EN ISO 10942:1998
(Main)Ophthalmic instruments - Direct ophthalmoscopes (ISO 10942:1998)
Ophthalmic instruments - Direct ophthalmoscopes (ISO 10942:1998)
Specification of minimum requirements in order to guarantee a sufficient quality of use.
Ophthalmische Instrumente - Direkte Ophthalmoskope (ISO 10942:1998)
Diese Internationale Norm legt zusammen mit ISO 15004 Mindestanforderungen und Prüfverfahren für direkte Ophthalmoskope in Form von Handgeräten fest, die dazu dienen, den Hintergrund des Auges im aufrechten Bild zu beobachten. Wenn Unterschiede vorliegen, hat diese Internationale Norm Vorrang vor ISO 15004.
Instruments ophtalmiques - Ophtalmoscopes directs (ISO 10942:1998)
Oftalmični instrumenti - Direktni oftalmoskopi (ISO 10942:1998)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 10942:2000
01-januar-2000
2IWDOPLþQLLQVWUXPHQWL'LUHNWQLRIWDOPRVNRSL ,62
Ophthalmic instruments - Direct ophthalmoscopes (ISO 10942:1998)
Ophthalmische Instrumente - Direkte Ophthalmoskope (ISO 10942:1998)
Instruments ophtalmiques - Ophtalmoscopes directs (ISO 10942:1998)
Ta slovenski standard je istoveten z: EN ISO 10942:1998
ICS:
11.040.70 Oftalmološka oprema Ophthalmic equipment
SIST EN ISO 10942:2000 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 10942:2000
INTERNATIONAL ISO
STANDARD 10942
First edition
1998-05-01
Ophthalmic instruments — Direct
ophthalmoscopes
Instruments ophtalmiques — Ophtalmoscopes directs
A
Reference number
ISO 10942:1998(E)
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ISO 10942:1998(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.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75% of the member bodies casting
a vote.
International Standard ISO 10942 was prepared by Techncial Committee
ISO/TC 172, Optics and optical instruments, Subcommittee SC 7,
Ophthalmic optics and instruments.
Annex A forms an integral part of this International Standard. Annexes B
and C are for information only.
© ISO 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet central@iso.ch
X.400 c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
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INTERNATIONAL STANDARD ISO ISO 10942:1998(E)
Ophthalmic instruments — Direct ophthalmoscopes
1 Scope
This International Standard, together with ISO 15004, specifies minimum requirements and test methods for hand-held
direct ophthalmoscopes designed for directly observing the eye fundus.
This International Standard takes precedence over the ISO 15004, if differences exist.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision,
and parties to agreements based on this International Standard are encouraged to investigate the possibility of
applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of
currently valid International Standards.
ISO 15004:1997
Ophthalmic instruments - Fundamental requirements and test methods
IEC 60601-1:1988
Medical eletrical equipment - Part 1: General requirements for safety
3 Definitions
For the purposes of this International Standard, the following definitions apply.
3.1
ophthalmoscope
optical instrument used to examine the external and internal parts of the eye, particularly the media and the fundus
3.2
direct ophthalmoscope
ophthalmoscope which provides an illuminating system, a viewing system and corrective lenses which allow the
observer to view the patient's eye directly, that is without the formation of an intermediate image
3.3
viewing lens
lens which is positioned between the observer's eye(s) and the eye to be examined in order to achieve optimum focus,
i.e. to correct for patient's and/or observer's refractive error and/or accommodation
NOTE - In direct ophthalmoscopes when a selection of such lenses is required, these are integrated with or mounted in a
disc or other mechanical means by which the user may easily position the lens of choice centrally in the visual path.
1
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3.4
auxiliary lens
additional corrective lens to facilitate access to higher refractive powers without requiring an excessive numbers of
lenses
NOTE - Auxiliary lenses are normally integral with or mounted on a separate disc or other mechanical means and when
required are used in conjunction with the viewing lenses.
3.5
ophthalmoscope graticule
pattern or target or graticule which can be optionally positioned in the illuminating light path within the instrument and
which will be imaged on the retina for diagnostic, measurement or therapeutic purposes
NOTE - These can be fixed or focusable.
3.6
illuminating system
light source and associated lenses, mirrors and/or prism which serve to provide and project light into or onto the
patient's eye
3.7
viewing system
those lenses and apertures which enable the observer to examine the patient's eye
3.8
field of view
angular field which is visible to a user when the entrance pupil is 12 mm behind the back surface of the
ophthalmoscope, measured from the centre of the entrance pupil
See 6.1.3 and figure 1.
3.9
field of illumination
angular field which is illuminated and which is measured with its apex positioned at the image of the light source
4 Classification
Direct ophthalmoscopes shall be classified as follows:
Group A: Direct ophthalmoscopes that comply with all the requirements of this International Standard.
Group B: Direct opthalmoscopes that comply with the reduced requirements specified in table 1 and all other
requirements specified in this International Standard except those in 5.4.2 and 5.4.4.
5 Requirements
5.1 General
The direct ophthalmoscope shall conform to the requirements specified in ISO 15004.
The direct ophthalmoscope shall conform to the specific requirements specified in 5.2 to 5.5.
These requirements are verified as specified in clause 6.
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5.2 Optical requirements
The requirements specified in table 1 and table 2 shall apply.
Table 1 — Requirements for optical specifications
Criterion Requirements
Group A Group B
Steps for the powers of viewing 0, +1, +2, +3, +4, +6, +8, +10, +15, +20 D 10 steps in the range
lenses
-1, -2, -3, -4, -6, -8, -10, -15, -20 D +10 D to 0 D to -10 D
o
Angle of field of view ϕ > 6° > 5
o
Angle of field of illumination > 9° > 7
Minimum diameter of the viewing 3 mm 2,5 mm
system
Table 2 — Requirements for optical accuracy
Criterion Tolerance
0 D to +3 D ± 0,37 D
0 D to -3 D
Accuracy of combined refractive > +3 D to +10 D ± 0,50 D
power
< -3 D to -10 D
> +10 D to +15 D
± 0,75 D
< -10 D to -15 D
> +15 D ± 1,00 D
< -15 D
0 D to +10 D 1,0 mm
Lens centration
0 D to -10 D
> +10 D 0,5 mm
< -10 D
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5.3 Construction and function of the viewing system
5.3.1 The viewing lenses shall be arranged so that, as viewed from the operator's side:
a) increments of positive power, indicated by black or green figures, increase when the disc is turned clockwise;
b) increments of negative power, indicated by red figures, increase when the disc is turned anticlockwise.
5.3.2 The viewing lens control shall be provided with indexing stops for each lens power.
5.3.3 Left-hand and right-hand operation of the viewing lens control shall be possible.
5.4 Construction and function of the illumination system
5.4.1 The illuminating system shall be achromatic and provide uniform illumination of the fundus.
5.4.2 The intensity of the illuminating system of group A direct ophthalmoscopes shall be adjustable at least between
the maximum and 10 % of the maximum.
5.4.3 The illuminance without filters at 200 mm distance from the exit aperture of the direct ophthalmoscope shall be
not less than 150 lx.
5.4.4 Group A direct ophthalmoscopes shall have a minimum of two aperture stops in the illuminating system. These
shall be a full aperture and a reduced aperture to facilitate viewing of the macula. Additionally a red-free filter shall be
included.
NOTE - Other filters, apertures, fixation graticules, slits or half-circles are optional.
5.5 Optical radiation hazard with direct ophthalmoscopes
5.5.1 General
This clause replaces clauses 32, 33 and 34 of IEC 60601-1:1988.
5.5.2 Limit values
The limit values given in items a) and b) shall apply to the radiation emerging from the direct ophthalmoscope used to
illuminate and view the human eye with light from 380 nm to 700 nm and in which the full beam homogeneously
illuminates a circular pupil of 8 mm diameter (see notes 2 and 5).
NOTE 1 These limit values are considered acceptable with respect to the risks when weighted against the performances
intended.
a) Short wavelength limit:
The amount of radiant power exiting the direct ophthalmoscope in the portion of the spectrum from 305 nm to 400 nm
2
shall have an irradiance no greater than 0,05 mW/cm as measured in the corneal plane when the instrument is
1)
operating at maximum intensity and, if the aperture can be varied, at maximum aperture.
________________________________
1) Maximum intensity is the highest brightness the direct ophthalmoscope is capable of delivering including the highest brightness achievable
if overvoltage is provided.
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b) Long wavelength limit:
The amount of energy exiting the direct ophthalmoscope in the wavelength range 700 nm to 1100 nm shall not exceed
2
100 mW/cm nor shall it exceed the amount of energy exiting the direct ophthalmoscope in the range between 380 nm
and 700 nm. The energy shall be measured in the corneal plane when the instrument is operating at maximum
intensity and maximum aperture.
NOTE 2 If, due to stops or other obstructions of the beam, a circular pupil of less than 8 mm diameter is illuminated, the
limit values may be increased by the ratio of the area of an 8 mm diameter pupil to the true area illuminated.
NOTE 3 It is recommended that the energy in the range of the spectrum below 420 nm be attenuated as much as
possible.
NOTE 4 For direct ophthalmoscopes with a large illuminating solid angle over the designated spectral range 305 nm to
Ω
400 nm, i.e. Ω > 0,031 sr, the limit values may be increased by the ratio of the true solid angle, expressed in steradians,
divided by 0,031.
NOTE 5 For direct ophthalmoscopes, the assumptions used to set the limit value for radiation of wavelength shorter than
400 nm are based on considerations of the typical spectral distribution of a 3000 K standard black body source, an
illuminating solid angle at the corneal plane of 0,031 sr, a maximum exposure time of 5 min and the weighting factors for
L (see Annex A). The limit is set to ensure that the fraction of the photochemical hazard dose due to radiation of
A
wavelength shorter than 400 nm is no greater than 1/8 of the total photochemical hazard dose over all wavelengths, when
that total dose is at the threshold limit for an 8 mm diameter pupil.
Using the American Conference of Governmental Industrial Hygienists (ACGIH) guidelines, that threshold limit is
2
14 J/(cm · sr). To convert from photochemical hazard weighted radiance to irradiance over the designated spectral range
305 nm to 400 nm, the conversion factor 0,276 is used. Thus the limit is then found by the formula
2 2
[14 J/(cm · sr)] x (0,031 sr) x [0,276/(300 s · 8)] = 0,05 mW/cm .
5.5.3 Variable brightness
For direct ophthalmoscopes where provision is made to vary the brightness, the manufacturer shall provide indications
for the proportion of the maximum intensity.
5.5.4 Particular information
The manufacturer shall provide the user with a graph showing the relative spectral output of
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