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Toshifumi Mihashi, Yoko Hirohara, Syunichi Morishima, Haruhiro Mori, Takahiro Hiraoka, Fumiki Okamoto, Tetsuro Oshika; Transparency Distribution of Cataractous Crystalline Lens from Analysis of Images Obtained by a Shack-Hartmann Wavefront Aberrometer.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5648.
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© ARVO (1962-2015); The Authors (2016-present)
When cataractous eyes are measured with a Shack-Hartmann wavefront aberrometer(SHWA), it is known that intensity distribution of point spread functions(PSF) observed in the measured image is similar to the image obtained with slit lamp with retro illumination. The image intensity of each PSF may represent the amount of light penetrating the crystalline lens from back of the eye. We evaluated the pattern of intensity distribution and compared it with retro illumination images to investigate if the transparency distribution of the crystalline lens can be evaluated with this method.
Twenty-one cataractous eyes were measured using an SHWA(KR-1W, Topcon). Slit lamp(DC3, Topcon) images and retro images were also obtained for these eyes. We compared the measurement images from SHWA to the retro images obtained via slit lamp. With the regular aberration analysis program of KR-1W, the peaks of PSFs were automatically detected. After removing wrongly detected points manually, the minimum and maximum intensities over the area around each PSF and difference between those values were obtained. We also calculated the average of the intensity differences over the pupil and compared the average to the LOCS III: nuclear opalescence(NO), nuclear color(NC), cortical cataract(C), and posterior subcapsular cataract(P).
We confirmed that the intensity distributions of the Shack-Hartmann images((b) in Fig) were similar to the spatial patterns in the retro images(a) . We also found relative intensity distributions over the pupil(c) by analyzing the image of the SHWA. In comparing the average intensities of the SH images to the LOCS III values, we did not find any statistically significant correlations, but found a trend, such that the average of the intensity distribution was small when the LOCS III P value was large(P = 0.079).
With intensity distributions of the HS images, relative transparency distributions of the crystalline lenses over pupil could be evaluated in each individual eye. Absolute values of transparency of the crystalline lens were difficult to determine because the amount of light reflected from the retina depends on the transparency of the crystalline lens itself and reflectance of the retina.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Retro illumination images(a), images obtained by HSWA(b), and intensity distributions(c). The sizes of circles represent relative intensities.
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