Ultrasonographic ocular diameters in Nigerians

There is little information on the biometric ultrasonography of the eyeball, especially in Africans. The eyeball diameters form the basis for the calculation of the intraocular lens power and diagnosis of axial hypermetropia and myopia

To determine the ocular diameters of healthy Nigerian eyes.

Measurements of the eyeball in volunteers were taken on the B-mode image using a Medison's Sonoace 1500 ultrasound machine using a 6.5 MHz curvi-linear transducer placed over the closed eyelid. The vertical, horizontal and axial diameters of the eyes of healthy subjects were recorded. The age and sex of the subjects were also recorded.

Four hundred eyes of 200 subjects comprising 125 females (62%) and 75 (38%) males (38%) were studied. The age range was 3-92 years with an overall mean age of 41.48 +/- 23.26 years for both sexes. The mean axial eyeball diameter for the entire study population was 21.7 +/- 0.16 mm. There was a gradual increase in all eyeball diameters with age. The highest value for eyeball diameter (22.5 +/- 0.18 mm) was recorded for the elderly age group. The (SD) mean eyeball diameters for males were slightly higher than that for the females; mean for males, 21.8 +/- 0.13 mm, 95% CI = 21.781-21.819, vs females, 21.6 +/- 0.14 mm, 95% CI = 21.581-21.619. However, the difference was not statistically significant (p = 0.409).

The eyeball diameters found in this sample of Nigerians are lower than the dimensions reported in Caucasians. These values may be used as reference values for normal African eyes.