Health informatics — Ophthalmic examination device data — Part 2: Specular microscope

This document specifies the data output formats for the specular microscope. The data are usually sent from the specular microscope to either an ophthalmic information system (OIS) or a hospital information system (HIS). This document addresses text-based analysis reporting of the specular microscope measured and analysed data such as the central corneal thickness, the density of endothelial cells per 1 mm2, the coefficient variant, and the ratio of endothelial cells with a hexagonal shape.

Informatique de santé — Données relatives aux dispositifs d'examen ophtalmique — Partie 2: Microscope spéculaire

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Status
Published
Publication Date
04-Jan-2023
Current Stage
6060 - International Standard published
Due Date
31-Aug-2023
Completion Date
05-Jan-2023
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TECHNICAL ISO/TS
SPECIFICATION 22218-2
First edition
2023-01
Health informatics — Ophthalmic
examination device data —
Part 2:
Specular microscope
Informatique de santé — Données relatives aux dispositifs d'examen
ophtalmique —
Partie 2: Microscope spéculaire
Reference number
ISO/TS 22218-2:2023(E)
© ISO 2023
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ISO/TS 22218-2:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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© ISO 2023 – All rights reserved
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ISO/TS 22218-2:2023(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction .................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 Specifications .......................................................................................................................................................................................................... 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 deviceCDA and persistent examination reports ....................................................................................................... 3

4.3 Data classification constitution in the file ..................................................................................................................... 4

4.4 OEDD structure ...................................................................................................................................................................................... 5

4.4.1 General ........................................................................................................................................................................................ 5

4.4.2 Data classifications .......................................................................................................................................................... 5

4.4.3 Attribute value and classification ....................................................................................................................... 5

4.4.4 Handling of common data .......................................................................................................................................... 6

4.4.5 Handling of ophthalmic examination data .................................................................................................. 8

4.4.6 Handling of units of measurement ..................................................................................................................... 9

4.5 OEDD XML schema .............................................................................................................................................................................. 9

Annex A (informative) Use cases of specular microscope .........................................................................................................11

Annex B (informative) Standard codes used for common data ...........................................................................................13

Annex C (informative) Standard codes for ophthalmic examination data ..............................................................14

Annex D (informative) Sample files ...................................................................................................................................................................19

Bibliography .............................................................................................................................................................................................................................35

iii
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ISO/TS 22218-2:2023(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 215, Health informatics.

A list of all parts in the ISO 22218 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www.iso.org/members.html.
© ISO 2023 – All rights reserved
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ISO/TS 22218-2:2023(E)
Introduction

Ophthalmic devices are used in hospitals and clinics to examine patients. The primary devices used in

these ophthalmic examinations provide the measurement of refraction, corneal curvature, intraocular

pressure, lens power, and visual acuity. Almost all patients who consult for a diagnosis in ophthalmology

undergo these examinations.

Besides such general ophthalmic devices, specular microscopes are often used to capture and analyze

an image of the corneal endothelium, which dehydrates the corneal stroma and maintains the cornea’s

clarity. Thus, measuring the cell density of the corneal endothelium is one of the most crucial and reliable

methods to determine its condition. The analysis results of the specular microscope are indispensable

for not only patients experiencing trouble in the cornea but also safe prescriptions for contact lenses.

Like other ophthalmic devices, various manufacturers supply specular microscopes. Thus, standardized

procedures for mutually communicating analysis results are crucial between the specular microscope

and ophthalmic information system (OIS).

However, the integration of this information is complex and potentially error-prone owing to variable

data formats provided by specular microscopes from different manufacturers and the lack of

interoperability. Thus, the integration of analysis results from various specular microscopes into an

OIS or hospital information system (HIS) warrants significant individual effort for each manufacturer’s

specular microscope.

This document specifies the content and format for the analysis results of specular microscopes,

identifying the information that could be included in the analysis results, as well as how it should be

formatted when communicated to an OIS, HIS, or other similar systems.
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TECHNICAL SPECIFICATION ISO/TS 22218-2:2023(E)
Health informatics — Ophthalmic examination device
data —
Part 2:
Specular microscope
1 Scope

This document specifies the data output formats for the specular microscope. The data are usually

sent from the specular microscope to either an ophthalmic information system (OIS) or a hospital

information system (HIS).

This document addresses text-based analysis reporting of the specular microscope measured and

analysed data such as the central corneal thickness, the density of endothelial cells per 1 mm , the

coefficient variant, and the ratio of endothelial cells with a hexagonal shape.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
corneal endothelium
monolayer of endothelial cells that constitutes the posterior corneal surface

Note 1 to entry: The corneal endothelium dehydrates the corneal stroma and maintains the cornea’s clarity.

Note 2 to entry: Measuring the endothelial cell density provides valuable information about the cornea’s

condition.
3.2
endothelial cell density

number indicating how many endothelial cells are present in one square millimeter (mm )

Note 1 to entry: This value is often referenced to determine the condition of the corneal endothelium. If the

corneal endothelium is young and healthy, the value is high, and if the corneal endothelium is old and damaged,

the value is low.
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ISO/TS 22218-2:2023(E)
3.3
coefficient of variation

ratio of the standard deviation to the mean in cell size, which is standardized measure of the dispersion

of the size of each endothelial cell

Note 1 to entry: This value is often referenced to determine the condition of the corneal endothelium, owing to

uniform cell size, healthy corneal endothelium has a small CV value.
3.4
hexagonality
HEX
morphology of endothelial cells, usually the percentage of hexagonal cells

Note 1 to entry: This value is often referenced to determine the condition of the corneal endothelium. Cells of

healthy corneal endothelium have uniform size and are primarily hexagonal.
3.5
dry eye
disease in which the stability of the tear film is reduced
3.6
Fuchs’ dystrophy

slowly progressing corneal dystrophy in which fluid builds up and the cornea gets swollen and puffy

3.7
bullous keratopathy
eye disorder due to oedema that involves a swelling of the cornea
3.8
ophthalmic information system
OIS

computer system that acquires, stores, retrieves and manages ophthalmic images and examination data

Note 1 to entry: The OIS gather and manage examination information from various ophthalmic devices and

submit persistent examination reports in CDA RMIM format to HIS.
[SOURCE: ISO/TS 22218-1:2022, 3.19]
3.9
deviceCDA

subset of the CDA RMIM dataset that only includes the information contained in a device

Note 1 to entry: Most ophthalmic examination devices do not support all the mandatory information required by

a complete CDA document, such as patient or operator identification, and additional information can be accessed

after the report is sent to an OIS or HIS.
[SOURCE: ISO/TS 22218-1:2022, 3.20]
3.10
hospital information system
HIS

comprehensive, integrated information system designed to manage all the aspects of a hospital's

operation

Note 1 to entry: In many implementations, a HIS covers hospital's operation such as medical, administrative,

financial, and legal issues and the corresponding processing of services.
[6]
[SOURCE: IS4H-MM ]
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ISO/TS 22218-2:2023(E)
4 Specifications
4.1 General

OEDD provides standards both for transferring clinical ophthalmic examination data from various

types of examination devices to an OIS, as well as submitting persistent reports based on those

examination data from an OIS to a HIS. The specular microscope is one such examination device.

Exemplary use cases are detailed in Annex A.

It is possible to handle multiple data types such as SPECULAR (Specular microscope), REF

(Refractometer), KM (Keratometer), TM (Tonometer), LM (Lensmeter), and PHOR (Phoroptor) within

one XML file. It is acceptable to compile SPECULAR, REF, KM, TM, LM, and PHOR in one file or separate

them into different files. Within the file, is the top tag in accordance with the rules

for CDA.

REF (Refractometer), KM (Keratometer), TM (Tonometer), LM (Lensmeter), and PHOR (Phoroptor) are

also ophthalmic examination devices described in this document.
For details, see 4.3.

The standard codes used in this document are shown in Annex C, and a sample XML file is shown in

Annex D.
4.2 deviceCDA and persistent examination reports

Most OEDD devices only output examination data and related information, and cannot provide

additional data items such as Patient, Operator, Custodian, and Authentication.

For such devices, OEDD introduces deviceCDA, a strict subset of CDA, that allows devices to transfer

examination data and related information as a deviceCDA dataset without the additional detailed

patient identification information that is required in complete CDA documents.

OIS plays the role of receiving examination data and related information as a deviceCDA dataset from

a device and then submitting a persistent examination report to a HIS with additional information

required for the complete CDA dataset.

deviceCDA is not a complete CDA dataset but still conforms to the same syntax. OIS, therefore, prepares

a complete OEDD that includes the CDA RMIM dataset with information such as Patient, Operator,

Custodian, and Authentication, and inserts the deviceCDA dataset received from the device into the

OEDD. (See Figure 1)
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ISO/TS 22218-2:2023(E)
Figure 1 — Concept of a deviceCDA
4.3 Data classification constitution in the file

Both a deviceCDA and a complete CDA file has and as

the top tag.

It is possible to collect information from all the OEDD classifications into one file, or they can be separated

into different deviceCDA/Complete CDA files. In the case of a single composite OEDD deviceCDA/

Complete CDA document, the data tags that are common across the devices shall be specified once, and

the OEDD data tags integrated separately. Table 1 shows some examples of such deviceCDA File data

block layouts. Data tags of REF, KM, RM, LM, and PHOR are stored in the file together with SPECULAR.

Implementations may encounter data classifications that are not included in the OEDD specification (e.g.

private extensions), in which case, implementations shall ignore non-recognized data classifications

and process the known data classifications accordingly.
Table 1 — Example deviceCDA file data block layouts
Common Data Common Data Common Data Common Data

SPECULAR Data SPECULAR Data SPECULAR Data TM Data




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ISO/TS 22218-2:2023(E)
TTabablele 1 1 ((ccoonnttiinnueuedd))
TM Data REF Data KR Data





TM Data SPECULAR Data





LM Data PHOR Data





File 1 File 2 File 3 File 4
4.4 OEDD structure
4.4.1 General

This specification is compliant with CDA-R2. For this reason, the complete detailed file structure can be

[6]
reviewed in HL7 CDA® Release 2 .
In this document, only descriptions particular to ophthalmology are included.
4.4.2 Data classifications

The data classifications of refractometer, keratometer, tonometer, and such are maintained as attribute

value (type) of tags.
4.4.3 Attribute value and classification
Table 2 shows ophthalmic examination device data classification values.
Table 2 — OEDD device classification values
Attribute value (code) Data classification
100066-0 Specular microscope data

Figure 2 shows the example of specular microscope data (SPECULAR) that uses a LOINC® code.

1) LOINC is the registered trademark of Regenstrief Institute. This information is given for the convenience of

users of this document and does not constitute an endorsement by ISO of the product named.

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ISO/TS 22218-2:2023(E)
Figure 2 — OEDD section tags
4.4.4 Handling of common data
4.4.4.1 General

Common data such as ophthalmic examination title are described in the CDA Header part between the

tag and < structuredBody>. This common data will be present only once in a file.

4.4.4.2 Common data tags
Table 3 shows available Common data tags.
Table 3 — Common data tags
Tag name Description Necessity
ClinicalDocument CDA-R2 D
Type ID. The compliant D
typeId CDA R2 specifications are
identified.
ID for unique identifica- D
id tion specified at hospitals,
etc. or groups
A code that represents the D
code
reporting category
Ex) Ophthalmic exami- D
title
nations
Date & time of the creation C
effectiveTime of the file (yyyymmddh-
hmmss)
Confidentiality level code. D
The confidentiality value
in the HL7 vocabulary do-
confidentialityCode
main is used
Ex) code="N"
languageCode D
languageCode
Ex) code="jpn"
versionNumber Document version number D
recordTarget Patient D
patientRole Patient information D
The items in the Necessity column have the following meanings:
D - Tags and values are necessary for both Complete CDA and deviceCDA
C - Tags and values are necessary for Complete CDA
O - No tags or values are necessary
Multiple settings are allowed for Patient No. Also, nullFlavor="NI" is allowed.

Multiple settings are allowed for the Patient names. If First name and Last name cannot be separated, the Last name

should be entered in the First name section. Also, nullFlavor="NI" is allowed.
Refer to "Annex B".
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ISO/TS 22218-2:2023(E)
TTabablele 3 3 ((ccoonnttiinnueuedd))
Tag name Description Necessity
Patient No. D
(number of the order of
id b
examination)
Ex) extension="123456"
patient Patient name C
name Alphabetic expression C
family family name C
given Given name C
Regional ideographic or O
name
phonetic name
family family name O
given Given name O
Patient's sex C
administrativeGenderCode
EX) F/M/UN
Patient’s date of birth C
birthTime
(yyyymmdd)
author Author D
Date & time of the creation D
time
(yyyymmddhhmmss)
Information of the organ- D
assignedAuthor ization that prepares the
document.
Assigned author ID D
id
"NI": If id is none
assignedAuthoringDevice Assigned authoring device D
Model name and No. for D
manufacturerModelName distinction among the
devices of the same model
softwareName Software and ROM version D
representedOrganization Represented organization C
Represented organiza- C
tion ID
id
"NI": If id is none
name Company name C
custodian custodian C
assignedCustodian Assigned custodian C
Represented custodian C
representedCustodianOrganization
organization
The items in the Necessity column have the following meanings:
D - Tags and values are necessary for both Complete CDA and deviceCDA
C - Tags and values are necessary for Complete CDA
O - No tags or values are necessary
Multiple settings are allowed for Patient No. Also, nullFlavor="NI" is allowed.

Multiple settings are allowed for the Patient names. If First name and Last name cannot be separated, the Last name

should be entered in the First name section. Also, nullFlavor="NI" is allowed.
Refer to "Annex B".
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ISO/TS 22218-2:2023(E)
TTabablele 3 3 ((ccoonnttiinnueuedd))
Tag name Description Necessity
Represented custodian C
organization ID
id
"NI": If id is none
documentationOf Operator C
serviceEvent code C
serviceEvent
EX) classCode="ACSN"
code serviceEvent code C
performer type code C
performer
EX) typeCode="PRF"
Function code C
functionCode
EX) code="SNRS"
assignedEntity assignedEntity C
id Operator ID C
The items in the Necessity column have the following meanings:
D - Tags and values are necessary for both Complete CDA and deviceCDA
C - Tags and values are necessary for Complete CDA
O - No tags or values are necessary
Multiple settings are allowed for Patient No. Also, nullFlavor="NI" is allowed.

Multiple settings are allowed for the Patient names. If First name and Last name cannot be separated, the Last name

should be entered in the First name section. Also, nullFlavor="NI" is allowed.
Refer to "Annex B".
4.4.5 Handling of ophthalmic examination data
4.4.5.1 General

Examination data are described in the section of the deviceCDA as follows:




---(Refer to 4.4.5.2 for detail content)



4.4.5.2 Ophthalmic examination data tags
Table 4 shows basic composition of tags used for ophthalmic examination data:
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ISO/TS 22218-2:2023(E)
Table 4 — Ophthalmic examination data tags
Tag name Description Necessity
component CDA-R2 component D
structuredBody D
Examination tag defined here -
Component CDA-R2 component D
section section D
LOINC's Exam Details Code D
code
EX) Set code of LOINC for SPECULAR: "100066-
examination title D
title
(HTML format)
text detail of examination D
entry D
Ex) classCode="OBS" moodCode="EVN" D
observation
(OBS=observation, EVN=examination results)
Examination code D
code
Ex) Magnification= "100067-8"
Date & time of the creation of the file (yyyym- D
effectiveTime
mddhhmmss)
entry D
Ex) classCode="OBS" moodCode="EVN" D
observation
(OBS=observation, EVN=examination results)
entryRelationship Detailed examination data D
Ex) classCode="OBS" moodCode="EVN" D
observation
(OBS=observation, EVN=examination results)
Examination code D
code
Ex) Cell Density Right= "100070-2"
value examination data & unit D
Ex) ID=”IMAGE1” classCode="OBS" mood- D
observationMedia
Code="EVN"
value Ex) mediaType="image/png" D
Ex) value="01_20150702_123821_A_R_EN- D
reference
HANCE.png
The items in the Necessity column have the following meanings:
D - Tags and values are necessary for both Complete CDA and deviceCDA.
O - No tags or values are necessary

Refer to Annex C for detail of examination data measured by each ophthalmic examination device.

4.4.6 Handling of units of measurement

The unit of measurement for numerical data is described as attribute value "unit".

ex)
4.5 OEDD XML schema
To comply with CDA-R2, CDA.XSD is designated as XML Schema.
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ISO/TS 22218-2:2023(E)
Ex) At the tag, it is designated as an attribute as follows.

xmlns: xsi = "https:// www .w3 .org/ 2001/ XMLSchema -instance" xmlns="urn: hl7 -org: v3">

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ISO/TS 22218-2:2023(E)
Annex A
(informative)
Use cases of specular microscope
A.1 Outline of specular microscope

Specular microscopes are often used to capture and analyze an image of the corneal endothelium, which

dehydrates the corneal stroma and maintains the cornea’s clarity. Thus, measuring the cell density

of the corneal endothelium is one of the salient and reliable non-invasive methods used to determine

its condition. For observing corneal endothelial cells, specular microscopes have been introduced in

almost all ophthalmic clinics. The analysis results of the specular microscope are indispensable for

not only patients experiencing problems in the cornea but also anyone who holds contact lenses safety

prescriptions. An image is occasionally attached to analysis results as a reference. This however is not

for analysis purposes but for providing physicians with the idea that the detected boundary lines are

acceptable.
A.2 Avoid surgically induced damage

Corneal endothelial cells do not regenerate, and they decrease with age, Fuchs’ corneal dystrophy, and

surgery. When the average density of corneal endothelial cells is ≤1 000 cells/mm , homeostasis cannot

be maintained.

The analysis data of specular microscopes provide evidence for determining whether it is safe to

perform cataract surgery, which causes additional loss of endothelial cells. In addition, it is used as

a postoperative monitoring device for cataract surgery. Thus, the specular microscope is essential

for surgical planning to avoid complications such as postoperative corneal opacification. The corneal

endothelium damages due to dry eye, Fuchs’ dystrophy, and epithelial basement membrane dystrophy

before surgery can also decrease the potential for positive surgical outcomes.

Reportedly, Fuchs’ corneal endothelial dystrophy has a potential prevalence of approximately 5 % in

Europe and the United States. If it decreases further, it causes bullous keratopathy, which causes vision

loss and eye pain. To estimate the prognosis of surgery, evaluation is indispensable before and after

surgery, such as cataract surgery.

Another benefit of checking the corneal endothelium often is to decide a better suitable approach

for cataract surgery. Occasionally, a less traumatic approach, such as a new femtosecond-phaco with

reduced phaco energy, should be chosen rather than conventional cataract surgery.

A.3 Postoperative evaluation and follow-up

Bullous keratopathy, which develops owing to a decrease in corneal endothelial cells, is a major cause

of corneal transplantation. In recent years, corneal endothelial transplantation and the injection of

cultured corneal endothelial cells have also been performed.

To evaluate this therapeutic effect, it is necessary to compare data over a more extended period than

ever before. Besides, there will be an international evaluation of new treatments. Further demands are

for specular microscope data interoperability, persistence, and international standards.

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ISO/TS 22218-2:2023(E)
A.4 Safe use of contact lenses
Periodic checking of the corneal endotheli
...

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