intended to be treated; it is possible that some patients identified by gonioscopy to have an anatomic narrow angle were scheduled to have prophylactic LPI but developed AACC before the anticipated LPI (45 patients in our study had undergone gonioscopy within only 1 week of developing AACC) (Table 4). Furthermore, because the angle between the cornea and the iris progressively narrows with age, a change in the anatomy may explain a “missed” diagnosis. Finally, all of the patients in the study had health insurance and lived in the United States. Therefore, our findings may not be generalizable to uninsured persons or those with other types of insurance or residence outside of the United States.

Conclusions

In this group of Medicare patients with AACC, there appear to have been multiple opportunities for interventions that may have averted crisis. Addressing risk factors associated with the underuse of eye care, coupled with the increased use of gonioscopy to identify patients with eyes at risk and the performance of prophylactic LPI when indicated, is a step in the right direction for preventing patients from developing AACC. Education aimed at increasing optometrist and ophthalmologist awareness and understanding of correct gonioscopy technique, reduction of financial barriers to gonioscopy, use of anterior segment imaging as adjunct testing, and implementation of electronic health record reminders to flag patients at risk and facilitate timely and appropriate ophthalmic assessments may be associated with reduced incidence of AACC, with the ultimate goal of reducing the risk of angle closure–associated vision loss.