ICS 11.040.70 
 
 
  
 
National Standard  
of the People's Republic of China 
  
GB 17342-200X 
 Replaces GB 17342-1998 
 
 
Ophthalmic instrument  
– Trial case lenses 
(ISO 9801:1997, Ophthalm ic instrument – Trial case lenses, MOD) 
 
 
   
Draft for approval 
(Draft completion date: May 2008) 
 
 
 
 Issue Date: XXXX – XX – XX Impl ementation Date: XXXX – XX – XX 
 
 
 
Issued by General Administration of Quality Supervision, Inspection and 
Quarantine of the People 's Republic of China  
 
 
 
 
 Table of Contents 
 Foreword...................................................................................................................... 3 
 1 Scope................................................................................................................ 4  2 Normative reference......................................................................................... 4  3 Terms and definitions....................................................................................... 4  4 Categorisation and application......................................................................... 6  5 Requirements.................................................................................................... 8  6 Test methods..................................................................................................... 13  7 Inspection rules................................................................................................. 14  8 Symbols, packaging, trans portation and storage............................................... 15- 3 -  
Foreword 
The entire technical content of  this Standard is mandatory. 
  This Standard is a modified version of ISO 9801:1997, Ophthalmic instrument – Trial case lenses, 
MOD.  The main technical differences between this Standard and ISO 9801:1997 are as follows: 
− Clause 4 of this Standard: the categorisa tion and application articles and additional 
descriptions for the supplementa l lenses have been added; 
− Article 5.2 of this Standard: the requirements fo r the basic configuratio n of trial case lenses 
and the configuration of supplemen tal lenses have been added; 
− Article 5.3 of this Standard: op tical property requirements, su ch as: adjustments made and 
provisions drawn up for the permissible errors for the cylinder power of spherical lenses; 
permissible errors for the pris matic power, spherica l power and cylinder power of prismatic 
lenses; the classification and permissible errors for the prismatic power at the lens geometric 
centres of spherical lenses a nd cylindrical lenses; the classi fication and permissible errors 
for the axial position of cylindrical lenses; the classification and permissible errors for the baselines of prismatic lenses; the technical requirements of cross-cylinder lenses, etc.; 
− Article 5.4 of this Standard: structure requirements includi ng adjustments made to the 
thickness of the trial case lenses and provisions made for the structures of the supplemental 
lenses; 
− Article 6.3 of this Stan dard: testing methods for the stru cture of the supplemental lenses 
have been added. 
− Article 7.1 of this Standard: th e requirements for the qualified rate of single unit spherical 
lenses, cylindrical lenses and prismatic lenses, and the requirements for qualified rate of 
box-full spherical lenses, cylindrical lenses and prismatic lenses have been adjusted. 
Provision has been made for lens errors. 
− Article 8.1 of this Standa rd: it is specified that  all types of technical indexes of double side 
lettered trial case lenses should m eet optical property requirements. 
 This Standard is proposed by the National Institute of Metrology P.R. China.  This Standard is under the jurisdiction of the Subcommittee on Ophthalmic Optics of the National 
Technical Committee on Optics and Optical Instrument under the Sta ndardisation Administration of 
China.  The main organisations which participated in the drafting of this Standard are:  
National Institute of Metrology P.R. China Shandong Institute of Metrology Lianyungang TianNuo Optical  Instrument Co. Ltd 
Shanghai Solarmoon Optical Instrument Co. Ltd  The main drafters of this Standard are:  Liu Wenli, Chen Yan, Ren Hongwei, Yang Lei, Ning Lixin, Fang Zhigang.  This Standard shall come into effect on the date that GB17342-1998, Ophthalmic instrument – Trial case lenses, is nullified. - 4 -            
Ophthalmic instrument – Trial case lenses 
 
 1  Scope 
This Standard specifies the basic requirements for al l types of trial case lenses used for detecting the 
refractive defects of human eyes.   This Standard applies to all types of the full ap erture and reduced apertu re trial case lenses.  
 2  Normative References 
The provisions of the following documents become  provisions of this Standard after being 
referenced. For dated reference documents, a ll later amendments (excluding corrigenda) and 
versions do not apply to this Standard; however, the parties to the agreem ent are encouraged to 
study whether the latest versions of these doc uments are applicable. For undated reference 
documents, the latest versions apply to this Standard.  ISO 9801-1997, Ophthalmic instruments – Trial case lenses  GB/T 10050-1988, Optics and optical inst ruments - Reference wavelengths 
 GB/T 10810.1 – 2005, Uncut finished spectacle lenses  GB/T 2828.1-2003, Sampling procedures for inspection by attributes – Part  1: Sampling schemes 
indexed by acceptance quality limit (AQL) for lot-by-lot inspection  GB/T 15464-1995, General purpose sp ecification for the packaging of instrumentation products 
 JJG 580-2005, Focimeters 
 3  Terms and definitions  
This Standard adopts the definitions listed below. 
 3.1 Vertex power 
Use metre as the unit, the reciprocal of the meas ured paraxial vertex le ngth of a lens. One lens 
consists of two vertex powers. 
 3.2 Back-vertex power 
Use metre as the unit, the reciprocal of the meas ured paraxial back vert ex length of a lens. As 
shown in Diagram 1, the distance from the back vertex to the paraxial back focus is called the paraxial back vertex length, indicated by symbol l'
f, and its reciprocal is called the back-vertex 
power, indicated by 1/l' f. The unit for back-vertex power is the reciprocal of metre (m-1), and is 
called the dioptre. 
Under normal conditions, the vertex power of a lens  refers to its back-vertex power. The vertex 
power of a trial case lens is related to the wave length. This Standard specifies that the selected 
wavelength is green mercury line, λe = 546.07nm. - 5 -  
F – Object focal point  F' – Image focal  point  H – Object principal point   
H'- Image principal point f – Object focal length f' – Image focal length 
If – Front vertex focal length   I' f – Back vertex focal length. 
Diagram 1 Schematic diagram of back vertex focal length of lenses 
 3.3 Prismatic power 
The deviation metric generated by the light ray went  through a specific point (u sually the centre) of 
the lens. The unit for prismatic power is centimetre per metre (cm/m) and the unit name is prismatic dioptre. 
Diagram 2 Schematic diagram of prismatic  
 3.4 Trial case lenses 
A trial case lens refers to a lens which is fitted in a lens holder for the purpose of determining the 
refractive defects of human eyes. 
 3.5 Full-aperture trial case lenses 
A full-aperture trial case lens refers to a lens which has the maximum limit of clear aperture and is 
fitted in a protection holder w ith a wall thickness of 1 mm. 
- 6 -  3.6 Reduced-aperture trial case lenses 
A reduced-aperture trial case lens refe rs to a lens with a clear apertu re which is visibly smaller than 
the external diameter of its holder and is evidently thin. 
 3.7 Additive-power trial case lenses 
This refers to trial case lenses which are combined  with spherical lenses, cylindrical lenses, or a 
combination of spherical lenses and cylindrical lenses. The back-vertex power measured from its 
final plane is equal to the combination of the nominal values of the meridian lines of all trial case lenses which are in the frames. 
 3.8 Spherical-power trial case lenses 
This refers to trial case lenses which can make the parallel light beams of the paraxial meet at the 
same point. 
 3.9 Cylinder-power trial case lenses 
This refers to trial case lenses which consist of  two main vertex powers and can make the parallel 
light beams of the paraxial m eet on two separate but mutually  orthogonal intersection lines. 
The vertex power of one principa l meridian of any cylinder-power  trial case lens is zero. The 
cylindrical power means the vertex power of the pr incipal meridian where its vertex power is not 
zero. 
 4 Categorisation and application 
In practical applications, the combination of all types of trial case lenses is called a trial lens set. A 
trial lens set is a type of ophthalmology measuri ng instrument used in ophthalmology departments 
in hospitals and opticians to dete ct the refractive state and strabismus, or amblyopia and other visual 
functions of the human eye. 
Trial case lenses mainly consist of positive and negative spherical-power trial case lenses, positive 
and negative cylinder-power trial case lenses and prismatic-power trial case lenses, as well as supplemental trial case lenses etc.  Trial case lenses can be divided into categories as below: 
 4.1 Spherical-power trial case lenses 
A spherical-power trial case lens consists of a positive and a negative spherical-power trial case 
lens. Positive spherical-power trial case lenses are used for the detection of hyperopia and 
presbyopia in the human eye; negative  spherical-power trial case lenses  are used for th e detection of 
myopia. 
 4.2 Cylinder-power trial case lenses 
A cylinder-power trial case lens consists of a positive and a negative cylinder-power trial case lens. 
Positive cylinder-power trial case lenses are used for the detection of the hyperopia, presbyopia and 
astigmatism in the human eye; negative cylinder-power trial case lenses are used for the detection of the myopia and astigmatism in humans. 
 4.3 Prismatic-power trial case lenses 
Used for the detection of the strabism us and heterophoria in the human eye. - 7 -  4.4 Supplemental trial case lenses 
Supplemental trial case lenses normally consist of  cross-cylinder lenses, maddox rod lenses, pinhole 
lenses, opaque lenses, stenopeic lenses, plano lenses, frosted lenses, crosshair lenses, filters and polarisers, etc. 
 4.4.1 Cross-cylinder lenses 
A cross-cylinder lens is a type of special cyli ndrical lens, which has two mutual perpendicular 
orientations, indicated by the sa me two numerical values with opposing plus and minus symbols, 
marking the positive and negative cylindrical vertex powers respectively. Cross-cylinder lenses are used for the detection of the axial position and the cylindrical power of cylindrical lenses. 
 4.4.2 Maddox rod lenses 
A maddox rod lens consists of a row of smooth cy linders with the same diameter, and has the 
function of light transmission. 
 4.4.3 Opaque lenses 
Opaque lenses are also called opaque discs. Thes e lenses are completely opaque and are used to 
cover whichever eye is not undergoing examination. 
 4.4.4 Pinhole lenses 
A pinhole lens is an opaque lens with  a clear aperture in the centre. It  is mainly used to distinguish 
whether hypophysial eyes are caused by refractive errors or pathologi cal change of the eyes.  The 
clear aperture should be round, smoo th, and other parts of the pinhole lens should not allow light to 
pass through. 
 4.4.5 Stenopeic slit lenses 
A stenopeic slit lens is an opaque  lens with a narrow sl it which allows light transmission. Stenopeic 
slit lenses are used for astigmatism inspection. 
 4.4.6 Frosted lenses 
Frosted lenses are semi-transpa rent and are used by young childre n or outdoors to replace opaque 
lenses. 
 4.4.7 Plano lenses 
Plano lenses are transparent and are used to test conditions such as  simulated blindness. 
 4.4.8 Crosshair lens 
 A crosshair lens is a plano lens which is etched with a crosshair shape. It is mainly used to 
determine the centre of an eye and determin e the eye position when checking strabismus. 
 4.4.9 Filters 
"Filters are plano lenses. They nor mally include red and green lens es, used for chromatoptometry. - 8 - The combination of red and green lenses can be us ed for binocular stereo vision testing, or for 
visual function testing of people with refractive media opacity. Red filters can also be used for 
amblyopia treatment and for chromatoptometry. There is also a tawny filter which can be used in 
lenses for examining the visi on of people with photophobia." 
 4.4.10 Polarisers 
A polariser can make natural light ch anges to plane polarised light and is used for the tests of visual 
functions such as heterophoria, strabism us, unequal eyesight, stereopsis, etc. 
 5 Requirements 
 5.1 General provisions 
When a box-full of trial case lenses leaves the factory, it should m eet the requirements specified in 
5.2, 5.3, 5.4, and 5.5, and is subject to inspections in  accordance with the requirements specified in 
Clause 6. 
 5.2 Configuration requirements 
When a box-full of trial case lenses leaves the factory, its basic configuration should meet the 
following requirements. 
 5.2.1 Spherical-power trial case lenses 
Spherical-power trial case lenses with the same specifications should have left and right lenses. 
For lenses which must include +0.12m-1 and -0.12m-1, the measuring range n eeds to be at least -
12.00m-1 ~ +12.00m-1. 
For lenses which are within the range of -0.25m-1 ~ -4.00m-1 and the range of +0.25m-1 ~ +4.00m-1, 
the interval of measured values  must not be greater than 0.25m-1. 
For lenses which are within the range of < -4.00m-1 ~ -8.00m-1 and the range of > +4.00m-1 ~ 
+8.00m-1, the interval of measured values must not be greater than 0.50m-1. 
For lenses which are with in the range of < -8.00m-1 ~ -12.00m-1 and the range of  >+8.00m-1 ~ 
+12.00m-1, the interval of measured values must not be greater than 1.00m-1. 
 5.2.2 Cylinder-power trial case lenses 
Cylinder-power trial case lenses with the same specifications should have left and right lenses. 
For lenses which must include +0.12m-1 and -0.12m-1, the measuring range n eeds to be at least -
4.00m-1 ~ +4.00m-1. 
For lenses which are within the range of -0.25m-1 ~ -3.00m-1 and the range of +0.25m-1 ~ +3.00m-1, 
the interval of measured values  must not be greater than 0.25m-1. 
For lenses which are within the range of < -3.00m-1 ~ -4.00m-1 and the range of > +3.00m-1 ~ 
+4.00m-1, the interval of measured values must not be greater than 0.50m-1. 
 5.2.3 Prismatic-power trial case lenses 
The measuring range for prismatic-p ower trial case lenses needs to be at least 8.0cm/m and there - 9 - should be two lenses, both of 0.5cm/m, 1.0cm/m, 2.0cm/m. 
For other lenses which are within  the range of 3.0cm/m~ 8.0cm/m, the interval of the measured 
value must not be greater than 1.0cm/m. 
 5.2.4 Supplemental trial case lenses 
Supplemental trial case lenses should include cross-cylinder lenses, maddox rod lenses, pinhole 
lenses, opaque lenses, stenopeic le nses, plano lenses, frosted lens es, red and green filters, etc. 
 5.3 Optical property requirements 
 5.3.1 Permissible error for the vertex power of plano lenses 
The permissible error for the vertex power of pl ano lenses should meet th e requirements specified 
in Table 1. 
Table 1 Permissible error for the vertex power of plano lenses 
Permissible error (MPE) Nominal 
value of 
vertex power 
(m
-1) Spherical power 
(m-1) Cylinder power 
(m-1) Prismatic power 
(cm/m) 
0 ± 0.03 ± 0.03 0.06 
 5.3.2 Permissible error for the vertex powe r of spherical-power trial case lenses 
The permissible error for the vertex power of s pherical-power trial case lenses should meet the 
requirements specified in Table 2. 
Table 2 Permissible error for the vertex pow er of spherical-power trial case lenses  
Unit: (m-1) 
Permissible error (MPE) Nominal value of 
vertex power 
(absolute value) Spherical power Cylinder power 
0.12 ± 0.03 ± 0.03 
(0.12, 6.00] ± 0.06 ± 0.03 
(6.00, 12.00] ± 0.09 ± 0.03 
> 12.00 ± 0.12 ± 0.05 
 5.3.3 Permissible error for the vertex powe r of cylinder-power trial case lenses 
The permissible error for the cylinder vertex powe r of cylinder-power trial case lenses should meet 
the requirements specified in Table 3. The permissi ble error for spherical power must not exceed ± 
0.06m-1 and the intrinsic prisma tic power must not be greater than 0.12cm/m. 
   - 10 - Table 3 Permissible error for the cylinder vertex  power of cylinder-power  trial case lenses  
       Unit: (m-1) 
Nominal value of cylinder power 
 (absolute value) Permissible error (MPE) 
0.12 ± 0.03 
(0.12, 1.00] ± 0.06 
(1.00, 4.00] ± 0.09 
(4.00, 6.00] ± 0.12 
> 6.00 ± 0.18 
 5.3.4 Permissible error for the prismatic power of prismatic-power trial case lenses 
The permissible error for the pris matic power of prisma tic-power trial case le nses should meet the 
specifications prescribed in Table 4, the spheri cal-power and the cylinder-power of the prismatic-
power trial case lenses which are within th e range of 0~5.0cm/m mu st not exceed ± 0.05m-1. 
Table 4 Permissible error for the prismatic power of prismatic-pow er trial case lenses 
Unit: (cm/m) 
Nominal value of prismatic pow er Permissible error (MPE) 
(0, 3.0] ± 0.10 
(3.0, 6.0] ± 0.12 
> 6.0 ± 0.25 
 5.3.5 Permissible error for the displacement of optical centres 
The displacement of the optical cen tre of a spherical-power trial case lens and a cylinder-power trial 
case lens is indicated by the pris matic power of the geometric ce ntre of its lens circle. The 
permissible error for the displacemen t of optical centres should meet the specifications prescribed in 
Table 5. 
Table 5 Permissible error for the displacement of optical centres 
 Nominal value of vertex power 
(absolute value) (m-1) Permissible error for prismatic power 
(MPE) 
(cm/m) 
[0.12, 1.00] ± 0.12 
[1.00, 4.00] ± 0.25 
[4.00, 7.00] ± 0.35 
[7.00, 10.00] ± 0.50 
[10.00, 12.00] ± 0.60 
>12.00 ± 0.80 
 5.3.6 Permissible error for the axial positi on of cylinder-power trial case lenses 
The direction of the axis fo r any cylinder-power trial ca se lens is defined as 0o ~ 180o, the deviation 
between the axis and the axial position marks of both  ends of the lens diameter should use the angle - 11 - value as an indication and the value should meet the specifications prescribed in Table 6. 
Table 6 Permissible error for the axial position of cylinder lenses 
Nominal value of cylinder power 
(absolute value) (m-1) Permissible error for axial position (MPE) 
(cm/m) 
[0.12, 0.50] ± 3o 
> 0.50 ± 2o 
 5.3.7 Permissible error for the baseline of prismatic lenses 
The axial positioning of any prismatic lens base is indicated by the prismatic baseline and its 
permissible error should meet the sp ecification prescribed in Table 7. 
Table 7 Permissible error for the baseline of prismatic lenses 
Nominal value of prismatic power 
(cm/m) Permissible error (MPE) 
(0, 0.50] ± 5o 
(0.50, 1.00] ± 4o 
(1.00, 2.00] ± 3o 
(2.00, 10.00] ± 2o 
> 10.00 ± 1o 
 5.3.8 Optical property requirements for cross-cylinder lenses 
For cross-cylinder lenses: see Table 2 for the perm issible error for spherical power lenses, Table 3 
for the permissible error for cylinder power lens es, Table 5 for the permissible error for optical 
centre displacement and Table 6 for the permissible error for axial positioning. 
Note: For cross-cylinder lenses, red marks s hould be selected to indicate the axial 
positioning of the negative cylinder lenses and blue (or black) marks should be selected to indicate the axial positioning of  the positive cylinder lenses. At the locations of the two 
different colour marks, under different measur ing modes, all optical property requirements 
should meet the above provisions. 
 5.4  Structure requirements 
These requirements apply to all types lens holders and fitted lenses. 
 5.4.1 Dimensional specifications 
If the edge of the lens holder for any fitted trial case lens is circular arc shaped, then the radius of 
the circular arc must not exceed 1.4 mm. The extern al diameter of the holde r of the fitted lens 
should be 38
0
-0.2 mm. 
The overall thickness of any trial case lens, including its holder, mu st not exceed 2.8 mm. The trial 
case lenses must be able to fit in to trial frames with an interval of 3 mm between each lens. Out of 
which, if the absolute value of any full-aperture spherical-power lens is greater than or equal to 4.00 
m-1, then the thickness of this type of lens can exceed 2.8 mm. If the prismatic power of any full-
aperture and reduced-aperture prisma tic lens is greater than or equa l to 3 cm/m, then the thickness 
of whichever is nearer to th e object side can exceed 2.8 mm. - 12 -  5.4.2 Effective clear aperture 
In the case of a trial case lens with the absolute value of the nominal value of its vertex power being 
smaller than 12 m-1, then the effective clear diameter of th e aperture for this lens must not be 
smaller than 18 mm; in the case of a trial case lens  with the absolute value of the nominal value of 
its vertex power bei ng greater than 12 m-1, then the effective clear diameter of the aperture for this 
lens must not be smaller than 16 mm. 
 5.4.3 Structures 
 5.4.3.1 Structure requirements for lens holder 
The surface of the lens holder for any trial case lens must be smooth, must not have any sharp 
edges, shape corners or rough surfaces which can cause  injures to patients or optometrists, and there 
should be no visible deformations and cracks. The trial case lens and its holder must be firmly 
fitted, not loose, and fitted neatly. The symbols on the lens holder should meet the requirements 
specified in Table 9. 
 5.4.3.2 Structure requirements for prismatic lenses 
When fitting a prismatic lens, the su rface of the lens which is nearest to the eye should be parallel to 
the mounting surface of the lens holder. The nomi nal value which is indicated on the lens holder 
should be the prismatic power when the light is vert ically incident to the eye side of the lens, and 
should be consistent with the va lue measured by the focimeter. 
 5.4.3.3 Structure requirements for maddox rod lenses 
The thickness difference between the two ends along the axis direction of a semi-cylinder Maddox 
rod lens and the plane must not exceed 0.08 mm. 
 5.4.3.4 Structure requirements for pinhole lenses 
The diameter of the clear aperture on any pinhol e lens should be within the range of 0.5 mm ~ 2.0 
mm. 
 5.4.3.5 Structure requirements for stenopeic lenses 
The width of the narrow slit for light transmission on any stenopeic lens should be within the range 
of 0.5 mm ~ 2.0 mm. 
 5.5 Quality of materials and surfaces 
 5.5.1 Materials 
The materials used to make the lens holder s should not contain any corrosive compounds. 
 5.5.2 Surface quality 
There must not be any air bubbles, defects, impuriti es, scratch marks or any visible irregular surface 
defects inside the clear aperture of any trial ca se lens. The trial case le nses should transmit light 
well, and must not be contaminated with any mildew. - 13 -  6 Test methods 
 6.1 Optical property test 
The test of the optical propertie s should adopt the technical index of the verification regulations 
which are set out in JJG 580 (Focimeters), to dete rmine the qualified primary reference focimeter. 
Before conducting tests on a trial case lens, the prim ary reference focimeter must have been placed 
in constant room temperature for at least 2 hours, and the tests must be carried out in an ambient 
temperature of 20oC ± 5oC and a relative humidity of less than 85%. 
When conducting tests on a trial case  lens, the graduation of the pr imary reference focimeter must 
first be set at 0.01 m-1, the Abbe number should be aroun d 58, the standard wavelength should 
select e-spectral line,  the lens bearer of the focimeter should be checked and all the dust removed before the test is conducted. 
While testing a trial case lens, the marked surface of the test lens should always be positioned 
facing up onto the lens bearer of th e focimeter. If both sides of the lens  are marked with letters, both 
sides of the lens should be tested. 
 6.1.1 Vertex power test method 
When testing the vertex pow er of any lens, the imaging centre of the test lens should coincide with 
the crosslines of the reticule, and bring the indi cation value of the prisma tic power to its minimum 
or zero. 
 6.1.2 Optical centre displacement test method 
When testing the optical centre displacement for a ny spherical-power trial case lens, cylinder-power 
trial case lens or cross-cylinder lens, firstly adjust the prismatic measuring modes of the focimeter 
to the polar coordinate display modes (such as “P-B” mode etc.), positioning the geometric centre 
of the test lens at the geometric centre of the lens bearer. The meas ured value of the prismatic power 
at this moment is the optical centre displacement of the test lens. 
 6.1.3 Axial positioning mark test method 
When testing the axial positioning marks for a ny cylinder-power trial case lens, the axial 
positioning marks of both ends of the lens circle should coincide with the connecting lines of the 
three points of the focimeter printing mechanism, so that the deviation of the axial position of the test lens can be read.  
 6.1.4 Prismatic power test method 
When testing the prismatic power of any prismatic tr ial case lens, the horizontal axis of the imaging 
should coincide with the horizontal axis of the reticule crosslines, as at this point the prismatic 
power, spherical power and cylinder power  of the test lens can be read. 
 6.1.5 Prismatic lens baseline test method 
When testing the prismatic lens baseline of any prismatic-power trial case lens, after carrying out 
the procedures specified in 6.1.4, ca refully rotate the test lens un til the baseline marking of one end 
of the lens circle coincides with  the connecting lines of the three points of the focimeter printing 
mechanism. At this point the baseline de viation of the test lens can be read. - 14 -  6.2  Testing material quality and surface quality 
The test should be conducted in an environment with a bright view fiel d and dark background 
without using any optical amplification device. Di agram 3 illustrates the sc hematic diagram of the 
recommended quality test system. The illuminati on around the test equipment should approximately 
be 2001x. The recommended light source should be fluorescent lamp of above 15 W or 
incandescent lamp of above 60 W and the illumination around where the lens is pointing toward 
should be at least 3501x. 
Note: Since this observation me thod is prone to certain subject ivity, the testing personnel are 
required to have a certai n practical experience. 
 
Diagram 3 Schematic diagram of the surface qua lity testing device for trial case lenses 
1 – Black non-reflective background (150 mm*360 mm); 
2 – Light source;   3 – Gobo (adjustable shield); 4 – Movable trial case lens;  5 – Eye observation plane; a – Adjustable gobo distance. 
 6.3 Structure test 
6.3.1 The testing of any lens holder structure should refer to the method specified in 6.2 to carry out 
visual testing. 
6.3.2 The testing of any Maddox rod lens structur e should use a micrometer with a minimum 
graduation not greater than 0.01 mm, to measure the thickness difference between the two ends 
along the axial direction of the semi-cylinder of the maddox rod lens and the plane. 
6.3.3 Structural testing of any stenopeic disk and pinhole disk should use a digital display calliper 
with the minimum graduation of 0.01 mm should be selected. 
 7 Inspection rules 
 7.1 Lens errors 
When a box-full of trial case lenses leaves the factory, s ituations causing lens errors can arise as 
follows: assembly errors between spherical-power trial case lenses, cylinder-power trial case lenses 
- 15 - and prismatic-power trial case le nses; among spherical-power trial case lenses and cylinder-power 
trial case lenses, assembly errors can occur betwee n the negative and positive lenses; out of stock or 
shortage of any category of the trial case lenses; the index of the spherical power for spherical-
power trial case lenses, the index of the cylinder power for cylinder-power tr ial case lenses, and the 
index of the prismatic power for prismatic-power trial case lenses twice exceeds each corresponding 
permissible error. 
 7.2 Products leaving the factory should be subjected to an integral acceptance quality check, box by 
box, in accordance with the requirements specified in this Standard. The single unit qualified rate 
for spherical-power trial case lenses, cylinder-power trial case lenses and prismatic-power trial case 
lenses in each box should not be lower than 90% and the qualified rate for a box-full of trial case 
lenses should not be lower than 90%.  When a box-full of lenses leaves  factory, if one lens or more 
than one lens is detected not to qualify, then this whole box of lenses should be treated as not 
qualifying.  
 7.3 Batch products leaving the factory should be su bjected to sampling inspection in accordance 
with the special inspection level S-4/AQL is 4.0, which is set out in GB/T 2828.1. See Table 8 for 
details. 
Table 8 
Product 
batch range 
N Sample size 
n Acceptance number 
Ac Rejection number 
Rc 
2~90 3 0 1 
91~500 13 1 2 
 
 7.4 Products with set specifications may set up a separate agreement be tween the supplier and 
buyer in accordance with their requests. 
 8 Symbols, packages, tr ansportation and storage 
 8.1 Symbols 
8.1.1 The nominal value of the vertex power or pris matic power for all type s of trial case lenses 
should be marked on the opposite side to the eye side  of the lens holders. If the nominal value is 
marked on both sides of the lens holder, then it should be ensured that a ll types of the technical 
index for both sides of the lens meet the permissible error requirements. 
8.1.2 For cylinder-power trial case lenses and prismatic -power trial case lenses, the axial position or 
baseline should be marked separately on the lens holder or lenses. If there are no measures to 
prevent the lenses rotating in the lens holder, then  the cylinder axial position or prismatic baseline 
should be directly marked on the lenses. 
8.1.3 The colours of symbols and spec ific lens holders can help to identify the types and categories 
of the lenses; the spherical power , cylinder power and the prismatic power can be directly read out 
from the indication values on the symbol. 
8.1.4 The mounting base plane of any prismatic-power  trial case lens should be parallel to the 
surface of the prismatic-power tria l case lens which is adjacent to the eye side. The nominal value - 16 - marked on the lens holder is usually the prismatic power when the incident li ght is perpendicular to 
the mounting base plane of the prismatic-power trial case lens. 
8.1.5 Give distinction to all types of lenses in ac cordance with different lens holder colours and/or 
different colours marked as prescribed in Table 9. 
Table 9 Lens identification marks 
Lens categorisation Letters or symbols Lens holder colours or 
identification marks 
Spherical-power, 
cylinder-power trial 
case lenses Nominal value of vertex power / 
Positive lenses + Black 
Negative lenses - Red 
Prismatic-power trial 
case lenses ∆ White/Grey 
Maddox rod lenses MR / 
Stenopeic lenses I or SS / 
Pinhole lenses ⊚ or PH White/black/grey 
Opaque lenses ● or BL / 
Frosted lenses FL / 
Crosshair Lenses ⊕ or CL / 
Red filters RF / 
Green filters GF / 
Polarisers PF / 
 
 8.2 Packaging 
 8.2.1 Trial case lenses should be separately packed into different boxes according to their 
categorisation. 
 8.2.2 There should be a user manual attached to th e inside of the box and th e configuration of the 
package list in the user manual should be consis tent with the actual conf iguration in the box. The 
user manual should also incl ude the following contents: 
a) name and address of the manufacturer; 
b)  introduction of the disinfection methods fo r trial case lenses; 
c) methodical description of additive power of trial case lenses; 
d) code of the implemented Standards; 
e) package list. - 17 -  8.2.3 Symbol of trial lens sets 
Trial lens set should include the following permanent symbols: 
a) name and address of the manufacturer; 
b) brand and type of the trial lens set; 
c) serial number for leaving the factory; 
In case any trial lens set has an internal box and an external box, then the permanent symbols such 
as the brand, type and serial number must be marked on the internal box. 
 8.3 The external packaging of any trial lens set should meet the requirements set out in GB/T 
15464-1995. 
 8.4 When transporting and handling th e trial lens set, it should be loaded and unloaded carefully, 
and it must not come into contact with any rainwater or moisture.  
 8.5 The storage space of any trial lens se t should be well ventilated and dry.