ISO 10343-2014 pdf free download

ISO 10343-2014 pdf free download.Ophthalmic instruments – Ophthalmometers. 4 Requirements 4.1 General The ophthalmometer shall conform to the requirements specified in ISO 15004-1. 4.2 Radius of curvature measurements The ophthalmometer shall conform to requirements given in Table 1 or Table 2. Conformity shall be verified as described in 5.2. If the instrument conforms to the requirement of Table 1 it is a “Type B” ophthalmometer. If the instrument conforms to the requirements of Table 2 it is a “Type A” ophthalmometer. Type A and Type B ophthalmometers have sufficient resolution and range to adequately measure human corneas. Type A ophthalmometers have sufficient resolution and range (see Table 2) to adequately measure the radii of curvature of contact lenses complying with ISO 18369-3:2006, 4.1.3, and Clause 5. It is assumed that the local corneal front surface and both contact lens surfaces are spherical or toroidal. 4.3 Measurement of direction of principal meridians The ophthalmometer shall conform to requirements given in Table 3. Conformity shall be verified as described in 5.2. 4.4 Eyepiece adjustment (if applicable) The dioptric adjustment range for distance-dependent instruments shall be a minimum of-4 D to +4 D,for which the scale from -3 D to +2 D shall be calibrated. 5 Test methods 5.1 General All tests described in this International Standard are type tests. 5.2 Checking optical requirements Conformity to the requirements specified in 4.2 and 4.3 shall be verified by use of measuring devices the measuring error of which is less than 10 % of the smallest value to be determined. Test results shall be evaluated according to the general rules of statistics. Conformity to the requirements of 4.2 shall be verified using three spherical test surfaces, one chosen from each of three radii ranges: s6,8 mm, 7,5 mm to 8,1 mm and 29,1 mm. These test surfaces shall have the following properties: a) uncertainty of sphere radius of curvature s1 um; b) local departure from sphericity s0,5 um; c surface roughness s0,05 um; d) diameter of effective surface 26 mm. Conformity to the requirements of 4.3 shall be verified with two test devices as described in Table 4. To fulfil the requirements of 4.3, each test device shall be used to measure in four different orientations,namely 0°, 45°, 90° and 135°. The orientation of the test devices shall be referenced to a local horizontal as established by a spirit level. One example of this test...