Electrophysiological characterization of rod and cone responses in the baboon nonhuman primate model

Many monogenic retinal diseases target the human macula, and evaluating genetic treatments for these diseases in rodent models which lack a macula can be limiting. To better test the likelihood that novel treatments will be relevant to patients, assessing expression and distribution may be undertaken in a nonhuman primate (NHP) model. The purpose of this study was to establish baseline functional characteristics in the baboon (Papio anubis) eye to establish a control dataset for future experiments testing novel genetic therapies. Electroretinography (ERG) was conducted on 12 young (~ 3 years of age) dark-adapted baboons. Scotopic responses were measured in response to a series of light intensities followed by a 10-min period of light adaptation after which photopic responses were measured following the same series of light intensities. At the highest flash intensity, scotopic amplitudes were 334 ± 10 µV and 458 ± 15 µV for a- and b-waves, respectively. At the highest flash intensity, photopic amplitudes were 82 ± 5 µV and 81 ± 4 µV for a- and b-waves, respectively. Waveforms for scotopic responses were similar in shape to rodent scotopic responses. In contrast, photopic baboon waveforms were quite different in shape from those of rodents and were more similar to waveforms recorded from humans or other NHPs. These results are consistent with the differences in the photopic visual system in rodents versus primates (presence of a macula) and provide an excellent baseline for future studies testing novel therapies in the baboon model.