A novel device for assessing dark adaptation in field settings

Area of Science:

• Ophthalmology
• Public Health
• Biomedical Engineering

Background:

• Aberrant dark adaptation is linked to various diseases like vitamin A deficiency and hypoxia.
• Current methods for assessing scotopic vision are subjective, time-consuming, and difficult in resource-limited settings.
• There is a need for a compact, affordable, and user-friendly device for field-based dark adaptation assessment.

Purpose of the Study:

• To design and evaluate a Portable Field Dark Adaptometer (PFDA).
• To assess the device's ease of use and accuracy in depicting the light intensity-pupil response relationship.
• To provide a novel tool for nutritional assessment in diverse field conditions.

Main Methods:

• The PFDA uses a digital camera, flash, and Ganzfeld light source within goggles to record pupillary responses.
• Infrared camera captures pupillary changes to graded light stimuli after dark adaptation.
• Open-source software analyzed pupil size in videos; pupillary responsiveness was calculated as percent change.

Main Results:

• The PFDA was successfully deployed with minimal issues in multiple countries.
• A clear, linear relationship was observed between increasing light intensity and pupillary constriction.
• Light intensity strongly predicted pupillary response, irrespective of initial pupil size.

Conclusions:

• The PFDA demonstrates reliable measurement of dark adaptation through consistent physiological responses.
• Future work includes validating PFDA results against biochemical markers for vitamin A status and hypoxemia.
• The PFDA presents a promising new technology for nutritional assessment and has potential clinical applications.