Purpose:
The mouse eye has been used for many important pathophysiologic studies of visually-significant diseases. Experimental paradigms frequently involve the injection of diagnostic and/or therapeutic agents into the vitreous cavity, and the analysis of data is dependent on the volume of the vitreous cavity. We assessed the variation in size of the vitreous cavity in 2-month old mice using high-resolution MRI.
Methods:
The vitreous volume of five 2-month old male C57BL/6 mice was measured by high resolution MRI at 11.7T. Multi-slice spin-echo image covering the entire left eye were acquired at 100 x 100 x 100 µm3 resolution (TR 1 sec, TE 35 ms, average 4). Vitreous was manually identified on each image as the region exhibiting higher intensity than lens, iris, and retina (Fig 1 A&B). To minimize the partial volume effect on vitreous volume measurement, the voxel volume at the edge of vitreous cavity was weighted by a factor of 0.5.
Results:
The average volume of the vitreous cavity in 2-month old mouse eyes has a 15% variation (Fig. 1C, mean = 4.4 ± 0.7 µl). Furthermore, the difference in vitreous cavity size is not correlated to the weight of the mouse (R2 = 0.17).
Conclusions:
The vitreous volume of the mouse eye can vary significantly in mice of the same age, and is not related to weight of the mouse. Therefore, accurate conclusions concerning the dose effect of an intravitreal injection in the murine vitreous cavity may be biased by the variation in size of the vitreous cavity.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • anatomy