Abstract
Purpose: :
To evaluate the feasibility of using telemetry for collecting intraocular pressure (IOP) measurements in New Zealand Albino rabbits.
Methods: :
Each of the right eyes of eight New Zealand Albino rabbits was implanted with a pressure transmitter DSI (Data Sciences International, St Paul, MN) TA11PA-C40 modified to have a 15-cm catheter and a 5-mm tip using a published procedure (McLaren, JW et al. IOVS 37:966-75, 1996). RMC-1 (DSI) receivers were used to capture the signals. IOPs were monitored intermittently for 4 months in the implanted right eyes using P3P Ponemah software (DSI). The contralateral eyes did not receive the implant. The effects of topical administration of some common ophthalmic solutions, such as balanced salt solution (BSS), 1% fluorescein, 0.25% proparacaine, 1% tropicamide and 10% phenylephrine were evaluated. 2% Trusopt was used to validate the test system.
Results: :
Two animals developed complications after the surgery and were excluded from the study. Within 7 days (or less) of the implantation, diurnal fluctuation of IOP showing a minimum in the morning and a maximum in the evening with a spread of 5 -10 mm Hg in the remaining 6 animals was noted. The rise in pressure corresponded to lights out in the room and a noticeable drop corresponded to lights on. Topical instillation of BSS and proparacaine had little effect on IOP. Tropicamide and fluorescein appeared to slightly reduce IOP in the 1-hour period after application while phenylephrine appeared to raise IOP slightly within the 1-hour period of application.
Conclusions: :
Using the published procedure, continuous telemetric monitoring of IOP in rabbits is feasible. Phenylephrine significantly elevated IOP while 2% Trusopt significantly reduced IOP in these rabbits. Fluorescein slightly reduced it and BSS, proparacaine and tropicamide had little effect on IOP.
Keywords: intraocular pressure • drug toxicity/drug effects