Effects of common anesthetics on eye movement and electroretinogram
- 424 Downloads
High-resolution magnetic resonance imaging (MRI) provides non-invasive images of retinal anatomy, physiology, and function with depth-resolved laminar resolution. Eye movement and drift, however, could limit high spatial resolution imaging, and anesthetics that minimize eye movement could significantly attenuate retinal function. The aim of this study was to determine the optimal anesthetic preparations to minimize eye movement and maximize visual-evoked retinal response in rats. Eye movements were examined by imaging of the cornea with a charge-coupled device (CCD) camera under isoflurane, urethane, ketamine/xylazine, and propofol anesthesia at typical dosages in rats. Combination of the paralytic pancuronium bromide with isoflurane or ketamine/xylazine anesthesia was also examined for the eye movement studies. Visual-evoked retinal responses were evaluated using full-field electroretinography (ERG) under isoflurane, ketamine/xylazine, urethane, and ketamine/xylazine + pancuronium anesthesia in rats. The degree of eye movement, measured as displacement per unit time, was the smallest under 1% isoflurane + pancuronium anesthesia. The ketamine/xylazine groups showed larger dark-adapted ERG a- and b-waves than other anesthetics tested. The isoflurane group showed the shortest b-wave implicit times. Photopic ERGs in the ketamine/xylazine groups showed the largest b-waves with the isoflurane group showing slightly shorter implicit times at the higher flash intensities. Oscillatory potentials revealed an early peak in the isoflurane group compared with ketamine/xylazine and urethane groups. Pancuronium did not affect the a- and b-wave, but did increase oscillatory potential amplitudes. Compared with the other anesthetics tested here, ketamine/xylazine + pancuronium was the best combination to minimize eye movement and maximize retinal function. These findings should set the stage for further development and application of high-resolution functional imaging techniques, such as MRI, to study retinal anatomy, physiology, and function in anesthetized rats.
KeywordsAnesthesia Eye movement ERG fMRI Magnetic resonance imaging
This work was supported by the NIH/NEI (R01 EY014211 and EY018855 to TQD) and MERIT awards from the Department of Veterans Affairs (TQD, MTP, DEO). We also thank Research to Prevent Blindness; NEI (P30EY006360); and Rehabilitation, Research and Development Service, Department of Veterans Affairs for their supports.
- 28.Shih YY, De La Garza BH, Muir ER, Rogers WE, Harrison JM, Kiel JW, Duong TQ (2011, in press) Lamina-specific functional MRI of retinal and choroidal responses to visual stimuli. Invest Ophthalmol Vis SciGoogle Scholar
- 34.Peng Q, Zhang Y, Oscar San Emeterio Nateras O, van Osch MJP, Duong TQ (2010, in press) Magnetic resonance imaging of blood flow of the human retina. Magn Reson MedGoogle Scholar
- 35.Bizheva K, Pflug R, Hermann B, Povazay B, Sattmann H, Qiu P, Anger E, Reitsamer H, Popov S, Taylor JR, Unterhuber A, Ahnelt P, Drexler W (2006) Optophysiology: depth-resolved probing of retinal physiology with functional ultrahigh-resolution optical coherence tomography. Proc Natl Acad Sci USA 103(13):5066–5071PubMedCrossRefGoogle Scholar
- 47.Wixson S, Smiler I (1997) Anesthesia and Analgesia in Laboratory Animals. Academic Press, NYGoogle Scholar
- 52.Flecknell P (1987) Laboratory Animal Anesthesia. Accademic Press, LondonGoogle Scholar
- 54.Pugh EN Jr, Falsini B, Lyubarsky AL (1998) The origins of the major rod-and cone- driven components of the rodent electroretinogram and the effect of age and light-rearing history on the magnitude of these components. In: TA Williams TP (ed) Photostasis and related phenomena. Plenum Press, New York, pp 93–128Google Scholar
- 65.Duong TQ, Pardue MT, Thule PM, Olson DE, Cheng H, Nair G, Li Y, Kim M, Zhang X, Shen Q (2008) Layer-specific anatomical, physiological and functional MRI of the retina. NMR Biomed 21(9):978–996Google Scholar