© 2002 American College of Veterinary Ophthalmologists Veterinary Ophthalmology (2002) 5, 1, 19 – 22 Blackwell Science Ltd SLO angiography: arterio-venous filling times in monkey and minipig Serge G. Rosolen,* Gérard Saint-Macary,† Vincent Gautier‡ and Jean-François Le Gargasson‡ *Clinique vétérinaire, 119 Boulevard Voltaire, 92600 Asnières, France, †Synthelabo-Recherche, 2 – 8 rue de Rouen, ZI Limay Porcheville, 78440 Gargenville, France, ‡INSERM U-483, 10 avenue de Verdun, 75010 Paris, France Abstract Confocal scanning laser ophthalmosocope (cSLO) is a new technique which enables ocular fundus image recording and dynamic retinal angiography to be performed. The ocular fundus image is acquired sequentially, point by point, and is reconstructed on a video monitor at the rate of 25 images per second. The aim of this paper is to evaluate the feasibility of measuring retinal arterio-venous filling times (AVFT) with a I + Tech cSLO. Three young adult cynomolgus monkeys and three young adult Göttingen minipigs were used as experimental models. All animals were anesthetized using a zolazepam + tiletamine mixture injected intramuscularly; heart rate and rectal temperature were monitored and corneal irrigation was regularly performed. For all subjects, prior to examination, hematocrit and globe axial length were measured. The images were recorded, stabilized and analyzed. The retinal examination consisted of retinal images with 40° field cSLO, retinal fluorescein angiography and arterio-venous 50% filling time measurements. For each subject all images were easily recorded while keeping the animals in a normally lighted room without having to use any additional optical device. AVFT using an I + Tech cSLO is easily performed in monkeys and minipigs. AVFT measurements in minipigs and monkeys are similar. These results suggest that minipigs can replace monkeys as an experimental species for AVFT investigations. Key Words: angiography, minipig, monkey, SLO Address communications to: Dr Serge G. Rosolen Tel.: +33 1 47 33 08 95 Fax: +33 1 47 33 30 37 e-mail: rosolen@club-internet.fr INTRODUCTION The confocal scanning laser ophthalmoscope (cSLO) mini- mizes blurring and reflected images and enhances contrast by illuminating only a limited portion of tissue at selected depths in the retina. Combined with digital image analysis its applications are multiple in investigations of dynamic retinal function, 1,2 particularly for measurement of early arterio-venous filling times (AVFT). 3,4 Many researchers have evaluated retinal microcirculation in animal models such as monkeys 5 or pigs by use of fluorescein dye. 6 For many, the adult minipig represents one of the best models to study the physiology system 7 including retinal blood flow. 8 Indeed, the visual system of the minipig is quite similar to that of humans. 9,10 The aim of this report is to test the feasibility of AVFT measurements during early retinal filling times in monkeys and minipigs. MATERIALS AND METHODS Our protocol adhered to the Association for Research in Vision and Ophthalmology Statement for the Use of Animals in Ophthalmic and Vision Research, and work was conducted in Sanofi-Synthelabo-Recherche facilities. Animals Three young adult healthy cynomolgus monkeys purchased from CRP (Center de Recherches Primatologiques, Mauri- tius Island) and three young adult healthy Göttingen mini- pigs (Ellegaard Göttingen minipig, Dalmose, Denmark) were included in this study. All animals were anesthetized with an intramuscular injec- tion of zolazepam + tiletamine (Zoletil ® , Virbac, Carros, France) mixture at a dose of 20 mg / kg. All had their heads placed in a retention device and clips assured a perfect globe fixity and opening of eyelids. Hydration of the cornea was maintained during the examinations using BSS eye drops (Alcon, Rueil- Malmaison, France). Prior to performing the examinations, hematocrit and globe axial length were measured and the pupils were maximally dilated with drops of tropicamide (Mydriaticum ® , MSD, Paris, France) in each eye to obtain a stable mydriasis for at least 1 hour before the recording session. Rectal tem- perature was periodically monitored as well as blood pressure and heart rate (Finapres 2300 ® , Ohmeda, Trappes, France).