Abstract
PurposeTo assess nuclear and cortical opacities through the objective analysis of Scheimpflug images, and to check the correlation with the Lens Opacity Classification System III (LOCS III).MethodsNuclear and cortical opacities were graded according to the LOCS III rules after pupil dilation. The maximum and average pixel intensity values along an elliptical mask within the lens nucleus were taken to analyse nuclear cataracts. A new metric based on the percentage of opaque pixels within a region of interest was used to analyse cortical cataracts. The percentage of opaque pixels was also calculated for half, third and quarter areas from the region of interest’s periphery.ResultsThe maximum and average intensity values along the nucleus were directly proportional to the LOCS III grade: The larger the LOCS III value, the larger maximum and average intensity ones. These metrics showed a positive and significant correlation with the LOCS grade: The larger the LOCS grade, the higher was percentage of opaque pixels along the cortex within the same mask’s size. This metric showed a significant correlation to the LOCS grade.ConclusionThe metrics used to assess nuclear opacities showed good correlation with the LOCS III. The percentage of opaque pixels showed to be a useful metric to measure objectively the severity of the cortical opacity. These metrics could be implemented in an algorithm to detect and grade lens opacities automatically and objectively.
Highlights
The Lens Opacity Classification System III (LOCS III) was developed to overcome the limitations of the LOCS II, i.e., unequal intervals between standards, only one standard for colour grading, only one integer grading, and wide 95% tolerance limit.[1]
The maximum and average intensity values along the nucleus were directly proportional to the LOCS III grade: The larger the LOCS III value, the larger maximum and average intensity ones
Nuclear and Cortical Cataracts: Objective Assessment severity of the cortical opacity. These metrics could be implemented in an algorithm to detect and grade lens opacities automatically and objectively
Summary
The Lens Opacity Classification System III (LOCS III) was developed to overcome the limitations of the LOCS II, i.e., unequal intervals between standards, only one standard for colour grading, only one integer grading, and wide 95% tolerance limit.[1]. Scheimpflug cameras detect back-scattered light coming into the eye to measure densitometric values. This technology has been shown to be superior to optical coherence tomography and ultrasound biomicroscopy techniques to quantify back-scattered light.[5] When it comes to grading the lens opacity, Scheimpflug photography has been shown to be more precise than the LOCS III, which relies on morphological lens changes.[5, 6] Scheimpflug technology allows the detection of more subtle amounts of cataract progression than the LOCS III [7], which grades lens opacities in steps.[2]
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