Normal Anatomic and Cytologic Features
Accurate interpretation of ocular pathology specimens requires a fundamental knowledge of normal ocular anatomy and histology. A general overview is presented here. The average adult eye measures about 25 mm horizontally, 23 mm vertically, and 21 to 26 mm anterior-posteriorly. The eye has an external approximate volume of 7.6 milliliters (ml), the aqueous has a volume of about ~250 microliters (decreasing with age to ~160 microliters), and the vitreous a volume of 4.0 ml. The eye is contained in the pear-shaped orbit that has dimensions of about 35 mm vertically, 45 mm horizontally, and 40-45 mm anteroposteriorly. The orbital volume is ~30 ml in the adult. The lacrimal gland is located superolaterally in the orbit, and lies posterior to the orbital septum.
At birth the mean dimensions of the eye are 18.3 mm (H) and 17.3 mm (v). The eye grows fastest in the first year of life. At birth the anteroposterior diameter is 16.5 mm, 22.75 mm by 3 years of age and reaches adult dimensions by 13 years.
Toris CB, Yablonski ME, Wang YL, Camras CB. Aqueous humor dynamics in the aging human eye. Am J Ophthalmol. 1999 Apr;127(4):407-12. [Pubmed]