Related Experiment Video
Updated: Aug 5, 2026
05:00
Intense Pulsed Light for the Treatment of Dry Eye Owing to Meibomian Gland Dysfunction
Published on: April 1, 2019
Dynamic Tear Film Stability Assessed via an Open-View Double-Pass Imaging System
Spyridon Tsoukalas1,2, Alexandros Pennos3, Clara Bonel Pla4,5
1Diestia Systems PC, Athens, Greece. s.tsoukalas@um.es.
Summary
A new optical metric, the Lacrima Stability Index (LaSI), objectively assesses tear film stability. Its derived time-to-90% decay (T90) effectively differentiates stable from unstable tear films, correlating well with existing measures.
Area of Science:
- Ophthalmology
- Optical physics
- Biomedical engineering
Background:
- Tear film stability is crucial for ocular comfort and visual acuity.
- Objective and reliable methods for assessing tear film stability are needed.
- Current methods like non-invasive break-up time have limitations.
Purpose of the Study:
- To evaluate a novel dynamic optical metric, the Lacrima Stability Index (LaSI), for objective tear film stability assessment.
- To determine the clinical utility of LaSI and its derived parameters.
Main Methods:
- Developed LaSI from double-pass imaging of retinal point spread functions at 15.4 Hz with pupil tracking.
- Defined LaSI as central point spread function energy normalized by total light.
- Introduced time-to-90% decay (T90) as the time for LaSI to decrease by 10%.
Main Results:
- LaSI traces were stable in normal tear film eyes and declined in unstable tear film eyes.
- T90 correctly classified 84.6% of eyes using a 10-second cutoff.
- T90 showed strong correlation with non-invasive break-up time (r=0.76, p<0.001).
Conclusions:
- LaSI offers a sensitive, time-resolved metric for tear film dynamics.
- T90 serves as a clinically interpretable marker for tear film stability.
- LaSI and T90 show promise for objective dry eye disease assessment.
