A Solute Gradient in the Tear Meniscus. II. Implications for Lid Margin Disease, including Meibomian Gland Dysfunction

Effects of Three Kinds of Carbohydrate Pharmaceutical Excipients-Fructose, Lactose and Arabic Gum on Intestinal Absorption of Gastrodin through Glucose Transport Pathway in Rats

BACKGROUND

Some glucoside drugs can be transported via intestinal glucose transporters (IGTs), and the presence of carbohydrate excipients in pharmaceutical formulations may influence the absorption of them. This study, using gastrodin as probe drug, aimed to explore the effects of fructose, lactose, and arabic gum on intestinal drug absorption mediated by the glucose transport pathway.

METHODS

The influence of fructose, lactose, and arabic gum on gastrodin absorption was assessed via pharmacokinetic experiments and single-pass intestinal perfusion. The expression of sodium-dependent glucose transporter 1 (SGLT1) and sodium-independent glucose transporter 2 (GLUT2) was quantified via RT‒qPCR and western blotting. Alterations in rat intestinal permeability were evaluated through H&E staining, RT‒qPCR, and immunohistochemistry.

RESULTS

Fructose reduced the area under the curve (AUC) and peak concentration (Cmax) of gastrodin by 42.7% and 63.71%, respectively (P < 0.05), and decreased the effective permeability coefficient (Peff) in the duodenum and jejunum by 58.1% and 49.2%, respectively (P < 0.05). SGLT1 and GLUT2 expression and intestinal permeability remained unchanged. Lactose enhanced the AUC and Cmax of gastrodin by 31.5% and 65.8%, respectively (P < 0.05), and increased the Peff in the duodenum and jejunum by 33.7% and 26.1%, respectively (P < 0.05). SGLT1 and GLUT2 levels did not significantly differ, intestinal permeability increased. Arabic gum had no notable effect on pharmacokinetic parameters, SGLT1 or GLUT2 expression, or intestinal permeability.

CONCLUSION

Fructose, lactose, and arabic gum differentially affect intestinal drug absorption through the glucose transport pathway. Fructose competitively inhibited drug absorption, while lactose may enhance absorption by increasing intestinal permeability. Arabic gum had no significant influence.

Efficacy of far infrared functional glasses in the treatment of meibomian gland dysfunction-related dry eye

Meibomian gland dysfunction (MGD)-related dry eye disease (DED) is a significant subtype of DED. In this research, we investigate the effectiveness of far infrared (FIR) functional glasses in the treatment of MGD-related DED. According to the TFO DEWS II diagnostic criteria, 61 eyes with MGD-related DED were included. All participants wore functional FIR glasses throughout the day for a period of 4 weeks and were followed up three times during the treatment. All subjects were followed up thoroughly in accordance with the DED clinical examination procedure. Ultimately, the treatment's impact was assessed. We found the Visual Analogue Scale and Ocular Surface Disease Index scores after FIR treatment were significantly lower than the baseline values (p < 0.05). Compared with the baseline, fluorescein tear breakup time and corneal fluorescein staining score after FIR treatment were significantly improved (p < 0.05). The eyelid margin signs, meibum quality, and meibomian gland expressibility after the 4-week treatment were significantly better than those at baseline (p < 0.05). We can see that wearing the FIR functional glasses significantly relieves the symptoms and signs of patients. We believe FIR therapy could be considered as a new method of MGD-related DED.

Effects of climate factors and Demodex infestation on meibomian gland dysfunction-associated dry eye diseases

We examined the effects of climatic factors and Demodex infestations on meibomian gland dysfunction (MGD)-associated dry eye disease (DED) in a cross-sectional study. This study included 123 patients from Tianjin and Chengdu regions, and climate factors and the Air Quality Index (AQI) were recorded for one year. Ocular surface parameters and Demodex infestations were evaluated using various tests. Significant differences in all climatic factors and AQI were observed between Tianjin and Chengdu (P < 0.01), and ocular surface parameters also differed significantly between the two regions (P < 0.05). Temperature, relative humidity, and precipitation positively correlated with tear break-up time (BUT), meibum gland expressibility, and lid margin irregularity but negatively correlated with lissamine green staining scores (P < 0.05). Wind speed and atmospheric pressure positively correlated with corneal fluorescein staining and lissamine green staining but negatively correlated with BUT and lid margin irregularity (P < 0.05). AQI positively correlated with DED symptoms and corneal findings but negatively correlated with tear film stability and meibomian gland characteristics (P < 0.05). Demodex infestation was only positively correlated with meibum quality scores (P < 0.05). Our findings suggest that geographic climates influence ocular surface characteristics in MGD-associated DED, with daily precipitation potentially playing a significant role, and Demodex infestation contributes to meibum gland degeneration.

A deep learning model established for evaluating lid margin signs with colour anterior segment photography

OBJECTIVES

To evaluate the feasibility of applying a deep learning model to identify lid margin signs from colour anterior segment photography.

METHODS

We collected a total of 832 colour anterior segment photographs from 428 dry eye patients. Eight lid margin signs were labelled by human ophthalmologists. Eight deep learning models were constructed based on VGGNet-13 and trained to identify lid margin signs. Sensitivity, specificity, receiver operative characteristic (ROC) curves and area under the curve (AUC) were applied to evaluate the models.

RESULTS

The AUC for rounding of posterior lid margin was 0.979 and was 0.977 and 0.980 for lid margin irregularity and vascularization. For hyperkeratinization, the AUC was 0.964. The AUCs for meibomian gland orifice (MGO) retroplacement and plugging were 0.963 and 0.968. For the mucocutaneous junction (MCJ) anteroplacement and retroplacement model, the AUCs were 0.950 and 0.978. The sensitivity and specificity for rounding of posterior lid margin were 0.974 and 0.921. For irregularity, the sensitivity and specificity were 0.930 and 0.938, and those for vascularization were 0.923 and 0.961. The hyperkeratinization model achieved a sensitivity and specificity of 0.889 and 0.948. The model identifying MGO plugging and retroplacement achieved a sensitivity of 0.979 and 0.909 with a specificity of 0.867 and 0.967. The sensitivity of MCJ anteroplacement and retroplacement were 0.875/0.969, with a specificity of 0.966/0.888.

CONCLUSIONS

The deep learning model could identify lid margin signs with high sensitivity and specificity. The study provided the potentiality of applying artificial intelligence in lid margin evaluation to assist dry eye decision-making.

Intense Pulsed Light Therapy with Optimal Pulse Technology as an Adjunct Therapy for Moderate to Severe Blepharitis-Associated Keratoconjunctivitis

Purpose

To evaluate the intense pulsed light (IPL) therapy with optimal pulse technology (OPT, M22™, Lumenis, USA) as an adjunct therapy for the prevention of recurrences in moderate to severe blepharokeratoconjunctivitis (BKC).

Methods

This open-label nonrandomized clinical trial evaluated 33 patients diagnosed with BKC. Twenty-one patients received four bilateral OPT therapy sessions with Meibomian gland expression (MGX) (treatment group), and 11 patients received MGX alone (controls). This trial was initiated after a four-week pharmacotherapy for BKC in both groups and was scheduled at four-week intervals. Efficacy outcome measures included meibum quality, Meibomian gland (MG) secretion function, eyelid margin signs, corneal fluorescein staining (CFS) score, noninvasive keratography breakup time (NIKBUT), ocular surface disease index (OSDI) score, Schirmer I test (SIT), classification of tear film lipid layer (TFLL), and Meibomian gland dropout (MGDR). Safety outcome measures included visual acuity, intraocular pressure, eye structure damage, and facial skin appearance at each visit.

Results

Quality of meibum, MG expressibility, eyelid margin signs, and OSDI score showed a statistically significant greater improvement in the treatment group after one to three treatment sessions, compared to controls (p < 0.05). While these improved in both groups in comparison to baseline, the NIKBUT and upper and lower eyelid MGDRs significantly improved only in the treatment group (p < 0.05). No adverse events occurred in both groups. No BKC recurrences were noted in the treatment group.

Conclusions

IPL is a safe and effective adjuvant treatment for BKC and possibly more effective in reducing eyelid margin inflammation and prevents recurrences than MGX alone. This trial is registered with ChiCTR-ONN-17013864.

A Comparison of Dry Eye Diagnostic Tests Between Symptomatic and Asymptomatic Age-Matched Females

PURPOSE

To quantify the strength of association of dry eye (DE) symptoms to DE diagnostic tests in age-matched females.

METHODS

Twenty females with DE symptoms (Ocular Surface Disease Index, OSDI, ≥13) were age-matched with 20 females without DE symptoms (OSDI<13) in this cross-sectional study. Noninvasive tear breakup time (NIBUT), ocular staining, meibum quality, number of obstructed meibomian glands (MGs), lid wiper epitheliopathy, Marx line placement, eyelid margin score, Schirmer test, meibography, and visual acuity were assessed in both groups.

RESULTS

Twenty participant pairs completed the study. The age (median/interquartile range [IQR]) of the symptomatic group was 60/15 and the asymptomatic group was 62/15. The tests (median/IQR, P value) that were significantly different between the symptomatic group and the asymptomatic group were OSDI (35.4/35.4 vs. 3.1/6.7, P<0.01), NIBUT (2.1/0.7 sec vs. 3.0/3.0 sec, P=0.01), meibum quality (3.0/0.0 grade units vs. 2.0/1.0 grade units, P<0.01), number of obstructed MGs (7.0/2.0 glands vs. 5.0/4.8 glands, P<0.01), and ocular staining (5.5/3.8 grade units vs. 0.5/1.0 grade units, P<0.01). The tests (area under curve, [AUC], odds ratio [OR]) that were most strongly associated with DE symptoms were ocular staining (0.93, 5.0), number of obstructed MGs (0.79, 2.6), meibum quality (0.76, 2.4), and NIBUT (0.74, 3.2) (all P<0.05). There was no significant difference between the two groups for the other DE tests (all P>0.05), and similarly, no significant association to DE symptoms (all P>0.05).

CONCLUSION

The diagnostic tests most strongly associated with DE symptoms in older women were ocular staining, meibum quality, number of obstructed MGs, and tear film stability.

Assessment of meibomian glands using a custom-made meibographer in dry eye patients in Ghana

BACKGROUND

Meibomian Gland Dysfunction (MGD) is a leading cause of evaporative Dry Eye Disease (DED). This makes non-invasive meibography an important procedure in the clinical evaluation of DED patients. Our purpose was to conduct a lead-off investigation focused on the practicality of performing meibography in a developing country, with limited access to complex ophthalmic imaging systems, using a custom meibographer, as a step to future comparative studies on meibomian glands and DED in Africa.

METHODS

Meibomian glands(MG) in 76 upper eyelids (UL) and 49 lower eyelids (LL) in 1 eye each of 125 patients randomly selected from a patient population presenting with subjective DED symptoms at a clinic were photographed using a custom meibographer. Single frames were captured, and the MG area determined by intensity threshold segmentation and area calculation using Image J software. MG loss (MGL) was quantified by outlining its area and expressing it as a percentage of the total MG per Pult's grading scheme. Dry eye measures included Tear Film Break Up - Time (TUBT), Schirmer's test and Ocular Surface Staining (OSS). Symptoms were evaluated using the SPEED II questionnaire. Correlations between MGL and age, ocular signs and symptoms were analyzed by Pearson's. Differences between comparable groups were analyzed by Mann - Whitney test; p < 0.05 was considered significant.

RESULTS

Overall mean MGL was 32.10% ± 25.0% (26.25% ± 22.40% for UL and 40.33% ± 26.70% for LL). MGL correlated significantly with age [r = 0.91, p = 0.001], SPEED scores [r = 0.90, p = 0.001], OSS [r = 0.75, p = 0.001] and TBUT [r = - 0.81, p = 0.001]. MGL scores were significantly higher in the UL than LL [U = 1293.5 p = 0.004].

CONCLUSION

This study for the first time presents data on the status of Meibomian glands in Africa. It furthermore suggests that it is feasible to examine Meibomian glands using a custom meibographer in developing countries with limited access to complex imaging systems. It also demonstrates the benefit and cost-effectiveness of a simple device by the observed significant relations between meibomian gland loss and DED in these patients.

Relation Between Dietary Essential Fatty Acid Intake and Dry Eye Disease and Meibomian Gland Dysfunction in Postmenopausal Women

PURPOSE

To evaluate the relationship between omega-3 (n-3) and omega-6 (n-6) fatty acids with dry eye disease (DED) and meibomian gland dysfunction (MGD).

DESIGN

Cross-sectional study.

METHODS

Postmenopausal women (n = 439) underwent a clinical evaluation and completed the Vio Food Frequency Questionnaire to estimate their dietary intake of n-3s and n-6s. Subjects were categorized into 2 binary classifications based on whether or not they had (1) DED and (2) MGD. Mean intake of dietary fatty acids was compared with 2-sample t tests. Univariate logistic regression models were used to estimate the odds ratios for each condition associated with each quintile of n-3s, n-6s, and n-6:n-3 ratios.

RESULTS

For DED vs non-DED, there were no significant differences in n-3 intake (1.95 ± 1.47 g vs 1.92 ± 1.24 g, P = .86), n-6 intake (15.58 ± 11.56 g vs 15.44 ± 10.61 g, P = .91), and n-6:n-3 (8.30 ± 2.57 vs 8.30 ± 2.57, P = .99). For MGD vs non-MGD, there were no significant differences in n-3 intake (1.87 ± 1.35 vs 1.96 ± 1.39, P = .61), n-6 intake (15.26 ± 11.85 vs 15.62 ± 10.93, P = .80), and n-6:n-3 (8.35 ± 2.94 vs 8.28 ± 2.42, P = .84). The odds ratios (OR) for DED did not differ significantly from 1.0 for n-3, n-6, or n-6:n-3. High n-3 consumption (OR = 0.22 [0.06–0.78]) and moderate n-6 consumption (OR = 0.37 [0.15–0.91]) were associated with a decreased frequency of MGD.

CONCLUSIONS

Dietary consumption of n-3s and n-6s showed no association with DED, but high n-3 consumption and moderate n-6 consumption were protective against MGD in this large sample of postmenopausal women.

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

PURPOSE

To investigate the relationship between chemotherapy-induced lacrimal drainage (LD) obstruction and obstructive meibomian gland dysfunction.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

TFOS DEWS II pathophysiology report

The TFOS DEWS II Pathophysiology Subcommittee reviewed the mechanisms involved in the initiation and perpetuation of dry eye disease. Its central mechanism is evaporative water loss leading to hyperosmolar tissue damage. Research in human disease and in animal models has shown that this, either directly or by inducing inflammation, causes a loss of both epithelial and goblet cells. The consequent decrease in surface wettability leads to early tear film breakup and amplifies hyperosmolarity via a Vicious Circle. Pain in dry eye is caused by tear hyperosmolarity, loss of lubrication, inflammatory mediators and neurosensory factors, while visual symptoms arise from tear and ocular surface irregularity. Increased friction targets damage to the lids and ocular surface, resulting in characteristic punctate epithelial keratitis, superior limbic keratoconjunctivitis, filamentary keratitis, lid parallel conjunctival folds, and lid wiper epitheliopathy. Hybrid dry eye disease, with features of both aqueous deficiency and increased evaporation, is common and efforts should be made to determine the relative contribution of each form to the total picture. To this end, practical methods are needed to measure tear evaporation in the clinic, and similarly, methods are needed to measure osmolarity at the tissue level across the ocular surface, to better determine the severity of dry eye. Areas for future research include the role of genetic mechanisms in non-Sjögren syndrome dry eye, the targeting of the terminal duct in meibomian gland disease and the influence of gaze dynamics and the closed eye state on tear stability and ocular surface inflammation.

TFOS DEWS II Tear Film Report

The members of the Tear Film Subcommittee reviewed the role of the tear film in dry eye disease (DED). The Subcommittee reviewed biophysical and biochemical aspects of tears and how these change in DED. Clinically, DED is characterized by loss of tear volume, more rapid breakup of the tear film and increased evaporation of tears from the ocular surface. The tear film is composed of many substances including lipids, proteins, mucins and electrolytes. All of these contribute to the integrity of the tear film but exactly how they interact is still an area of active research. Tear film osmolarity increases in DED. Changes to other components such as proteins and mucins can be used as biomarkers for DED. The Subcommittee recommended areas for future research to advance our understanding of the tear film and how this changes with DED. The final report was written after review by all Subcommittee members and the entire TFOS DEWS II membership.

Correlation Analysis of Ocular Symptoms and Signs in Patients with Dry Eye

Purpose. To analyze the correlations between the ocular surface signs and symptoms in patients with dry eye. Methods. In this observational study, 176 dry eye patients, including 60 males and 116 females, were enrolled and their dry eye symptoms and ocular signs were observed. Partial correlation analysis was conducted between OSDI score and each ocular surface sign, and the correlations were further discussed in different age groups. Then multiple linear regression analysis was used to further explore the influence of these signs on OSDI score. Results. Our correlation analyses showed that rounding of lid margins, notching of lid margins, vascularity of lid margins, hyperkeratinization, plugging of orifices, main duct dropout, and conjunctival congestion all had a positive correlation with OSDI score, while main duct number (central 1 cm) and BUT had a negative one. Further analysis suggested that these correlations varied in different age groups. Multiple linear regression analysis indicated that main duct number (central 1 cm), rounding of lid margins, and hyperkeratinization significantly affected OSDI score. Conclusions. Close attention should be paid to the morphology and structure of the eyelid margin and the function of meibomian gland in the diagnosis, treatment, and follow-up of dry eye diseases.

Meibocyte differentiation and renewal: Insights into novel mechanisms of meibomian gland dysfunction (MGD)

This paper reviews our current understanding of age-related meibomian gland dysfunction (MGD) and the role of the nuclear receptor, peroxisome proliferator-activated receptor gamma (PPARγ), in the regulation of meibomian gland function, meibocyte differentiation and lipid synthesis. The studies suggest that PPARγ is a master regulator of meibocyte differentiation and function, whose expression and nuclear signaling coupled with meibocyte renewal is altered during aging, potentially leading to atrophy of the meibomian gland as seen in clinical MGD. Study of meibomian gland stem cells also suggest that there is a limited number of precursor meibocytes that provide progeny to the acini, that may be susceptible to exhaustion as occurs during aging and other environmental factors. Further study of pathways regulating PPARγ expression and function as well as meibocyte stem cell maintenance may provide clues to establishing cellular and molecular mechanisms underlying MGD and the development of novel therapeutic strategies to treating this disease.

Differential Profiling of T-Cell Cytokines as Measured by Protein Microarray Across Dry Eye Subgroups

PURPOSE

The purpose of this study is to explore the role of the adaptive immune system in patients with aqueous-deficient dry eye (ADDE) and lipid-deficient dry eye (LDDE).

METHODS

Patients (n = 29) with moderate to severe dry eye (dry eye workshop [DEWS] severity grading scheme) were enrolled in a cross-sectional study and classified as ADDE (Schirmer < 10), LDDE (abnormal meibum), combined (meeting both criteria), or generic (meeting neither criterion). Tears were collected by Schirmer strips, and samples for both eyes were pooled for each subject. Thirty micrograms of total protein was used in a normalized volume for microarray analysis (Quantibody Human Inflammation Array 3; RayBiotech). Six markers of TH1 cells (interferon [IFN]γ, interleukin [IL]-2), TH2 cells (IL-4, IL-5, IL-13), and TH17 cells (IL-17) were assessed.

RESULTS

ADDE demonstrated the highest total cytokine concentration, followed by the LDDE, combined, and generic groups. IFNγ and IL-2 were detectable in all subgroups. IL-4, -5, and -13 were detectable in ADDE and LDDE, but only IL-13 was detected in both the combined and generic groups. IL-17 was present in the ADDE, LDDE, and combined groups.

CONCLUSIONS

TH1 cells seem to be involved in all forms of dry eye. ADDE and LDDE seem to be mediated by TH1, TH2, and TH17 cells. The combined-mechanism group is mediated by TH1 and TH17 cells, and generic dry eye seems to be mediated by TH1 cells only. ADDE has the greatest overall T-cell-mediated pathophysiology compared with the other subgroups, which is consistent with previous reports of improved efficacy with antiinflammatory therapy in these patients.

Lid wiper epitheliopathy

Some recent research has resulted in a hypothesis that there is a common 'lid wiper' region that is apposite to the ocular surface or anterior lens surface (where contact lenses are worn), responsible for spreading tears during blinking. In the upper eyelid, it extends about 0.6 mm from the crest of the sharp posterior (inner) lid border (i.e. the mucocutaneous junction, or line of Marx) to the subtarsal fold superiorly and from the medial upper punctum to the lateral canthus horizontally. Histologically, it is seen as an epithelial elevation comprising of stratified epithelium with a transitional conjunctival structure of (moving posteriorly) squamous cells then cuboidal cells, with some parakeratinised cells and goblet cells. Lid wiper epitheliopathy (LWE) denotes staining of the lid wiper observed after instillation of dyes such as fluorescein, rose bengal or lissamine green. There have been some reports of higher rates of LWE in dry eye patients and contact lens wearers, but others have failed to find such associations. The primary cause of LWE is thought to be increased friction between the lid wiper and ocular or anterior contact lens surface due to inadequate lubrication, which could be caused by dry eye and may be exacerbated by factors such as abnormal blinking patterns, poor contact lens surface lubricity and adverse environmental influences. Recent evidence suggests that LWE is associated with sub-clinical inflammation. LWE has the potential to provide the missing mechanistic link between clinical observation and symptoms associated with dry eye and contact lens wear. Clinical and fundamental research into LWE is still in its infancy and in many instances equivocal; however, it is an idea that provides a potentially important new avenue for further investigation of anterior eye discomfort associated with ocular dryness and contact lens wear.

Comparison of conjunctival staining between lissamine green and yellow filtered fluorescein sodium

OBJECTIVE

To compare conjunctival staining between lissamine green and fluorescein sodium using a yellow barrier filter.

DESIGN

Retrospective cross-sectional study.

PARTICIPANTS

Thirteen eyes of 13 patients with dry eyes.

METHODS

All patients underwent ocular surface staining with fluorescein sodium and lissamine green. Ocular surface staining with fluorescein sodium was observed through slit-lamp examination under cobalt blue illumination and a yellow filter. Temporal (0-5) and nasal (0-5) conjunctival staining grade was separately graded according to the Oxford scheme. The contrast score was defined as the absolute difference between mean grey values of punctate staining and background. Conjunctival staining grade and contrast scores were compared between these 2 staining methods.

RESULTS

The sum of the conjunctival staining grade (0-10) for the nasal and temporal conjunctiva was 4.7 ± 2.5 for fluorescein sodium, which was significantly higher than that of lissamine green, 4.1 ± 2.5 (p = 0.005). The contrast score of temporal and nasal conjunctival staining was 34.6 ± 12.0 and 34.7 ± 10.3, respectively, for fluorescein sodium, which was also significantly greater than for lissamine green (23.4 ± 8.1 and 21.0 ± 9.0, respectively; p = 0.003 and p = 0.003, respectively).

CONCLUSIONS

Conjunctival staining with fluorescein sodium and a yellow filter seems to be more sensitive for the detection of conjunctival damage than lissamine green. Fluorescein staining with the yellow filter has the advantage of simultaneous observation of both corneal and conjunctival damage in patients with dry eye without the need for additional vital staining.

Meibomian Gland Dysfunction in Cranial Nerve VII Palsy

PURPOSE

To examine clinical findings on meibomian gland dysfunction (MGD) in patients with unilateral cranial nerve VII (CN VII) palsy.

METHODS

This prospective observational study included 35 patients with unilateral CN VII palsy. The following features were compared between the affected and the unaffected sides: incidence of eyelid abnormalities (irregular eyelid margin, vascular engorgement, and plugged meibomian gland orifices), Marx line score, meibom expression score, area and density scores for corneal fluorescein staining, Schirmer test I (without topical anesthesia), and tear break-up time.

RESULTS

The affected side demonstrated significantly higher incidences of vascular engorgement (p = 0.004) and plugged meibomian gland orifices (p < 0.001) than the unaffected side. The incidence of an irregular eyelid margin was similar for both sides (p = 0.168). The scores for the Marx line (p < 0.001), meibom expression (p < 0.001), area (p = 0.034), and density (p = 0.026) were significantly higher for the affected side than for the unaffected side. The affected side showed a significantly higher Schirmer value than the unaffected side (p = 0.030). Tear break-up time was significantly shorter on the affected side than on the unaffected side (p = 0.023).

CONCLUSIONS

MGD was more markedly demonstrated on the affected side in patients with unilateral CN VII palsy.

En-face optical coherence tomography as a novel tool for exploring the ocular surface: a pilot comparative study to conventional B-scans and in vivo confocal microscopy

PURPOSE

To explore the potential of spectral-domain optical coherence tomography (SD-OCT) using the en-face technology for the imaging of ocular surface diseases and to correlate the findings with in vivo confocal microscopy (IVCM) images.

PATIENTS AND METHODS

113 eyes of 75 subjects with various ocular surface diseases were investigated with the RTVue(®) anterior-segment en face OCT. En face OCT images were compared to B-scan OCT and IVCM images.

RESULTS

Patients with corneal dystrophies, corneal deposits, keratitis, pterygium, conjunctivochalasis, or ocular surface squamous neoplasia and patients who underwent lamellar corneal surgeries were included. En-face OCT images showed ocular surface tissue changes that were not discernible using conventional B-scan OCT. Nevertheless, there was a good correlation with IVCM analysis. Compared with IVCM, the major advantages of en-face OCT included easy operation and rapid image acquisition, with minimal operator experience required. In addition, the non-contact method avoided patient discomfort and external pressure on the globe, which was especially useful in patients with corneal dystrophies, ulcers, or corneal abscesses. Although the resolution of en-face OCT was lower than that of IVCM, it allowed useful overall visualization of corneal lesions due to the larger areas analyzed.

CONCLUSION

En-face SD-OCT is a novel, valuable tool to assess a wide variety of ocular surface diseases. It can provide additional information and new insight into different ocular surface conditions with no corneal contact.

The relation between blinking and conjunctival folds and dry eye symptoms

PURPOSE

To investigate the relationship between blink action, dry eye symptoms, and lid-parallel conjunctival folds (LIPCOF).

METHODS

In 30 subjects (14 were women; mean [standard deviation {SD}] age, 42.4 [±12.3] years), spontaneous blinks were recorded from a temporal-inferior view (high-speed video), and the blink extent (incomplete [IC], almost complete [AC], and complete [CC]) was evaluated. Dry eye symptoms were evaluated using the Ocular Surface Disease Index (OSDI), and nasal and temporal LIPCOF grades were noted. Correlations between groups were calculated with Pearson correlation (or Spearman rank in nonparametric data), and differences between groups were calculated with an unpaired t-test (or U-test Mann-Whitney in nonparametric data).

RESULTS

Blink rate was significantly higher in females (22.0% [±16.8]) than in males (8.6% [±7.2]; unpaired t-test: p = 0.007). The percentage of AC of all blinks (AC%) was significantly correlated to LIPCOF sum (nasal + temporal) and OSDI scores (r > 0.570, p < 0.001). The percentage of IC was significantly correlated to LIPCOF sum (r = -0.541, p < 0.001) but not to OSDI.

CONCLUSIONS

The frequency and type of blinking may have an effect on dry eye symptoms and LIPCOF severity since almost all complete blinks were significantly related to both factors.

Rethinking dry eye disease: a perspective on clinical implications

Publication of the DEWS report in 2007 established the state of the science of dry eye disease (DED). Since that time, new evidence suggests that a rethinking of traditional concepts of dry eye disease is in order. Specifically, new evidence on the epidemiology of the disease, as well as strategies for diagnosis, have changed the understanding of DED, which is a heterogeneous disease associated with considerable variability in presentation. These advances, along with implications for clinical care, are summarized herein. The most widely used signs of DED are poorly correlated with each other and with symptoms. While symptoms are thought to be characteristic of DED, recent studies have shown that less than 60% of subjects with other objective evidence of DED are symptomatic. Thus the use of symptoms alone in diagnosis will likely result in missing a significant percentage of DED patients, particularly with early/mild disease. This could have considerable impact in patients undergoing cataract or refractive surgery as patients with DED have less than optimal visual results. The most widely used objective signs for diagnosing DED all show greater variability between eyes and in the same eye over time compared with normal subjects. This variability is thought to be a manifestation of tear film instability which results in rapid breakup of the tearfilm between blinks and is an identifier of patients with DED. This feature emphasizes the bilateral nature of the disease in most subjects not suffering from unilateral lid or other unilateral destabilizing surface disorders. Instability of the composition of the tears also occurs in dry eye disease and shows the same variance between eyes. Finally, elevated tear osmolarity has been reported to be a global marker (present in both subtypes of the disease- aqueous-deficient dry eye and evaporative dry eye). Clinically, osmolarity has been shown to be the best single metric for diagnosis of DED and is directly related to increasing severity of disease. Clinical examination and other assessments differentiate which subtype of disease is present. With effective treatment, the tear osmolarity returns to normal, and its variability between eyes and with time disappears. Other promising markers include objective measures of visual deficits, proinflammatory molecular markers and other molecular markers, specific to each disease subtype, and panels of tear proteins. As yet, however, no single protein or panel of markers has been shown to discriminate between the major forms of DED. With the advent of new tests and technology, improved endpoints for clinical trials may be established, which in turn may allow new therapeutic agents to emerge in the foreseeable future. Accurate recognition of disease is now possible and successful management of DED appears to be within our grasp, for a majority of our patients.

TearLab® Osmolarity System for diagnosing dry eye

Dry eye (DE) disease is an impairment of the lachrymal unit function and one the most frequent eye problems. A major challenge is to find accurate diagnostic criteria to be able to define DE severity, as symptoms poorly correlate with clinical signs. Tear osmolarity is considered a key factor in DE onset and perpetuation; its measurement is now possible in clinical setting by an innovative electrical impedance-based lab-on-a-chip technology. This article outlines the features of DE disease and the limitations of current clinical tests. The role of tear osmolarity in DE etiopathogenesis is surveyed, and the pitfalls in measurement are discussed. Diagnostic performance, accuracy and clinical applications of the technology in focus are critically reviewed. The instrument offers the possibility to measure tear osmolarity in a rapid and reliable way in daily practice. As scientific evidence grows, it is expected in the future that it will represent an objective indicator of ocular surface health in the management of DE disease and in clinical trials.

Evaluation of dry eye

Dry eye is a common yet complex condition. Intrinsic and extrinsic factors can cause dysfunction of the lids, lacrimal glands, meibomian glands, ocular surface cells, or neural network. These problems would ultimately be expressed at the tear film-ocular surface interface. The manifestations of these problems are experienced as symptoms such as grittiness, discomfort, burning sensation, hyperemia, and secondary epiphora in some cases. Accurate investigation of dry eye is crucial to correct management of the condition. Techniques can be classed according to their investigation of tear production, tear stability, and surface damage (including histological tests). The application, validity, reliability, compatibility, protocols, and indications for these are important. The use of a diagnostic algorithm may lead to more accurate diagnosis and management. The lack of correlation between signs and symptoms seems to favor tear film osmolarity, an objective biomarker, as the best current clue to correct diagnosis.

A solute gradient in the tear meniscus. I. A hypothesis to explain Marx's line

Marx's line is a line of mucosal staining behind the mucocutaneous junction. It can be demonstrated throughout life in all normal lids by staining with lissamine green and related dyes. Of all the body orifices, only the mucosae of the eye and mouth are directly exposed to the atmosphere. In this paper, we suggest that for the eye, this exposure leads to the formation of Marx's line. The tear meniscus thins progressively toward its apex, where it is pinned at the mucocutaneous junction of the lid. It also thins toward the black line, which segregates the meniscus from the tear film after the blink. We predict that, because of the geometry of the tear meniscus, evaporation generates a solute gradient across the meniscus profile in the anteroposterior plane, which peaks at the meniscus apices at the end of the interblink. One outcome would be to amplify the level of tear molarity at these sites so that they reach hyperosmolar proportions. Preliminary mathematical modeling suggests that dilution of this effect by advection and diffusion of solute away from the meniscus apex at the mucocutaneous junction will be restricted by spatial constraints, the presence of tear and surface mucins at this site, and limited fluid flow. We conclude that evaporative water loss from the tear meniscus may result in a physiological zone of hyperosmolar and related stresses to the occlusal conjunctiva, directly behind the mucocutaneous junction. We hypothesize that this stimulates a high epithelial cell turnover at this site, incomplete epithelial maturation, and a failure to express key molecules such as MUC 16 and galectin-3, which, with the tight junctions between surface epithelial cells, are necessary to seal the ocular surface and prevent penetration of dyes and other molecules into the epithelium. This is proposed as the basis for Marx's line. In Part II of this paper (also published in this issue of The Ocular Surface), we address additional pathophysiological consequences of this mechanism, affecting lid margins.