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Lydia Mineeva, Christopher L Passaglia, Leonid Balashevich, David Richards, Leonid Shubin, Andrey Kabanov, Brian Madow, Erin Greenberg; Quantitative analysis of fundus images as affected by cataract. Invest. Ophthalmol. Vis. Sci. 2019;60(9):163.
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To evaluate a quantitative method for grading the "blurriness" of ocular fundus images in patients with varying degrees of cataract in order to improve the quality of fundus examination when it is affected by opacification of the crystalline lens, and to develop an objective method for measuring severity of cataract.
We studied 16 patients (32 eyes) with a range of lens opacities. Age range was 70.19 ± 7.9 years. Degree of transparency of the lens was graded on the LOCS III system. Visual acuity was determined with 20/200 ETDRS at a distance of 4 m (ESV-3000). Images of the fundus were taken with a Topcon Mark II TRC retinal camera NW7SF Type IA (Japan). Image Resolution was 8 TIFF. An image processing algorithm (Reference 1: Passaglia, C. L., Arvaneh, T., Greenberg, E., Richards, D., & Madow, B. (2018). Automated Method of Grading Vitreous Haze in Patients With Uveitis for Clinical Trials. Translational vision science & technology, 7(2), 10. doi:10.1167/tvst.7.2.10) that combined bandpass filtering, entropy analysis. and power spectral integration was used to quantify image haziness in terms of two inversely-related scales: “Blur Score” and “Clarity Score”. Data were analyzed via Spearman's rank correlation coefficient.
The two scales provide similar information, but in opposite directions. LOCS III lens opacities (NC and C) showed a positive correlation with Blur Score [NC: R 0.44; t(N-2) 2.15; p=0.04]; [C: R 0.48; t(N-2) 2.36; p=0.02] and negative correlation with Clarity Score [NC: R -0.44; t(N-2) -2.15; p=0.04]; [C: R -0.48; t(N-2) -2.37; p=0.02]. This indicates that a lower Blur Score [visual acuity: R -0.64; t(N-2) -3.72; p=0.001], or higher Clarity Score [visual acuity: R 0.65; t(N-2) 2.04; p=0.05], correlates with better visual acuity. The values of LOCS III NO and P, on the other hand, showed no reliable correlation with Blur or Clarity scores.
Changes of the values of LOCS III lens opacities (NC and C) are correlated with the objective Blur and Clarity scores. The published computer algorithm (Reference 1), originally designed to grade vitreous haze, can also be used to assess the degree of transparency of cataract at various stages, thus providing an objective measure of the degree of cataract.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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