Myopia occurs when the light beam stops before entering the retinal layer, resulting in blurred long-distance vision. Myopia in children is very common nowadays, requiring prompt intervention and effective treatment. Thus, research on myopia among children is aggressively conducted to propose better treatment technology. One of the aspects of myopia research is to analyse the shape of the eyeball and its association with this abnormality. Eyeball imaging is commonly conducted via magnetic resonance imaging (MRI). Thus, this paper presents eyeball segmentation in MRI images of myopic children based on the Chan-Vese Level Set method. MRI eye images of 35 myopic children were used. The measurement of pertinent lines was also done. The accuracy of the lines’ measurement was compared with the manual measurement. An average difference of 0.2825 mm (std 0.2386mm) for the left eye and 0.2677 mm (std 0.2526 mm) for the right eye were obtained. Also, statistical t-test evaluation showed that both measurements were statistically similar, confirming the agreement between the two. In conclusion, the process of segmentation and measurement of the eyeball is important to furnish the need for myopia treatment research and study on any treatment efficacy.