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The portable field dark adaptometer: Validating a novel device for field-based screening and detection of vitamin A deficiency and night blindness, a debilitating condition associated with high maternal and child mortality

Gaibandha, Bangladesh


Night blindness, the inability to see after dusk in individuals with normal day-time vision, is a common manifestation of moderate to severe vitamin A deficiency (V AD). Apart from causing disability, night blindness is also associated with increased infections and maternal and infant mortality. Biochemical methods exist to assess serum V A, but are invasive and have high laboratory costs. Dark adaptometry (DA), an approach based on the identification of poor vision under low light, is an indirect method for the assessment of early V AD. Several DA methods, including measuring delayed pupillary responses to light, have been developed. These tests are also difficult under field conditions due to the need for a completely dark room. We invented and built a portable field dark adaptometry (PFDA) device for the rapid screening of subjects for impaired pupillary response under field conditions, without a dark room. This advancement over previously validated pupillary response tests allows for a non-invasive yet quantitative measure of vitamin A deficiency in individuals. Preliminary tests suggest high acceptance of this device in rural Bangladesh. A JHSPH Seed Award permitted significant improvements and integration into a laptop-based, field worker-friendly platform. Our device stores pupillary telemetry for research and expert review. We propose a nested study of270 women enrolled in a large community trial in Bangladesh to calibrate the PFDA against serum retinol and to propose PFDA cutoffs for VAD in this population. Validation is necessary before the PFDA can serve as an alternative to existing invasive assessments of VA status.


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