These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Quantitative electroretinogram measures of phototransduction in cone and rod photoreceptors: normal aging, progression with disease, and test-retest variability.
    Author: Birch DG, Hood DC, Locke KG, Hoffman DR, Tzekov RT.
    Journal: Arch Ophthalmol; 2002 Aug; 120(8):1045-51. PubMed ID: 12149058.
    Abstract:
    OBJECTIVES: To determine (1) reference values for cone and rod phototransduction variables derived from the a-wave of the electroretinogram, (2) their dependence on age, (3) the progression in cone and rod variables in patients with X-linked retinitis pigmentosa (XLRP), and (4) the test-retest variability in these a-wave measures compared with the variability in cone and rod b-wave measures. PARTICIPANTS: One hundred control subjects aged 5 to 75 years and 24 patients with XLRP aged 5 to 38 years. METHODS: High-intensity stimuli were used to elicit electroretinograms in the dark and in the presence of a rod-saturating background. Computer averaging and computer subtraction of cone components from mixed rod-cone responses were used to derive rod-only and cone a-waves. Rod and cone phototransduction variables were derived by computer fitting physiologically based computational models to the leading edges of a-wave ensembles. RESULTS: Phototransduction efficiency, as indexed by the sensitivity variable (S), decreased with age for cone and rod-only responses, whereas maximum cone and rod photoresponses (Rm(P3)) remained constant. In patients with XLRP tested annually for 4 years, Rm(P3) for rods and, to a lesser extent, cones declined with disease progression, whereas S remained stable. The test-retest variability in the a-wave Rm(P3) is lower than previously reported measures of the variability in b-wave peak-to-peak amplitude. CONCLUSION: The leading edge of the a-wave of the electroretinogram can be related to rod and cone phototransduction variables through quantitative models. Rm(P3), rather than S, should be the outcome measure of choice when using the a-wave to follow photoreceptor function in prospective studies and treatment trials.
    [Abstract] [Full Text] [Related] [New Search]