Nyctalopia

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nyctalopia

[‚nik·tə′lō·pē·ə]
(medicine)

Nyctalopia

 

night blindness, a visual disorder manifested by partial or total inability to see objects in the twilight or at night.

Nyctalopia may arise in connection with certain organic diseases of the retina, choroid coat, or optic nerve, or with glaucoma (symptomatic nyctalopia); in connection with poor general nutrition due to starvation, certain liver diseases, malaria, alcoholism, or other conditions accompanied by a deficiency or total absence of vitamin A (functional nyctalopia); or in connection with congenital pigment degeneration of the retina (congenital nyctalopia). The immediate cause of nyctalopia is connected with structural changes in the retinal rods or a deficiency of rhodopsin (visual purple), which disintegrates in the light but is restored in the dark in the presence of vitamin A. Nyctalopia patients suffer from photophobia in bright light and sharply reduced vision in the twilight and at night. They may also suffer from reduced color sensitivity with respect to blue and yellow. Sometimes their visual field is narrowed and its acuity diminished. Nyctalopia is usually exacerbated in early spring because of insufficient vitamin A in the food.

A fully balanced diet, cod liver oil, and intake of vitamins A, B1, B2, and C are important to both treatment and prevention. In cases of symptomatic nyctalopia the causative disease should be treated.

REFERENCE

Katsnel’son, A. B. Vitaminy i avitaminozy v oftal’mologii.[Cheliabinsk] 1947.

S. I. TAL’KOVSKII

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The International Vitamin A Consultative Group (IVACG) recommended that the rates of maternal nightblindness should be routinely investigated in nutrition and health surveys, given the associated risk for health and nutritional status (4,18).
Thus, the aim of the present study was to describe the prevalence of gestational nightblindness among postpartum women and to evaluate the association of ocular symptom with a biochemical indicator (serum retinol levels) and with obstetric history, antenatal care, sociodemographic and anthropometric variables.
The prevalence of nightblindness and of serum vitamin A deficiency will not be identical.
To identify nightblindness among the study subjects, we used the standardized interview as proposed by WHO (21) and OPS/Pan American Health Organization (8), including the questions: (i) do you have difficulty seeing during the day?
The interviews aimed at diagnosing nightblindness were validated based on their association with the biochemical indicator-serum retinol levels (1).
The bivariate analysis did not show any association between nightblindness and these characteristics.
Bivariate analysis was done to determine the association of a total of 15 factors with nightblindness of the children.
Fifty-two percent of the children who complained of nightblindness had ocular signs of vitamin A deficiency compared to 9.
The characteristics of the children with and without nightblindness were compared with the 15 factors, and the characteristics found to be significantly associated with nightblindness are shown in Table 1.
No significant association of nightblindness with education of mothers, knowledge of mothers about vitamin A capsule, total number of children, socioeconomic status, duration of diarrhoea, dehydration status, associated ARI, and intake of vitamin A containing foods was found, although a higher proportion of the nightblind children had poor socioeconomic status and some dehydration, and were not consuming vitamin A-containing foods.
9%) children, who received vitamin A capsules, complained of nightblindness compared to 22 (24.
Seven factors (Table 1) showed a significant association with nightblindness, and these factors were subjected to stepwise logistic regression, taking the status of nightblindness (nightblind-0, not nightblind-1) as a dependent variable.