Glaucoma data standards are common standards for describing and communicating diagnostic test results, findings, diagnoses, and image data in glaucoma clinical practice and research. Although the widespread use of electronic health records (EHR) has improved access to clinical data, data sharing between EHR and picture archiving and communication systems (PACS) remains a major challenge.
The need for data standardization is driven by the following three factors.
Efficiency of clinical practice: In busy glaucoma clinics, it is necessary to compare visual field and OCT results of many patients daily with past data. By extracting indices such as mean deviation and pattern standard deviation from visual field and OCT and integrating them into electronic health records, they can be displayed alongside intraocular pressure and visual acuity history.
Integration of research data: In large multicenter studies, data from hundreds to thousands of individual patients must be extracted from multiple EHR and PACS and converted into a common format. In studies using machine learning, data from diverse and geographically broad patient populations is required to avoid bias in training data.
Reduction of medical waste: The PPP for primary open-angle glaucoma recommends retesting for unreliable test results 3). Without standardized transmission of visual field and OCT measurements, unnecessary duplicate testing may occur at referral sites.
Longitudinal comparison of multiple imaging tests such as visual field testing and OCT is essential for glaucoma follow-up. However, currently, clinical data stored in EHRs and image data stored in PACS are often separated. Additionally, there is no compatibility of measurements between different OCT devices 1)2), making it difficult to achieve multicenter research and efficient clinical workflows without data standardization.
DICOM (Digital Imaging and Communications in Medicine) is an international standard for communicating medical imaging examinations and their results. All EHR and PACS software is required to be DICOM compliant. It supports storage of raw image data, calculated indices from examinations, and creation of structured reports.
The main DICOM supplements related to glaucoma are shown below.
| Supplement | Year | Subject |
|---|---|---|
| 110 | 2007 | Retinal nerve fiber layer (RNFL) and anterior chamber angle examination |
| 146 | 2010 | Storage and representation of visual field data |
| 152 | 2011 | RNFL thickness measurement |
Supplement 146 standardizes quality indicators such as fixation loss and false positive rate, foveal sensitivity, mean sensitivity, and mean deviation. In 2025, Supplement 247 was published, adding structured data fields for structured reporting documents and DICOM encapsulated PDFs.
Currently, there is no DICOM standard for structured optic nerve OCT measurements. Supplement 143 (2008) exists for macular grid thickness and volume.
SNOMED-CT
Full name: Systematized Nomenclature of Medicine — Clinical Terms
Purpose: Comprehensive coding of medical concepts
Features: Assigns a unique code to each concept, links related concepts, and is continuously maintained
Glaucoma example: “Glaucoma (disorder)” = SCTID 23986001
Usage: A 2005 study showed the broadest coverage in ophthalmology
LOINC
Full name: Logical Observation Identifiers Names and Codes
Purpose: Standardization of clinical measurements for transmission between devices
Features: Provides six dimensions (component, attribute, time, system, scale, method) for each observation
Glaucoma case: Right eye intraocular pressure = LOINC 79892-6
Target: Measurements of visual acuity, intraocular pressure, corneal thickness, visual field, and RNFL thickness
OMOP CDM (Observational Medical Outcomes Partnership Common Data Model) is a common data model maintained by the OHDSI (Observational Health Data Sciences and Informatics) program. It standardizes the structure and content of observational data, enabling efficient multi-site research analysis. The US “All of Us” research program converts EHR data into OMOP CDM.
The OHDSI Eye Care & Vision Research Workgroup is promoting the development of data standards in ophthalmology.
With a DICOM-compliant perimeter, visual field indices such as MD and PSD can be stored and communicated in a structured format. Data can be integrated into the EHR via a DICOM-compliant PACS and displayed alongside changes in intraocular pressure and visual acuity over time. It also facilitates data comparison across institutions and data provision for large-scale studies.
Visual field testing is a key diagnostic test for evaluating glaucoma progression. The DICOM “Ophthalmic Perimetry (OPV) File Format” has become the gold standard for storing and communicating visual field results.
Major perimeters include the Zeiss Humphrey Field Analyzer 3 (HFA3) and the Haag-Streit Octopus 900, each offering different test strategies, patterns, and indices. The HFA3 reports test strategies such as SITA Standard/Fast/Faster and indices such as VFI, MD, PSD, and GHT.
OCT is widely used as a quantitative imaging assessment in glaucoma diagnosis 1)2). Three parameter groups are measured and analyzed: the optic nerve head, peripapillary retinal nerve fiber layer, and macular inner layers 2).
However, OCT measurements have important limitations.
No interoperability between devices: Spectral-domain OCT and swept-source OCT differ in technical characteristics, software, and reference databases, so values measured with different OCT devices are not interchangeable 1)2). This is one of the key motivations for data standardization.
Limitations in advanced stages: In advanced glaucoma, a floor effect occurs, and further disease progression is no longer reflected as thinning of the retinal nerve fiber layer or macular parameters 1). Macular parameters show a later onset of the floor effect compared to retinal nerve fiber layer thickness.
Segmentation errors: In high myopia or tilted optic discs, artifacts and software segmentation errors are more likely to occur 1). Clinicians need to evaluate image quality and the validity of segmentation analysis.
Diagnosis of glaucoma based solely on a single test result should be avoided 1).
Retinal nerve fiber layer thickness and macular inner layer thickness values measured with different OCT devices are not interchangeable 1)2). This is because each device has different technical specifications, analysis software, and normative databases. It is recommended to continue using the same device for follow-up. In the future, the widespread adoption of data standards is expected to enable comparison of data across different devices.
In February 2024, glaucoma researchers and informatics experts from 10 academic institutions in the United States held an online workshop to share current practices and challenges in large-scale extraction of visual field and OCT data.
Dr. Xu from the University of Southern California (USC) reported the challenge that the PACS system stores each visual field test as a separate PDF, preventing batch access. A method to extract visual field indices from PDFs using a Python OCR algorithm developed by Dr. Saifee was introduced.
Dr. Wang from Stanford University reported that export in XML or DICOM format is now possible using the Advanced Data Export (ADE) tool of FORUM (Zeiss data management system). Alignment with the standard format of SOURCE (Sight Outcomes Research Collaborative), a large multicenter repository, is underway.
Data standardization in the glaucoma field is expected to develop in the following directions.
