Epidemiologic Trends of Chemical Ocular Burns in the United States

Key Points

Question  What populations are at highest risk for ocular chemical burns?

Findings  In a cross-sectional analysis of the US Nationwide Emergency Department Sample, children aged 1 to 2 years are at a significantly higher risk for ocular chemical burns than any other group. In general, ocular chemical burn injuries are most common among individuals aged between 18 and 64 years (73.2%).

Meaning  Children aged 1 to 2 years are at much higher risk for an ocular chemical burn than previously recognized, and effective prevention efforts must include considerations for this age group.

Importance  Determining the national epidemiologic trends of chemical ocular burns can assist physicians and policy makers in appropriate allocation of resources for treatment and prevention.

Objective  To describe the epidemiologic trends and risk factors for chemical burns of the eye.

Design, Setting, and Participants  Between August 1, 2015, and April 25, 2016, data from the Nationwide Emergency Department Sample were analyzed from January 1, 2010, through December 31, 2013. A sample of 900 emergency departments (EDs) across the United States was used. Patients presenting to EDs with a diagnosis of alkali or acid ocular burn, chemical conjunctivitis, or a combination of nonspecific ocular chemical burn and chemical poisoning or toxic effects were eligible for inclusion. Injured patients’ age, sex, primary health care insurance, income quartile, and other demographics were described. A subset consisting of those injuries identified as alkaline or acidic burns was further characterized.

Main Outcomes and Measures  Age-specific rates of ED presentation for chemical ocular burn injuries, independent factors associated with all, alkali, and acid injuries, and total ED-associated charges.

Results  From January 1, 2010, through December 31, 2013, a total of 144 149 chemical ocular burns were diagnosed at EDs nationwide. Men represented 56.6% of all cases (n = 81 496). Median age was 32 years, with female patients presenting at a younger age than male patients (median of 32 vs 34 years; P < .001). Injury rates were highest among children aged 1 to 2 years (28.61 and 23.49 injuries per 100 000 population, respectively). Adults aged between 18 and 64 years also have these injuries at an increased rate, although this rate was half that of infants (mean, 13.28 per 100 000 population). Alkali injuries were more common than acid injuries (53.6% [n = 9137; 95% CI, 51.6%-56.0%] vs 46.4% [n = 7909; 95% CI, 44.0%-48.9%]), and all chemical eye injuries most commonly occur in residential locations (10.3% [n = 14 772]; 95% CI, 9.6%-10.9%) and among individuals in the first and second (lowest and second-lowest) income quartiles (≤$48 749) (56.0% [n = 80 691]; 95% CI, 54.4%-57.7%). Injuries most commonly occurred among those who had private health care insurance (31.9% [n = 45 900]; 95% CI, 30.9%-32.9%), and occurred more in the South (36.8% [n = 53 008]; 95% CI, 34.6%-39.1%). Emergency department charges due to these injuries totaled $106.7 million.

Conclusions and Relevance  Young children represent the single highest-risk group for ocular chemical injuries. Education and other interventions concerned with preventing these injuries will be most effective if used accordingly.

Quiz Ref IDChemical burns to the eye or ocular adnexa represent a serious form of injury with potentially long-term consequences relevant to vision and overall quality of life.^1-4 These injuries are associated with early and extended concerns of ocular pain, decreased visual acuity, ectropion, and extended risk for infection, although visual prognosis depends on the extent of corneal, limbal, and conjunctival involvement.^1,2,4,5 Vision loss has been associated with increased risk for serious injuries, depression, delirium, chronic disease, and social health.^6-13 These conditions and associated sequelae can also affect quality of life generally, as well as reduce economic productivity.^1-3,14-16

Chemical burns to the eye are usually caused by either acidic or alkaline agents.^17-19 Although both are serious injuries, alkaline burns tend to have a more injurious profile owing to the ability of alkaline substances to cause cellular membrane lysis, rapidly penetrate the cornea and anterior chamber, and soften tissues.^20-22 Conversely, acidic agents tend to precipitate proteins in the eye, which may collectively serve as a barrier to further invasion of intraocular structures and limit damage.^2,5 Common agents of acidic ocular burns include sulfuric, hydrochloric, hydrofluoric, and battery acids; in the case of alkaline agents, common agents include cement or lime, sodium hydroxide (present in oven cleaners and drain cleaners), chlorine bleach (sodium hypochlorite), and ammonia products.^3,23

Despite the critical nature of chemical ocular injury, little is known regarding the national or international incidence, and existing information is dependent on case series, individual or small multicenter medical record reviews, or setting-specific reports, such as those from the US Bureau of Labor Statistics.^{1,3,17,18,20-22,24-27} A 2013 publication from the American Association of Poison Control Centers reported approximately 98 000 calls associated with ocular exposures of concern, although it is unclear how many exposures were due to potentially injurious agents or the number of resulting injuries.²⁸ Case series generally report high numbers of ocular chemical burns caused by industrial or occupational exposure, suggesting that men aged between 18 and 64 years may be at highest risk for injury.^1,3,17,18,21 Some series, however, have noted that such injuries among the young, including household injuries, should not be ignored as a potentially serious and preventable form of injury.^2,22,23

Despite the level of detail provided by the case series and medical record reviews in the existing literature, estimates of national incidence and population characteristics are vital to the development of appropriate prevention and treatment strategies at all levels of industry, health care, and government. Using a nationally representative sample of US emergency departments (EDs), we identified and characterized the ED burden of chemical ocular burns from January 1, 2010, through December 31, 2013.

The Nationwide Emergency Department Sample, part of the Healthcare Cost and Utilization Project, is the nation’s largest all-health care insurance ED database and contains discharge data on approximately 30 million ED visits annually from more than 900 hospitals nationwide.²⁹ It is a 20% stratified sample of national ED visits, designed to be weighted to the level of the US population to provide national estimates associated with ED care.

Cases were identified using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)³⁰ codes. Our case definition included any visits to EDs from January 1, 2010, through December 31, 2013, that comprised ICD-9-CM diagnosis codes of alkaline burn of the cornea and conjunctiva (code 940.2), acid burn of the cornea and conjunctiva (code 940.3), chemical conjunctivitis (code 372.06), or a combination of a nonspecific burn of the cornea and/or conjunctiva (code 940.4) and either any poisoning by a topical medication (code 976.x) or any toxic effect by a chemical (code 989.x).³⁰ Any records that were missing data on age or sex were excluded from analysis; to avoid double counting, we also excluded any visits that were coded as a follow-up (ICD-9-CM code V67).

Using these case identification criteria, we queried the Nationwide Emergency Department Sample from January 1, 2010 (the first year of the chemical conjunctivitis ICD-9-CM code), through December 31, 2013, and examined the ED incidence of ocular chemical burns by injury-level characteristics, such as the setting of injury; patient-level factors, such as age, sex, primary health care insurer, and income quartile were also examined, as were hospital region and total ED charges. Injury-setting descriptions were combined into 4 categories: residential, including home and other residential facilities; commercial, including industrial sites, mines, and farms; public, including schools and other public buildings, streets and highways, and sports and recreational facilities; and other locations, or were classified as missing. This study was designed and conducted between August 1, 2015, and April 25, 2016, and the Johns Hopkins Medicine Institutional Review Board approved this study and waived the need for informed consent. The Nationwide Emergency Department Sample is a limited data set from which all personally identifiable information has been removed except dates less than 1 year and geographic locations smaller than a state.

The identification of an appropriate denominator for rate calculation was difficult because we were unable to define or describe the population at risk for injury; thus, calculated incidence rates are based on age-specific population sizes and intercensal estimates from the US Census Bureau.³¹ Median annual household income quartiles were estimated by zip code based on data collected by the Agency for Healthcare Research and Quality from Nielsen Claritas, Inc, and were defined as follows: first quartile (≤$39 249), second quartile ($39 250-$48 749), third quartile ($48 750-$64 499), and fourth quartile (≥$65 000).³²

Standard descriptive statistical methods were used (α = .05). Statistical analyses were conducted using the Stata statistical software package (StataCorp LP).

From January 1, 2010, through December 31, 2013, there were 144 149 ED visits associated with chemical ocular burns in the United States. After excluding those cases missing age and sex or that were coded as follow-up visits, 143 985 records remained in our sample, corresponding to an average of 35 996 visits per year (Table 1). Men represented 56.6% of all cases (n = 81 496). Median age was 32 years, with female patients presenting at a younger age than male patients (median of 32 vs 34 years; P < .001) . Injuries most commonly occurred in residential settings (n = 14 722 [10.3%; 95% CI, 9.6%-10.9%]), were more common among individuals in the first and second income quartiles (n = 80 691 [56.0%; 95% CI, 54.4%-57.7%]) and those who had private health care insurance (n = 45 900 [31.9%; 95% CI, 30.9%-32.9%]), and occurred more in the South (n = 53 008 [36.8%; 95% CI, 34.6%-39.1%]). The settings of injury varied substantially by age (Figure).

Quiz Ref IDAge-specific incidence rates per 100 000 population were highest among individuals aged 20 to 29 years (average, 17.4), followed by age 30 to 39 years (14.9), 40 to 49 years (13.2), and 9 years or younger (12.1) (Figure). Among rates for individual years of life, however, injuries were most common among 1-year-old (average, 28.6) and 2-year-old (23.5) children. The rate for 1-year-old infants was 49.9% higher than that of the highest rate among adults (28.6 vs 19.1 per 100 000 among 24-year-old adults). Individuals aged between 6 and 14 years and those older than 74 years had the lowest rates of injury. Men and women aged between 18 and 64 years comprised 73.2% (n = 105 334) of all chemical ocular burns, despite only comprising 62.8% (n = 785 887 831) of the population during the study period.^31,33

Although all injuries were chemical ocular burns, 17 021 (11.8%) were identified as either acidic or alkaline injuries; other injuries were caused by either unknown agents or substances with unknown acidity. Of these injuries, 9117 (53.6%; 95% CI, 51.6%-56.0%) were alkaline associated; this proportion varied significantly by decade of life, however, ranging from a high of 74.7% (n = 724) among children 9 years and younger to a low of 46.1% (n = 501) among those aged 60 to 69 years (Table 2). Among individuals with acidic or alkaline injuries, those aged 3 years and younger had more alkaline burns, which composed 78.0% (n = 534) of patients in that age group; as a comparison, only 52.5% (n = 7559) of acidic or alkaline injuries were alkaline among individuals aged between 18 and 64 years (P < .001, χ² test).

Quiz Ref IDChemical ocular burns comprised approximately $106.7 million in ED charges or an average of $26.6 million per year; these totals underestimate the cost of these injuries, however, because 21 458 records (14.9%) were missing ED charge-associated data.

Chemical burns to the eye and adnexa are a serious problem in the United States, comprising almost 36 000 ED visits and $26.6 million in ED-associated charges every year. From January 1, 2010, through December 31, 2013, these injuries comprised more than 144 000 ED visits and more than $106 million in ED charges. The economic effect of these injuries, including lost workdays for the individuals who were burned and their family members, loss of productivity, administrative costs, and the cost of continued care for medical sequelae and lost visual acuity, comprises more than these data reflect.

Although most literature emphasizes the increased risk for ocular chemical burns among men aged between 18 and 64 years, we found that the age-specific risk for chemical ocular injuries is highest among 1- and 2-year-old children.^1,3,22 Furthermore, among injuries classified as either alkaline or acidic, children 3 years and younger had more alkaline burns than men aged between 18 and 64 years (78.0% [n = 534] vs 52.5% [n = 7559]; P < .001, χ² test). Alkaline agents, commonly found in household cleaning chemicals, often cause more serious burns than acidic injuries in the home; spray bottles containing these agents represent an important source of injury among pediatric populations and may be a cause of the high rates of chemical ocular burns we observed.^19,23 It is important to note, however, that 11.8% (n = 17 021) of chemical injuries were classified as alkaline or acidic; the remaining 88.2% (n = 126 964) may represent burns by chemical agents of unknown acidity or even burns from unknown chemicals.

As a group, individuals aged between 18 and 64 years are at high risk for chemical eye injuries. This population comprises more than 26 000 ED visits and more than $20.5 million in ED charges every year. Like their pediatric counterparts, although to a lesser extent, individuals aged between 18 and 64 years were more prone to have an alkaline ocular burn than an acidic burn. Although injuries in this age group occurred in settings categorized as other than residential, commercial, or public properties, incidence in residential locations (8.7%, n = 9181) was similar to that of commercial settings (8.2%, n = 8612). This equivalency of residential vs commercial setting was unique to individuals aged between 18 and 64 years, as injuries among other age groups occurred more in residential settings (14.5%, n = 5604) than commercial (0.5%, n = 178).

Quiz Ref IDThis study highlights an important opportunity for effective injury prevention efforts. Chemical ocular injuries among young children are almost entirely preventable if dangerous agents are properly stored. Household chemicals should not be stored under sinks, in ground-level cabinets, or in other places that would be potentially accessible to young children. The installation and use of appropriate cabinet locks may also be an effective prevention strategy.³⁴ Because young children are at high risk for many types of injuries, especially burns, counseling parents and other caregivers regarding appropriate primary prevention strategies is important.^35,36 Likewise, secondary prevention efforts, including education for police officers, parents, paramedics, and health care professionals regarding appropriate and timely treatment of these chemical burns (ie, copious and immediate irrigation with clean water), may be effective in alleviating the long-term effects of injuries.³⁷

Preventing workplace injuries should be a priority of corporate leadership and government regulators. Guidelines mandating employer-purchased worker safety equipment, such as those issued by the Occupational Safety and Health Administration in 2007, are important for reducing the burden of these injuries among individuals aged between 18 and 64 years.³⁸

As with any study conducted using administrative data, this effort had limitations.³⁹ Although we were able to identify blindness and reduced visual acuity as a diagnosis on discharge, we were unable to diagnose injuries caused by unknown agents or substances, which limited our ability to examine visual outcomes. In addition, because our data set was limited to ED visits, we were unable to measure the incidence of patients presenting to either outpatient (eg, ophthalmologists, optometrists, or primary care physicians) or urgent care centers for treatment.

Ocular chemical burns are a large problem in the United States, and the risk to young children is substantially higher than previous estimates showed. Individuals aged between 18 and 64 years are most commonly affected by these injuries. Public health efforts and policies should concentrate on the appropriate storage and handling of chemicals in the home and in the workplace. Continued efforts by the Occupational Safety and Health Administration to strengthen and enforce regulations associated with protective eyewear in the workplace will also be important to preventing these injuries. Although further research is necessary to examine the effectiveness of intervention efforts, such policies should use age-appropriate and setting-appropriate strategies.

Correction: This article was corrected on January 26, 2017, to fix editing errors in the Methods and Results sections.

Accepted for Publication: June 13, 2016.

Corresponding Author: Eric B. Schneider, PhD, Center for Surgery and Public Health, Brigham and Women’s Hospital, One Brigham Circle, 1620 Tremont St, Ste 4-020, Boston, MA 02120 (eschneider3@partners.org).

Published Online: August 4, 2016. doi:10.1001/jamaophthalmol.2016.2645

Author Contributions: Dr Haring and Mr Canner had full access to all the data in the study and take responsibility for the integrity of the data and accuracy of the data analysis.

Study concept and design: Haring, Channa, Schneider.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Haring, Sheffield, Channa.

Critical revision of the manuscript for important intellectual content: Haring, Channa, Canner, Schneider.

Statistical analysis: Haring, Sheffield, Schneider.

Administrative, technical, or material support: Channa, Canner.

Study supervision: Schneider.

Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Schneider is a member of Bergeim, LLC. No other disclosures were reported.