Abstract
We compared objective Double-Pass (DP) image quality data with subjective visual parameters measured within the same modified instrument for different amounts of scatter. The original DP imaging channel of a clinical instrument was maintained intact and two additional channels were included, one for visual testing and another for tear film (TF) imaging by using a retro-illumination technique. Contrast sensitivity (CS) was compared with measurements of the Objective Scattering Index (OSI) obtained from DP retinal images corresponding to different scatter levels induced by pre-defined filters. OSI values were correlated with the change in CS for different spatial frequencies measured with the same instrument. Since TF and DP images were recorded at the same rate, this provided additional information about the dynamic spatial stability of the tear film. This new DP instrument has been proven to provide accuracy and repeatability, and to be suitable for clinical diagnosis, with a complete evaluation of the eye's performance by a simultaneous objective and subjective assessment under the same experimental conditions.
Highlights
The double-pass (DP) method is an objective technique based on recording images of a pointsource object after reflection on the retina and a double passage through the ocular media [1]
We have reported a modified clinical DP instrument to combine objective and subjective visual testing measurements
The biggest advantage of this version of the DP instrument is the combination of objective measurements and subjective visual testing in a unique platform
Summary
The double-pass (DP) method is an objective technique based on recording images of a pointsource object after reflection on the retina and a double passage through the ocular media [1]. A version of the DP device (OQAS-II, Visiometrics SL, Tarrasa, Spain) has been used in clinical environments to measure the retinal image quality under different conditions [6,7,8,9,10]. This instrument has a clear clinical potential, it cannot provide a direct correlation between the subject’s visual performance and the retinal image quality estimates. Standard visual tests such as visual acuity (VA) and contrast sensitivity function (CSF) are usually measured separately
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