A simple field test for identification of night-blindness.

Area of Science:

• Ophthalmology
• Nutritional Science

Background:

• Dark adaptation is crucial for vision in low light.
• Night blindness (NB) can impair daily activities.
• Vitamin A deficiency is a known cause of NB.

Purpose of the Study:

• To develop and validate a simple, replicable field test for measuring dark adaptation time.
• To compare dark adaptation times in individuals with and without night blindness.
• To explore the correlation between serum vitamin A levels and dark adaptation time.

Main Methods:

• A novel field test utilizing a darkened room, controlled light flashes, and a stopwatch was employed.
• The test was administered to three groups: night-blind children (NB), non-night-blind controls (NNB), and a healthy high-income group (PC).
• Serum vitamin A levels were measured and correlated with the measured dark adaptation times.

Main Results:

• The night-blind group (NB) exhibited significantly longer mean dark adaptation times (14.9 seconds) compared to both the non-night-blind controls (NNB, 11.9 seconds) and the healthy high-income group (PC, 11.3 seconds).
• Mean serum vitamin A levels differed across groups, with the NB group showing the lowest levels (15.8 µg/dL) compared to NNB (17.5 µg/dL) and PC (29.5 µg/dL).
• A correlation was observed between serum vitamin A levels and dark adaptation times across all groups.

Conclusions:

• The developed field test is a reliable method for assessing dark adaptation.
• Impaired dark adaptation is significantly associated with night blindness.
• Serum vitamin A levels appear to play a role in dark adaptation efficiency.