This study was a retrospective cohort study at a single tertiary care center. It was approved by the Institutional Review Board of Wills Eye Hospital and was in accordance with Health Insurance Portability and Accountability Act regulations. Because this was a retrospective study with de-identified data, informed consent was not required. The medical records of patients who arrived at the Wills Eye Emergency Room between October 1, 2020, and March 31, 2021, and were referred for outpatient glaucoma follow-up were reviewed. All patients were included regardless of whether they followed up for outpatient care; only the first visit was included in the analysis if duplicate visits were documented by the same patient within this time frame. Of note, all patients seen in the Wills ER with acutely elevated IOP requiring medical anti-hypertensive management are referred for outpatient glaucoma follow-up.
Demographic data were collected, including age, gender, self-reported race, level of education, zip code, primary language spoken, and insurance status. RUCA codes were collected using patient zip codes in reference to 2010 data from the United States (US) Department of Agriculture and the US Census Tracts.2 These codes were then classified into metropolitan, micropolitan, small town, or rural areas. Area deprivation index (ADI) was determined using patient addresses and a database compiled by the Health Resources & Services Administration. Higher ADI is associated with greater socioeconomic disadvantage.3 As outlined by Ghirimoldi et al., ADI was stratified into low, medium, and high groups based on percentile.18
Additional data collected included medical comorbidities, prior procedures for glaucoma, date of prior glaucoma diagnosis, number of glaucoma medications, and whether the present ER visit was the first time glaucoma was diagnosed for the patient. The diagnosis of definite or suspected glaucoma was at the discretion of the ophthalmologists at the ER (resident trainees supervised by attending ophthalmologists); all exam findings (including anterior/posterior exams, CDR, and IOP) were confirmed by an attending physician. Patients who received a “new” diagnosis of definite or suspected glaucoma in the ER: 1) were not referred from outside providers, 2) did not self-report a prior diagnosis of glaucoma and did not have a glaucoma diagnosis listed in Epic, 3) were not on IOP-lowering medications, and 4) had not undergone prior glaucoma-related surgeries or procedures (per exam and per self-reporting) at the time of the visit.
Initial characteristics of the ER presentation included date of the visit, day of the week, time of visit, and average number of COVID cases in Pennsylvania on that day as reported by the Pennsylvania Department of Health.19 Initial clinical characteristics included visual acuity (VA, by distance Snellen with and without pinhole measured by an trained nurse), intraocular pressure (IOP, either by Tonopen or applanation tonometry measured by a resident trainee or an attending), cup-to-disc ratio (CDR), and urgency of the visit. For the purposes of this study, a fellowship-trained glaucoma specialist reviewed all cases and determined whether a visit was urgent or non-urgent based on diagnosis and severity of presentation. Based on IOP alone, urgent presentation was defined as IOP > 30 mmHg. Urgent procedural interventions were those that needed to be performed within 1 week, and the need for this was determined by the glaucoma specialists evaluating the patient. Possible interventions included trabeculectomy, glaucoma drainage device, cyclophotocoagulation, minimally invasive glaucoma surgery, cataract extraction and intraocular lens insertion, laser peripheral iridotomy, or selective laser trabeculoplasty. Worse eyes were defined as having worse visual acuity.
All patients who visited the ER and were told to follow-up in the outpatient glaucoma clinic were advised to do so within 30 days. Follow-up characteristics that were recorded included surgical data (i.e., type of surgery performed and date performed) and relevant characteristics on subspecialty clinic follow-up (i.e., VA, IOP, CDR, and laterality of the worse eye). Blindness in one or both eyes on presentation and follow-up was categorized according to Chan et al., in which patients were stratified into three groups: one eye with BCVA ≤ 20/200, two eyes with ≤ 20/200, or none.1,20
Statistical Analysis
Continuous variables were summarized by mean, standard deviation, median, and range; they were compared using two-sample independent T-test or rank sum test. Categorical variables are summarized as proportions and compared using Chi-square test or Fisher’s Exact test. Univariable and multivariable logistic regression were conducted to assess the association between risk factors and needing surgical intervention. A two-sided p-value of < 0.05 was considered for statistical significance. Inter-eye correlation was adjusted for eye level analyses. All statistical analysis were done using SAS 9.4.