Validation of a new objective method to assess lipid layer thickness without the need of an interferometer

Abstract

Purpose This study aimed to develop and validate new metrics to objectively assess the lipid layer thickness (LLT) through the analysis of grey intensity values obtained from the Placido disk pattern reflected onto the tear film. Methods Ocular surface parameters were measured using Oculus Keratograph 5 M in 94 healthy volunteers (43.8 ± 26.8 years). Subjects’ LLT was subjectively classified into 4 groups using an interferometry-based grading scale. New metrics based on the intensity of the Placido disk images were calculated and compared between groups. The repeatability of the new metrics and their diagnostic ability was analysed through receiver operating characteristics (ROC) curves. The level of agreement between the new objective tool and the existing subjective classification scale was analysed by means accuracy, weighted Kappa index and F-measure. Results Mean pixel intensity, median pixel intensity and relative energy at 5.33 s after blinking achieved the highest performance, with a correlation with LLT between r = 0.655 and 0.674 (p < 0.001), sensitivity between 0.92 and 0.94, specificity between 0.79 and 0.81, area under the ROC curve between 0.89 and 0.91, accuracy between 0.76 and 0.77, weighted Kappa index of 0.77 and F-measure between 0.86 and 0.87. Conclusion The analysis of grey intensity values in videokeratography can be used as an objective tool to assess LLT. These new metrics could be included in a battery of clinical tests as an easy, repeatable, objective and accessible method to improve the detection and monitoring of dry eye disease and meibomian gland dysfunction.

Evaluation of Celligent® Biomimetic Water Gradient Contact Lens Effects on Ocular Surface and Subjective Symptoms

“…Tear film stability assessment with non-invasive automated technology is a potentially effective methodology to evaluate the ocular environment differences created by SCL [ 20 ]. The provided information on tear film kinetics and the resulting interpretations of tear film rupture and coverage cycles, or periods of atmospheric exposure between pre-SCL and precorneal flickers [ 21 , 22 ] can help to collect objective data on changes to lacrimal dynamics or the ocular surface, with or without previous symptoms [ 23 , 24 ]. Additionally, independently evaluating factors, such as evaporation rates, tear film volume, and meibomian expression, or using validated questionnaires, such as the Contact Lens Dry Eye Questionnaire (CLDEQ8) or Standard Patient Evaluation of Eye Dryness (SPEED) [ 25 , 26 ] can be used as a method to anticipate clinical management or to modify factors, such as adjustment, materials, mode of use, care systems, or even the discontinuation of SCL use [ 27 , 28 ].…”

Dry eye disease and tear film assessment through a novel non-invasive ocular surface analyzer: The OSA protocol

“…Keratograph 5M uses four interferometric patterns instead of five 1 = open mesh (13–15 nm); 2 = closed mesh (30–50 nm); 3 = wave (50–80 nm); and 4 = color fringe (90–140 nm). In both devices, the subjectivity of the observer is influential during classification; this type of measurement is considered to be more reliable and repeatable, with less deviation in the results ( 36 – 38 ).…”

Association between Dry Eye Parameters Depends on Tear Components

“…The FTBUT was shorter in patients with MGD than in those without MGD [ 16 ]. In addition to the commonly adopted lid margin and meibography evaluation of MG, quantification of lipid layer thickness (LLT) with or without interferometer instruments has become an important technology in the evaluation of MG function and treatment effects [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Subjective symptoms are one of the major diagnostic criteria in dry eyes.…”