Dimensional growth of the rabbit eye

The rabbit eye has been used experimentally in research in vision and ophthalmology. However, there is little information about postnatal growth. The purpose of this study was to determine growth patterns of the rabbit globe from birth to young adult status focusing in particular on the fibrous outer tunic of the globe, the sclera. Eyes of both sexes of New Zealand White rabbits were examined on postnatal days 1, 7, 14, 28, 42 and 56. Axial length, equatorial diameter and corneal diameter were measured using a digital caliper. Plastic-embedded tissue was used to quantify scleral thickness and cellular density at anterior, equatorial and posterior sites. Axial length increased 230% between postnatal days 1 and 56. The rate of growth was not linear and revealed two peaks. The first peak occurred between postnatal days 1-7, and the second between days 14-28. Eye opening occurred on days 9-11. Sex differences were seen, with the male eye being larger (p = 0.00001). Surface area measurements of sclera and cornea revealed that the sclera occupies approximately 5/6 of the outer surface of the globe and the cornea 1/6. Scleral thickness increased from day 1 to day 42 (70-155 microm at the equator) while fibroblast density was found to decrease (0.32 to 0.05 cells/microm(2)). The results suggested that eye opening precedes a unique increase in the rate of eye growth and visual processes may be playing a role in modulating the growth pattern between days 14 and 28.