[Case-control study of epidemic optic neuropathy in Cuba, 1993]

The purpose of this study was to identify the risk factors for epidemic optic neuropathy, which occurred in Cuba in 1992 and 1993, as well as to formulate a hypothesis about its etiology. The study sample consisted of 551 pairs of cases and controls matched for age, sex, and area of residence. The cases were patients aged 15 years and over who were diagnosed in April 1993. Diagnosis was made in accordance with major criteria (diminished visual acuity, alteration in color vision, scotomata, and changes in the papillo-macular tract) and minor criteria (pallor of the optic disk, photophobia, and others). Cases were selected through systematic sampling of all the country's provinces. The controls were selected from the population registers of the primary care districts. By means of a 52-section questionnaire, information was obtained from the cases and controls about their sociodemographic characteristics, drug and food habits, and exposure to toxic environmental substances. The population group most affected was that of persons 25 to 64 years of age who lived in urban areas. No evidence was found to support biological transmission of the disease, nor were any environmental toxins discovered to be causal agents. Construction of logistic models showed an irregular diet (95% confidence interval of the odds ratio [95%CI OR]: 2.43-3.63), smoking (95% CI OR: 2.60-3.13), and elevated ingestion of sugar (95% CI OR: 1.74-2.52) to be risk factors for the disease. Despite the study's limitations, it supports the hypothesis that the epidemic's pathogenesis is toxic-nutritional. According to this hypothesis, nutritional deficiencies could be responsible for a marked alteration in metabolic detoxification mechanisms, which would increase susceptibility to a noxious agent.