The Changes of ERG b-wave and Oscillatory Potentials in White Rats according to Dark Adaptation and Stimulus Light Intensity

Authors studied changes of ERG b-wave and oscillatory potentials(OPs) in white rats according to dark adaptation and stimulus light intensity for experimental setting. For this purpose we performed ERG tests on 10 normal white rats(20 eyes) during progressive dark adaptation. ERG b-wave and OPs values increased significantly during the first 30 minutes and then made plateau pattern. Based on this result we concluded that 30 minutes dark adaptation was sufficient for getting stable rat ERGs. After 30 minutes of dark adaptation, ERG b-wave and OPs were measured in response to 0.3J(2.25 cd.s/m2), 0.6J(6.5 cd.s/m2) , 2J(27.5 cd.s/m2) light intensity. In ERG b-wave there was no significant differene between 0.3J and 2J. In OPs between 0.3J and 0.6J, the sum of amplitude was significantly increased(p0.05). We concluded that 0.3J(2.25 cd.s/m2) was sufficient in ERG testing. And in OPs at least 0.6J(6.5 cd.s/m2) was needed for proper stimulation.

Safety of intravitreally injected ciprofloxacin in phakic rabbit eyes

This study was designed to determine the maximal safe drug concentration of intravitreal ciprofloxacin in phakic rabbit eyes. Twenty-two eyes of New Zealand pigmented rabbits received midvitreal ciprofloxacin of 100, 200, 400, 600 or 800 microgram in BSS Plus, or BSS Plus only. Retinal toxicity was dose-dependent as determined with electroretinography, light microscopy, and transmission electron microscopy. At a dose of greater than 400 microgram, disorganization of the outer segments was a main pathological finding in transmission electron microscopy. We evaluated retinal function by measuring the electroretinograms for a graded series of flash intensities and by fitting electroretinogram b-wave amplitudes to the Naka-Rushton equation. At a dose of greater than 600 microgram, Rmax was significantly decreased and log K was significantly increased. N-value tended to decrease. A decrease of b-wave amplitudes caused by retinal toxicity could be detected very sensitively with lower luminance stimuli. Determination of retinal toxicity with lower luminance electroretinography revealed a significant decrease of b-wave amplitudes at a dose of greater than 400 microgram. We concluded that a safe dose of intravitreal ciprofloxacin in phakic rabbit eyes was 200 microgram in phakic eyes.

Safety of Intravitreal Ciprofloxacin in Phakic Rabbit Eyes Determined with Electroretinography

This study was conducted to determine the safe intravitreal dosage of ciprofloxacin. Twenty-four phakic eyes of New Zealand pigmented rabbits were used. Each group(4 eyes) received midvitreal ciprofloxacin of 100, 200, 400, 600, 800 micro gram in 0.1ml BSS Plus, or 0.1ml BSS Plus only as control. We evaluated retinal function by measuring the electroretinograms for a graded series of flash intensities and fitting b-wave amplitudes to the Naka-Rushton equation. At a dose of greater than 600 micro gram, Rmax decreased signifantly and log K increased signifantly. N-value decreased slightly. B-wave amplitude decreased as a toxic response of intravitreal ciprofloxacin in a dose dependent manner, and this response was best detected using lower luminance stimuli. Lower luminance electroretinography revealed a significant decrease in b-wave amplitude in eyes injected with a dose of 400 micro gram or more. We concluded that 200 micro gram will be the safe intravitreal dosage of ciprofloxacin in phakic rabbit eyes.