Tear Film Lipid Layer Research Articles

Tear film and ocular surface assessment in psoriasis

BackgroundPsoriasis is a skin disease with also systemic involvement: its impact on the eye is not well established and often clinically underestimated. Aim of this study was to investigate the...

Increase in tear film lipid layer thickness after instillation of 3% diquafosol ophthalmic solution in healthy human eyes

PurposeTo evaluate the effect of 3% diquafosol ophthalmic solution on tear film lipid layer thickness (LLT) in normal human eyes by tear interferometry. MethodsForty-seven healthy men (mean age of 42.4 years) randomly received one drop of artificial tears in one eye and one drop of 3% diquafosol ophthalmic solution in the other. LLT of each eye was quantified by tear interferometry before and 15, 30, and 60 min after instillation. Ocular symptoms were assessed before and 30 min after instillation. Baseline LLT, tear film breakup time (TBUT), meibomian gland area (meiboscore) of the upper and lower eyelids, and Schirmer test value were evaluated on a different day before treatment. ResultsLLT before and 15, 30, and 60 min after diquafosol instillation was 62.3 ± 31.1, 77.0 ± 39.5, 79.3 ± 40.5, and 77.7 ± 43.6 nm, respectively, with the diquafosol-induced increase in LLT being significant at each time point. Artificial tears did not result in a significant increase in LLT. TBUT (ρ = 0.32, P = 0.026), meiboscore of the lower eyelid (ρ = −0.33, P = 0.022), and the maximum difference in LLT between before and after diquafosol instillation (ΔLLTmax) (ρ = 0.35, P = 0.016) were significantly correlated with baseline LLT in the diquafosol group. Age was not significantly related to baseline LLT or ΔLLTmax. Symptoms did not differ significantly between the two groups. ConclusionsTopical instillation of 3% diquafosol ophthalmic solution increased LLT for up to 60 min in normal human eyes regardless of age.

Meibomian Gland Dysfunction in Patients With Chemotherapy-Induced Lacrimal Drainage Obstruction.

To investigate the relationship between chemotherapy-induced lacrimal drainage (LD) obstruction and obstructive meibomian gland dysfunction. Twenty patients who had received chemotherapy were divided into 2 groups, according to the presence of LD obstruction: the LD obstruction group (n = 10) and control group (n = 10). Upper and lower meibomian gland loss was evaluated using noncontact meibography, and tear film lipid layer thickness was measured using an interferometer. The mean values of the right and left eyes of each patient were used to compare parameters between both groups. The LD obstruction group had higher levels of meibomian gland loss in both upper (42.9% ± 16.4%) and lower meibomian glands (80.1% ± 16.7%) than did the control group (17.3% ± 6.7% and 22.8% ± 13.0%, respectively) (P < 0.001 and P < 0.001, respectively). In the LD obstruction group, meibomian gland loss in the lower eyelid was significantly higher than that in the upper eyelid (P < 0.001). The lipid layer was significantly thinner in the LD obstruction group (28.4 ± 9.7 nm) than it was in the control group (72.9 ± 22.5 nm) (P < 0.001). Patients with chemotherapy-induced LD obstruction had greater meibomian gland loss and thinner lipid layers than did patients without LD obstruction. Chemotherapeutic agents that induce LD obstruction can also block the meibomian gland orifice, resulting in obstructive meibomian gland dysfunction through the same mechanism.

The impact of dysfunctional tear films and optical aberrations on chronic migraine

BackgroundMigraine is a multifactorial disorder with complex neuronal and vascular mechanisms that encompasses a wide clinical spectrum of symptoms, including ocular manifestations. Dry eye disease and dysfunction of ocular somatosensory pathways have been implicated in the pathogenesis. The current study investigates the association between a dysfunctional tear film and ocular aberrations with migraine.MethodsSixty eyes of 30 patients with migraine and 60 eyes of 30 controls were studied. Dry eye evaluation included Schirmer’s test, tear film break-up time, corneal esthesiometry and lipid layer analysis using Lipiview® interferometer. Wavefront aberrations were measured using Optical Path Difference before performing the dry eye evaluation. The intraocular light scatter was quantified using the objective scatter index (OSI) of the optical quality analysis system. Measured parameters were compared between the migraine and the control group using independent sample t-test. Statistical analysis was performed using commercial software. A p value of ≤ 0.05 was considered statistically significant.ResultsThere were 19 females and 11 males in each group. Statistically significant difference was found between the two groups with respect to total aberrations (p = 0.049), higher order aberrations (p = 0.009), coma (p = 0.03), spherical aberrations (p = 0.018), Lipiview interferometric coloric units (p < 0.001) and OSI (p < 0.001). Trefoil (p = 0.26) and TBUT (p = 0.398) were not significantly different between both groups.ConclusionsOcular aberrations are higher in patients with migraine as compared with controls. Tear film abnormalities add to the aberrations in otherwise asymptomatic patients and may also be associated with migraineous attacks. Treating the ocular surface to obtain a healthy tear film might introduce a potential modifiable factor in the prevention of migraneous attacks.

Automated Measurement of Tear Film Dynamics and Lipid Layer Thickness for Assessment of Non-Sjögren Dry Eye Syndrome With Meibomian Gland Dysfunction.

To investigate automated values from an advanced corneal topographer with a built-in real keratometer, color camera, and ocular surface interferometer for the evaluation of non-Sjögren dry eye syndrome (NSDES) with meibomian gland dysfunction (MGD). Sixty-four patients (64 eyes) diagnosed with NSDES with MGD were enrolled. All eyes were evaluated using the Ocular Surface Disease Index (OSDI), fluorescence staining score, tear film breakup time (TBUT), Schirmer test, and MGD grade. Noninvasive Keratograph average tear film breakup time (NIKBUTav), tear meniscus height (TMHk), meibomian gland (MG) dropout grade, and lipid layer thickness (LLT) using interferometry were measured. Among automated indexes, NIKBUTav (mean 7.68 ± 4.07 s) and the MG dropout grade (mean 1.0 ± 0.5) significantly correlated with the OSDI (mean 40.6 ± 22.9) (r = -0.337, P = 0.006; and r = 0.201, P = 0.023, respectively), as did all conventional indicators, except the Schirmer score (mean 9.1 ± 5.9 mm). TMHk (mean 0.21 ± 0.18 mm) had significant correlation with the Schirmer score, the staining score (mean 1.2 ± 0.7), TBUT (mean 3.8 ± 1.8 s), and NIKBUTav (r = 0.298, P = 0.007; r = -0.268, P = 0.016; r = 0.459, P < 0.001; and r = 0.439, P < 0.001, respectively), but not any MGD indicator, even the MG dropout grade. NIKBUTav showed significant correlations with all clinical parameters and other automated values, except the Schirmer score and LLT (mean 83.94 ± 20.82 nm) (all (Equation is included in full-text article.)≥ 0.25 and P < 0.01). The MG dropout grade highly correlated with all indexes except TMHk (all (Equation is included in full-text article.)≥ 0.25 and P < 0.05). LLT was significantly associated with TBUT, MGD grade (mean 2.0 ± 0.7), and MG dropout grade (r = 0.219, P = 0.047; r = -0.221, P = 0.039; and r = 0.433, P < 0.001, respectively), although it was not related to patient symptoms. Automated noninvasive measurements using an advanced corneal topographer and LLT measured with an ocular surface interferometer can be alternatives to conventional methods to evaluate tear conditions on the ocular surface; the former device can provide information about conformational MG changes in NSDES with MGD.

The Effect of Phospholipids on Tear Film Lipid Layer Surface Activity.

We illustrate the importance of small quantities (<10 mol%) of polar phospholipids on the surface-active behavior of meibum-like lipid compositions. Artificial meibum-like lipid mixture containing cholesteryl and wax esters was mixed with differing amounts of phosphatidylcholine (PC). The surface activity of these mixtures was investigated at the air-water interface by recording surface pressure created by the lipid layer as a function of molecular area at 37°C. The PC proportion in the mixtures was 0, 2.5, 5, 7.5, or 10 mol%, and the remaining proportion in the mixture was 50:50 (mol/mol) of cholesteryl oleate (CO) and behenyl oleate (BO). Also, the effect of temperature was investigated. The surface activity of the mixtures increased in a very predictable and consistent fashion as a function of the PC proportion. The lipid mixture containing only CO and BO showed miniscule surface activity. However, already 2.5% PC mixed with the nonpolar CO and BO generated considerable increase in surface pressure. At small surface areas, the behavior of 7.5% and 10% PC compositions started to approach that of a pure PC monolayer. The temperature did not have a considerable impact on the surface-active behavior of the PC-containing compositions. The polar phospholipids have a considerable effect on the surface-active properties of artificial tear film lipid layer (TFLL) compositions. Surprisingly, this takes place already at very low and physiologically relevant PC proportions. The effect is more dependent on the actual amount of the phospholipids at the air-tear interface than on the relative amount of these lipids in TFLL.

Potential for use of hydroxypropyl guar in tear substitute therapy

Of the large number of polymers used in artificial tear formulations, natural polysaccharides - hydroxypropyl guar, sodium hyaluronate, chondroitin sulfate, dextran, etc., are gaining more and more popularity. Hydroxypropyl guar stands out through its ability to form a long-lasting structured matrix adhered to the damaged ocular surface and ensuring good wettability of the latter and regeneration of epithelial cells. At that, the viscosity of hydroxypropyl guar increases with increasing tear pH (which, in turn, correlates with the severity of xerosis) and further prolongs the moisturizing effect. According to experimental studies, the in vitro protective activity of hydroxypropyl guar surpasses that of sodium hyaluronate, which is widely used. Thus, corneal epithelial cell cultures were more tolerant to drying and pericardial leaflets showed lower friction coefficient, if pretreated with hydroxypropyl guar and not hyaluronic acid. Subsequent clinical studies showed that Systane Ultra was more effective in patients with dry eye syndrome than a carboxymethylcellulose and glycerol-containing drug. It has been also proved that Systane Balance provides a greater increase in thickness of the tear film lipid layer and in overall stability of the tear film as compared to SootheXP, which has a similar lipid composition. The present review also covers potential utility of other artificial tear formulations that, besides the moisturizing effect, are able to reduce the tear film osmolarity, prevent further oxidative stress, and abate the inflammatory process.

Correlation Analysis of Tear Film Lipid Layer Thickness and Ocular Surface Disease Index

Correlation Analysis of Tear Film Lipid Layer Thickness and Ocular Surface Disease Index

The effect of repeated lateral compression and expansions mimicking blinking on selected tear film polar lipid monofilms

The tear film lipid layer is formed on the anterior surface of the eye, functioning as a barrier to excess evaporation and foreign particles, while also providing stability to the tear film. The lipid layer is organized into a polar lipid layer consisting of phospholipids, ceramides, and free fatty acids that act as a surfactant to a non-polar multilayer of wax and cholesterol esters. Due to shear forces from eye movement and the compression and expansion of blinking, the tear lipids are under constant stress. However, tear film is able to resist immediate rupture and remains intact over multiple blinks. This work aimed to better understand the lateral organization of selected tear film polar lipids. The polar lipid biomimetic studied here consisted of dipalmitoyl phosphatidylcholine (DPPC), dipalmitoyl phosphatidylethanolamine (DPPE), palmitoyl glucosylceramide (PGC), and palmitoyl sphingomyelin (PSM). Surface pressure-area isocycles mimicked blinking and films were visualized by Brewster angle microscopy (BAM). All lipid systems formed relatively reversible films as indicated by limited hysteresis. However, pure DPPC and PSM films experienced greater changes in lipid packing upon compression and expansion compared to pure PGC and DPPE. This suggests that the driving force behind maintaining the lateral organization of the polar lipids from tear film may be the hydrogen bonding propensities of the head groups. Additionally, isocycles of films containing DPPC, DPPE, and PGC mixtures exhibited evidence for reversible multilayer formation or folding. This was supported by 3D analysis of structures that formed during compression but reintegrated back into the bulk lipid film during expansion near the in vitro tear film surface pressure of the open eye. Therefore, the polar lipids of tear film may be directly involved in preventing film rupture during a blink.

Behavior of sphingomyelin and ceramide in a tear film lipid layer model

Tear film lipid layer is a complex lipid mixture forming the outermost interface between eye and environment. Its key characteristics, such as surface tension and structural stability, are governed by the presence of polar lipids. The origin of these lipids and exact composition of the mixture are still elusive. We focus on two minor polar lipid components of the tear film lipid later: sphingomyelin and ceramide. By employing coarse grain molecular dynamics in silico simulations accompanied by Langmuir balance experiments we provide molecular-level insight into behavior of these two lipids in a tear film lipid layer model. Sphingomyelin headgroups are significantly exposed at the water–lipids boundary while ceramide molecules are incorporated between other lipids frequently interacting with nonpolar lipids. Even though these two lipids increase surface tension of the film, their molecular-level behavior suggests that they have a stabilizing effect on the tear film lipid layer.

Parallel definition of tear film maps on distributed-memory clusters for the support of dry eye diagnosis

Background and objectivesThe analysis of the interference patterns on the tear film lipid layer is a useful clinical test to diagnose dry eye syndrome. This task can be automated with a high degree of accuracy by means of the use of tear film maps. However, the time required by the existing applications to generate them prevents a wider acceptance of this method by medical experts. Multithreading has been previously successfully employed by the authors to accelerate the tear film map definition on multicore single-node machines. In this work, we propose a hybrid message-passing and multithreading parallel approach that further accelerates the generation of tear film maps by exploiting the computational capabilities of distributed-memory systems such as multicore clusters and supercomputers. MethodsThe algorithm for drawing tear film maps is parallelized using Message Passing Interface (MPI) for inter-node communications and the multithreading support available in the C++11 standard for intra-node parallelization. The original algorithm is modified to reduce the communications and increase the scalability. ResultsThe hybrid method has been tested on 32 nodes of an Intel cluster (with two 12-core Haswell 2680v3 processors per node) using 50 representative images. Results show that maximum runtime is reduced from almost two minutes using the previous only-multithreaded approach to less than ten seconds using the hybrid method. ConclusionsThe hybrid MPI/multithreaded implementation can be used by medical experts to obtain tear film maps in only a few seconds, which will significantly accelerate and facilitate the diagnosis of the dry eye syndrome.

Surface chemistry of the interactions of cationic nanoemulsions with human meibum films

PurposeIkervis® (IKV) cationic nanoemulsions (CNE) were demonstrated to enhance tear film stability in vivo possibly via effect on tear film lipid layer (TFLL). Therefore the interactions of IKV and of binary and ternary mixtures of its constituents were studied with human meibum (MGS) films. The binary mixtures consisted of 2% mid chain triglycerides (MCT) blended with 0.005% cetalkonium chloride (CKC) and 0.3% Tyloxapol (e.g. MCT/CKC and MCT/Tylo respectively). The ternary mixture contained MCT/CKC/Tylo (2%/0.005%/0.3%). The impact of 0.1 μM bovine submaxillary mucin (BSM) on CNE/MGS interactions was also evaluated.MethodsMGS and CNE oils were spread at the air/water interface of a Langmuir surface balance in range of 2D ratios (20/1, 10/1, 5/1, 3/1, 2/1 and 1/1) at two measurement regimes: with (i) MGS or (ii) total lipid amount kept constant. The films capability to reorganize during dynamic area cycling was evaluated. The layers dilatational rheology was probed via the step/relaxation method. Films structure was monitored with Brewster Angle microscopy.ResultsThe binary mixtures showed limited spreading and miscibility with MGS resulting in poor mechanical properties. The ternary mixture and IKV spread and mixed well with MGS. At fixed MGS amount, the inclusion of CNEs enhanced the structure, properties and elasticity of the layers. At fixed total lipid, the films remained primarily elastic, but at high (≤3/1) CNE content the elasticity slightly decreased and heterogeneities in layers structure were observed. BSM enhanced the ternary mixture (IKV)/ MGS interactions.ConclusionsAt physiologically relevant MGS/CNE ratios MCT/CKC/Tylo and IKV interact favorably with MGS films. The positive effect of BSM suggests that polyanionic polysaccharides can enhance CNE/TFLL interactions in vivo.Support: Collaborative study grant by Santen SAS, Evry, France.

Assessment of the Tear Film Lipid Layer Thickness after Cataract Surgery

ABSTRACTPurpose: To evaluate changes in the tear film lipid layer thickness (LLT) after cataract surgery and the effects of cataract surgery on dry eye syndrome (DES) and meibomian gland dysfunction (MGD). Methods: LLT measurements obtained using the LipiView interferometer, tear break-up time (TBUT) measurements, Schirmer’s tests, Oxford staining scores, lid margin and meibomian gland findings, and the Ocular Surface Disease Index (OSDI) questionnaire scores were evaluated before and one and three months after cataract surgery. Results: Forty-three eyes (43 patients) were included. LLT was significantly thinner one month after surgery than at baseline (P = 0.004). TBUT was significantly shorter at both one (P < 0.001) and three (P < 0.001) months after surgery than at baseline. OSDI scores were significantly higher (P < 0.001) and the meibum quality was significantly poorer (P = 0.001) at one month after surgery than at baseline. TBUT was significantly and positively correlated with LLT (r = 0.29, P < 0.001), while the OSDI (r = −0.38, P < 0.001) and Oxford staining (r = −0.30, P = 0.001) scores and the meibum quality (r = −0.21, P = 0.01) were significantly and negatively correlated with LLT. Conclusions: The tear film LLT was significantly thinner and DES and MGD parameters showed deterioration after cataract surgery. In addition, LLT was significantly correlated with DES and MGD parameters. These results suggest that clinicians should consider the tear film lipid layer while managing the exacerbation of DES after cataract surgery.

The relief of dry eye signs and symptoms using a combination of lubricants, lid hygiene and ocular nutraceuticals

PurposeTo determine the combined effect of TheraTears® Lubricant Eye Drops, TheraTears® SteriLid Eyelid Cleanser, and TheraTears® Nutrition on dry eye signs and symptoms. MethodsThis prospective study enrolled 28 dry eye participants. Participants were instructed to use the Lubricant Eye Drops at least 2–4× a day, SteriLid 1–2× a day, and Nutrition 3 gel caps once a day. Participants were followed up at baseline, 1 month and 3 months. Outcome variables were the Ocular Surface Disease Index (OSDI), Symptom Assessment iN Dry Eye (SANDE) questionnaire, non-invasive tear break-up time (NIBUT), osmolarity, number of meibomian glands blocked (#MG blocked), meibum quality, eyelid margin features, Schirmer's test, tear film lipid layer thickness (LLT), meniscus height, corneal and conjunctival staining. ResultsTwenty participants (mean age=43, from 23 to 66, 17F, 3M) completed the study. Participants reported having used, on average, the Lubricant Eye Drop 2.4×/day, the SteriLid 1.1×/day, and the Nutrition 3 gel caps 1×/day. There was a significant change over time (p<0.05) for OSDI (−21.2 points), SANDE (−32.4 points), NIBUT (+0.43s), eyelid margin features (−1.1 grade), meibum quality (−1.0 grade), and #MG blocked (−4.0 glands). ConclusionBy using a combination of TheraTears® Lubricant Eye Drop, SteriLid, and Nutrition, patients experience significant relief in both dry eye symptoms and signs.

Evaporation and Hydrocarbon Chain Conformation of Surface Lipid Films

PurposeThe inhibition of the rate of evaporation (Revap) by surface lipids is relevant to reservoirs and dry eye. Our aim was to test the idea that lipid surface films inhibit Revap. MethodsRevap were determined gravimetrically. Hydrocarbon chain conformation and structure were measured using a Raman microscope. Six 1-hydroxyl hydrocarbons (11-24 carbons in length) and human meibum were studied. Reflex tears were obtained from a 62-year-old male. ResultsThe Raman scattering intensity of the lipid film deviated by about 7 % for hydroxyl lipids and varied by 21 % for meibum films across the entire film at a resolution of 5 μm2. All of the surface lipids were ordered. Revap of the shorter chain hydroxyl lipids were slightly (7%) but significantly lower compared with the longer chain hydroxyl lipids. Revap of both groups was essentially similar to that of buffer. A hydroxyl lipid film did not influence Revap over an estimated average thickness range of 0.69 to >6.9 μm. Revap of human tears and buffer with and without human meibum (34.4 μm thick) was not significantly different. Revap of human tears was not significantly different from buffer. ConclusionsHuman meibum and hydroxyl lipids, regardless of their fluidity, chain length, or thickness did not inhibit Revap of buffer or tears even though they completely covered the surface. It is unlikely that hydroxyl lipids can be used to inhibit Revap of reservoirs. Our data do not support the widely accepted (yet unconfirmed) idea that the tear film lipid layer inhibits Revap of tears.

Surface properties and exponential stress relaxations of mammalian meibum films

The surface properties of meibomian secretion (MGS), the major constituent of the tear film (TF) lipid layer, are of key importance for TF stability. The interfacial properties of canine, cMGS, and feline, fMGS, meibum films were studied using a Langmuir surface balance. These species were selected because they have blinking frequency and TF stability similar to those of humans. The sample's performance during dynamic area changes was evaluated by surface pressure (π)-area (A) isocycles and the layer structure was monitored with Brewster angle microscopy. The films' dilatational rheology was probed via the stress-relaxation technique. The animal MGS showed similar behavior both between each other and with human MGS (studied previously). They form reversible, non-collapsible, multilayer thick films. The relaxations of canine, feline, and human MGS films were well described by double exponential decay reflecting the presence of two processes: (1) fast elastic process, with characteristic time τ<10s and (2) slow viscous process, with τ>100s-emphasizing the meibum layers viscoelasticity. The temperature decrease from 35 to 25°C resulted in decreased thickness and lateral expansion of all MGS layers accompanied with increase of the π/A hysteresis and of the elastic process contribution to π relaxation transients. Thus, MGS films of mammals with similar blinking frequency and TF stability have similar surface properties and stress relaxations unaltered by the interspecies MGS compositional variations. Such knowledge may impact the selection of animal mimics of human MGS and on a better understanding of lipid classes' impact on meibum functionality.

Super-resolved thickness maps of thin film phantoms and in vivo visualization of tear film lipid layer using OCT.

In optical coherence tomography (OCT), the axial resolution is directly linked to the coherence length of the employed light source. It is currently unclear if OCT allows measuring thicknesses below its axial resolution value. To investigate spectral-domain OCT imaging in the super-resolution regime, we derived a signal model and compared it with the experiment. Several island thin film samples of known refractive indices and thicknesses in the range 46 - 163 nm were fabricated and imaged. Reference thickness measurements were performed using a commercial atomic force microscope. In vivo measurements of the tear film were performed in 4 healthy subjects. Our results show that quantitative super-resolved thickness measurement can be performed using OCT. In addition, we report repeatable tear film lipid layer visualization. Our results provide a novel interpretation of the OCT axial resolution limit and open a perspective to deeper extraction of the information hidden in the coherence volume.

Evaluation of an automatic dry eye test using MCDM methods and rank correlation.

Dry eye is an increasingly common disease in modern society which affects a wide range of population and has a negative impact on their daily activities, such as working with computers or driving. It can be diagnosed through an automatic clinical test for tear film lipid layer classification based on color and texture analysis. Up to now, researchers have mainly focused on the improvement of the image analysis step. However, there is still large room for improvement on the machine learning side. This paper presents a methodology to optimize this problem by means of class binarization, feature selection, and classification. The methodology can be used as a baseline in other classification problems to provide several solutions and evaluate their performance using a set of representative metrics and decision-making methods. When several decision-making methods are used, they may offer disagreeing rankings that will be solved by conflict handling in which rankings are merged into a single one. The experimental results prove the effectiveness of the proposed methodology in this domain. Also, its general purpose allows to adapt it to other classification problems in different fields such as medicine and biology.

Sebum/Meibum Surface Film Interactions and Phase Transitional Differences.

PurposeSebum may contribute to the composition of the tear film lipid layer naturally or as a contaminant artifact from collection. The aims of this study were to determine: if sebum changes the rheology of meibum surface films; if the resonance near 5.2 ppm in the 1H-NMR spectra of sebum is due to squalene (SQ); and if sebum or SQ, a major component of sebum, interacts with human meibum.MethodsHuman meibum was collected from the lid margin with a platinum spatula. Human sebum was collected using lipid absorbent tape. Langmuir trough technology was used to measure the rheology of surface films. Infrared spectroscopy was used to measure lipid conformation and phase transitions. We used 1H-NMR to measure composition and confirm the primary structure of SQ.ResultsThe NMR resonance near 5.2 ppm in the spectra of human sebum was from SQ which composed 28 mole percent of sebum. Both sebum and SQ lowered the lipid order of meibum. Sebum expanded meibum films at lower concentrations and condensed meibum films at higher concentrations. Sebum caused meibum to be more stable at higher pressures (greater maximum surface pressure).ConclusionsPhysiological levels of sebum would be expected to expand or fluidize meibum making it spread better and be more surface active (qualities beneficial for tear film stability). Sebum would also be expected to stabilize the tear film lipid layer, which may allow it to withstand the high shear pressure of a blink.

IDEAS: A web-based system for dry eye assessment

Background and objectivesDry eye disease is a public health problem, whose multifactorial etiology challenges clinicians and researchers making necessary the collaboration between different experts and centers. The evaluation of the interference patterns observed in the tear film lipid layer is a common clinical test used for dry eye diagnosis. However, it is a time-consuming task with a high degree of intra- as well as inter-observer variability, which makes the use of a computer-based analysis system highly desirable. This work introduces iDEAS (Dry Eye Assessment System), a web-based application to support dry eye diagnosis. MethodsiDEAS provides a framework for eye care experts to collaboratively work using image-based services in a distributed environment. It is composed of three main components: the web client for user interaction, the web application server for request processing, and the service module for image analysis. Specifically, this manuscript presents two automatic services: tear film classification, which classifies an image into one interference pattern; and tear film map, which illustrates the distribution of the patterns over the entire tear film. ResultsiDEAS has been evaluated by specialists from different institutions to test its performance. Both services have been evaluated in terms of a set of performance metrics using the annotations of different experts. Note that the processing time of both services has been also measured for efficiency purposes. ConclusionsiDEAS is a web-based application which provides a fast, reliable environment for dry eye assessment. The system allows practitioners to share images, clinical information and automatic assessments between remote computers. Additionally, it save time for experts, diminish the inter-expert variability and can be used in both clinical and research settings.