After over a decade of its discovery, the Electroretinogram (ERG) still remains
the objective tool that is conventionally used in assessment of retinal function in
health and disease. Although there is ongoing research in developing ERG recording techniques, interpretation and clinical applications, there is still a limited
understanding on how each photoreceptor class contribute to the ERG waveform
and their role and/or susceptibilities in various retinal diseases still remains
unclear. Another limitation with currently used conventional testing protocols in a
clinical setting is the requirement of an adaptation period which is time consuming.
Furthermore, the ERG responses derived in this manner are recorded under different stimulus conditions, thus, making comparison of these signals difficult. To address these issues and develop a new testing method, we employed silent substitution paradigm in obtaining cone- and rod- isolating ERGs
using sine- and square- wave temporal profiles. The ERGs achieved in this
manner were shown to be photoreceptor-selective. Furthermore, these
responses did not only provide the functional index of photoreceptors but their
contributions to their successive postreceptoral pathways. We believe that the
substitution stimuli used in this thesis could be a valuable tool in functional
assessment of individual photoreceptor classes in normal and pathological conditions. Furthermore, we speculate that this method of cone/rod activity isolation could possibly be used in developing faster and efficient photoreceptor-selective testing protocols without the need of adaptation.Bradford School of Optometry and Vision Sciences scholarshi
