GC: n

S: NCBI – (last access: 12 November 2015); (last access: 13 November 2015).

N: 1. First Known Use: 1684. The word nyctalopia emanates from Greek roots: nyct (night) + aloas (obscure or blind) + opsis (vision), which means “nightblind vision”.
Nychthemeron is an allied word. It is from Greek nycht (night) + hemera (day) and is the full 24-hour period of a night and a day. For example, to understand the behavior of babies, one must study them throughout the nychthemeron, an opportunity often afforded by babies to new parents.
2. Night blindness; failure or imperfection of vision at night or in a dim light, with good vision only in bright days.
3.The causes of night blindness fall into two categories: treatable and nontreatable.
– Treatable causes:

  • Cataracts
  • Nearsightedness
  • Use of certain drugs
  • Vitamin A deficiency (rare)

– Nontreatable causes:

  • Birth defects
  • Retinitis pigmentosa.

4. Nyctalopia and hemeralopia are the rare examples of words that may lead to a good deal of controversy and confusion among doctors of different linguistic backgrounds, because of different definitions and meanings.
Nyctalopia is a word from the Greek medical antiquity, defined as “night blindness” or defective dark adaptation. hemeralopia is a word that originated in the 18th century, which means “day blindness” or visual defect characterised by the inability to see as clearly in bright light as in dim light.
Standard English dictionaries also conform with the meanings of nyctalopia and hemeralopia as “night blindness” and “day blindness”, respectively. However, the words have been used in an opposite sense by many non‐English‐speaking doctors.
To reduce confusions, it is recommended that correctly understandable terms such as “night blindness” and “day blindness” be used.

S: 1. TFD – (last access: 12 November 2015); MN – (last access: 12 November 2015); MW – (last access: 12 November 2015). 2. DORLAND – (last access: 12 November 2015). 3. PMC NCBI – (last access: 12 November 2015). 4. MEDLP – (last access: 12 November 2015).

SYN: night blindness

S: NCBI – (last access: 12 November 2015); WHO – (last access: 13 November 2015).

CR: amaurosis, amblyopia, blindness, Chagas disease, diplopia, ophthalmology, Refsum’s disease, stye, xerophthalmia