PROductivity Study of Presbyopia Elimination in Rural-dwellers (PROSPER)
Phase: NA
Conditions: Presbyopia
Sponsor: Congdon Nathan

PROSPER Full Protocol  
Study Identification  
NCT number:  NCT03228199  
Date of the document: 24 December 2017  
Unique Protocol ID: "PROSPER (IRB - LNEH/88/2017)"  
Brief Title: PROSPER 
Official Title: PROductivity Study of Presbyopia Elimination in Rural-dwellers 
(PROSPER)    
Study Status  
Record Verification:  December 2017    
Overall Status: Recruiting  
Study Start:  July 24, 2017 [Actual]  
Primary Completion: October 7, 2017 [Actual]  
Study Completion:  October 28, 2017 [Actual]  
Sponsor/Collaborators  
Sponsor: 
Congdon Nathan   
Responsible Party: Sponsor-Investigator 
Investigator: Congdon Nathan [cnathan] 
Official Title: Professor 
Affiliation: Sun Yat-sen University & Queen’s University Belfast 
Collaborators:    
Queen's University, Belfast 
Clearly.World 
COMMUNITY EYE CARE FOUNDATION (CECF) 
Aravind Eye Care System 
University of British Columbia 
Amalgamated Plantations Private Limited 

VisionSpring 
Oversight  
U.S. FDA-regulated Drug:  
No    
U.S. FDA-regulated Device:  No    
U.S. FDA IND/IDE:  No    
Human Subjects Review:  Board Status: Approved     Approval Number: LNEH/88/2017   
Board Name: Dr. Ashok Mahadik  
Board Affiliation: Lion's NAB Eye 
Hospital  
Phone:   Email:   
Address:  
Lion's NAB Eye Hospital  
Sangli, Maharastra, India  
Data Monitoring:  
Yes  
Plan to Share IPD:  
No  
FDA Regulated Intervention:  No  
  
Study Description  
Brief Summary:   
This trial seeks to establish, using a randomized, controlled design, the impact of near 
eyesight correction on the productivity of presbyopic agricultural workers in India, as 
measured by weight of tea picked.  
   
I.  
Background: Importance of research topic, Particular Features of setting   
Uncorrected presbyopia is an expensive problem for the world. Lost productivity among 
adults who need eyeglasses has been estimated to cost the global economy $227 billion 
every year, [1,2] and illiteracy may lead to a further $3 trillion in annual global economic 
losses. It has been shown that 74% of illiterate adults failed one or more parts of a vision 
screening. [3] However, in order to motivate governments, industry and other key 
stakeholders to invest in solving the problem of uncorrected near vision in adults, higher-

quality data on the productivity impact of correction are needed. Current studies are 
suggestive, but carefully-performed randomized trials are still lacking in the published 
literature.  
An unpublished University of Michigan (USA) working paper found that correcting near-
vision loss with glasses yields an increase in productivity of up to 34%, though no control 
group was included, and the outcome assessed was not precisely defined. An unpublished 
impact assessment conducted by Building Resources Across Communities (BRAC), the 
world's largest NGO in number of staff, concluded that 90% of individuals experiencing 
near-vision loss in Bangladesh encountered problems with their daily work; and, on 
average, 23% reported that their income was compromised.[4] In Rwanda, Lifetime 
Consulting & Partners found that workers with poor vision who did not wear glasses were 
three times more likely to be asked by supervisors to repeat their work of sorting coffee 
beans than after receiving and wearing glasses.[4] Again, no control group was included, 
and this work has not been published. Furthermore, a Dalberg Global Development 
Advisors study of adults in India who had their vision corrected with glasses found that 
65% reported an increase in independence in movement and travel, and 59% reported 
improved work productivity, [5] but these outcomes were not confirmed quantitatively or 
objectively. Finally, a population study of 1008 older adult in Shenyang, northern China, 
found that those with uncorrected presbyopia (69%) were more likely to report diminished 
accomplishment due to vision (P = 0.01, adjusted for age, sex, education, and distance 
vision) than were those without presbyopia. [6] The impact of correcting presbyopia was 
not studied in prospective fashion.  
In summary, available data are consistent with the idea that correcting presbyopia can lead 
to significant improvements in productivity among adult workers. However, in the absence 
of high-quality randomized trials, it is very difficult to be certain about cause and effect: it 
is equally plausible that the economic burden of poverty could result in failure to purchase 
glasses, rather than the reverse. Lack of control groups and carefully-defined productivity 
outcomes in many studies further hinder interpretation. Policy makers and industry partners 
require more convincing data in order to commit to the support of programs of vision 
correction.  
Features of this setting:  
A high proportion (> 50%) of workers have presbyopia in this large workforce, and 
previous projects by Vision Spring have shown that the large majority of these workers 
have no presbyopic correction.   
The primary outcome (daily weight of tea picked) is measured and recorded by 
Amalgamated Tea as part of routine practice.  
The work population is very stable, and data from previous years have been used for 
sample size calculations.  
The project will be carried out during the high season (July through October) when the 
amount of tea picked is limited by the labourer and not by growth of the plants. Further, 

these agricultural workers are strongly incentivized to pick more tea, because they are paid 
by weight, and thus gain in income when their personal productivity increases.  
II. Experimental plan  
Study design: Randomized, investigator-masked controlled trial  
 
 
Methods to be used:  
Population: Presbyopic (generally age >= 40 years) tea workers at the Amalgamated 
Plantations Pvt Ltd (APPL) in Assam, India.  
Baseline data acquisition: Demographic and clinical: Age, sex, contact information, 
habitual and best corrected visual acuity at near and distance; power of distance and near 
refractive error in each eye; workers with acuity not improving to 6/7.5 in either eye at 
distance will undergo dilated fundus examination and will be referred to a local 
collaborating facility for care if needed. Work productivity: Daily mean weight of tea 
picked during a 4 weeks baseline period prior to randomisation.  
Recruitment and consent: Approximately 1500 APPL workers aged 40 years or more will 
undergo assessment of above clinical criteria ("Baseline data acquisition") by VisionSpring 
local staff, assisted by APPL as part of the on-going Clear Vision Workplace program. 
Those meeting inclusion criteria (see below) will be invited to join to the study and 
complete informed consent forms. Recruitment will continue until approximately 700 
persons have joined the study (see sample size calculations below). Baseline work 
productivity will be measured as outlined above for a 4-week period).  
Inclusion Criteria:  
• 
Employee of APPL for 1 year   
• 
Aged >= 40 years  
• 
Habitual near visual acuity of >= 0.8M (<=6/12) at 40cm in both eyes, correctable 
to <=0.5M (>=6/7.5) in both eyes with near glasses   
• 
Uncorrected distance vision >= 6/7.5 in the better-seeing eye   
• 
The participant worked and has data available on weight of tea picked for >=10 
days in the previous 4 weeks (This will largely exclude men in this setting).   
• 
Ability to give informed consent  
Exclusion Criteria:  
• 
Eye disease detected on baseline eye exam   
• 
Current ownership of near correction capable of improving near visual acuity to <= 
0.8M (>= 6/12) in either eye   
• 
Unlikely to complete follow-up due to unsatisfactory work performance, plans to 
move out of the area, etc.  

• 
Need for distance correction to achieve distance vision of >= 6/7.5 in the better-
seeing eye.  
• 
Inability to achieve best-corrected visual acuity with spherical power glasses only 
(that is: need for astigmatic correction to achieve best-corrected near visual acuity)  
Persons with eye problems detected on examination will be referred for definitive care at 
local facilities, and distance refractive errors will be corrected with free bifocals for those 
with uncorrected VA < 6/12 in the better-seeing eye.  
Randomization, Balancing and Intervention: Eligible workers completing baseline 
productivity assessment will be enrolled into the study, and assigned at random to one of 
the below groups:  
Intervention Group: Will immediately receive a free pair of presbyopic glasses through the 
Clear Vision Workplace program. These glasses will correct the worker's vision to their 
usual working distance, and will not correct astigmatism.  
Control Group: Will be deferred to receive free presbyopic spectacles after the 12 weeks 
evaluation period.  
Balance of the groups on age and baseline work productivity will be assessed and 
maintained insofar as possible, and allocation concealment prior to randomisation will be 
ensured through the use of a secure process so that neither the participant nor the person 
recruiting them to the study will know in advance whether or not they will receive 
spectacles immediately or after 12 weeks.  
Randomization methodology:  Eligible workers completing baseline data collection will 
be enrolled into the study, and stratified into eight groups according to age (<50, >=50), sex 
and baseline work productivity (<median, >=median), then participants among each of the 
eight groups will be assigned at random to one of the study arms as shown in the following 
figure.   
An independent statistician having no contact with participants will generate the 
randomization sequence using a computer system that is inaccessible until after 
recruitment. The participants in each stratified group will be assigned to either the 
intervention or control group in a 1:1 ratio with block size of six. The participants will 
know their group assignment. However, the APPL staff measuring the weight and quality 
outcomes will be masked to a worker’s group assignment by having an intermediate person 
receive the tea from the worker at the weighing station each day.  
 
 

  
Enrollment (n=700)  
  
 
  
Main outcome and masking: The daily mean weight of tea picked will be calculated for 
each worker for the 4 weeks baseline and for the 12 weeks evaluation period. The 
difference between these two means will be calculated for each worker, and the mean of 
this value will be calculated for each randomised group, with the main study outcome being 
the difference between these values for each group. It will not be practical to mask 
participants to their study group assignment (the investigators do not feel that providing 
sham near correction of plano power is ethical). However, the APPL staff measuring the 
weight outcomes will be masked to a worker's group assignment by having an intermediate 
person receive the tea from the worker and carry it to the weighing station each day. 
Secondary outcomes will include visual quality of life in both groups, self-reported wear of 
the study spectacles in the intervention group, self-reported purchase and use of glasses in 
the control group, independent compliance observations, quality of tea picked (if possible 
to assess) and the proportion of workers who work than less than 10 days in a month during 
the 12 weeks evaluation period.  
Study hypothesis: Productivity gains in the Intervention Group will be significantly greater 
than those in the Control Group when the 12 weeks evaluation period is compared to the 4 
weeks baseline period.  
Sample size calculations: With two-sided significance level of P=0.05, power of 80%, a 
daily mean of 25.0 (SD: 5.0) kg of tea picked at baseline (among persons working >= 10 
days in a month), and allowing for 20% loss to follow-up, a sample size of 160 persons (80 
per group) will be sufficient to detect a 10% greater increase in daily mean weight of tea 
picked in the intervention group compared to the control group (primary outcome). 
However, in order to have sufficient data to conduct adequately powered analyses to 
compare the results for persons aged 40 years and above, with those for persons aged at 
Randomization  
Randomization  
Randomization  
Control  
Randomization  
Stratification （ n=700 ）  
Age<50 &  
Productivity  <  
median  
Intervent 
- ion  
Age<50 &  
Productivity  ≥  
median  
Age ≥50 &  
Productivity  <  
median  
Age ≥50 &  
Productivity ≥  
median  
Interven - 
tion  
Control  
Interven 
- tion  
Control  
Interven 
- tion  
Control  

least 45 years and at least 50 years, we will aim to recruit a total of 700 participants. These 
subgroup analyses will be important for informing future policy, for example if choices 
need to be made about which, if any, age groups should be targeted for eyeglasses.  
Statistical Plan: The analysis of the primary outcome (as defined above) between 
randomised groups will be done in intention to treat fashion with and without adjustment 
for potential determinants of productivity at baseline (including age, age*group interaction, 
sex, marital status, attitudinal variables and time spent as a tea picker) and during the 
evaluation period (including self-reported use of glasses in the intervention group and self-
reported purchase and use of glasses among the control group). The mean daily data for 
participants working <10 days in a month during the evaluation period will be excluded 
from the main analyses in sensitivity analyses to assess the impact of these workers on the 
overall results (both in relation to the effect estimate and its confidence interval).  Co-
linearity of potential determinant variables will be checked, in order to avoid including 
colinear variables together in the final model.  
 
Interaction of age and group will be examined, as it is expected that Interaction group 
participants will have a greater productivity response, while those in the Control may have 
less. 
 
Analysis of the main outcome will also include age-stratified analysis of participants (for 
example, 40-44, 45-49, 50-59, and 60 and above).  
Baseline characteristics between the groups will be compared. 
Prevalence of presbyopia by age group among all participants will be assessed. 
The secondary outcome, visual function quality of life using the VFQ25 will be compared 
between the two groups, with and without adjustment for baseline characteristics and 
potential determinants during the evaluation period (such as time since receipt of glasses 
when the VFQ was administered, in the Intervention group). 
Compliance monitoring: Weekly (except for holidays), un-announced examinations of both 
groups will be carried out, to assess compliance with glasses wear in the Intervention 
group, and to determine if any participants in the Control group have purchased glasses. 
Study Roles and Monitoring: The principal investigator will be responsible for final 
approval of the study protocol, overall study coordination and completing the UK ethical 
review. The principal investigator has a long-standing working relationship with 
VisionSpring (VS) and extensive experience in design and execution of randomised trials 
on refractive error in settings of limited resources. The principal investigator will visit India 
on two occasions: During the Study Preparation period and at the time of the Baseline 
examination. The VS India team will be responsible for coordinating field work. VS has 
worked in India for 10 years, and with APPL since 2014, and has extensive experience in 
carrying out presbyopic screening and provision of near spectacles in India and a wide 
variety of LMIC settings. APPL will provide support for the baseline examination, 
administration of the intervention and the end line distribution of glasses to the Control 

Group. APPL will also be primarily responsible for collection of the primary study 
outcome (mean daily weight of picked tea) and the secondary outcome of the quality of 
picked tea in both groups.   
Dissemination strategy: The project management team will prepare a dissemination strategy 
which balances the requirements of academic audiences (peer reviewed journal 
publications and conference presentations) with those of policy-makers and local patients 
and practitioners in both the UK and India and our NGO partners. In submitting findings to 
a range of academic journals, the investigators will focus on internationally-recognized 
journals with high impact, particularly those such as BMJ and Lancet Global Health with 
open access policies, making the papers more available to researchers and policy-makers in 
LMICs. The investigators will collaborate with the Cochrane Eyes and Vision group to help 
them update reviews on the economic impact of correction of refractive error. At the 
conclusion of the main trial, principal results will be available in English and several Indian 
languages and in graphic format on a mobile-friendly project website. Results will also be 
shared through organizations such as our Indian research partners and various locally-active 
eye health NGOs.  
Funding: Primary funding provided by Clearly (Clearly.World), free glasses provided by 
VisionSpring (VisionSpring.org).   
Contacts/Locations  
Central Contact Person: Nathan Congdon  
    Telephone:   +44 7748 751393  
    Email:   ncongdon1@gmail.com    
Central Contact Backup: Priya Adhisesha Reddy  
    Telephone:   +91 9101104452  
    Email:   priyaadhi@gmail.com    
Study Officials:  Nathan Congdon  
Study Principal Investigator  
Queen's University Belfast    
  Locations:  India  
Amalgamated Plantations Private Limited (APPL) , Tezpur, Assam, India    
     Contact: Priya Adhisesha Reddy    +91 9101104452    priyaadhi@gmail.com  
References  
Citations:  
  

1. Fricke TR, Holden BA, Wilson DA, Schlenther G, Naidoo KS, Resnikoff S, Frick 
KD. Global cost of correcting vision impairment from uncorrected refractive error. 
Bull World Health Organ.  
2012 Oct 1;90(10):728-38. doi: 10.2471/BLT.12.104034. Epub 2012 Jul 12.   
PubMed ID: 23109740  
2. Frick KD, Joy SM, Wilson DA, Naidoo KS, Holden BA. The Global Burden of 
Potential Productivity Loss from Uncorrected Presbyopia. Ophthalmology. 2015 
Aug;122(8):1706-10.   PubMed ID: 26190438  
3. Johnson R, Zaba J. The link: Vision and illiteracy. J of Behav Optometry 
1994;5:41-3  
4. EYEIliance, Eyeglasses for global development: Bridging the visual divide. June 
2016 report  
5. Dalberg Global Development Advisors 2015. Impact study of Essilor's Eye Mitra 
optician programme in India (a programme of the Essilor Group's 2.5 New Vision 
Generation division)  
6. Lu Q, Congdon N, He X, Murthy GV, Yang A, He W. Quality of life and near 
vision impairment due to functional presbyopia among rural Chinese adults. Invest 
Ophthalmol Vis Sci. 2011 Jun 13;52(7):4118-23. doi: 10.1167/iovs.10-6353.   
PubMed ID: 21508106  
 
 
 

Annexure  
Ophthalmic Examination Procedures  
  
Key Points  
  
Proceed to Distance visual acuity if:  
• Subject is 40yrs or older 
Distance Acuity Test 
• Chart at 4m distance, 1m above ground 
• Consistent lighting (as possible) across trial period 
• Pinhole if unaided distance visual acuity is 0.5 LogMAR or worse in either eye 
Proceed to near visual acuity if: 
• Unaided Distance Acuity is better than 0.5 LogMAR in both eyes OR acuity improves 
through pinhole 
Near Acuity Test 
• Chart at 40cm distance, at the level of subject’s chin 
• Chart held by examiner, subject occludes own eyes using palm of hand 
• Maintain 40 cm working distance 
Distance refraction 
• Retinoscopy end-point is neutrality or fastest ‘with’ motion (least myopic correction) 
• Trial frame refraction end-point is maximum sphere for best corrected acuity 
Proceed to near refraction if: 
• Habitual near visual acuity of >= 0.8M at 40cm in both eyes 
 Near Refraction 
• Use a ‘standardized’ tea bush as target 
• Let subject determine ‘ideal/desired’ working distance without trial frame and prior to 
performing the near refraction 
• Measure and record the ‘ideal/desired’ working distance 
• Maintain ‘ideal/desired’ working distance throughout testing 
• Near refraction end-point is the highest plus sphere value (near-point addition) that enables 
the subject to identify 2-3 leaves and a bud that are appropriate for picking at the 
‘ideal/desired’ working distance.  
• Measure acuity at 40cm through near refraction end-point 
 
Inclusion Criteria:  
Employee of APPL for 1 year; aged >= 40 years; Habitual near visual acuity of >= 0.8M at 40cm in 
both eyes, correctable to <=0.5M in both eyes with near glasses; uncorrected distance vision of 0.1 
LogMAR in the better-seeing eye; the individual has worked and has data available on weight of tea 
picked for >=10 days in the previous 4 weeks; ability to give informed consent.  
Exclusion Criteria:  
Eye disease detected on baseline eye exam; current ownership of near correction capable of 
improving near visual acuity to <= 0.8M (>= 6/12) in either eye ; unlikely to complete follow-up due 
to unsatisfactory work performance, plans to move out of the area, etc.; need for distance correction 
to achieve distance vision of 0.1 LogMAR in the better-seeing eye; inability to achieve best-corrected 
near visual acuity with spherical power glasses only (that is: need for astigmatic correction to achieve 
best-corrected near visual acuity)  
 
  
 

Flowchart  
  
 
  
  
  
  
  
 
 

Vision Assessment  
  
Distance Visual Acuity  
• 
Distance visual acuity is measured with a printed Tumbling E LogMAR chart based 
on the “reduced” ETDRS test chart configuration as described by Rosser et al. 
(2001).   
• 
Distance vision should be measured in a well-lit room or, if no room is available 
and you find that you must take your measurements outside please ensure that both 
the subject and the chart are in a shaded area and that all measures are taken to keep 
lighting consistent across the experiment.   
• 
People waiting to be examined should not be able to see the chart so as to preclude 
the potential for prior learning.    
• 
The examiner shall ensure than the distance vision chart is located at a distance of 4 
metres from the subject.  The chart shall be clean and placed approximately 1 metre 
above the ground.    
• 
Ensure that there are no bright lights directed toward the subject’s eyes and check 
that there are no distracting reflections on the distance vision chart.    
• 
Ensure that the subject is seated comfortably and encourage them not to ‘squint’ 
when looking at the chart (a reduction in the palpebral aperture could create a 
pinhole effect).  
• 
Explain to the subject that you are interested in finding out how far down the chart 
they can see and that they are welcome to guess if required.  
• 
Show them how to demonstrate the orientation of the E’s using their fingers as a 
means of representing the legs of the letter E.  
• 
Stand next to the chart to point out which letters are being tested.  
• 
Ask the subject to keep both eyes open, but to cover their left eye with the palm of 
their left hand (without pressing firmly).  Ensure that they are not looking between 
their fingers.  
• 
Show them a single letter from each line starting at the top and work your way 
down the chart.  
• 
When a letter is misread move two lines up the chart and ask them to identify all the 
letters on that line.  
• 
If they can identify any two of the three letters on a line they should move onto the 
line below.  
• 
The test stops when the subject cannot identify more than one letter on a line.  
• 
The subject’s distance vision is given by the LogMAR number (0.0 to 1.0) on the 
right-hand side of the chart next to the last line they were able to identify correctly.  
• 
Record this number on the form provided.  
• 
Repeat the entire procedure for the left eye and record the result.  
  
 
 
Pinhole Test  
• 
The pinhole test shall be performed on any eye that scored 0.5 or more on the 
distance reduced LogMAR chart.  
• 
Ask the subject to keep both eyes open.  The examiner shall cover the eye not being 
examining with the palm of their hand.  

• 
Let the subject hold the Pinhole plate in their hand and encourage them to look 
through the hole in the centre of it.  
• 
Ask the subject to look at the smallest line of optotypes visible during the distance 
visual acuity assessment and ask them to identify the letters on that line.  
• 
If their visual acuity improves while viewing the chart through the pinhole plate, 
then the examiner may continue with the refraction procedures  
• 
If the subject’s visual acuity does not improve while looking at the chart through the 
pinhole plate, then the examiner should refer for further examination   
  
Near Visual Acuity  
• 
Near visual acuity is measured with a printed Tumbling E LogMAR chart based on 
the “reduced” ETDRS test chart configuration as described by Rosser et al. (2001) 
and scaled for use at a distance of 40cm.   
• 
The examiner shall hold the chart at the level of the subject’s chin and use a ruler to 
measure out a distance of 40cm between the chart and the subject.  It is essential 
that the subject doesn’t move closer or further away from the chart, so the examiner 
must encourage the subject to remain still.    
• 
The examiner must remain vigilant of movement of the chart closer to - or further 
away from - the subject to ensure that inaccuracies in the near visual acuity 
measurement are not introduced.  
• 
Ensure that there are no bright lights directed toward the subject’s eyes and that 
there are no distracting reflections on the near vision chart.  
• 
Ensure that the subject does not ‘squint’ when looking at the near vision chart (a 
reduction in the palpebral aperture could create a pinhole effect).  
• 
Ask the subject to keep both eyes open but to cover their left eye with the palm of 
their left hand.  
• 
Use the back of a pen to show them a single letter from each line starting at the top 
and work your way down the chart.  
• 
When a letter is misread move two lines up the chart and ask them to identify all the 
letters on that line.  
• 
If they can identify at least two of the three letters on a line they should move onto 
the line below.  
• 
The test stops when the subject cannot identify more than one letter on a line.  
• 
The subject’s near vision is given by the LogMAR number (0.0 to 1.0) on the 
righthand side of the chart next to the last line they were able to identify correctly.   
• 
Record this number on form provided.  
• 
Repeat the entire procedure for the left eye and record the result.  
  
 
 

Refraction Procedures  
  
Distance Refraction  
  
1. 
Determine starting point using static retinoscopy  
2. 
Refine retinoscopy result using non-cyclopegic subjective refraction  
  
1. Static Distance Retinoscopy  
  
• 
Adjust the height of the examination chair so as to ensure that the subject’s eyes are 
at the same level as the examiner’s.  
• 
Measure the subject’s interpupillary distance.  
• 
Place the trial frame on the subject, ensuring that it is adjusted to the subject’s 
interpupillary distance.    
• 
The examiner shall seat himself/herself such that his/her head blocks the view of the 
distant target for the eye being examined (ensure that the subject can still see the 
target with the eye not being examined). This ensures that retinoscopy is performed 
as close to the visual axis as possible If the subject finds it difficult to ignore the 
light shining into his/her eye the examiner may move off the line of sight of the eye 
being examined to facilitate testing.  
• 
The retinoscope shall be is held at the examiner’s preferred working distance 
(usually either 40cm, 50cm or 67cm).  Place the collimating lens (the inverse of the 
retinoscopy working distance in metres) in the trial frame and instruct the subject to 
keep both eyes open while looking at the target (remind subject that the target may 
appear blurred).   
• 
Examine the subject’s right eye by moving the beam of the retinoscope across the 
eye and observe the motion of the light reflected off the retina through the pupil.   
• 
Rotate the retinoscope beam through 360 degrees. If the reflex and the beam 
orientation are not continuous throughout the rotation, the eye is astigmatic, and the 
principle meridians must be identified.    
Spherical eyes  
• If ‘against’ motion is observed, place minus lenses in front of the eye in steps of 0.25 
D until the motion disappears and neutrality is reached. If ‘with’ motion is 
observed, place lenses of positive power in front of the eye in steps of 0.25 D until 
the motion disappears and neutrality is achieved.   
Astigmatic eyes  
• 
Rotate the retinoscope beam through 360 degrees. If the reflex and the beam 
orientation are not continuous throughout the rotation, the eye is astigmatic, and 
the principle meridians must be identified.    
• 
Once the orientation of the principle meridians have been identified, the 
examiner shall selects the least myopic (or most hyperopic) meridian to scope 
along and neutralizes it through the use or plus or minus spheres.   
• The retinoscope beam is then rotated by 90 degrees and the examiner scopes along the 
remaining meridian (which should have ‘against movement’).   
• Minus cylinder shall then be placed in the trial frame such that its axis lies parallel to the 
orientation of the retinoscope beam (i.e. parallel to the orientation of the remaining principle 
meridian).  
• Minus cylinder power is added to the trial frame in steps of 0.25 D until neutrality is reached.  

• If neutrality cannot be reached leave the eye with the lowest positive (most negative) power 
that is closest to neutrality (i.e smallest ‘with’ movement possible)   
• Recheck both principle meridians, ensuring that both are ‘neutral’.    
• Repeat the process for the left eye  
• Remove the collimating lenses and proceed to the subjective refraction  
  
2. Non-cycloplegic Subjective Refraction  
  
Spherical Refinement  
• 
The right eye is tested first and then the left eye. The starting refraction determined 
through static distance retinoscopy shall be placed in the trial frame; the left eye is 
occluded with an occluder lens and the examiner shall determine the lowest line on 
the reduced LogMAR chart for which the subject can read at least 2 of 3 letters.  
• 
With the subject focused on the smallest letters that he/she can read, a +0.50 D 
sphere is held in front of the trial frame over the right eye, and the subject is asked 
if the lens makes the vision clearer, blurrier, or keeps the vision exactly the same. 
(“Clearer, Blurrier, or No change” preferred but “Better, Worse, or No change” can 
be used)  
• 
If vision is clearer or there is no change, the sphere in the trial frame is replaced 
with a sphere that is 0.50 D more plus or less minus. The subject should be asked to 
read the letters through the +0.50 challenge lens to demonstrate that vision is indeed 
clearer or the same.  
• 
The +0.50 D sphere is again held in front of the trial frame over the right eye and 
the subject is asked again if the lens makes the vision clearer, blurrier, or keeps the 
vision exactly the same.  
• 
If vision is again clearer or there is no change, the sphere in the trial frame is 
replaced with a sphere that is 0.50 D more plus or less minus.  
• 
This process of increasing the plus sphere or decreasing the minus sphere in the 
right eye is repeated until the +0.50 D sphere makes the vision blurrier.  
• 
When the +0.50 D sphere makes the vision blurrier, no additional change in the 
sphere is made at this time. By this process the highest plus or least minus sphere 
for best vision is determined.  
• 
After determining the highest plus or least minus sphere, the subject is asked to read 
the smallest line possible (the reading should be at least as good as the initial 
reading).  A -0.25 D sphere is held in front of the trial frame before the right eye 
and the subject is asked if the lens allows them to read more optotypes.  
• 
If vision is not improved, the +0.50 D sphere is held in front of the trial frame 
before the right eye once again to see if the subject will accept more plus.  
• 
If the subject reports that the –0.25 D lens improves vision, the subject is requested 
to read the smallest line possible while the –0.25 D lens is held in front of the trial 
frame.  
• 
If there is an actual improvement in acuity and the examiner is convinced that the 
subject is able to read at least one additional optotype, then the sphere in the trial 
frame is replaced by a sphere that is 0.25 D less plus or more minus.  
• 
For each change in spherical power, visual threshold must be determined by asking 
the subject to read the smallest line or letters possible either prior to increasing 
minus or decreasing plus spherical power (if using a -0.25 D challenge lens) or after 
the lens power has been changed.  

• 
Minus spherical power is added in –0.25 D increments in this fashion as long as the 
subject continues to read at least one additional optotype.  
• 
If the subject is unable to read any more optotypes, the sphere is not changed, even 
if the subject reports that the vision with the extra minus is better or clearer (or 
sharper and darker or more distinct).  
• 
The final check in the initial sphere evaluation should be the presentation of a +0.50 
D sphere to determine if any more plus sphere will be accepted initially.  
  
Cylinder Axis Refinement  
• For purposes of this discussion, only minus cylinder techniques are presented.  Plus 
cylinders may be used instead of minus cylinders to determine the axis and power of the 
cylinder. If plus cylinders are used, the procedure described must be revised to reflect this 
change in sign.  
• If the starting refraction contains a cylinder correction, changes in cylindrical axis are 
tested by holding a 0.50 D Jackson Cross Cylinder in front of the trial frame, first with 
the negative axis 45 degrees to one side of the cylinder axis, and then with the negative 
axis 45 degrees to the opposite side of the cylinder axis (in most cases, the handle of the 
Jackson Cross Cylinder lens should be aligned directly over the axis of the cylinder lens 
in the trial frame).     
• Instruct the subject to focus on an optotypes two lines above the smallest line on which 
he/she can read at least 2 of 3 optotypes.  
• Explain to the subject: I am going to show you two views of this “E” and neither view 
may be clearer than the view you have right now. I would like to know which of the two 
views is the clearer of the two, or are both views about the same or equally blurry. Ask: 
Is the “E” clearer on view 1 [flip the lens] or view 2, or are both views about the same or 
equally blurred?  
• Since neither position may produce a clear image, the subject is encouraged to select the 
orientation that offers the least blur.  
• If the subject cannot choose between the two orientations of the Jackson Cross Cylinder 
at the beginning of this test, the axis of the cylinder is moved 5-15 degrees, first in one 
direction and then in the other, with the Jackson Cross Cylinder being checked in each 
position to confirm that the original axis was indeed correct.  
• If the subject does prefer one position of the cross cylinder to the other, the axis of the 
cylinder is moved 5-15 degrees toward the negative axis of the cross cylinder when in the 
position the subject said was better.  
• When the power of the cylinder is low, and/or the subject’s discrimination is poor, larger 
shifts will produce more clear-cut responses.  
• The cross cylinder is tried again with the negative axis 45 degrees to one side of the new 
cylinder axis and then with the negative axis 45 degrees to the opposite side of the new 
cylinder axis; the subject is asked which position is the clearer of the two or if the two 
views are about the same or equally blurry.  
• If the subject prefers one position to the other, the axis of the negative cylinder is moved 
toward the negative axis of the cross cylinder.  
• Testing for change of axis is repeated until the subject cannot decide that one position of 
the cross cylinder is clearer than the other by reporting that both views are about the same 
or equally blurry.  
  

Cylinder Power Refinement  
• Before refining cylinder power, once again establish visual threshold by determining the 
smallest line or letters the subject can read on the chart. Change in cylinder power is now 
tested by adding the 0.25 D cross cylinder, first with the negative axis and then with the 
positive axis coincident with the cylinder axis.  
• Again, instruct the subject to focus on an optotype two lines above the smallest line for 
which the subject could correctly identify 2 of 3 optotypes. Explain to the subject: Once 
again I am going to show you two views of this “E” and neither view may be clearer than 
the view you have right now.  I would like to know which of the two views is the clearer 
of the two, or are both about the same or equally blurry.  Ask: Is the “E” clearer on view 
1 [flip the lens] or view 2, or are both views about the same or equally blurred?  
• If the subject prefers the negative axis coincident with cylinder axis, the power of the 
correcting negative cylinder is increased by an additional -0.25 D.  
• If the subject prefers the positive axis coincident with the cylinder, the power of the 
cylinder is reduced by 0.25 D.  
• The process is repeated until the subject cannot choose one of the cross-cylinder positions 
as clearer than the other (i.e., until both positions are about the same or equally blurred).  
• Whenever the cylinder is changed by 0.50 D, a 0.25 D of sphere of opposite sign is added 
as well (the changing of the sphere occurs during the procedure as soon as the cylinder 
has been changed by 0.50 D rather than making the adjustment following the completion 
of the refinement).  
• If all cylinder power is removed during cylinder power refinement (i.e., sphere only in 
the trial frames), check for the presence of astigmatism, following the steps axis 
refinement above. In addition, if the cylinder power has been changed by more than 0.50 
D, the axis should be refined again.  
  
Checking Cylinder When Beginning Refraction is a Sphere  
• If the beginning refraction is a sphere and does not contain a cylinder, the presence of 
astigmatism can be tested by one of two methods:  
• Instruct the subject to focus on an optotype one-two lines above the smallest line of 
optotypes that he/she can read.  Using a Jackson Cross Cylinder appropriate for the 
current acuity (0.25 D for visual acuity of 0.5 or better; 0.5 D for visual acuity poorer 
than 0.5), test for the presence of cylinder power by placing the cross cylinder with the 
plus axis alternately at 90 degrees and 180 degrees, and then alternately at 45 degrees and 
135 degrees.   
• 
If the subject reports that the Jackson Cross Cylinder makes the optotype clearer 
than the spherical correction in any of the four axis locations, insert a cylinder 
matching the “minus” presentation of the JCC at the preferred axis and continue the 
refraction by refining the cylinder axis and power, as described above.  

  
Refraction Recheck/Final Sphere Refinement  
• The power of the sphere is rechecked according to the sphere refinement protocol 
above by using +0.25 D and -0.25 D spheres and changing the spherical power by 
0.25 D increments of the appropriate sign until the subject reports that the +0.25 
lens blurs the vision and the -0.25 does not improve vision. If the sphere is changed 
at this point by 0.50 D or more, the cylinder axis and power should be rechecked. 
This process is repeated until no further significant lens changes are made.   
  
 
 
Near Refraction  
• 
Remove the trial frame with the distance refraction from the subject’s face.  
• 
Ask the subject to stand near a tea bush (representative of the height of the majority 
of tea bushes likely to be worked on over the course of the study) and assume the 
stance that they usually use while picking leaves. Instruct them to handle the leaves 
on the bush as they would while working.  
• 
Ask the subject whether it would be more comfortable to hold their head closer or 
further away from the bush while working.  Remind them that its ok if the leaves on  

the bush are blurry at their ‘ideal’ viewing distance, and that they should not 
concern themselves with whether they can see well or not because you are going to 
find out whether glasses can improve their vision.  The key consideration here 
should be that the subject is able to maintain a posture and working distance that 
will prove comfortable for them over time.  
• 
Measure this distance and record on form  
• 
Measure the distance between the subject’s eyes and the leaves and buds (remind 
the subject to handle the leaves and buds on the table as they would while working)   
• 
Place the trial frame back on the subject’s face and use an occluder lens to occlude 
the left eye.  
• 
It is essential that the subject doesn’t move closer or further away from the leaves 
so the examiner must encourage the subject to remain still.  The examiner must 
remain vigilant of movement of the subject closer to - or further away from - the tea 
bush to ensure that inaccuracies in the near prescription measurement are not 
introduced.  
• 
Place a positive sphere with a power equal to the inverse of the working distance (in 
meters) in the rear lens holder of the trial frame  
• 
With the subject focused on the leaves and buds in their hands, a +0.25 D sphere is 
held in front of the trial frame over the right eye, and the subject is asked if the lens 
improves their vision or not.  
• 
If the subject reports that there is no change then increase the add power in the trial 
frame by +0.25D and repeat the above step.  
• 
The procedure is terminated when the patient reports that the lens makes their 
vision blurrier.  
• 
The final addition power requirement is determined as the highest positive lens 
power that allows the subject to identify 2-3 leaves and a bud that are appropriate 
for picking at their preferred working distance.  
• 
Measure near visual acuity at 40cm through the near end-point using the procedure 
described under ‘Near Visual Acuity’ above.  This acuity measurement should be 
recorded while the subject is wearing the lenses that provide their chosen near 
refraction end-point.  Note: given that it is likely that subjects will choose near-point 
additions that provide optimal vision correction at a distance other than 40cm, this 
visual acuity measurement is for record keeping purposes only and does not have 
implicit diagnostic or prognostic value.