Purchase this article with an account.
R. S. Jonnal, J. C. Derby, B. Cense, W. Gao, O. P. Kocaoglu, Q. Wang, D. T. Miller; Stability of Cone Reflectance Under Temporally-coherent Illumination. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5172.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Fast, stimulus-evoked changes in the reflectance of cones have been reported using an adaptive optics (AO) flood camera and temporally-coherent illumination . This phenomenon, termed cone scintillation, is hypothesized to be due to common path interference in the outer segment (OS) and may allow detection of optical path length (OPL) changes in cones much smaller than the wavelength of the imaging source. While the dynamics of the cone reflectance have been characterized over short durations of several seconds, similar characterization over longer durations has not. Here we investigate the stability of cones over several hours in the absence of a visible stimulus.
Cone mosaic videos were acquired using an AO retina camera (described in ) at 190 Hz over 0.53 sec intervals (100 frames), and over a 1.8 deg patch located at 1.8 deg eccentricity. The imaging source, a laser diode ( = 915 nm, Δ = 3 nm), had coherence length longer than the OS. Videos were collected at 5 min intervals over one hour, 15 min intervals over two hours, and one hour intervals over five hours: 3 to 8 pm. Frames were registered and co-added into a high quality image. These images were registered to follow the reflectance of single cones over time. Each cone's reflectance was quantified as ΔI/I.
Linear regression showed no significant departure of ΔI/I from zero. R2 values were low, with only 15 cones having R2>0.25. Average slope of models was 2.27x10-6 min-1. Spectral analysis showed no significant periodicity of the reflectance of cones. RMS of ΔI/I was 0.0052, 0.0053, 0.0055, 0.0056, and 0.0059 over the intervals of 15, 30, 60, 120, and 300 min, respectively. The reflectance of most cones was stable over time, but a small fraction did oscillate, some sinusoidally with periods between 150 and 250 min.
This PDF is available to Subscribers Only