Comparison of ocular tissue weights (volumes) and tissue collection techniques in commonly used preclinical animal species.

Abstract Purpose Ocular pharmacokinetic and distribution studies are key elements for the development of ophthalmic drugs and are used to correlate drug levels in preclinical species with human dosages and exposures. The purpose of this study was to compare ocular tissue weights for five commonly used preclinical species using two collection techniques. Methods Standard ocular tissues were collected from five males and five females of each species; New Zealand white (NZW) and Dutch Belted (DB) rabbits, beagle dogs, Gottingen minipigs, and Cynomolgus monkeys. Two collection techniques were used; a collection from fresh eyes (OS, immediately following enucleation) or a collection from frozen eyes (OD, following flash freezing). A specific procedure and collection sequence was followed for each technique. Results Aqueous and vitreous humor, cornea, lens, iris‐ciliary body, retina, choroid, and sclera were collected from each species; these tissues represented mean values of 70.0‐82.0% and 84.3‐88.9% of the total eye weight, respectively, for fresh and frozen collection. Tissue recovery levels were consistently higher using the frozen collection technique. Mean combined male & female vitreous humor weights using the frozen collection were 1.41, 1.31, 2.22, 2.34, and 2.04 g for NZW & DB rabbits, dogs, minipigs, and monkeys, respectively. Other tissue weights will be compared. Conclusion Comparative ocular tissue weights are presented for common preclinical species using fresh or frozen collection techniques. Vitreous humor and other tissue weights collected by the frozen technique accurately represent the weight (and volume assuming a VH density of 1) of the total tissue for comparative purposes to human vitreous volumes.