Light damage (LD) treatment led to ERG amplitude reduction. They found that functional losses were detectable prior to anatomical changes and that a loss of 75% of the cones resulted in an immediate loss of photopic b-waves of similar magnitude, but that a substantial recovery was observed, albeit incomplete and transient on the scale of months. Recently, Riccitelli et al., thoroughly examined the light-damage effects of brief (12–24 h) 1000 lux exposures on retinal morphology, anatomy, function and some molecular signatures as well. The CFF curve was suppressed over an intensity range of six log units, with the largest decrease in CFF in the photopic range. Williams et al., observed deficits in behavioral CFF in rats exposed to 500 lux for 8 days. Sensitivity to a flickering light can be quantitatively assessed by a measure of the critical flicker frequency (CFF), that is the maximum flicker frequency that will elicit a behavioral response or a criterion voltage in an ERG recording. Sugawara, Sieving and Bush showed reductions in the dark- and light-adapted ERG in rats exposed to 1000–3000 lux for up to 48 h. However, the characterization of rods as more vulnerable to light damage is not consistently reported. The recovery of the b-wave amplitude and flicker sensitivity demonstrates the plasticity of retinal circuits following photopic injury. Photopic behavioral CFF was slightly lower following light damage. There was a small, but significant dip in scotopic ERG CFF. The a-wave was permanently reduced, while the b-wave amplitude recovered over three weeks after light damage. Dark- and light-adapted ERG flash responses were significantly reduced after light damage.
Flicker-ERG and behavioral responses to flicker were used to determine critical flicker frequency (CFF) under scotopic and photopic conditions before and up to 90 d after a 10-day period of low-intensity light damage. A comparison of ERG to behavioral responses in a light-damage model of retinal degeneration allows us to better understand the functional implications of electrophysiological changes. However, the relationship between the ERG response amplitudes and visually guided behavior, such as flicker detection, is not well understood. The full-field ERG is useful for index rod- or cone-mediated retinal function in rodent models of retinal degeneration.
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