Tracking the Reflective Light Particles Spreading on the Cornea: An Emerging Assessment for Tear Film Homeostasis.

Abstract

PurposeTo implement an emerging noninvasive approach for assessing the dynamic tear film (TF) homeostasis.MethodsThe video records of dynamic TF from 12 healthy orthokeratology lens wearers were obtained by a clinically available TF analyzer and decomposed as image sequences. The trajectories of TF particles were analyzed by two tracking models, the full-span model (FSM) and the fixed-duration model (FDM). FSM tracked a particle for a complete opening blink cycle, while FDM tracked 1 second of the same cycle. A power-law fitting operation newcommand{bialpha}{boldsymbol{alpha}}newcommand{bibeta}{boldsymbol{beta}}newcommand{bigamma}{boldsymbol{gamma}}newcommand{bidelta}{boldsymbol{delta}}newcommand{bivarepsilon}{boldsymbol{varepsilon}}newcommand{bizeta}{boldsymbol{zeta}}newcommand{bieta}{boldsymbol{eta}}newcommand{bitheta}{boldsymbol{theta}}newcommand{biiota}{boldsymbol{iota}}newcommand{bikappa}{boldsymbol{kappa}}newcommand{bilambda}{boldsymbol{lambda}}newcommand{bimu}{boldsymbol{mu}}newcommand{binu}{boldsymbol{nu}}newcommand{bixi}{boldsymbol{xi}}newcommand{biomicron}{boldsymbol{micron}}newcommand{bipi}{boldsymbol{pi}}newcommand{birho}{boldsymbol{rho}}newcommand{bisigma}{boldsymbol{sigma}}newcommand{bitau}{boldsymbol{tau}}newcommand{biupsilon}{boldsymbol{upsilon}}newcommand{biphi}{boldsymbol{phi}}newcommand{bichi}{boldsymbol{chi}}newcommand{bipsi}{boldsymbol{psi}}newcommand{biomega}{boldsymbol{omega}}{rm{MMS}}left( t right) = {rm{alpha }} times {t^{ - {rm{beta }}}} was used to extract homeostasis markers based on the tracking model for each subject.ResultsComparing two tracking models (N = 6), only one subject had statistical difference in averaged momentary moving speed (MMS; P = 0.0488), while none had significant difference in averaged momentary moving direction (MMD). However, both models showed good correlations in average MMS (ρ = 0.94, P = 0.0048) and MMD (ρ = 1.00, P < 0.0001) and all extracted homeostasis markers [α, β, MMS(0.1), and MMS(2.0)]. Assessing interblink reliability in these markers under FDM tracking (N = 12), only one subject in the MMS (0.1) and another subject in the MMS (2.0) were outside 95% limits of agreement, respectively.ConclusionsFDM is a good alternative to FSM and has tracking properties of higher efficiency and easier implementation. The homeostasis markers under FDM tracking showed a good interblink consistence; therefore this approach will be a promising method for analyzing dynamic TF homeostasis in future practice.Translational RelevanceFDM analytical architecture can practice the past experimental platform on a TF analyzer to obtain homeostasis markers of TF.