Metabolomics of the aqueous humor in the rat glaucoma model induced by a series of intracamerular sodium hyaluronate injection.

Glaucoma models are helpful to study disease characteristics and to design new therapeutic options. Metabolomic profiling approach have been used to elucidating the molecular characteristics of the aqueous humor. Juvenile male Wistar rats experimental (n = 15) and controls (n = 6) were used for these studies. Experimental rats received weekly intracamerular injection of 25 µl of sodium hyaluronate in the left eye and sterile saline solution in the right eye, consecutively for ten weeks. Rats were subjected to anterior/posterior eye segment examinations, intraocular pressure (IOP), and flash electroretinograms (ERG). The aqueous humor was collected at endpoints and analyzed by Nuclear Magnetic Resonance. Elevated IOP and significant reduction of a, b waves and amplitude of oscillatory potential was observed in the left eyes compared to control eyes. The aqueous humor metabolomic profile from control and the experimental eyes were compared. Concentrations of metabolites (amino acids, lipids and carbohydrates) significantly changed after the sodium hyaluronate injections series, compared to the sham-operated eyes. Metabolic changes in the hypertensive eyes correlated with the impaired retinal function. Observed metabolomic changes in aqueous humor in hypertensive state may play a significant role in glaucoma pathogenesis.

Effects of morphine-alfaxalone-midazolam premedication, alfaxalone induction and sevoflurane maintenance on intraocular pressure and tear production in dogs.

Intraocular pressure (IOP) and tear production are commonly affected by general anaesthesia. It is necessary to have a good control of both to guarantee successful ophthalmic surgery. The purpose of this research was to evaluate if the protocol based on the administration of morphine-alfaxalone-midazolam as premedication, alfaxalone as induction and sevoflurane as maintenance, can induce changes on IOP and Schirmer's tear test (STT-1) in healthy dogs. Twenty-two adult mixed-breed dogs scheduled for an ovariohysterectomy were enrolled for the study. IOP and STT-1 were registered at baseline (T0), 5 minutes (T1), 10 minutes (T2) and 15 minutes (T3) after premedication with a morphine-alfaxalone-midazolam combination; 5 minutes (T4) after induction with alfaxalone and 15 minutes (T5) and 25 minutes (T6) after maintenance with sevoflurane. A one-way analysis of variance was performed to analyse the difference between IOP and STT-1 over time, respectively. The present study shows a slightly statistically significant increase in IOP (P<0.05) after premedication, induction and maintenance that can be associated with this anaesthetic protocol. STT-1 showed a statistically significant reduction during all the procedures (P<0.001). These results should be taken into consideration, especially in dogs with damaged corneas, in those predisposed to glaucoma and in those due to undergo intraocular surgery. Ocular lubrication is necessary if this protocol is used.