PresbyopiaPROSPERIINCT04629820
PROductivity Study of Presbyopia Elimination in Rural-dwellers II
A study testing Spectacles in people with Presbyopia, run by Queen's University, Belfast at 1 site in India.
Trial summary
The investigators will conduct a randomized-controlled trial. The participants will be textile workers aged 35 years and above with uncorrected presbyopia who are employed by a single Indian garment manufacturer - employed by Shahi Exports Private Limited, Karnataka, India - at facilities equipped to measure… Read more about this study
- Who is it for?
- Ages 35 years and older
- Conditions the study is for
- Presbyopia
- What is being tested?
- Spectacles
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 682 participants
- Where
- 1 siteIndia
- Study dates
- 3 Aug 2023to 30 Dec 2024
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 35 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Aged 35 years and older
- Have presbyopia, defined as an unaided near visual acuity of N6.3 or worse in both eyes
- Require a new pair of glasses to improve their near vision
- Have a corrected near visual acuity of N4 or better in both eyes
- Have worked in Shahi's production department as tailors or Kajbutton operators for 6 weeks or more
Who cannot join
- Have ocular pathology in either eye detected during the eye examination, or history of such disease based on self-report
- Have a low likelihood of completing follow-up in the study due to current plans to move out of the area or leave employment at Shahi during the follow-up period
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Effects of Near Vision Spectacle Correction on Work Productivity Among Textile Factory Workers in India
The investigators will conduct a randomized-controlled trial. The participants will be textile workers aged 35 years and above with uncorrected presbyopia who are employed by a single Indian garment manufacturer - employed by Shahi Exports Private Limited, Karnataka, India - at facilities equipped to measure individual productivity. PROSPER II will assess the impact of free reading glasses on productivity for workers in a textile factory.
Read the detailed description
Globally, 3 billion people do not have the eyeglasses they need to earn, learn, travel safely in traffic and participate in civic life. Among these, 1.1 billion people lack a simple pair of reading glasses to correct impaired near vision, called presbyopia. Presbyopia, the essentially universal decline in unaided near vision that occurs with aging, is the world's most common cause of vision impairment. Loss of accommodation (ability to change focus from distance to near) due to presbyopia can begin as early as age 30 years, commonly becomes functionally apparent by 40, and is essentially complete by 55, meaning that presbyopia is most common at the height of the working years.
Study Plan: This is a randomized trial designed to assess the impact of free spectacles on workplace productivity among Indian textile workers.
Research question: Will providing free glasses to presbyopic Indian textile workers increase work productivity?
Design: Investigator-masked, multi-center randomized controlled trial
Rationale: Although presbyopia is safely, effectively and inexpensively treated with glasses, rates of optical correction in LMICs are as low as 10%. The global productivity loss due to uncorrected presbyopia has been estimated to exceed US$25 billion, and presbyopia is shown to be associated with significant impairment in activities of daily living. Few trials have been published which address the question of whether healthcare interventions can improve work performance as well as workplace retention, especially among persons over the age of 40 in low and middle-income countries (LMICs). The largest reported effect sizes among such trials was the PROSPER trial, which showed that providing inexpensive near vision glasses increased the daily weight of tea picked among presbyopic, mostly-female Indian agricultural workers by more than 5 kg (21.6%) compared to those in the control group. Costs were low, over half of pickers aged >= 40 years met criteria to receive glasses, and wearing compliance reached nearly 90%. There is interest to understand if these results from the agricultural setting can be extended to other financially-important sectors.
Methods : The investigators will enrol 800 textile workers aged 35 years and above with uncorrected presbyopia who are employed by Shahi Exports Private Limited in Karnataka, India. Eligible participants will be randomly assigned to Intervention and Control Groups (1:1). Intervention group participants will receive free reading glasses within a week of undergoing a vision screening at the factory. Control group participants will receive reading glasses at the end of the assessment period (three months after vision screening).
The main outcome 3 months later will be work productivity; secondary outcomes are change in skill grade, change in monthly wage, participants' adherence with spectacle wear, self-assessed self-efficacy score and change of quality of life scores. The intervention cost-effectiveness will be studied.
- Conditions
- Presbyopia
- Being tested
- Spectacles
- Keywords
- Presbyopia, Refractive error, Work productivity, Spectacle wear compliance
- Medical subject headings
- Presbyopia, Refractive Errors
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
SpectaclesDevice
Also called Near eyeglasses, Reading glasses
Intervention group workers receive free glasses within one week of undergoing vision assessment (September 2021). The assessment period will be three months
| Study group | Role | What they receive |
|---|---|---|
| Intervention | Experimental | Workers assigned to the intervention group will receive free spectacles of a design they select, based on the worker's measured refractive power and dispensed one week later at the factory by the study ophthalmic personnel. Receives: Device: Spectacles |
| Control | No intervention | Workers assigned to the Control group will receive similar free glasses at the end of the study assessment (3 months). |
What is being measured
The primary outcome is the main question the study is designed to answer.
Difference in change in mean efficiency between intervention and control group
Efficiency is calculated as the proportion of target production realized by a worker per unit time
Measured: Over the three month follow-up period from enrolment to study completion
Secondary outcomes (6)
Three-month change in skill grade
Skill grade ranges from A triple star (highest) to A double star, A star, A, B, and C + (lowest)
Measured: Between baseline and study end three months later
Change in monthly wage
Monthly wage (Factory administrative data)
Measured: Between baseline and study end three months later
Adherence with spectacle wear
measured weekly by enumerator's unannounced observations of the presence of spectacles worn on the participant's face.
Measured: Between baseline and study end three months later
Group difference in three-month change in self-assessed self-efficacy scores
Self-assessed self-efficacy scores measured using the Cantril's Ladder, with the best possible score being a 10, and the worst being a 0 (Cantril's Ladder)
Measured: Between baseline and conclusion of the study three months later
Group difference in three-month change of quality of life scores
Quality of life scores measured using the Andhra Pradesh Eye Disease Study (APEDS) Visual Function Questionnaire (VFQ), with a 5-point Likert scale: 1=No difficulty, 2=Little difficulty, 3=Moderate difficulty, 4=Great difficulty but still can manage, 5=Cannot manage. A highest score represents great difficulty in vision function. Minimum score = 16; Maximum score = 80.
Measured: Between baseline and conclusion of the study three months later
Cost effectiveness
Full programme costs per individual identified and corrected with presbyopia. Programme costs include costs incurred in screening test, glasses / replacement and direct/indirect costs for facilitating work-based site. Benefit will be measured using work productivity. We will report cost effectiveness distinguishing between study costs and program costs
Measured: Between baseline and study end three months later
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted16 Nov 2020
- Study start3 Aug 2023
- Primary completion30 Dec 2024
- Study completion30 Dec 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for PresbyopiaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- 800 textile workers aged 35 years and above with uncorrected presbyopia will be randomized to receive free glasses within one week of undergoing vision assessment, or free glasses at the end of the study assessment (3 months after vision assessment).
- Masking
- Double blind
- Who is masked
- Investigator, Outcomes assessor
- Enrolment
- 682 participants (actual)
Sponsor and investigators
- Lead sponsor
- Queen's University, Belfast
- Sponsor type
- University, hospital or other
- Collaborators
- VisionSpring, University of Michigan, Good Business Lab, Zhongshan Ophthalmic Center, Sun Yat-sen University, Clearly
- Responsible party
- Principal investigator, Nathan Congdon, Queen's University, Belfast
- Investigators
- Nathan G Congdon, MD, MPH, Principal investigator, Queen's University, Belfast
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04629820
- Sponsor's protocol ID
- MHLS 20_82
- Acronym
- PROSPERII
- Status last verified
- Aug 2026
- First submitted
- 21 Oct 2020
- Last updated
- 20 Aug 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: De-identified data will be made available for download on the Queen's University Belfast website.
Publications
Pant S, Bagwe S, Esther S, MacKenzie G, Sigwadhi LN, Prakash WD, Chan VF, Gade S, Dhir S, Joshi S, Calderon S, Piyasena MP, Clarke M, Lohfeld L, Cooke M, Gudwin ER, Adhvaryu A, Nyshadham A, Congdon N. PROductivity Study of Presbyopia Elimination in gaRment workers (PROSPER II): a randomised trial on the productivity impact of providing near glasses to Indian garment factory workers. Br J Ophthalmol. 2026 Apr 27:bjo-2025-328563. doi: 10.1136/bjo-2025-328563. Online ahead of print.
PubMed 42045075
Study at a glance
From the registry record, last updated by the sponsor on 20 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Near Vision Spectacle Correction on Work Productivity Among Textile Factory Workers in India
- ClinicalTrials.gov ID
- NCT04629820
- Acronym / sponsor ID
- PROSPERII / MHLS 20_82
- Conditions
- Presbyopia
- Keywords
- Presbyopia, Refractive error, Work productivity, Spectacle wear compliance
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 682 participants (actual)
- Lead sponsor
- Queen's University, BelfastUniversity, hospital or other
- Collaborators
- VisionSpring, University of Michigan, Good Business Lab, Zhongshan Ophthalmic Center, Sun Yat-sen University, Clearly
- Study start
- 3 Aug 2023 (actual)
- Primary completion
- 30 Dec 2024 (actual)
- Study completion
- 30 Dec 2024 (actual)
- First posted
- 16 Nov 2020 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The investigators will conduct a randomized-controlled trial. The participants will be textile workers aged 35 years and above with uncorrected presbyopia who are employed by a single Indian garment manufacturer - employed by Shahi Exports Private Limited, Karnataka, India - at facilities equipped to measure individual productivity. PROSPER II will assess the impact of free reading glasses on productivity for workers in a textile factory.
Detailed description
Globally, 3 billion people do not have the eyeglasses they need to earn, learn, travel safely in traffic and participate in civic life. Among these, 1.1 billion people lack a simple pair of reading glasses to correct impaired near vision, called presbyopia. Presbyopia, the essentially universal decline in unaided near vision that occurs with aging, is the world's most common cause of vision impairment. Loss of accommodation (ability to change focus from distance to near) due to presbyopia can begin as early as age 30 years, commonly becomes functionally apparent by 40, and is essentially complete by 55, meaning that presbyopia is most common at the height of the working years.
Study Plan: This is a randomized trial designed to assess the impact of free spectacles on workplace productivity among Indian textile workers.
Research question: Will providing free glasses to presbyopic Indian textile workers increase work productivity?
Design: Investigator-masked, multi-center randomized controlled trial
Rationale: Although presbyopia is safely, effectively and inexpensively treated with glasses, rates of optical correction in LMICs are as low as 10%. The global productivity loss due to uncorrected presbyopia has been estimated to exceed US$25 billion, and presbyopia is shown to be associated with significant impairment in activities of daily living. Few trials have been published which address the question of whether healthcare interventions can improve work performance as well as workplace retention, especially among persons over the age of 40 in low and middle-income countries (LMICs). The largest reported effect sizes among such trials was the PROSPER trial, which showed that providing inexpensive near vision glasses increased the daily weight of tea picked among presbyopic, mostly-female Indian agricultural workers by more than 5 kg (21.6%) compared to those in the control group. Costs were low, over half of pickers aged >= 40 years met criteria to receive glasses, and wearing compliance reached nearly 90%. There is interest to understand if these results from the agricultural setting can be extended to other financially-important sectors.
Methods : The investigators will enrol 800 textile workers aged 35 years and above with uncorrected presbyopia who are employed by Shahi Exports Private Limited in Karnataka, India. Eligible participants will be randomly assigned to Intervention and Control Groups (1:1). Intervention group participants will receive free reading glasses within a week of undergoing a vision screening at the factory. Control group participants will receive reading glasses at the end of the assessment period (three months after vision screening).
The main outcome 3 months later will be work productivity; secondary outcomes are change in skill grade, change in monthly wage, participants' adherence with spectacle wear, self-assessed self-efficacy score and change of quality of life scores. The intervention cost-effectiveness will be studied.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (investigator, outcomes assessor)
- Number of arms
- 2
- Model description
- 800 textile workers aged 35 years and above with uncorrected presbyopia will be randomized to receive free glasses within one week of undergoing vision assessment, or free glasses at the end of the study assessment (3 months after vision assessment).
| Arm | Type | Receives |
|---|---|---|
| Intervention | Experimental | Device: SpectaclesWorkers assigned to the intervention group will receive free spectacles of a design they select, based on the worker's measured refractive power and dispensed one week later at the factory by the study ophthalmic personnel. |
| Control | No intervention | –Workers assigned to the Control group will receive similar free glasses at the end of the study assessment (3 months). |
Who may qualify
- Ages
- 35 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Aged 35 years and older
- Have presbyopia, defined as an unaided near visual acuity of N6.3 or worse in both eyes
- Require a new pair of glasses to improve their near vision
- Have a corrected near visual acuity of N4 or better in both eyes
- Have worked in Shahi's production department as tailors or Kajbutton operators for 6 weeks or more
Key exclusion criteria (2 listed)
- Have ocular pathology in either eye detected during the eye examination, or history of such disease based on self-report
- Have a low likelihood of completing follow-up in the study due to current plans to move out of the area or leave employment at Shahi during the follow-up period
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| SpectaclesAlso: Near eyeglasses, Reading glassesIntervention group workers receive free glasses within one week of undergoing vision assessment (September 2021). The assessment period will be three months | Device | Intervention |
Primary outcome
Difference in change in mean efficiency between intervention and control group
Time frame: Over the three month follow-up period from enrolment to study completion
Efficiency is calculated as the proportion of target production realized by a worker per unit time
6 secondary outcomes
Three-month change in skill grade
Time frame: Between baseline and study end three months later
Change in monthly wage
Time frame: Between baseline and study end three months later
Adherence with spectacle wear
Time frame: Between baseline and study end three months later
Group difference in three-month change in self-assessed self-efficacy scores
Time frame: Between baseline and conclusion of the study three months later
Group difference in three-month change of quality of life scores
Time frame: Between baseline and conclusion of the study three months later
Cost effectiveness
Time frame: Between baseline and study end three months later
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 20 Aug 2026.
- Derived from this study: PubMed 42045075Pant S, Bagwe S, Esther S, MacKenzie G, Sigwadhi LN, Prakash WD, Chan VF, Gade S, Dhir S, Joshi S, Calderon S, Piyasena MP, Clarke M, Lohfeld L, Cooke M, Gudwin ER, Adhvaryu A, Nyshadham A, Congdon N. PROductivity Study of Presbyopia Elimination in gaRment workers (PROSPER II): a randomised trial on the productivity impact of providing near glasses to Indian garment factory workers. Br J Ophthalmol. 2026 Apr 27:bjo-2025-328563. doi: 10.1136/bjo-2025-328563. Online ahead of print.
- Individual participant dataSharing planned: Yes. De-identified data will be made available for download on the Queen's University Belfast website.
Related trials for Presbyopia
Recruiting
Evaluation of Functional Superiority of the Morrow eProgressive
Presbyopia
Active, not recruiting
Clinical Trial With Artiflex Presbyopic (Artiplus)
Presbyopia, Ametropia
Recruiting
VisDura VisAbility™ Micro Insert System Pre-market Clinical Trial
Presbyopia
Recruiting
Volumetric Visual Fields at Intermediate and Near Distances in Presbyopic Patients Using Occupational and General-Purpose Progressive Addition Lenses
Presbyopia
Recruiting
Volumetric Visual Fields at Different Distances in Presbyopic Patients Using Occupational (PC-133 and PC-200) and General-Purpose Progressive Addition Lenses
Presbyopia
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Nathan G Congdon, MD, MPH principal investigator
Queen's University, Belfast
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Spectacles in people with Presbyopia, run by Queen's University, Belfast at 1 site in India.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 20 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in India. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Difference in change in mean efficiency between intervention and control group (time frame: Over the three month follow-up period from enrolment to study completion). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT04629820, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 20 Aug 2026.