A novel device for assessing dark adaptation in field settings
| Autor: | Keith P. West, Katherine Healy, Theodor C. Sauer, Amanda Palmer, Sucheta Mehra, Alain B. Labrique, Alfred Sommer |
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| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Adult
Male medicine.medical_specialty business.product_category 030309 nutrition & dietetics Dark Adaptation Diagnostic Techniques Ophthalmological Reflex Pupillary Pupil Photometry 03 medical and health sciences Young Adult 0302 clinical medicine Light source Pregnancy Ophthalmology medicine Pupillary response Pupillary threshold Humans Scotopic vision Vitamin A Child Cardiopulmonary disease Digital camera Dark adaptometry Aged 0303 health sciences Pixel business.industry Vitamin A Deficiency Night blindness General Medicine Equipment Design Middle Aged 3. Good health Light intensity Nutrition Assessment Technical Advance 13. Climate action Child Preschool 030221 ophthalmology & optometry Pupil dynamics Optometry Female sense organs business |
| Zdroj: | BMC Ophthalmology |
| ISSN: | 1471-2415 |
| Popis: | Background Aberrant dark adaptation is common to many ocular diseases and pathophysiological conditions, including vitamin A deficiency, cardiopulmonary diseases, and hypoxia. Scotopic vision and pupillary responsiveness have typically been measured using subjective, time-consuming methods. Existing techniques are particularly challenging for use in developing country settings, where vitamin A deficiency remains a major public health problem. Our aim was design a compact, low cost, and easily operated device to assess dark adaptation in the field. Methods The Portable Field Dark Adaptometer (PFDA) incorporates a digital camera, a retinal bleaching flash, and a Ganzfeld light source inside a pair of light-obscuring goggles. After a ~10 min period of dark adaption, the infrared camera digitally records afferent pupillary responses to graded light stimuli (−2.9 to 0.1 log cd/m2). We tested this device in a variety of field settings to assess: a) ease of use and b) whether test data could clearly and accurately depict the well-known dose-response relationship between light intensity and pupil contraction. A total of 822 videos were collected. We used an open source video analysis software to measure pupil size in pixel units. Pupillary responsiveness was expressed as the percent change in pupil size from pre- to post-light exposure. Box plots, t test, and multi-level mixed effects linear regression modeling were used to characterize the relationship between light intensity and pupillary response. Results The PFDA was employed with only minor technical challenges in Bangladesh, Kenya, Zambia, and Peru. Our data show a clear linear increase in pupillary constriction with increasing log light intensity. Light intensity was a strong predictor of pupillary response, regardless of baseline pupil size. Conclusions The consistent physiological response demonstrated here supports the use of the PFDA as a reliable tool to measure dark adaptation. As a next step, PFDA measurements will be validated against biochemical indicators of vitamin A status and hypoxemia. Ultimately, this new technology may provide a novel approach for nutritional assessment, with potential clinical applications. Electronic supplementary material The online version of this article (doi:10.1186/s12886-015-0062-7) contains supplementary material, which is available to authorized users. |
| Databáze: | OpenAIRE |
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