Vitamin A Deficiency
Ocular manifestations of vitamin A deficiency (VAD), termed
“xerophthalmia” or “dry eye” has been recognised for a long time. The most
frequently encountered of these signs is night blindness, which is the earliest
manifestation of xerophthalmia. In VAD, the time required to regenerate
rhodopsin is prolonged, thereby delaying adaptation time to dark environments.
Night-blind young children tend to stumble when going from bright to dimly-lit
areas and they tend to remain inactive at dusk and at night. No field applicable
objective tool is currently available for measuring night blindness. There is also
no clearly defined blood retinol level that is associated with the occurrence
of the symptom.
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