Use of the corneal bioreactor to assess deswelling efficacy of hyperosmotic eye drops

AbstractPurposeThe preclinical testing of the efficacy and safety of hyperosmotic anti‐edematous eye drops is complicated by the lack of a simple in vivo and ex vivo animal model. Our patented corneal bioreactor (BR) allows prolonged preservation of the human cornea by restoring physiological intraocular pressure and renewing the culture medium. Under certain experimental conditions, the corneas preserved in BR are nevertheless thicker than normal (684 ± 52 um, A J Transplantation 2019).AimTo use this characteristic of corneas stored in the BR to test the efficacy of new hyperosmotic eye drops prototypes.MethodsHuman corneas (n = 4) discarded by our eye banks were used whatever their endothelial status. They were first stored for 2 weeks into the BR filled with CorneaMax (Eurobio, France), with 21 mmHg in the endothelial chamber to allow regeneration of a normal epithelium as previously shown. Using a specific BR lid allowing sterile instillation in front of corneal center, each cornea was treated topically with 3 drops, every 2 hr, repeated 3 times. The epithelial chamber was emptied just before instillation and filled again with CorneaMax 2 min after instillation. Three corneas were treated with a commercial eyedrop containing 5% NaCl and 0.15% sodium hyaluronate and one cornea with Balanced Salt Solution (BSS) as a control. Central corneal volume (on an 8mm disc, CCV8 in mm3) was measured with OCT (Casia, Tomey) immediately before and after each instillation. The decrease in CCV was calculated for each instillation and before the first and the third instillation.ResultsFor corneas treated with NACl 5%, CCV decreased by (mean ± SD) 1.0 ± 0.4, 0.7 ± 0.1 and 0.6 ± 0.2 mm3, respectively, for the first, the second and the third instillation, and globally by 2.4 ± 1.1 mm3. The cornea treated with BSS remained unchanged.ConclusionsThe BR is an efficient tool to quantify the efficacy of hyperosmotic eye drops designed to deswell human cornea.