PROductivity Study of Presbyopia Elimination in Rural-dwellers II

Effects of Near Vision Spectacle Correction on Work Productivity Among Textile Factory Workers in India


Lead Sponsor: Queen's University, Belfast

Collaborator: VisionSpring
University of Michigan
Good Business Lab
Zhongshan Ophthalmic Center, Sun Yat-sen University
Clearly Initiatives

Source Queen's University, Belfast
Brief Summary

The investigators will conduct a randomized-controlled trial. The participants will be textile workers aged 30 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 500 textile workers aged 30 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 month 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.

Overall Status Not yet recruiting
Start Date 2021-09-06
Completion Date 2022-04-04
Primary Completion Date 2022-01-04
Phase N/A
Study Type Interventional
Primary Outcome
Measure Time Frame
Difference in change in mean efficiency between intervention and control group Over the three month follow-up period from enrolment to study completion
Secondary Outcome
Measure Time Frame
Three-month change in skill grade Between baseline and study end three months later
Change in monthly wage Between baseline and study end three months later
Adherence with spectacle wear Between baseline and study end three months later
Group difference in three-month change in self-assessed self-efficacy scores Between baseline and conclusion of the study three months later
Group difference in three-month change of quality of life scores Between baseline and conclusion of the study three months later
Cost effectiveness Between baseline and study end three months later
Enrollment 500

Intervention Type: Device

Intervention Name: Spectacles

Description: Intervention group workers receive free glasses within one week of undergoing vision assessment (September 2021). The assessment period will be three months

Arm Group Label: Intervention



Inclusion Criteria: - Aged 30 years and above - Distance visual acuity >= 6/12 in both eyes - Presence of presbyopia, defined as the inability, correctable with reading glasses, to read the N8 line using both eyes together, on a tumbling near vision chart at a distance of 40cm - Employed at the factory for >=3months in the sewing department Exclusion Criteria: - Current ownership of reading or distance glasses (regardless of accuracy) - Obvious evidence of ocular disease in either eye detected during the eye examination, or history of such disease based on self-report - 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



Minimum Age:

30 Years

Maximum Age:


Healthy Volunteers:


Overall Official
Last Name Role Affiliation
Nathan G Congdon, MD, MPH Principal Investigator Queen's University, Belfast
Overall Contact

Last Name: Nathan G Congdon, MD, MPH

Phone: 07748751393

Email: [email protected]

Verification Date


Responsible Party

Type: Principal Investigator

Investigator Affiliation: Queen's University, Belfast

Investigator Full Name: Nathan Congdon

Investigator Title: Professor

Has Expanded Access No
Condition Browse
Number Of Arms 2
Arm Group

Label: Intervention

Type: Experimental

Description: 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.

Label: Control

Type: No Intervention

Description: Workers assigned to the Control group will receive similar free glasses at the end of the study assessment (3 months).

Patient Data Yes
Study Design Info

Allocation: Randomized

Intervention Model: Parallel Assignment

Intervention Model Description: 500 textile workers aged 30 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).

Primary Purpose: Treatment

Masking: Double (Investigator, Outcomes Assessor)

Masking Description: Study personnel assessing trial outcomes will be masked as to participants assignment, which will be simplified by the fact that there will be participants with and without glasses at both Intervention and Control. It is not ethical in this setting to provide Control participants with placebo treatment (glasses with zero power lenses), but participants will not be informed of either the overall design of the study or the explicit treatment intervention assignment.

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