ISO 10938 pdf download

ISO 10938 pdf download.Ophthalmic instruments — Chart projectors 1 Scope This International Standard, together with ISO 15004, specifies minimum requirements and test methods for chart projector systems, including an optical projector and a screen, for the projection of targets used for the determination of visual acuity, the refractive status and the binocular functions of the human eye. This International Standard takes precedence over ISO 15004, if differences exist. 2 Normative references The following standards contain provision which, through reference in this text, constitute provision 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 encourage 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 8596:1994 Ophthalmic optics – Visual acuity testing – Standard optotype and its presentation ISO 8597:1994 Optics and optical instruments – Visual acuity testing – Method of correlating optotypes ISO 15004:1997 Ophthalmic instruments – Fundamental requirements and test methods IEC 60601-1:1988 Medical electrical equipment – Part 1: General requirements for safety 3 Requirements 3.1 General The chart projector shall conform to the requirements specified in ISO 15004. 3.2 Functional requirements The chart projector shall conform to the requirements specified in 3.2.1 to 3.2.5. NOTE – Verification of these requirements is described in clause 4. 3.2.1 Optotypes If designed to be used for certification purposes, the chart projector shall be equipped either with the standard optotype according to ISO 8596 in the grades specified therein, or with optotypes which are correlated to the standard optotype by the method described in ISO 8597.3.2.2 Test area and positioning of optotypes If designed to be used for certification purposes, the target of the chart projector system shall comply with the requirements of clause 5 and 6.1 of ISO 8596:1994. NOTE – It is recommended that there be at least 5 presentations (see 6.2 of ISO 8596:1994) of each optotype size. 3.2.3 Resolving power When tested as described in 4.2, the chart projector shall conform to the following requirements: The minimum resolution on the screen (expressed in lines per millimetre) shall be 4/ V times the line separation corresponding to the limb width on the smallest optotype which the system is designed to project, where V is the decimal acuity grade of the...