Background: 
A pilot diabetic retinopathy (DR) screening project was initiated as part of the Johns Hopkins International (JHI) Trinidad and Tobago Health Sciences Initiative project, a 5-year plan which included a co-ordinated diabetes care programme, to reduce the increasing burden of the disease and its related complications. Approximately ~180,000 people have diabetes in Trinidad (14.5%).
Aims: 
The aim of the study was to provide the 3 year DR outcomes for the region and to extrapolate the findings to anticipate the DR outcomes if a National DR screening programme in Trinidad was to be implemented.
Methods:
A register of people with diabetes in the SWRHA area has been established since 2015 which included approximately 25,000 people with diabetes. Between 2013 and 2016 a total of 7 sites were used for screening with a team of 4 screeners conducting screening using Canon CR2 cameras. Visual acuity was measured using Snellen charts and 2X45 degree digital retinal images were captured per eye following dilation. Images were transferred to a central grading office for primary grading. Secondary and tertiary grading was performed by ophthalmologists.
Results:
Over a 3 year period a total of 6,143 people were offered appointments with 5,591 attending screening (91% attendance rate). The majority had Type 2 diabetes (97.3%) with 58.8% having diabetes for less than 10 years. 29.3% of those screened required referral to ophthalmology with 9.5% having sight-threatening eye diseases. DR accounted for 47.1% of hospital referrals, 3.3% due to DR +/- other lesions and 49.6% due to other lesions only (cataract and glaucoma were the main causes).
Discussion/Conclusion:
Currently the pilot programme has screened ~20% of diabetic subjects in SWRHA over a 3 year period. Based on a 30% referral rate extrapolation to the remaining population in this region means that an additional ~6000 people could require referral to ophthalmology with ~10% deemed urgent. Further extrapolation to the anticipated population with diabetes in Trinidad and Tobago then a National DR screening programme could expect to detect 18,000 with sight-threatening eye diseases and an equal number with non-DR lesions requiring treatment.

Findings from a PILOT diabetic retinopathy screening service in Trinidad and Tobago: a basis for a national programme