Purpose: To assess the human rod photopigment distribution and sensitivity with high spatial resolution within the central ±15° and to compare the results of pigment absorption, sensitivity and rod density distribution (number of rods per square degree). Method: Rod photopigment density distribution was measured with imaging densitometry using a modified Rodenstock scanning laser ophthalmoscope. Dark-adapted sensitivity profiles were measured with green stimuli (17′ arc diameter, 1° spacing) using a Tübingen manual perimeter. Sensitivity profiles were plotted on a linear scale and rod photopigment optical density distribution profiles were converted to absorption profiles of the rod photopigment layer. Results: Both the absorption profile of the rod photopigment and the linear sensitivity profile for green stimuli show a minimum at the foveal center and increase steeply with eccentricity. The variation with eccentricity corresponds to the rod density distribution. Conclusion: Rod photopigment absorption profiles, retinal sensitivity profiles, and the rod density distribution are linearly related within the central ±15°. This is in agreement with theoretical considerations. Both methods, imaging retinal densitometry using a scanning laser ophthalmoscope and dark-adapted perimetry with small green stimuli, are useful for assessing the central rod distribution and sensitivity. However, at present, both methods have limitations. Suggestions for improving the reliability of both methods are given.
Multifocal ERG is a novel technique, very well suited to reveal the topography of cone function. Using two-color threshold perimetry affords an opportunity to differentiate between rod and cone functional defects. Both together helped to establish the diagnosis of macular cone dystrophy in the present family.
Scanning laser densitometry with a modified Rodenstock SLO is a useful method to assess the human photopigment distribution. Densitometry results were confirmed by dark adapted two color static perimetry. Photopigment distribution and retinal sensitivity profiles can be measured with high spatial resolution. This may help to measure exactly the temporal development of retinal diseases and to test the success of different therapeutic treatments. Both methods have limitations at the present state of development. However, some of these limitations can be overcome by further improving the instruments.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.