Analysis Of Lens Parameters Measured Using Brillouin Scattering

To evaluate the repeatability of a novel device (Brillouin Optical Scanning System (BOSS, Intelon Optics, Woburn, MA, USA)) that uses light to quantify material properties in measuring crystalline lens characteristics, and to investigate the dependence of these measurements on participant age, lens thickness, refractive error, and scanned location.

School of Optometry, Aston University, Birmingham, West Midlands, United Kingdom.

Sixty-three eyes (48 OD, 15 OS) of 63 adults (ages 18 to 67 years, median=21; 27 males) underwent 3 measurements using a BOSS: the first two 15 minutes apart, and a third measurement 15 days later, along with a Central Lens Thickness (CLT) using an Anterion OCT (Heidelberg Engineering Ltd, Germany). Six parameters were extracted from the BOSS scans: Brillouin elastic modulus (BLens), Top Plateau length (TopPl), Bottom Plateau length (BotPl), Anterior Slope (AntSl), Posterior Slope (PostSl) and distance of the measured point from the centre of the lens (Offset). Repeatability was assessed as bias and 95% limits of agreement (LOA). Refractive error was measured as spherical equivalent using a WAM-5500 (Grand Seiko, Japan) autorefractor.

The mean values of the BOSS parameters were: BLens 3.384 ± 0.056 GPa, TopPl 2.80 ± 0.51 mm, BotPl 4.23 ± 0.58 mm, AntSl 1.553 ± 0.412 GPa/mm and PostSl −1.533 ± 0.557 GPa/mm. Mean CLT was 3.90 ± 0.40 mm. The intrasession bias for the BLens was 0.001 GPa (LOA −0.091 to 0.104), whereas the intersession bias was −0.004 GPa (LOA −0.124 to 0.119). All the other parameters showed a lower degree of repeatability. Statistically significant correlations were found with age (BLens, TopPl, BotPl, PostSl, CLT), Offset (TopPl, BotPl) and CLT (BLens, TopPl, BotPl, PostSl). Using Decision Tree Analysis, a model was developed to explain lens parameters; the calculated risks of these models varied from 0.002 to 0.192.

The inter and intra session repeatability of Brillouin elastic modulus measurement for the crystalline lens is extremely high. Repeatability for other parameters is lower. Age, central thickness and scanned location influence measurement of lens characteristics.