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Correlation of nuclear cataract lens density using Scheimpflug images with Lens Opacities Classification System III
Dilraj S Grewal1, Gagandeep S Brar, Satinder Pal Singh Grewal
1Grewal Eye Institute, Chandigarh, India. dilraj@gmail.com
Purpose:
To calculate the average lens density (ALD) and nuclear lens density (NLD) using Scheimpflug images and to determine their correlation with logarithmic minimal angle resolution (logMAR) best-corrected visual acuity (BCVA), contrast sensitivity (CS), and lens grading based on the Lens Opacities Classification System (LOCS) III.
Design:
Cross-sectional observational study.
Participants:
One hundred ten patients with age-related nuclear cataract.
Methods:
The logMAR BCVA was recorded using Early Treatment Diabetic Retinopathy Study charts and photopic contrast-sensitivity using CSV-1000LV (Vector Vision, Greeneville, OH). Fifty Scheimpflug images (Pentacam, Oculus, Germany) covering 360 degrees of the lens were obtained for 1 eye of each patient after dilation. All Scheimpflug images were exported to ImageJ software (NIH, Bethesda, MD) for analysis wherein the ALD and NLD (using a mask applied to the lens nuclear area) were calculated in pixel-intensity units. Repeatability was determined using coefficient of variation (CoV) and intraclass correlation coefficient (ICC). Lens opacity on slit-lamp images was graded using LOCS III for nuclear opalescence (NO) and nuclear color (NC).
Main Outcome Measures:
We evaluated ALD and NLD on Scheimpflug images and their correlation with NO and NC LOCS III grading, BCVA, and photopic CS.
Results:
The ICC for ALD and NLD were 0.983 and 0.99, respectively; the CoV were 3.92+/-1.76% and 2.57+/-0.74%, respectively. The ALD correlated with NO (r = .774; P<0.001), NC (r = .732; P<0.001), BCVA (r = 0.696; P<0.001), and CS at 3 cycles per degree CPD (P = 0.011), 6, 12, and 18 CPD (P<0.001). The NLD correlated with NO (r = .859; P<0.001), NC (r = .81; P<0.001), BCVA (r = .760; P<0.001), CS at 3 CPD (P = 0.002), 6, 12, and 18 CPD (P<0.001). The NLD had a significantly stronger correlation with BCVA (P<0.05), NO (P<0.01), NC (P<0.01), and CS at 6 CPD (P<0.01) and 12 CPD (P<0.005) compared with ALD.
Conclusions:
Repeatable 360 degrees lens density measurements were obtained using Scheimpflug imaging. A stronger correlation was observed between NLD and LOCS III grading, BCVA, and photopic CS than with ALD. The NLD is an objective and repeatable method for assessment of lens density, which could be helpful in longitudinal studies monitoring nuclear cataracts.
