PURPOSE: To compare the demographic and socioeconomic background of patients with spasmus nutans (SN) and patients with idiopathic infantile nystagmus (IIN).

METHODS: This study was performed according to an observational case-control design. Parents or guardians of 23 patients with SN and 24 patients with IIN completed a 28-point questionnaire on demographic, socioeconomic, behavioral, personal, and family history. Mann-Whitney U tests were used to compare continuous dependents and χ² analyses for categorical variables. Correlation between variables was calculated by Spearman ρ tests and odds ratios for SN by Mantel-Haenszel estimates.

RESULTS: Comparing SN and IIN, Afro-American, and Hispanic ethnicity was significantly more common in SN (14 patients, 61%) than in IIN (1 patient, 4%). Significant differences between the groups were also found for gestational age (mean SN: 37.7 weeks, IIN: 40.3 weeks), home luminance at birth was reported to be brighter in more IIN patients (22 patients, 96%) as compared with the SN patients (15 patients, 71%). Factors reflecting a lower socioeconomic status were more prevalent in SN patients (annual household income, individual financially responsible for the household, source of income, availability of private medical insurance). In the SN group there were fewer married parents living together (9 families, 39%) than in the IIN group (21 families, 88%). Psychiatric disorders, including alcohol and drug abuse, were more frequent among parents of SN (10 parents, 47%) than of IIN (none). Annual household income and ethnicity correlated significantly with number of rooms/household.

CONCLUSION: This study demonstrated differences between SN and IIN patients and their families with regard to socioeconomic status, ethnicity, gestational age, psychiatric diseases of parents, and parental estimation of light exposure early in life. We conclude that low socioeconomic status represents a risk factor for the development of SN.