A look at the back of the eye in Kenyan over-50s

Research details

  • Type of funding: MRC/Fight for Sight Clinical Research Training Fellowship
  • Grant Holder: Dr Andrew Bastawrous
  • Institute: London School of Hygiene and Tropical Medicine
  • Region: London
  • Start date: August 2012
  • End Date: January 2015
  • Priority:
  • Eye Category:

Overview

Africa carries the greatest burden of blindness worldwide, most of which is preventable or treatable. There is increasing evidence that conditions affecting the back of the eye are a major problem in Africa. These conditions include glaucoma, diabetic retinopathy and macular degeneration. However, there is very little reliable information on how many people are affected or how fast these conditions progress.

The team is investigating these questions through a study in Kenya. In 2007/8, 4381 people aged ≥50 were randomly selected across a district, and had detailed eye examinations. The team is retracing these participants to re-examine their eyes, five years after their first examination. This will allow them to estimate how many new cases arise, risk factors for key “back-of-the-eye” conditions, and the rate of progression among people affected at the time of the previous eye examination.

The information will help inform and guide prevention of blindness programmes in Africa, by identifying how many new cases are expected to occur each year, who is at risk of these conditions, and who is most vulnerable to experiencing the negative consequences of their eye condition.

The project is being undertaken as a collaboration between the London School of Hygiene & Tropical Medicine and Rift Valley Provincial Hospital in Kenya.
  • Scientific summary

    Incidence and progression of posterior segment eye disease in a population-based cohort in Kenya

    There has been limited focus on posterior segment eye diseases (PSED) by ‘prevention of blindness’ programmes in Africa. Diagnostic challenges surround these conditions and assumptions have been made that they are rare. However, recent surveys indicate that PSED are now responsible for up to one third of visual impairment and blindness in Africa. There is currently a great lack of data on the incidence and progression of PSED in Africa.

    This study aims to assess the 5-year incidence and progression of diabetic retinopathy (DR), age-related macular degeneration (AMD) and glaucoma in a Kenyan population aged ≥50 as a follow up of the Nakuru PSED study.

    Recruitment: In 2007/8, 4381 participants aged ≥50 years were recruited in a population-based survey in Nakuru, Kenya. They underwent comprehensive ophthalmic examination and fundus image capture. These participants will be re-invited to attend for examination at a local centre, tracked through GPS points taken of their homes. A pilot follow-up study undertaken in January 2009 suggests that 5-years post baseline, at least 65% of the original participants (n=2,848) would be retraced and examined, approximately 2,205 of whom will have gradable images from baseline.

    Data Collection: Study participants will each undergo: 1) Visual acuity testing; 2) Visual field assessment; 3) Anterior segment assessment with a slit lamp and measurement of intra-ocular pressure; 4) Retinal photography using a Topcon non-mydriatic camera (dilated); 5) Clinical assessment of posterior segment (dilated) with slit lamp biomicroscopy and OCT); 6) Random blood glucose; and 7) Interview on eye conditions and treatment.

    Analysis: The Moorfields Grading Centre will grade retinal images for signs and stages of DR, AMD and glaucoma, using fundus photos. Assessment of disease progression and independent predictors of progression will be undertaken on participants with signs of DR, AMD or glaucoma at baseline. The incidence and predictors of individual PSED development will be analysed on those participants without PSED at baseline.

    These data will contribute to establishing diagnostic and prevention strategies, advocacy for provision of resources and identification of high-risk groups. Specifically, Africa is on the cusp of a diabetes epidemic and the impact of DR needs to be assessed. People from African populations appear to be more vulnerable to glaucoma, however, currently incidence and progression data are lacking. The baseline data on AMD suggests this disease presents differently in the Kenyan population, and it is important to assess how it progresses.

  • Research update

    As a result of the logistic difficulty of doing this study in remote and hard to access locations, Dr Bastawrous was inspired to develop The Portable Eye Examination Kit (known as Peek). It’s a smartphone, camera adaptor and set of apps for diagnosing conditions that affect the back of the eye. Data from this study have been used to test and compare Peek’s ability to do the job as well and accurately as standard equipment – an essential part of developing the toolkit. Here are some of the outcomes:

  • Publications