Subclinical Keratoconus Detection And Characterization Using Motion Tracking Brillouin Microscopy

To characterize focal biomechanical alterations in subclinical keratoconus (SKC) using motion tracking (MT) Brillouin microscopy and evaluate the ability of MT Brillouin metrics to differentiate SKC eyes from normal controls.

Academic Practice

Prospective cross-sectional study evalauting 30 eyes from 30 patients, including 15 eyes from 15 bilaterally normal patients and 15 SKC eyes from 15 patients.  All patients underwent Scheimpflug tomography and MT Brillouin microscopy imaging using a custom-built device. Mean and Minimum (Min) MT Brillouin values within the anterior plateau region (Plateau) and anterior 150 microns (A150) were generated.  Scheimpflug metrics evaluated included Inferior-Superior (IS) Value, K Max, Thinnest Corneal Thickness (TCT), asymmetry indices, BAD-D, and ART max.  Receiver operating characteristic (ROC) curves were generated for all Scheimpflug and MT Brillouin metrics evaluated.

There were no significant differences between groups for age, sex, corrected distance visual acuity CDVA, K Max, or KISA% index.  Among Scheimpflug metrics, there were significant differences between groups for TCT (556mm vs. 522mm, p < 0.001), IS Value (0.29D v s 1.05D, p <0.001), IVA (0.10 vs 0.19, p <0.001) and KI (1.01 vs 1.05, p <0.001). Among MT Brillouin metrics, there were clear differences between Control and SKC eyes for Mean Plateau (5.71 GHz vs. 5.68 GHz, p<0.0001), Min Plateau (5.69 GHz vs. 5.65 GHz, p<0.0001), Mean A150 (5.72 GHz vs. 5.68 GHz, p<0.0001) and Min A150 (5.70 GHz vs. 5.65 GHz, p<0.001).  All MT Brillouin Plateau and A150 Mean and Min metrics fully differentiated groups (AUROC = 1.0 for each).

MT Brillouin microscopy metrics effectively characterized focal corneal biomechanical alterations in SKC eyes and clearly differentiated these eyes from controls, including eyes that were not accurately differentiated using Scheimpflug metrics.