The influence of retrobulbar adipose tissue volume upon intraocular pressure in obesity.

BACKGROUND/AIM It is known that glaucoma is associated with elevated intraocular pressure and obesity, yet the precise etiology remains unclear. The aim of this study was to determine whether there is a potential causality between the volume of retrobulbar adipose tissue and the level of intraocular pressure in obese subjects compared with non-obese. METHODS A total of 100 subjects were divided according to the body mass index (BMI), into two groups: normal weight (n = 50, BMI = 18-24.9 kg/m2) and obese (n = 50, BMI > or = 30 kg/m2) subjects. Anthropometric measurements, body composition analysis, measurement of intraocular pressure, as well as magnetic resonance imaging (MRI) of the head at the level of the optic nerve, and the derived retrobulbar adipose tissue volume, were undertaken in all subjects. RESULTS The obese subjects, as compared with normal weight ones, had a significantly higher mean retrobulbar adipose tissue volume (6.23 cm3 vs 4.85 cm3, p < 0.01) and intraocular pressure (15.96 mmHg vs 12.99 mmHg, p < 0.01). Furthermore, intraocular pressure correlated positively with retrobulbar adipose tissue volume. CONCLUSION In obese people, elevated intraocular pressure may be caused by changes in ocular blood flow, affected by the physical pressure exerted by higher retrobulbar adiposity, and/or by internal vascular changes secondary to complications of obesity. These findings indicate the need for more frequent measurement of intraocular pressure in obese individuals to earlier detect glaucoma, and in so doing prevent irreversible blindness.