The Clinical Trial of Myopia Control in Schoolchildren Using the Multi-segment (MS) Lens
Phase: NA
Conditions: Myopia
Sponsor: The Hong Kong Polytechnic University

 
 
 
Clinical Research Protocol 
The Clinical trial of myopia control for children using the Multi-segment (MS) lens 
 
Registration Number: 
clinicaltrials.gov Identifier: NCT02206217 
Human ethics approved 
by Departmental 
Research Committee: 
Reference no. 
HSEARS20140630003 
Principal Investigator: 
Name: Prof. Carly SY Lam 
Institution: School of Optometry, The Hong Kong 
Polytechnic University 
Telephone: 2766 6091 
E-mail:carly.lam@polyu.edu.hk 
 
Name: Prof. Chi Ho To 
Institution: School of Optometry, The Hong Kong 
Polytechnic University 
Telephone: 2766 6102 
E-mail: chi-ho.to@polyu.edu.hk 
 
Co-investigators: 
Name: Dr. Wing Chun Tang 
Institution: School of Optometry, The Hong Kong 
Polytechnic University 
Telephone: 34002910 
E-mail: wing.tang@polyu.edu.hk 
 
Approval date of the document: 25 July 2014    
 

 
 
The Clinical trial of myopia control for children using the Multi-segment (MS) lens 
 
 
1. 
List of Abbreviations ………………………………………………………….. 3 
2. 
Protocol Summary……………………………………………………………... 4 
3. 
Study Rationale and Objectives 
 
3.1. 
Background ……………………………………………………………… 5 
3.2. 
Aims of the study……………………………………………………... 
5 
 
 
4. 
Methods and Study Design 
 
4.1. 
Subjects: inclusion and exclusion criteria……………………………….. 
6 
4.2. 
Study design……………………………………………………………... 
6 
4.3. 
Sample size estimation ………………………………………………….. 
6 
4.4. 
Spectacle lenses……………………………………………………… 
7 
4.5. 
Randomization process…………………………………………………... 7 
4.6. 
Masking………………………………………………………………….. 
7 
4.7. 
Study outcomes and its measurement……………………………………. 8 
4.8. 
Study visits and eye examination procedures……………………………. 9 
4.9.      Questionnaire…………………………………………………………….. 12 
4.10.    Visual performance of lenses……………………………………………. 
12 
4.11.    Statistical analysis………………………………………………………... 13 
 
 
5. 
Clinical Examination Procedures 
 
5.1. 
Introduction……………………………………………………………… 
14 
5.2. 
Determination of dominant Eye………………………………………… 
15 
5.3. 
Papillary distance measurement………………………………………… 
15 
5.4. 
Non- cycloplegic autorefraction and keratometry……………………… 
15 
5.5. 
Subjective refraction……………………………………………………. 
16 
5.6. 
Visual acuity…………………………………………………………….. 
17 
5.7. 
Phoria measurement……………………………………………………... 
17 
5.8. 
Stereopsis………………………………………………………………… 17 
5.9. 
Amplitude of accommodation…………………………………………... 
17 
5.10.    Lag of accommodation………………………………………………….. 
18 
5.11.    Choroidal thickness measurement………………………………………. 
19 
5.12.    Intra-ocular pressure and cycloplegi…………………………………….. 
19 
5.13.    Cycloplegic autorefraction ……………………………………………... 
19 
5.14.   Axial length measurement ……………………………………………… 
20 
5.15.   Final prescription…………………………………………………………. 20 
 
 
6. 
Clinical Examination by UMI  
 
6.1. 
Visual performance of spectacle lenses……………………………….. 
21 
 
7. 
References …………………………..………………………………………… 
23 
8. 
Appendix ……………………………………………………………………… 
24 

 
 
 
 
1. List of abbreviations  
 
AL 
 
 
 
axial length 
 
MD 
 
 
 
myopic defocus 
MI 
 
 
 
masked investigator 
MS 
 
 
 
multi-segment 
IOP 
 
 
 
intra-ocular pressure 
PD 
 
 
 
Pupillary distance 
Rx 
 
 
 
refractive error 
SER 
 
 
 
spherical equivalent refraction 
SFCT  
 
 
subfoveal choroidal thickness 
SD 
 
 
 
standard deviation 
SD-OCT  
 
 
spectral Domain Optical Coherence Tomography  
SV 
 
 
 
single vision 
UMI 
 
 
 
unmasked investigator  
 
 
 
 

 
 
2. Protocol Summary 
Title 
The Clinical trial of myopia control for children using the Multi-
segment (MS) lens 
Venue of data collection Centre for Myopia Research, School of Optometry, The Hong Kong 
Polytechnic University 
Application of device 
Myopia (shortsightedness) myopia in children and youngsters 
Study design 
2-year prospective, randomized and double-masked clinical study 
Primary outcome 
Changes in cycloplegic autorefraction (diopters, D) 
Secondary outcome 
Changes in axial length (mm) 
Rationale for Number of 
Subjects 
Treatment group: 90 
Control group: 90 
Subject criteria 
Inclusion criteria: 
 Hong Kong Chinese 
 Age at enrolment: 8-13 year.  
 Spherical equivalent refraction (SER): -1.00 to -5.00D 
 Astigmatism and anisometropia: 1.50 D or less  
 Spectacle corrected monocular VA: 0.0 logMAR or better  
 No strabismus: checked by cover test at far and near.  
 No prior treatment of myopic control, e.g. orthokeratology, 
progressive addition lenses, bifocal lenses, drugs (e.g. atropine), 
etc. 
 Willingness to wear spectacle lenses regularly 
 Parents’ understanding and acceptance of random allocation of 
grouping 
Exclusion criteria 
 Any ocular and systemic diseases and abnormalities might 
affect visual functions or refractive development  
Any eye pathology and conditions  
Intervention device / 
Treatment 
Multi-Segment (MS) lens (re-named as Defocus Incorporated Multiple 
Segments (DIMS) spectacle lens later) 
 
Control  
Control: single vision  (SV) spectacle lens 
Wearing module 
Full-day wear  
Visits of the study /main 
data collection  
Baseline visit, follow-up visits every 6 months for 2 years 
Total: 5 data taking visits 
 
 
 

 
 
The Clinical trial of myopia control for children using the Multi-segment (MS) lens 
3. STUDY RATIONALE AND OBJECTIVES 
 
3.1 Background 
Myopia (also called ‘shortsightedness) is a common refractive eye disorder. The prevalence 
of myopia is alarmingly high in many Asian countries such as Hong Kong and Singapore, as 
many as 80% of young adults is myopic. 1-3 There is a trend of increasing prevalence of 
myopia and increasing severity of myopia in the last decade. Myopic eyes are prone to a 
number of ocular diseases, such as retinal degeneration and glaucoma, which can lead to 
severe visual impairment.4,5 
 
We have invented a contact lens, ‘Defocus Incorporated Soft Contact (DISC) lens’, for slowing 
progression of myopia in children. The DISC lens is a bifocal soft contact lens and is designed 
by the principle of simultaneous defocus. It provides clear vision and constant myopic defocus 
simultaneously for wearers in all viewing distances. The recent study has shown that DISC lens 
slowed myopia progression up to 50% in Hong Kong schoolchildren.6  
 
The Hong Kong Polytechnic University and Sponsor (a lens company) have jointly invented 
a spectacle lens design using simultaneous defocus principle -Multi-Segment (MS) lens.  The 
sponsor is able to manufacture the technical design which aims at correcting distance vision 
and at the same time producing MD images on the retina for all distances in the form of a 
spectacle lens. The MD aims at slowing down myopia progression.  The purpose of this study 
is to investigate if the MS lens can slow myopia progression in schoolchildren.  
 
3.2 Aims of the study  
 
 To determine if wearing the MS lenses slows the progression of myopia and axial 
elongation in myopic schoolchildren over 2 years. 
  
 To compare the changes in refractive error (Rx) and axial length (AL) in children 
wearing MS lens with those children wearing single vision (SV) spectacle lens 
(control). 
 
 

 
 
4. METHODS AND STUDY DESIGN 
4.1 Subjects: inclusion and exclusion criteria 
Hong Kong Chinese myopic children aged from 8-13 years will be recruited in this study.  
This age range is selected because myopia progression rate has been found to be fastest 
compared with other ages and the mean progression rate in myopic children is about 1D 
annually.3  
 
Inclusion criteria 
Specific inclusion criteria are as follows:  
 
 Ethnicity: Hong Kong Chinese 
 Age at enrolment: 8-13 years 
 Spherical equivalent refraction (SER): -1.00 to -5.00 Dioptres (D) 
 Astigmatism and anisometropia of 1.50 D or less  
 Spectacle corrected monocular VA: 0.0 logMAR or better  
 Free of ocular and systemic abnormalities might affect visual functions or refractive 
development 
 Willingness to wear spectacle lenses regularly 
 Parents’ understanding and acceptance of random allocation of grouping 
 
Exclusion criteria 
 Any ocular and systemic diseases and abnormalities might affect visual functions or 
refractive development  
Any history of prior myopia control treatment, e.g. orthokeratology, progressive addition 
lenses, bifocal lenses, drugs (e.g. atropine), etc. 
 
4.2 Study Design 
This is a 2-year prospective, randomized and double-masked clinical trial. After visual 
screening, the children are fulfilled the inclusion criteria will be enrolled in the study. The 
children will be randomly allocated to wear either MS lenses or regular SV spectacle lenses.  
Allocation will be determined by a random software sequence in Excel.  
Their refraction and AL will be followed up every 6 months over 2 years: baseline, 6-, 12-, 
18- and 24-month visits.  The changes in cycloplegic refraction and AL between two groups 
of children will be compared. Data collection will be performed in Centre for Myopia 
Research, the Hong Kong Polytechnic University (PolyU).  Written assent and informed 
consent will be obtained from children and their parents before participation respectively.  
 
4.3 Sample size estimation 
The number of subjects required for the clinical trial is based on the power calculation for 
subject numbers.  We use 90% power to detect 0.50D difference (with 0.6D of standard 
deviation (SD))6 in myopia progression between two groups with a significance alpha level of 
0.01 (2-tailed); the minimum subject number required to complete the study in each group is 
43.  Assuming a conservative dropout rate of about 40%, 72-75 children are required in each 
group. 

 
 
 
The project will recruit altogether 180 subjects: 90 for control group and 90 for experimental 
group. 
 
4.4 Spectacle lenses 
MS lenses and spectacle prescription 
The MS lens is a custom-made plastic spectacle lens. The lens power matches distant 
prescription. There are multi small defocusing zones of relatively positive embedded in the 
lens. Such design allows to introduce MD and to maintain clear vision simultaneously. The 
controls are the ordinary SV spectacle lenses are made of 1.6CR39HMC. 
 
The final distance prescription of spectacles is determined on cycloplegic subjective 
refraction. The children will be instructed to wear lenses all the time.   
 
Treatment group: MS spectacle lenses 
Control group: SV spectacle lenses 
 
4.5 Randomization process 
A simple randomization will be adopted in this study. Group allocation will be determined by 
the random sequence generated by Excel.  
 
4.6 Masking 
In order to minimize observation bias, this study is designed as double-masked trial. 
Therefore, both the participated children (including their parents) and the masked 
investigator(s) responsible for assessing study outcomes will be aware of the treatment (DISC 
lenses) assignment. All children will be identified on all study documents by an identifying 
number that is not related to treatment assignment.  
The study design is same as that in our previous study. Masked investigator (MI) is masked 
from grouping and not allow to see and handle contact lenses throughout the study. MI is 
responsible for refracting and conducting relevant ocular data measurement. The other is 
unmasked investigator (UMI) and responsible for group allocation, lens fitting and aftercare, 
measuring lens performance, record keeping and compliance checking, answering queries 
from subjects. The children and their parents will be not told which lens design was 
prescribed. 
The masking procedures will follow the ‘Consolidated Standards of Reporting Trials 
‘requirements for a double-masked trial.  
 
 
 
 

 
 
 
 
4.7 Study outcomes and its measurement 
Primary outcomes 
- 
Changes in auto-refraction (SER in diopters) with cylcoplegia 
Secondary outcomes 
- 
Changes in axial length (mm) with cycloplegia  
 
Refraction and AL under cycloplegia will be measured at baseline and at six-month intervals 
for 2 years.  One drop of proparacine 0.5% and then 1-2 drops of cyclopentolate HCL 1 % 
will be instilled to induce cycloplegia. Cycloplegic refraction will be measured by the open-
field autorefractor (Shin-Nippon NVision-K 5001 autorefractor). Five measurement are 
obtained for each eye. The SER of the representative value from these 5 readings was used 
for statistical analysis. AL will be measured by IOL Master (Carl Zeiss) Five measurements 
will be taken and then averaged.  
 
Myopia progression (change in refraction) over 2 years will be determined by the difference 
between SER (from cycloplegic autorefraction) at the fifth and the first (baseline) visits.  
 
 

 
 
4.8 Study visits, eye examination procedures 
 
Figure 4.1 illustrates the overall plan of visits throughout the study. The participating 
children and their parents (or guardians) go through screening phone call, vision screening, 
baseline examination, lens delivery visit, contact lens follow-up visits and 4 comprehensive 
eye examinations (main data collection) at study months 6, 12, 18 and 24 months.  
4.8.1 Subject recruitment and phone screening 
The subjects are recruited through placing posters, public media and the study website. The 
screening phone call are carried out for recruit potentially eligible subjects, to exclude 
children who are not eligible, such as asking for age of the child, history of recent eye 
exam, spectacle prescription, etc.  Then, a vision screening will be schedule vision 
screening for the potential children to confirm if they really fit for our study criteria 
(depend the schedule of the subject). 
Phone screening 
Vision screening /Pre-baseline evaluation 
MI: Baseline visit 
 UI: frame selection, segment 
height measuemnt 
6 Month Visit 
12 Month Visit 
18 Month Visit 
24 Month Visit 
-
UI: spectacle delivery and 
visual performance 
measurement 
 
Order new  lenses if SER 
changes is 0.5D or more or 
VA worsenr than logMAR 
0.2 as compared with 
wearing spectacle Rx 
spectacle delivery 
visit 
Figure 4.1 Overall plan of different visits in the study 

 
 
4.8.2 Pre-baseline visual screening, baseline and main follow-up visits  
Some screening tests are performed to determine if the children fit for our study criteria. 
The pre-baseline screening tests include: autorefraction, cover tests, non-contact IOP, 
subjective refraction, best corrected VA and external ocular health exam by slit-lamp. 
If the subjects pass the screening tests, they and their guardians will be asked to sign the 
consent if they agree to join the clinical trial after explaining the nature and details of the 
study by UMI. Then the participated children will have a comprehensive eye examination 
and baseline data measurement without and with cycloplegia. These procedures will be 
repeated every 6-month over 2 years. Key baseline measurements included refraction, axial 
length (AL), keratometry and phoria biometry will be undertaken either at the same time as 
the vision screening session or in a follow-up session.  
The lists of the study procedures and measurements to be performed at different visits and 
is summarized in Table 4.1. All the data collection will be conducted at our Optometry 
Research Clinic, School of Optometry, the Hong Kong Polytechnic University.  
The following measurement and eye tests will be performed by MI at baseline, 6, 12, 18 
and 24M visits (5 visits over 2 years). 
 
Without cycloplegia 
- 
Determination of dominant eye 
- 
Subjective and objective refraction 
- 
Best corrected visual acuity 
- 
Corneal curvature/ topography 
- 
Binocular vision tests: phoria tests, stereopsis 
- 
Accommodative tests: amplitude of accommodation, lag of accommodation with 3D 
stimulus 
- 
Pupil diameters under different illumination, during distance and near viewing 
- 
Non-contact IOP 
- 
Subfoveal choroidal thickness (SFCT) by Spectral Domain Optical Coherence 
Tomography (SD-OCT) 
 
With cycloplegia  
- 
Subjective refraction (as reference for the prescription of contact lenses) 
- 
Objective refraction: measured by using Shin-Nippon NVision-K 5001 (open-field) 
autorefractor. Five measurement are obtained for each eye and the average of SER of 
was used for statistical analysis. 
- 
AL measurement: measured by IOL Master (Carl Zeiss). Five measurements were 
taken and averaged. 
- 
Peripheral refraction: measured by using a Shin-Nippon NVision-K 5001 
autorefractor at center, 10, 20 and 30 degrees at the nasal and temporal visual field 
across the horizontal meridian. 
- 
Dilated fundus examination 
 
 

 
 
Table 4.1 Examination procedures/ items for each visit.  
Procedures 
/measurements 
*Screening 
 
Baseli
ne 
2 
wk 
1M 3M 
6M 
12M 
18M 
24M 
Consent form 
signed 
 
x 
 
 
 
 
 
 
 
History-initial  
x 
x 
 
 
 
 
 
 
 
History-Update 
 
 
x 
x 
x 
x 
x 
x 
x 
Non-cycloplegic 
autorefraction 
x 
x 
 
 
 
x 
x 
x 
x 
Habitual spec 
VA 
x 
x 
 
 
 
x 
x 
x 
x 
Subjective 
refraction 
x 
x 
 
 
 
x 
x 
x 
x 
Best-corrected 
VA 
x 
x 
 
 
 
x 
x 
x 
x 
Cover test 
(distance, near) 
x 
 
 
 
 
 
 
 
 
Phoria (distance 
and near) 
 
x 
 
 
 
x 
x 
x 
x 
Lag of 
accommodation 
 
x 
 
 
 
x 
x 
x 
x 
Amplitude of 
accommodation 
 
x 
 
 
 
x 
x 
x 
x 
Stereopsis 
 
x 
 
 
 
x 
x 
x 
x 
Pupil size 
 
x 
 
 
 
x 
x  
x 
x 
Keratometry  
 
x 
 
 
 
x 
x 
x 
x 
Slit-lamp exam, 
external ocular 
health check 
x 
x 
 
 
 
x 
x 
x 
x 
IOP 
measurement 
x 
x 
 
 
 
x 
x 
x 
x 
Choroidal 
thickness 
measurement 
 
x 
x 
x 
x 
x 
x 
x 
x 
Eye drops: 
Anesthetic, 
Cycloplegics 
 
x 
 
 
 
x 
x 
x 
x 
Cycloplegic 
subjective 
refraction 
 
x 
 
 
 
x 
x 
x 
x 
Cycloplegic 
autorefraction 
 
x 
 
 
 
x 
x 
x 
x 
Axial length 
measurement 
 
x 
 
 
 
x 
x 
x 
x 
Peripheral 
refraction 
 
x 
 
 
 
x 
x 
x 
x 
Dilated fundus 
exam 
 
x 
 
 
 
x 
x 
x 
x 

 
 
VA with 
habitual 
spectacle  
 
 
x 
x 
x 
x 
x 
x 
x 
Questionnaire of 
visual habits and 
spectacle lens 
performance 
 
 
 
 
 
 
 
 
x 
* Screening day may be at the same day of baseline measurement.  
 
 
4.8.3 Spectacle prescription and visual performance of lenses 
 
The final distance prescription of spectacles is determined on cycloplegic subjective 
refraction performed by the masked optometrist. UI do frame adjustment, mark and measure 
PD and fitting heights for all subjects whatever they are wearing MS lenses or SV lenses 
because the subjects are masked from the grouping.  
Visual performance, including visual acuity at distance and near under high and low contrast, 
with spectacle lenses will be assessed at the first delivery visit. Subject will wear lenses on a 
daily  
The lens will be replaced and upgraded if the equivalent sphere of refraction (SER) is 
changed by 0.5D or more (or habitual aided LogMAR VA worsen than 0.2) in either eye as 
compared with wearing spectacle refraction. The children will be instructed to wear lenses all 
the time throughout the study.  Aided VA at both distance and near will be measured in 
delivery of new spectacles. 
 
4.9 Questionnaire  
Parents or guardians will be complete a questionnaire regarding the child’s vision habits and 
parents’ Rx, and the number of years that the child has been myopic before they enroll in this 
trial. Questions regarding how much time the children spend reading and outdoor activities 
will be included. In addition, patient-reported measures on lens performance are also assessed 
using questionnaire.  
 
4.10 Visual performance of lenses  
Visual performance tests of the lenses will be carried out in the visit of contact lens delivery. 
The items include:  
 
 Objective Visual Assessment 
 Distance and near visual acuity in low and high contrast: 
 Binocular vision tests: 
- 
Horizontal phoria at distance and near  
- 
Stereoacuity (minute of arc)  
- 
Amplitude of accommodation (D)  
- 
Lag of accommodation 
 

 
 
 Patient-Reported Measures of Lens Performance using questionnaire. 
 
 
4.11 Statistical analysis 
Data of two groups will be presented as the mean ± SD. Only data of the right eyes will be 
used for data analysis if there are high correlation of data between two eyes.  Baseline data 
between two groups between males and female will be analyzed by unpaired t-tests. Welch 
correction is applied if the difference of SD between the groups is statistically significant.  
Primary outcomes 
- 
Changes in auto-refraction (SER in diopters) with cylcoplegia 
Secondary outcomes 
- 
Changes in axial length (mm) with cycloplegia 
 
1. Repeated measures ANOVAs were used to compare the changes from the baseline 
visit in SER, and AL over time and between the two study groups in study. 
Interactions between time and groups were also assessed. If repeated measures 
ANOVA showed significant results between groups and significant interaction 
between time and groups, unpaired t tests were used to test for differences in SER, 
AL, between the two groups after the 24-month follow up period, and plots of the 
change will be plotted for showing trends. Bonferroni corrections were used to take 
account of post-hoc comparisons. The efficacy of myopic control will be determined 
by dividing the difference in mean SER changes of two groups with the mean SER 
change in the SV group times 100%. 
 
2. The correlations between changes in Rx, biometric parameters and related factors 
(e.g. lens wear time, time spent on outdoor activities) are analyzed using Pearson 
correlations. Multivariate analyses of variance are used to examine the effect on 
treatment outcomes of various factors, including age, gender, initial refraction, etc. 
 
3. To examine the choroidal response to MD in MS lens, changes in choroidal thickness 
over time and between two groups will be compared by the same statistically methods 
used for SER and AL mentioned above (point 1). Besides, the correlation between 
changes in choroidal thickness and axial length will be calculated using Pearson’s 
correlation coefficient. Correlation between the pupil sizes, peripheral refraction and 
the effect in myopic control in terms of axial length elongation will be calculated 
using Pearson’s correlation coefficient. 
 
 
 

 
 
5 CLINICAL EXAMINATION PROCEDURES BY MI 
 
5.1 Introduction 
In order to maintain the integrity of double masked study, clinical examination will comprise 
two sessions: Clinical Examination by masked MI (or masked optometrist) and UMI 
(unmasked optometrist). The MI will be responsible for obtaining the required key data.  
Objectives: 
i. 
to collect required data 
ii. 
to provide Rx for contact lens prescription  
iii. 
to maintain integrity of double masked design 
 
Summary of eye examination procedures and data collection 
Without cycloplegia 
- 
Determination of dominant eye 
- 
Pupillary distance (PD) 
- 
Subjective refraction 
- 
Autorefraction and kerometry 
- 
Best corrected visual acuity 
- 
Binocular vision tests: phoria tests, stereopsis 
- 
Accommodative tests: amplitude of accommodation, lag of accommodation 
- 
Pupil diameters under different illumination, during distance and near viewing 
- 
Non-contact IOP 
- 
Subfoveal choroidal thickness (SFCT) by Spectral Domain Optical Coherence 
Tomography (SD-OCT) 
- 
 
With cycloplegia  
- 
Subjective refraction (as reference for the prescription of contact lenses) 
- 
Objective refraction: autorefraction 
- 
AL measurement: measured by IOL Master (Carl Zeiss). Five measurements were 
taken and averaged. 
- 
Peripheral refraction: measured by using a Shin-Nippon NVision-K 5001 
autorefractor at center and 10, 20 and 30 degrees at the nasal and temporal visual field 
across the horizontal meridian.3  
- 
Dilated fundus examination 
 
One drop of proparacine 0.5% and then 1-2 drops of cyclopentolate HCL 1 % will be instilled 
to induce cycloplegia. Cycloplegic refraction will be measured by the open-field autorefractor 
(Shin-Nippon NVision-K 5001 autorefractor). Five measurement are obtained for each eye. 
The SER of the representative value from these 5 readings was used for statistical analysis. 
AL will be measured by IOL Master (Carl Zeiss) Five measurements will be taken and then 
averaged.  
 
 

 
 
5.2 Determination of dominant eye 
Procedures: 
i. 
Ask subject to make a circle with thumbs and first fingers 
ii. 
Hold arms straight in front and view the spot light 
iii. 
Researcher to occlude each eye in turn to determine which eye is seeing the 
letter with habitual glasses 
 
5.3 PD measurement 
Shin-nippon PD-82 will be used to measure monocular and binocular PDs. 
Procedures: 
i. 
Turn the target distance lever to infinity. 
ii. 
Press the main switch. 
iii. 
Apply the instrument to the subject’s forehead and nose, using the forehead rest 
and the nose rest. 
iv. 
Instruct the subject to look at the fixation target inside the instrument 
v.  
Slide either of the PD levers for right and or left, and match the PD pointer with 
the bright point reflecting on the subject’s pupil. 
vi. 
Read the digital values (in mm) shown on the display window on the instrument 
top. The value in the center shows the interpupillary distance. The values R and 
L indicate the distances from the nose center to the right and left pupils 
respectively. Record PD, RPD and LPD. 
vii. Measure near PD. Set the target distance lever to 40cm and repeat step iv. – vi 
 
5.4 Non-cycloplegic Autorefraction and keratometry 
The Shin-Nippon NVision-K 5001 autorefractor will be used to measure Rx 
objectively. 
Procedures: 
i. 
Set the measurement mode into ‘R’ and ‘K’ that allows to measure the 
autorefraction and corneal curvature/ power at the same time. 
ii. 
Place the fixation target (Figure 5.1) 6 m from the machine. 
iii. 
Vertex distance is set to 12 mm. 
iv. 
The subject’s chin is set on the chin rest and his/her forehead against the 
forehead rest. 
v. 
The subject should be able to see the fixation target in front of him/her through 
the “wide view” window. 
 
 
 
 
 
 
 

 
 
 
 
 
 
Figure 5.1 Fixation target 
                                                            
 
vi. 
Ask the subject to look at the white circle in the middle of the fixation target 
(Figure 5.1). 
 
 
 
 
 
 
              Figure 5.2 Reticle circles and corneal reflex spot 
 
vii. While viewing the right eye on the CRT screen, carry out alignment: position 
the reticle circles so that they are both completely located inside the boundary 
of the pupil. (Figure 5.2) 
viii. The subject will see a faint red on the “wide view” window once the start button 
is pressed, and the subject will be requested to report the target position relative 
to the red ring. 
ix. 
The target will be adjusted as necessary until it is judged to be located at the 
centre of the red ring. The non-tested eye is then uncovered. 
x. 
Carefully maneuver the joystick to reduce corneal reflex spots to their smallest 
size. Press the button on the joystick to start measurements. 
xi. 
Five measurements will be taken.  
xii. Repeat the step vi. – xi. for the left eye. 
xiii. Press PRINT key and attach the printout to the record sheet. 
xiv. Record the representative value as the result of auto-refraction which is under 
the dashed line in the printout, for both eyes. 
 
5.5  Subjective Refraction 
Procedures: 
i. 
Starting with autorefraction obtained above, refine subjectively. 
ii. 
Occlude the left eye. 
iii. 
Determine best sphere first. 
Add +0.25D and ask if “worse or the same”. If “the same” add +0.25D and 
repeat until the answer “worse” is given. If “worse” add -0.25D and ask if 
“better or the same”. If “better” add -0.25D and check for improvement in VA; 
repeat until the answer given is “the same”. Do not add the -0.25 D at this stage. 
iv. 
Determine cylindrical error. 
Add -0.25D to best sphere and carry out cross-cylinder. Check axis and then 
power. Using a non-directional letter as a target. 
Reticle circles 
Corneal reflex spot 

 
 
v. 
Refine sphere using +1.00D blur back test monocularly and finish by offering a 
binocular +0.25D add. Give this if “no difference”. Stop if “worse”. Repeat until 
“worse”. 
vi. 
Binocular balance (prism dissociation): with the monocular subjective result in 
the phoropter, add +1.00D to each eye, then add 3∆ base-down OD and 3∆base-
up OS. Use the 0.3 logMAR line as the target. If the upper line letter appears 
clearer than the lower line letters, add +0.25D to right eye. If the lower line 
letters appear clearer than the upper line, add +0.25D to left eye. Stop when no 
difference between the upper and lower line. 
 
5.6 Visual acuity  
 Distance VA, including BCVA of both eyes will be assessed using Logarithmic 2000 
series ETDRS Chart and Low Contrast ETDRS Charts at 4 m (Precision Vision Inc.) 
with the illuminator cabinet (450 cd/m2). 
 Near VA (40cm) will be measured by the Near Vision Test Card from the Hong Kong 
Polytechnic University. 
 
5.7 Phoria measurement 
Procedures: 
i. 
Howell phoria card will be used to measure phoria 
ii. 
Insert 6∆ base down right eye into the trial frame with the best subjective 
refraction 
iii. 
Phoria at distance is measured by asking the subject to indicate the number on 
the bottom line that is nearest to the top arrow, when viewing the large phoria 
chart at 3 m. Always ask the subject to keep the letters clear. 
iv. 
The blue even numbers indicate exophoria and the yellow odd numbers indicate 
esophoria 
v. 
Phoria at near is measured by asking the subject to indicate the number on the 
bottom line that is nearest to the top arrow, when viewing the small phoria chart 
at 33 cm. Always ask the subject to keep the letters clear. 
vi. 
Record the distance and near phoria (-ve: exo; +ve: eso) 
 
5.8 Stereopsis 
 
Stereoacuity (minute of arc) will be measured with Randot Stereotest (refer to user guide) 
at 40 cm with Polaroid goggles.  
 
5.9 Amplitude of accommodation 
 
Amplitude of accommodation (D) will be measured with RAF ruler for monocluarly 
and binocularly. Average of 3 measurements will be used for data analysis. 
 
 
 

 
 
5.10 Lag of Accommodation 
Procedures: 
i. 
Place the subject’s best subjective refraction in the trial frame and position the 
subject in the Shin-Nippon NVision-K 5001 autorefractor. 
ii. 
Place the distance target (0 logMAR letters) at 6 m. While encouraging the 
subject to look clear the letters, take 5 readings on the subject’s right eye, 
followed by 5 readings on the left eye. The eye not being measured will be 
occluded. 
iii. 
Place the near target (0 logMAR letters) at 33 cm (3D near stimulus). While 
encouraging the subject to look clear the letters, take 5 readings on the subject’s 
right eye, followed by 5 readings on the left eye. The eye not being measured 
will be occluded. 
iv. 
The lag of accommodation will be calculated for each eye by summating the 
difference in the mean spherical equivalents between the 5 distance readings 
and the 5 near reading s and 3D (matrix is also used in calculation). 
 
 
 
 
 

 
 
5.11 Choroidal thickness measurement 
Choroidal thickness measurement will be measured at the following schedule (please refer to 
Table 4.1): 
 
 Baseline visit 
 Delivery of 1st pair of CL, 2 week of CL wear, 1 month of CL wear, 3 month of CL 
wear 
 6-month FU, 12-month FU, 18-month FU and 24-month FU.  
 
Choroidal thickness will be obtained by a modified dual wavelength Spectral Domain Ocular 
Coherence Tomograper (SD-OCT) by Heidelberg Engineering (Spectralis HRA+OCT, 
Heidelberg Engineering, Germany) using enhanced depth imaging mode and with the help of 
1060nm. This OCT uses a dual light source of 870nm and 1060nm at scanning speed of 
40000A-scan/second. Cross sectional images with axial resolution of 3.9µm and transverse 
resolution of 14µm will be obtained. Choroid in an OCT image is defined as the boundary 
between the highest reflected interfaces from retinal pigmented epithelium to the chorio-
scleral junction. The choroidal thickness is determined using the built-in software of SD-OCT 
(Heidelberg Eye Explorer) automatically. Subfoveal and parafoveal choroidal thickness at 
1mm and 3mm away from the fovea in temporal, nasal, superior and inferior quadrants will 
be measured. The changes in choroidal thickness are compared between the MS lens and the 
SV groups. 
 
To avoid diurnal variation of CT, we will arrange data collection for subject at similar time in 
each follow-up visit if possible.  
 
 
5.12 IOP and cycloplegia 
 
i. 
Measure non-contact IOP using Nidek NT-4000. Excluded if  IOP > 22 mm Hg 
and CD ratio >0.6. 
ii. 
Explain purpose of eyedrops to parent. Handout sheet stating normal reaction 
will be given to the parent with telephone numbers. Ask to contact if any 
different reaction occurs. 
iii. 
Cycloplegia is induced by instilling 1 drop proparacaine (0.4%) then 2 drops 
cyclopentolate HCL (1%) into each eye at 5-minute intervals. Subject is asked 
to hold puncta. 
 
5.13 Cycloplegic Autorefraction 
 
Procedures: 
iv. 
30 minutes later check pupils. If dilated, measure amplitude of accommodation 
using push-up method. If not dilated add one further drop of cyclopentolate to 
each eye.  
v. 
Autorefract when accommodation <2.00D. 

 
 
vi. 
Carry out autorefraction using Shin-Nippon NVision-K 5001 (open-field) 
autorefractor as in Non-cycloplegic Autorefraction section.  Five 
measurements are obtained for each eye. 
vii. The SER of the representative value of will be used for statistical analysis. 
 
5.14 Axial Length Measurement with will be used 
The Zeiss IOL Master will be used to measure axial length. 
Procedures: 
i. 
Press bottom to input new subject data or select old subject data. 
ii. 
Finished entering then press <NEW> button. This will automatically activate 
the “Overview”mode. 
iii. 
The fixation light and the illumination LEDs are on 
iv. 
Align the eyes with the red marks on the side rails of the headrest. 
v. 
Ask the subject to look at the yellow fixation light in the middle 
vi. 
Adjust the instrument until the 6 light spots appear focused on the screen. 
vii. The circle of lights should be approximately centered to the pupil and cross hairs 
viii. Then push button on the joystick 
ix. 
Make sure “phakic” mode is on. It can be checked in the AL Setting in the screen 
x. 
The instrument now automatically changes the magnification: a smaller section 
of the eye becomes visible with the reflection of the alignment light and vertical 
line. 
xi. 
Ask the subject to look at the red fixation light. On the display, a crosshair with 
a circle in the middle appears. 
xii. Fine-align the instrument so that the reflection of the alignment light appears 
within the circle 
xiii. Push the button on the joystick to start the measurement 
xiv. By pressing the button on the joystick continuously, next measurements will be 
started. 
xv. If the result of one measurement differs by more than 0.2mm from the others, 
an “Evaluation” message will be displayed in place of the average. 
xvi. If the signal received by the instrument was poor, an exclamation mark will be 
shown besides the value of that measurement. 
xvii. All the value marked with special marking as stated above will be deleted.  
xviii. Five consecutive readings were made for each measurement; each reading 
showing signal-to-noise ratio above 2.0 and differing by less than 0.20 mm from 
the others. Any reading which not fit the criterion was deleted and re-measured. 
(Not more than 20 measurements can be taken on each eye per day). 
xix. Record the mean axial length in mm. 
 
5.15 Final Prescription 
 
The final distance prescription of spectacles will be determined on cycloplegic subjective 
refraction. Masked Optometrist to write final prescription on the clinical examination record 
(Masked) and take subject, parent and Rx to the unmasked investigator (UI) for lens ordering. 
The lens will be replaced and upgraded if the equivalent sphere of refraction (SER) is 
changed by 0.5D or more (or habitual aided LogMAR VA worsen than 0.2) in either eye as 

 
 
compared with wearing spectacle refraction. The children will be instructed to wear lenses all 
the time.   
 
If dispensing and frame adjustment are necessary, proceed to spectacle lens dispensing and 
delivery visit. All dispensing works are performed by UI. 
 
6. CLINICAL EXAMINATION BY UMI 
The UMI will be responsible for measuring the aided VA, to check contact lens fitting and 
related measurement. 
Objectives: 
i. 
to measure aided VA 
ii. 
to check contact lens fitting 
iii. 
to modify contact lens fitting and prescription when necessary 
iv. 
to educate the parents and the subjects how to insert and remove contact lens  
safety, about lens cleaning and disinfection procedures, etc. 
v. 
to perform the tests for assessing visual performance of contact lenses  
vi. 
to ask history, ask the child and parent to sign consent form, fill in questionnaire, 
etc. 
vii. to maintain integrity of double mask design 
 
Starting from the first 6-month intervals Clinical Examination visit, UMI will be responsible 
for: 
i. 
the entry of subject details, 
ii. 
measurement of aided logMAR VA at distance and near 
iii. 
checking the contact lens fitting 
iv. 
checking the contact lenses 
v. 
re-adjustment of the CL fitting and prescription when necessary 
vi. 
external ocular health checking 
vii. checking compliance of CL  
viii. collect and check the logsheet about lens wear time and lens compliance  
ix. 
collect contact lens (to maintain masking) and take the child and parent to 
masked optometrist 
 
Child and parent will be informed not to raise any questions about contact lenses with the 
masked optometrist or MI. Those questions should be addressed to the unmasked optometrist 
or UMI.   
6.1 Visual performance of spectacle lenses 
 
 Objective Visual Assessment 
 
1. Visual acuity in low and high contrast: 
 Distance Log MAR VA High contrast (100%) and low contrast (10%) LogMAR VA 
will be assessed under both low and low illumination using Logarithmic 2000 series 
ETDRS Chart and Low Contrast ETDRS Charts at 4 m (Precision Vision Inc.) with 

 
 
the illuminator cabinet (450 cd/m2) respectively. The high and low near VA (40cm) 
will be measured by the Near Vision Test Card from the Hong Kong Polytechnic 
University under both high and low illumination. 
 
2. Binocularity: 
 
Horizontal phoria at distance and near will be measured with Howell-Phoria cards. 
 
Stereoacuity (minute of arc) will be measured with Randot Stereotest at 40 cm with 
Polaroid goggles. 
 
Amplitude of accommodation (D) will be measured with RAF ruler. 
 
Accommodative Response- Refractive state will be measured by the open-field auto-
refractor binocularly with a target 33cm away.  
 
Patient-Reported Measures of Lens Performance 
Vision performance and vision comfort with lenses will be graded by the subjects themselves 
through questionnaires.  The subjective rating on vision performance includes vision at 
distance and near, stability of perceived vision at distance and at near. (Appendix 1) 
 
 
References 
1. Saw SM, Shankar A, Tan SB,Taylor H, Tan DT, Stone RA, Wong TY. A cohort study of 
incident myopia in Singaporean children. Invest Ophthalmol Vis Sci.2006;47:1839-44. 
2. Lam CS, Goldschmidt E, Edwards MH. Prevalence of myopia in local and international 
schools in Hong Kong. Optom Vis Sci. 2004;81:317-22. 
3. Lam CS, Lam CH, Cheng SC, Chan LY. Prevalence of myopia among Hong Kong 
Chinese schoolchildren: changes over two decades. Ophthalmic Physiol Opt. 2012;32:17-
24. 
4. Vongphanit J, Mitchell P, Wang JJ. Prevalence and progression of myopic retinopathy in 
an older population. Ophthalmology. 2002;109:704-11. 
5. Xu L, Wang Y, Wang S, et al. High myopia and glaucoma susceptibility the Beijing Eye 
Study. Ophthalmology. 2007;114:216–20. 
6. Lam CS, Tang WC, Tse DY, Tang YY, To CH. Defocus Incorporated Soft Contact 
(DISC) lens slows myopia progression in Hong Kong Chinese schoolchildren: a 2- year 
randomised clinical trial. Br J Ophthalmol. 2014;98:40-5. 
 
 

 
 
7. Appendix 1 
Questionnaire: Evaluation of a new myopic control lenses 
Name: _________________________  
 
    Date: ____________________ 
Record #: _____________________ 
Section A.  Please estimate the time that you spend on the following activities.   
School time 
Hours per day 
(a) Weekdays: 
Mon-Fri 
(b) Weekends: 
Sat -Sun 
Hours per day on 
average 
=  (5a + 2b)/2 
Wear our spectacles 
 
 
 
Do you wear other optical aids 
during this study?  (e.g. contact 
lenses, other spectacles, etc.) 
Yes 
(go to Q2) 
No 
 
Contact lenses: 
_______________ 
 
 
 
 
Spectacles: 
___________________ 
 
 
 
 
Near work (e.g. reading, doing 
homework, smart-phone and i-
pads, etc.)  
 
 
 
Mid-working distance activities 
(e.g. watch TV, computer, 
playing musical instruments, 
etc.) 
 
 
 
Outdoor activities 
 
 
 
Indoor activities  
 
 
 
Sleeping time 
 
 
 
 
 
 

 
 
Long holidays 
Hours per day 
(a) Weekdays:  
Mon-Fri  
(b) Weekends:  
Sat -Sun 
Hours per day on 
average  
=  (5a + 2b)/2 
Wear our spectacles 
 
 
 
Near work (e.g. reading, doing 
homework, smart-phone and i-
pads, etc.)  
 
 
 
Mid-working distance 
activities (e.g. watch TV, 
computer, playing musical 
instruments, etc.) 
 
 
 
Outdoor activities 
 
 
 
Indoor activities  
 
 
 
Sleeping time 
 
 
 
 
Section B. 
Please rate the performance of your current spectacles. (Please circle the choice and rating) 
 
 
Poorest 
 
acceptable 
 
Fair 
 
 
Good 
 
Excellent 
1 
Vision at distance 
(clarity) 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
2 
Vision stability at 
distance 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
3 
Clarity of vision 
for intermediate 
distance (e.g. 
computer, 
watching TV) 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
4 
Clarity of vision 
for near tasks (e.g 
reading, using 
smartphone) 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 

 
 
5 
Vision stability at 
near 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
6 
Vision comfort 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
8 
Vision during 
outdoor 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
9 
Easiness of lens 
adaption 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
10 
Overall 
performance 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
 
Do you have the following symptoms when wear this spectacles? 
 
 
Never  Seldom 
 
Some-
times 
 
 
Often 
 
Always 
1 
Blurred vison at 
far distance 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
2 
Blurred vision at 
intermediate 
distance (e.g. 
computer) 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
3 
Blurred vision at 
near (e.g. 
reading, smart-
phone) 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
4 
Ghosting image 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
5 
Unstable vision 
at distance 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
6 
Unstable vision 
at near 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
7 
Difficulty or 
slowness in 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 

 
 
refocusing your 
eyes from one 
distance to other 
8 
Eyestrain 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
9 
Double vision 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
10 
Dizziness 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
Headache 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
 
Other comments: 
________________________________________________________________