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Scheimpflug imaging of backscatter predicts cataract grade, visual acuity
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Scheimpflug imaging generated lens backscatter metrics that proved useful in grading cataract and predicting visual outcomes, according to a study.
“Overall, metrics of nuclear scatter were predictive of visual acuity and contrast sensitivity, whereas metrics of cortical cataract were predictive of visual performance under glare,” the study authors said.
The study included 342 eyes of 177 patients with a mean age of 79 years who underwent comprehensive clinical assessment and Scheimpflug imaging with the Pentacam system (Oculus).
Images of nuclear and cortical cataract were used to generate 13 measures of cataract backscatter and new metrics for cortical cataract. Stepwise multiple linear regression was used to establish associations between lens scatter metrics, visual performance and opacity grades.
The Lens Opacities Classification System III (LOCS III) was used to gauge cataract grade.
Study results showed that average backscatter in the anterior half of the nucleus and the whole nucleus average was most effective in predicting LOCS III nuclear opalescence grade. Contrast sensitivity and the number of image slices with significant cortical cataract best predicted LOCS III cortical grade. Combined anterior half and whole nucleus averages were most effective in predicting visual acuity. A combination of anterior half and whole nucleus averages and calculated percentage of cortical cataract best predicted contrast sensitivity under glare. All correlations between image criteria and anatomic or visual results were statistically significant (P < .001).
Perspective
Back to TopJohn A. Hovanesian, MD, FACS
Objectively measuring opacification of the crystalline lens has been an area of interest for many researchers, and several techniques have been proposed over the past couple of decades. In an era where measuring everything in and on the eye has become incredibly precise (think topography, OCT, UBM, tear osmolarity, etc), it is somewhat remarkable that our field has not accepted a standard for measuring lens opacity. There is certainly scientific merit in the idea. Moreover, I suspect in coming years, third-party payers including Medicare will begin to require a set, objective standard of lens opacity before a cataract is considered visually significant, when cataract surgery becomes a covered service. Studies like this one give us more validated options to consider as measurement modalities. That is probably good for everyone.
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