[Study on the growth of orbital volume in individuals at different ages by computed tomography]

To study the growth aspects of orbital volume and to establish the normal value of orbital volume by computed tomography (CT).

One hundred and twenty three individuals without eye diseases (64 males, 59 females) were divided into 5 groups according to the age. Orbital volume and length of horizontal transverse axis and anterior-posterior axis of the eye were measured at different levels in original or reconstructive CT images. The relationship between orbital volume and age, gender and eyeball volume was analyzed.

There was no difference between the left and right orbital volume in all age groups. Orbital volume grew rapidly before 20 years of old. Mean orbital volume in males aged 17 and females aged 13 was 23.54 and 21.75 ml, respectively, which reached 95% of the adult orbital volume. In normal adult, orbital volume in the male was larger than that of the female. The mean orbital volume of adult male and female was (25.04 +/- 2.37) ml and (22.89 +/- 2.67) ml, respectively. A strong linear correlation was presented between the age and orbital volume (P < 0.05). The difference of orbital volume between the male and female was statistically non-significant before 14 years old (P = 0.315). The growth of eyeball volume was consistent with that of the orbital volume, the ratio of eyeball/orbit volume was decreased with age from 0.40 to 0.26.

There is no difference between the right and left orbital volume. Orbital volume is correlated with age and gender. Orbital volume grows rapidly before 20 years of old and still grows slowly after 40 years old.