AbstractObjectiveTo evaluate the current body of literature pertaining to the use of ocular point-of-care ultrasound (POCUS) in the emergency department (ED).
MethodsA comprehensive literature search was conducted on Scopus, Web of Science, MEDLINE, and Cochrane Central Register of Controlled Trials (CENTRAL) databases. Inclusion criteria were studies written in English and primary clinical studies involving ocular POCUS scans in an ED setting. Exclusion criteria were nonprimary studies (e.g., reviews or case reports), studies written in a non-English language, nonhuman studies, studies performed in a nonemergency setting, studies involving non-POCUS ocular ultrasound modalities, or studies published more than 10 years prior. Data extraction was guided by the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) recommendations.
ResultsThe initial search yielded 391 results with 153 duplicates. Of the remaining 238 studies selected for retrieval and screening, 24 met the inclusion criteria. These 24 included studies encompassed 2,448 patients across prospective, retrospective, cross-sectional, and case series study designs. The majority of included studies focused on the use of POCUS in the ED to measure optic nerve sheath diameter as a proxy for papilledema and metabolic aberrations, while a minority of studies used ocular POCUS to assist in the diagnosis of orbital fractures or posterior segment pathology.
ConclusionThe vast majority of studies investigating the use of ocular POCUS in recent years emphasize its utility in measuring optic nerve sheath diameter and fluctuations in intracranial pressure, though additional outcomes of interest include pathology of the posterior segment, orbit, and globe.
INTRODUCTIONOcular pathology is present in nearly 10% of all emergency department (ED) visits each year [1,2]. Rapid and accurate diagnosis of ocular emergencies is critical to prevent irreversible vision loss. The ED examination for ocular emergencies includes visual acuity, pupil reactivity, intraocular pressure, extraocular muscle motility, external periorbital changes, Wood lamp examination with fluorescein staining, and fundoscopic exam without dilation. Such ED examination is conducted alongside detailed ophthalmologic examination, often conducted by an ophthalmologist, using slit-lamp microscopy and indirect fundoscopy, both of which are widely recognized as gold standard tools for diagnosing eye conditions [3]. However, the required tools may not always be available, especially in resource-limited environments. The inconvenience of dilated exams can compound these challenges.
Point-of-care ultrasound (POCUS) is a noninvasive imaging technique used as a diagnostic adjunct for detecting ocular disease. It is particularly useful for detecting fundal pathologies that are not readily appreciated on external physical exam, such as vitreous hemorrhage, retinal detachment, and retinal hemorrhage [4]. This scoping review presented here aims to evaluate the current body of primary literature on the utility of POCUS in detecting ocular pathology. By assessing the existing literature, we hope to provide insights into the feasibility, accuracy, and practical implications of POCUS as a primary or adjunctive screening tool in the ED setting.
METHODSSearch strategyA literature search was conducted using Scopus, Web of Science, MEDLINE, and Cochrane Central Register of Controlled Trials (CENTRAL) databases using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) recommendations. Article publication dates were restricted to the last decade (earliest publication date of January 1, 2013). Search terms included “ophthal*,” “ultrasound,” “emergen*,” and “point-of-care.” The complete list of search terms, truncations, and Boolean operators used are listed in Supplementary Table 1. While a systematic review would aim to answer a specific research question by summarizing evidence on the topic, our work in this scoping review provides a broader preliminary assessment of the current body of evidence discussing the use of ocular POCUS in the emergency setting, while helping to identify knowledge gaps and inform future research.
Screening of studiesTitles and abstracts of studies were independently evaluated by three authors (CDY, CKK, and APB). These selections were then compared, and discrepancies were resolved via further discussion with the senior author (SS). Final study selections were performed independently by the three authors (CDY, CKK, and APB) after examining full-text articles. References from articles identified through our search were also evaluated and included if they met all inclusion criteria.
Inclusion and exclusion criteriaAll reviewed articles were subject to the following inclusion criteria: studies written in English and primary clinical studies involving ocular POCUS scans in an ED setting. No restrictions were placed on the included number of patients or patient demographics. All reviewed articles were subject to the following exclusion criteria: nonprimary studies (e.g., reviews or case reports), studies written in a language other than English, nonhuman studies, studies performed in a nonemergency setting, and studies involving non-POCUS ocular ultrasound modalities. After articles were selected, the Methodological Index for Nonrandomized Studies (MINORS) criteria were used to evaluate the quality of nonrandomized studies and assess the risk of bias for selected studies [5]. Each item on the MINORS checklist was independently scored by two authors.
Data extractionFollowing qualitative analysis, data were extracted from included articles to a predefined table (Supplementary Table 2) for the following variables: author, year of publication, country of origin, publication journal, practice setting, sonographer type (emergency physician, ophthalmologist, or radiologist), type of study (e.g., prospective/retrospective, cross-sectional/cohort/diagnostic), indication for POCUS, study population/size, ocular structure assessed, outcome measure(s), and key research findings. Descriptive data were isolated from this extracted data set and comprised author and publication year, study design, sample size, sonographer title, sonographic intervention, and a brief study description. Level of evidence (LOE) was determined for each study per the GRADE (Grading of Recommendations Assessment, Development and Evaluation) guidelines established by Sackett [6], in which increasing LOE inversely correlates with quality of evidence; the majority of included articles (75%) was LOE III, while LOE II (8.33%) and LOE IV (16.67%) were less frequent. Two independent scorers (MMC and PK) rated the quality and bias of the included articles using the MINORS scale [5].
RESULTSThe initial database search yielded 391 results, where 154 studies were identified from Scopus, 121 from MEDLINE, 99 from Web of Science, and 17 from Cochrane CENTRAL. We excluded 153 duplicate studies and screened the remaining 238 (Fig. 1). We excluded 122 studies because they were the wrong type (i.e., case reports, narrative reviews, editorials, nonprimary studies), 63 because they used a non-POCUS ultrasound modality (e.g., A-scan biometry) or lacked a measurable primary outcome, 26 because they were not conducted in emergency settings, and 3 because they were either nonhuman or cadaveric studies. A total of 24 articles encompassing 2,448 patients was included [7–30]. All included articles were published from 2013 to 2023 and represented the use of POCUS for ocular pathology in an emergency setting.
Most sonographers were emergency medicine attending physicians (50.0%), and the others were emergency medicine residents (16.7%), emergency medicine fellows (12.5%), trained sonographers or unspecified medical staff (12.5%), radiologists (4.2%), and pediatric ophthalmologists (4.2%). All included studies utilized high-frequency linear ultrasound probes to evaluate the eye and surrounding periocular tissue (Table 1) [7–30].
Outcome measures and primary findings were isolated from the initially extracted data set (Table 2) [7–30]. Of the 24 included studies using POCUS for ocular assessment in an emergency setting, 18 assessed optic nerve sheath diameter (ONSD) as a primary endpoint, three assessed the posterior segment, and three grossly assessed the globe and orbit.
Of the 18 studies utilizing POCUS to evaluate ONSD as a primary endpoint, eight used sonographic intervention to detect changes in intracranial pressure (ICP)/papilledema. All eight found that POCUS-measured ONSD was accurate and precise to sensitively and specifically detect ICP changes. Of the remaining 10 articles, three used sonographic intervention to detect cerebral edema associated with hyperglycemia or diabetic ketoacidosis (DKA). One of three articles found a significant change in ONSD in patients with DKA-associated cerebral edema [25]. One study used sonographic intervention to detect linear, depressed, and lateral orbital fractures and found that POCUS was 93.7% sensitive and 96.8% specific for this use [27]. Another study used sonographic intervention to prognosticate post-cerebrovascular event mortality and found that ONSD was significantly larger in patients who succumbed to acute stroke, with a ONSD threshold of 3.99 mm or greater exhibiting 83.3% sensitivity and 59.2% specificity in predicting death secondary to acute stroke [16]. Another study used POCUS-measured ONSD to support the diagnosis and clinical picture of acute cerebrovascular disease and found that patients with acute cerebrovascular disease exhibited a significantly higher ONSD compared to control patients, with an ONSD cutoff of 5 mm displaying 98.1% sensitivity and 81.8% specificity for diagnosis of acute stroke [13]. A separate study used POCUS-measured ONSD to inform posttraumatic brain injury (post-TBI) decision-making and found it to be a useful proxy for monitoring fluctuations in ICP after TBI in limited-resource settings [29]. A different study used POCUS-measured ONSD to detect ventriculoperitoneal shunt failure and found that POCUS had a limited sensitivity of 61.1% and specificity of 22.2% for that use [7]. The final analyzed study compared the accuracy of POCUS in measuring ONSD dimensions compared to conventional computed tomography imaging and found that POCUS is efficacious in the context of ONSD measurement, with an intraclass correlation coefficient of 0.9 [8].
Of the three articles utilizing POCUS to evaluate the posterior segment as a primary endpoint, two used sonographic intervention to evaluate retinal detachment (with sensitivity ranging from 75% to 91% and specificity ranging from 94% to 96%) [10,14] and one used sonographic intervention to diagnose retinal detachment, vitreous hemorrhage, or vitreous detachment (sensitivity was 96.9%, 81.9%, and 42.5%, respectively; specificity was 88.1%, 82.3%, and 96.0%, respectively) [15]. Of the three articles utilizing POCUS to grossly evaluate the globe and orbit, two used sonographic intervention to detect general orbital pathology and trauma, with sensitivity ranging from 34.42% to 97.8% and specificity ranging from 98.7% to 99.7% [12,16], and one used sonographic intervention to detect skull fracture, with a sensitivity of 93.7% and specificity of 96.8% [27].
DISCUSSIONOcular pathology can lead to significant disease burden [1,2], and there is recent and renewed interest and research in the utility of ocular POCUS in the emergency setting [31]. The present review is a synthesis of recently published work describing applications of ocular POCUS in the emergency setting with clearly defined and measurable study endpoints. The majority of the studies we identified focused on ONSD as a proxy for papilledema and metabolic aberrations, while a minority used ocular POCUS to assist in the diagnosis of orbital fractures or pathology of the posterior segment, orbit, and globe. In summarizing these findings, we contribute reference data to a growing body of evidence discussing the use of ocular POCUS in an emergency setting.
In recent years, ocular POCUS appears to have been especially effective in measuring ONSD as a proxy for changes in ICP and demonstrates good positive predictive value and specificity as a diagnostic tool for papilledema. This implies that POCUS is an adequate tool to emergently evaluate the effects of elevated ICP on the optic nerve, which include but are not limited to TBI, neoplasm, neurovascular compromise (e.g., cranial nerve compression or cerebrovascular ischemia), hemorrhage, and/or edema. Interestingly, emergent ocular POCUS appears to be equivocally efficacious in assessing ONSD as a novel proxy for DKA-associated cerebral edema. Emergent ocular POCUS also appears to be quite sensitive and specific for the detection of TBI [29], skull fracture [27], cerebrovascular ischemia [13,16], retinal pathology [10,14,15], and orbital trauma [12,16,27]. Notably, globe rupture is a contraindication for ocular POCUS as any pressure on the globe or adnexa in this circumstance can lead to vision-threatening reductions in intraocular pressure (hypotony) and subsequent irreversible vision loss [32]. Our findings suggest that ocular POCUS is an invaluable part of the diagnostic toolkit in managing ocular disease in the emergency setting. As such, we believe that the integration of ocular POCUS should be implemented as a standard of care workflow for diagnosis of posterior segment disease and papilledema in the emergency setting.
The use of ocular POCUS in the emergency setting has increased in recent years, enabling the evaluation of vision-threatening conditions before formal ophthalmology consultation and allowing expeditious screening of ocular pathologies requiring immediate consultation [31]. Despite the utility of ocular POCUS, some ED clinicians may defer its usage due to other pressing clinical tasks that obviate its widespread integration. To encourage the implementation of ocular POCUS into the emergency room workflow, healthcare institutions could consider the adoption of medical imaging committees to iteratively evaluate current approaches to ocular imaging. Ocular POCUS can be implemented as an initial screening tool while patients await evaluation with radiography or magnetic resonance imaging. The convenience and affordability of ocular POCUS offer benefits that should be considered in the development of clinical practice guidelines.
There are several limitations to this review. First, data on the reporting of other emergency ocular POCUS applications, such as diagnosis of full-thickness retinal detachment, were not specifically elicited. Second, our search criteria excluded nonprimary studies and studies not conducted in an ED. This restriction likely precluded a comprehensive synthesis of the known applications of emergency ocular POCUS, especially those for which there is robust empiric backing, such as diagnosis of posterior segment pathology. It may have also excluded the reporting of recently published papers describing new applications of ocular POCUS research, such as the use of POCUS-measured ONSD for neuroprognostication after resuscitation in patients undergoing cardiac arrest.
Additionally, the primary endpoints identified in the included articles differed, hindering quantitative comparison of study outcomes. This difference adds to the call for standardization of the design and reporting of future emergency ocular POCUS studies. Nonetheless, this review supports the continued development and implementation of ocular POCUS as a tool in the ED. A complete understanding of the clinical and economic implications of emergency ocular POCUS will inform the development of system-level initiatives that integrate this imaging technology to enhance patient care and clinician efficiency. Future studies should incorporate standardized implementation and reporting methods to ensure facile quantitative comparison and monitoring. In doing so, they can shed light on the true benefits and downsides of emergency ocular POCUS.
NOTESAuthor contributions
Conceptualization: AdS, MG, EH, SS, JCF, KD; Data curation: CDY, CKK, MMC, PK, APPB; Formal analysis: CDY, CKK, SS; Investigation: CDY, CKK, SS; Methodology: CDY, CKK, MMC, PK, APPB; Writing-original draft: CDY; Writing-review & editing: all authors. All authors read and approved the final manuscript.
Supplementary materialsSupplementary Table 1.Search terms (January 1, 2013–December 26, 2023)
Supplementary Table 2.Comprehensive summary of extracted data
Supplementary materials are available from https://doi.org/10.15441/ceem.24.249.
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Fig. 1.PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flowchart for article identification and selection. CENTRAL, Central Register of Controlled Trials; POCUS, point-of-care ultrasound. ![]() Table 1.Description of studies selected for review
LOE, level of evidence; ONSD, optic nerve sheath diameter; POCUS, point-of-care ultrasound; CT, computed tomography; ICP, intracranial pressure; DKA, diabetic ketoacidosis; NIHSS, National Institutes of Health Stroke Scale; MRI, magnetic resonance imaging; ACEP, American College of Emergency Physician; NA, not applicable. Table 2.Outcome measures and primary findings
MINORS, Methodological Index for Nonrandomized Studies; POCUS, point-of-care ultrasound; ONSD, optic nerve sheath diameter; VPS, ventriculoperitoneal shunt; CT, computed tomography; ICP, intracranial pressure; RD, retinal detachment; ED, emergency department; DKA, diabetic ketoacidosis; NIHSS, National Institutes of Health Stroke Scale; MRI, magnetic resonance imaging; OND, optic nerve diameter; ETD, eyeball transverse diameter; EVD, eyeball vertical diameter; NA, not available; TBI, traumatic brain injury. |
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