Standards Development Strategy for Glaucoma
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Overview
With the wide-scale deployment of electronic health records (EHRs) has come a corresponding surge in interest regarding the role of clinical data standards in representing data in those systems and facilitating the exchange of clinical data between them. This interest is well founded, as data standards are essential for the interoperability of clinical systems. The latter is essential to data harmonization, which is key to enabling clinical research with large, diverse datasets on a national or international scale. Given clinical data standards span the clinical and technical domains, their development requires the involvement of clinical and informatics experts.
Beyond the development of data standards, the identification of which standards are used to solve certain problems is key; it is easy to suboptimally use a given standard or redundantly resolve an issue with two different standards. To avoid these pitfalls, this document is intended to guide the field on which clinical and technical needs are best addressed by which standards. Below we summarize the relevant efforts in the field of glaucoma and summarize strategies for using each standard to advance glaucoma care and research.
Before continuing below, consider learning more about data standards:
Digital Imaging and Communications in Medicine (DICOM)
DICOM is one of our most mature data standards and has served the needs of medical imaging well over decades. Eye care has developed multiple DICOM supplements covering most of the in-office testing performed in our clinics.
Groups working on DICOM in eye care
DICOM has a very structured approach to standards development which is also fairly efficient (not the case for all standards!) DICOM Working Group 9 was created in 1999 to work on standards related to ophthalmology. Minutes from prior meetings are available to learn more about the work of this group.
Use of existing DICOM supplements
Available standards include those for data from automated perimetry (Supplement 146), ophthalmic photography (disc, macula, RNFL photos - Supplement 91), and ophthalmic tomography (OCT of RNFL, macula - Supplement 110). In addition, other supplements are available for generally used eye care measures related to biometry (Supplement 144), refractive measurements (Supplement 130), and corneal topography (Supplement 168). Many of these standards are in need of work to improve adoption.
Recommended development of new DICOM supplements
Given its history as a standard for representing medical images and the available supplements relevant to glaucoma, DICOM is our best option for storing and exchanging data produced by in-office testing used in glaucoma care. New measures of optic nerve structure and function should, therefore, be evaluated as potential DICOM standards when they become available and are likely to be widely used.
In addition to the development of new standards when needed, the field should pursue DICOM structured reports for key imaging metrics related to glaucoma. At this time, potential projects include structured reports for measures of the optic nerve head, peripapillary nerve fiber layer, and segmented macular thicknesses (full retinal thickness, ganglion cell complex, etc.)
Systematized Nomenclature of Medicine (SNOMED)
SNOMED is another mature standard focused on representing terminology related to medicine, including concepts (anatomy, pathophysiology, diseases, procedures, etc.) and the relationship between those concepts (a concept “is a” specific example of another: trabecular meshwork is a scleral structure, a concept can be a causative agent of another: the human herpes simplex virus causes HSV iritis). Given its maturity, SNOMED is widely implemented in clinical information systems as a means of organizing content for better search and linkage between data elements. As an example, one could search an EHR for glaucoma, and the search could return not only notes with the term “glaucoma” but also medications and procedures related to glaucoma. SNOMED is used in the Veterans Affairs (VA) Computerized Personal Record System (CPRS) as well as by large electronic health records systems.
With regard to eye care content in SNOMED, the American Academy of Ophthalmology worked to add terms to the standard starting in the early 2000’s. At the time, the AAO adopted SNOMED as its official terminology.
Groups working on SNOMED in eye care
As an overall effort to update eye care terminology in SNOMED, multiple subgroups began work in 2022. This work is coordinated under the Eye Care Clinical Reference Group of SNOMED. Current efforts are focused on updating terminology for glaucoma-related diagnoses and exam findings, although group members are also providing input on queries submitted regarding terms across various ophthalmic subspecialties.
Recommended updates to SNOMED
While concepts related to anatomy, pathophysiology, and pharmacology seem well represented, there is a need for more work on standardizing terminology related to exam findings as well as adding more specific diagnoses (e.g., adding “ocular hypertension” in addition to “glaucoma” for some conditions where nerve damage is not present). Including such terms will help the field by standardizing descriptions of important clinical findings, which could then serve as a template for EHR developers, thereby facilitating data exchange between those systems. This work will be challenging, as there is a high degree of variability in how clinicians document exam findings.
Some gaps in SNOMED that have been recently addressed in 2023 include defining methods of tonometry, creating concepts/terms for maximum intraocular pressure and target intraocular pressure, and creating concepts/terms for gonioscopic exam findings.
Fast Healthcare Interoperability Resources (FHIR)
Health Level 7 (HL7) is a non-profit data-standards organization focused on exchange, integration, sharing and retrieval of electronic health information. The most recent standard created by HL7 is FHIR. The focus of FHIR is facilitating clinical data exchange between systems, relying on modern, web-based application programming interfaces (APIs).
One important role of FHIR is as the standard used in the US to facilitate data exchange between electronic health records. This data exchange is also important to share electronic health information with auxiliary applications. For example, Information exchanged using FHIR can be coupled with CDS Hooks and SMART (Substitutable Medical Apps, Reusable Technology) applications to provide clinical decision support. FHIR is recognized by the US Core Data for Interoperability, an evolving standard of core clinical data elements.
Groups working on FHIR in eye care
While organized under the auspices of the HL7 organization, FHIR lacks some of the structured processes seen in DICOM. Given that, there has not been a coherent approach to FHIR standards related to eye care. One work group has proposed implementation guidance for some aspects of eye care.
Recommended updates to FHIR
Given its role as a means of data exchange between information systems, and the weight of US government regulation behind its use, additions to FHIR should focus on the role of FHIR for data exchange to/from EHRs. Given most of the data related to eye care are not relevant to other specialties, it may never be the case that a critical mass of eye care-related elements enter the mandatory USCDI standard. Recognizing this limitation, the US Office of the National Coordinator for Health IT has created an optional set of data elements that are housed under “USCDI+”. A short-term approach will be to help specify standards under an eye care-related section of USCDI+ (USCDI+Eye) that are most relevant to eye care while also serving a broader role in health care. Examples of such items likely includes visual acuity, intraocular pressure, and refractive error. While US EHR vendors would not be required to implement USCDI+Eye elements, their existence would signal their importance to those vendors, particularly in the eye care field.
Logical Observation Identifiers Names and Codes (LOINC)
LOINC is a commonly used standard for representing health observations and measurements. For instance, it is among the most commonly used standards for laboratory values. In eye care, LOINC is frequently used for representation of observations or measurements such as visual acuity and intraocular pressure. The representation of visual acuity in LOINC has considerable variability, with terms variably containing information regarding laterality, distance of measurement (e.g., near, intermediate, distance), whether correction was used, and method of measurement (e.g., Snellen, ETDRS, etc.). The National Eye Institute (NEI) Office of Data Science and Health Informatics, AAO data standards workgroup, and the OHDSI Workgroup in Eye Care & Vision Research are embarking on a systematic analysis of visual acuity representation in LOINC to reduce duplication and promote consistency of representation.
Observational Medical Outcomes Partnership (OMOP)
The Observational Health Data Sciences and Informatics (OHDSI) program is an interdisciplinary collaborative and open-source community to encourage data standardization and harmonization. OHDSI operates the Observational Medical Outcomes Partnership (OMOP) Common Data Model, a model that defines the structure and content of observational health data to facilitate data sharing and harmonization of EHR and other data across multiple sites. The Eye Care & Vision Research Workgroup is working on identifying gaps in the OMOP Common Data Model regarding ophthalmic data elements and working with OHDSI as well as source vocabulary organizations (e.g., LOINC, SNOMED) to address those gaps. An initial gap analysis conducted by workgroup members identified substantial missingness in the OMOP Common Data Model for data elements relevant to eye care.
International Classification of Disease (ICD)
The ICD system of codes is maintained by the World Health Organization and input is solicited as part of updates. There are currently no efforts to modify ICD codes.
Current Procedural Terminology (CPT)
CPT codes are maintained by the American Medical Association and are primarily used to facilitate billing in the US. Given their closed (as opposed to open) nature and lack of applicability outside the US, there are currently no efforts to augment CPT from a data standards perspective.
