Open AccessMeasuring directionality of the retinal reflection with a Shack-Hartmann wavefront sensor
Author(s) -
Weihua Gao,
Ravi S. Jonnal,
Barry Cense,
Omer P. Kocaoglu,
Qiang Wang,
Donald T. Miller
Publication year - 2009
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.17.023085
Subject(s) - optics , wavefront sensor , wavefront , materials science , retinal , physics , ophthalmology , medicine
The directional sensitivity of the retina, known as the Stiles-Crawford effect (SCE), originates from the waveguide property of photoreceptors. This effect has been extensively studied in normal and pathologic eyes using highly customized optical instrumentation. Here we investigate a new approach based on a Shack-Hartmann wavefront sensor (SHWS), a technology that has been traditionally employed for measuring wave aberrations (phase) of the eye and is available in clinics. Using a modified research-grade SHWS, we demonstrate in five healthy subjects and at four retinal eccentricities that intensity information can be readily extracted from the SHWS measurement and the spatial distribution of which is consistent with that produced by the optical SCE. The technique is found sufficiently sensitive even at near-infrared wavelengths where the optical SCE is faint. We demonstrate that the optical SCE signal is confined to the core of the SHWS spots with the tails being diffuse and non-directional, suggesting cones fail to recapture light that is multiply scattered in the retina. The high sensitivity of the SHWS to the optical SCE raises concern as to how this effect, intrinsic to the retina, may impact the SHWS measurement of ocular aberrations.