The relationship between obesity and idiopathic intracranial hypertension

To evaluate the association between obesity and idiopathic intracranial hypertension (IIH) and establish whether there is a relationship with visual outcome. To calculate the prevalence and degree of obesity in a group of patients with IIH.

34 patients (31 female and 3 male) were recruited between 1993 - 1997 with a diagnosis of IIH. Assessment included visual acuity, visual field assessment (Humphrey automated and Goldmann manual perimetry), fundus assessment and measurement of body mass index (BMI). Obesity was defined as a BMI of 30 kg/m2.

70.5% of patients were obese. The relative risk for obesity and IIH was significant at 8 (95%CI: 2,29). This increased to 17 (95%CI: 5,62) for obese females aged 16 to 24 years and 10 (95%CI: 3,35.5) for obese females aged 25 to 34 years. Morbid obesity (BMI > 40) was significantly associated with poor visual outcome. Serial obesity measures showed generally little change in weight over time and there was no correlation between weight change and visual improvement.

This study has documented a relationship between obesity and IIH. A high degree of obesity was associated with a poor visual function and identified as a risk factor for poor outcome. Obesity may be an aetiological factor in this condition although it is unlikely to be the sole cause but more probably a precipitating factor. Weight loss is recommended although failure to lose weight is common. Any weight reduction programme must therefore be actively encouraged and monitored.