Effect of prior oxygen exposure on the electroretinographic responses of infant rats.

PURPOSE To study electroretinographic responses of infant rats with a history of exposure to high-ambient oxygen. METHODS Electroretinographic responses to a range of full-field stimuli were recorded from 13-day-old (n = 8) and 18-day-old (n = 10) rats with a history of intermittent exposure to 80% oxygen and age-matched controls. The a-waves were fitted with a model of rod cell sensitivity and saturated response amplitude. The amplitudes and implicit times of the b-wave and oscillatory wavelets were examined as a function of stimulus energy. Response parameters in oxygen-exposed rats were compared to those in controls. RESULTS The amplitude of the saturated rod response was reduced in oxygen-exposed 13-day-old but not 18-day-old rats. The sensitivity of the rod response was reduced in both 13- and 18-day-old oxygen-exposed rats. The saturated amplitude and sensitivity of the b-wave did not differ significantly between oxygen-exposed and control rats age 13 days, but both amplitude and sensitivity were significantly decreased in 18-day-old oxygen-exposed rats. Oscillatory potentials, which could be investigated only in 18-day-old rats, showed significant attenuation of OP3 but not OP4 amplitudes in the oxygen-exposed rats. The sensitivity of OP2 did not differ significantly between oxygen-exposed and control rats. The avascular area in the oxygen-exposed rats was not correlated with any of the rod cell, b-wave, or oscillatory potential response parameters. CONCLUSION The function of the rod photoreceptors, as well as the inner retina, is altered in infant rats with a history of oxygen exposure.