With the widespread adoption of electronic health records (EHR), interest in the role of clinical data standards has rapidly increased. Data standards are essential for interoperability of clinical systems and enable large-scale, diverse datasets for clinical research at national and international levels.
In glaucoma care, various examination data such as visual field tests, OCT, intraocular pressure measurements, and fundus photography are generated 1)2). To accurately exchange and harmonize these data across systems, development and proper use of data standards spanning both clinical and informatics domains are necessary.
This strategy is a guide indicating which standard is optimal for which clinical and technical needs. It aims to avoid inappropriate use of a specific standard or redundant resolution of a single problem with two different standards.
Clinical data standards are common specifications for accurately exchanging and sharing data between different EHR systems. Without standardization, data would be recorded in different formats at each facility, making multi-center collaborative research and large-scale data analysis difficult. In glaucoma care, multiple examination data such as visual field tests, OCT, and intraocular pressure need to be managed over the long term, and ensuring interoperability directly improves care quality and advances research.
| Standard | Main Role | Relevance to Glaucoma |
|---|---|---|
| DICOM | Storage and exchange of medical images | OCT, visual field, fundus photography |
| SNOMED | Medical terminology representation | Diagnosis names, test findings |
| FHIR | Inter-system data exchange | Information sharing between EHRs |
DICOM is the most mature medical imaging standard, having met the needs of medical imaging for decades. In 1999, DICOM Working Group 9 was established for ophthalmic standardization.
Existing ophthalmic DICOM supplements
Supplement 146: Standardization of automated perimetry data
Supplement 91: Ophthalmic photography (optic disc, macula, RNFL photographs)
Supplement 110: Ophthalmic tomography (OCT of RNFL and macula)
Supplements 144/130/168: Biometry, Refraction Measurement, Corneal Topography
Recommended New Developments
DICOM Structured Reports: Standardized report format for measurements of the optic nerve head, peripapillary RNFL, and macular retinal thickness
Response to New Measurement Methods: When new measurement methods for optic nerve structure and function are expected to be widely used, they should be evaluated as DICOM supplements
Promotion of Dissemination: Many existing supplements require further efforts to promote dissemination
DICOM is the optimal choice for storing and exchanging in-hospital examination data used in glaucoma care.
SNOMED is a mature standard that systematizes medical terminology concepts and their relationships. It is widely implemented in EHRs as a means to improve search and organize linkages between data elements.
The American Academy of Ophthalmology (AAO) has been working on adding terms to SNOMED since the early 2000s and has adopted SNOMED as its official terminology. In 2022, work began on updating ophthalmic terminology under the Eye Care Clinical Reference Group.
Recommended Updates:
In 2023, the definition of intraocular pressure measurement methods, creation of concepts for maximum and target intraocular pressure, and creation of terms for gonioscopy findings were completed.
FHIR is the latest data exchange standard created by Health Level 7 (HL7). It facilitates clinical data exchange between systems using modern web-based APIs. In the United States, it has been adopted as the standard for data exchange between EHRs.
Information exchanged using FHIR can be combined with CDS Hooks and SMART applications to provide clinical decision support.
Recommended Items for USCDI+Eye
Visual acuity: Important ophthalmology-related data in general healthcare
Intraocular pressure: Basic indicator for glaucoma management1)2)
Refractive error: Data relevant to a wide range of ophthalmic practice
Position of USCDI+: Not mandatory, but serves as a signal to EHR vendors about importance
Challenges of FHIR in Ophthalmology
Lack of structured processes: A systematic approach like that seen in DICOM has not yet been established
Limitations of ophthalmology-specific data: Many ophthalmic data are unrelated to other specialties, making it difficult to be widely adopted as mandatory standards in USCDI
Implementation guidance: A workgroup is currently proposing implementation guidance for several aspects of ophthalmic care
Integration with EHRs: Additional FHIR elements should focus on their role in data exchange with EHRs
LOINC is a standard for representing health-related observations and measurements. It is frequently used in ophthalmic care to represent visual acuity and intraocular pressure.
There is currently considerable variation in how visual acuity is represented in LOINC, with inconsistent inclusion of information about laterality, measurement distance, correction status, and measurement method. The National Eye Institute (NEI), the AAO Data Standards Workgroup, and the OHDSI Ophthalmic Care and Vision Research Workgroup have begun a systematic analysis to reduce duplication and improve consistency.
The OMOP Common Data Model, operated by the OHDSI (Observational Health Data Sciences and Informatics) program, facilitates the sharing and harmonization of EHR data across multiple institutions. The Eye Care and Vision Research Working Group is working to identify gaps in OMOP regarding ophthalmic data elements, and initial analysis has identified substantial deficiencies.
ICD (International Classification of Diseases): A coding system maintained by WHO, with opportunities for public comment during updates. Currently, there are no specific activities addressing glaucoma-related revisions.
CPT (Current Procedural Terminology): A billing code set maintained by the American Medical Association. Due to its proprietary nature and limited international applicability, no extensions have been made from a data standardization perspective.
It is important to use different standards depending on the purpose. DICOM is optimal for storing and exchanging in-hospital examination data (OCT, visual field, fundus photography). SNOMED is used for terminology representation of diagnoses and examination findings. FHIR is recommended for data exchange between EHRs. LOINC is used for representing test measurements, and the OMOP Common Data Model is used for harmonizing multi-institutional data. Rather than trying to cover everything with a single standard, it is important to leverage the strengths of each standard appropriately.
Standardization of clinical data for glaucoma is progressing rapidly, but the following challenges remain.
The development of clinical data standards provides the foundation for large-scale clinical studies, registry research, and AI-based diagnostic support systems for glaucoma. Continuous collaboration between clinical experts and informatics specialists is essential.
- 日本緑内障学会. 緑内障診療ガイドライン（第5版）. 日眼会誌. 2022;126:85-177.
- European Glaucoma Society. Terminology and Guidelines for Glaucoma, 6th Edition. Br J Ophthalmol. 2025.
