Single-Tear Proteomics: A Feasible Approach to Precision Medicine

Lacrimal fluid is an attractive source of noninvasive biomarkers, the main limitation being the small sample amounts typically collected. Advanced analytical methods to allow for proteomics profiling from a few microliters are needed to develop innovative biomarkers, with attractive perspectives of applications to precision medicine. This work describes an effective, analytical pipeline for single-tear analysis by ultrahigh-resolution, shotgun proteomics from 23 healthy human volunteers, leading to high-confidence identification of a total of 890 proteins. Highly reproducible quantification was achieved by either peak intensity, peak area, or spectral counting. Hierarchical clustering revealed a stratification of females vs. males that did not emerge from previous studies on pooled samples. Two subjects were monitored weekly over 3 weeks. The samples clustered by withdrawal time of day (morning vs. afternoon) but not by follow-up week, with elevated levels of components of the immune system in the morning samples. This study demonstrates feasibility of single-tear quantitative proteomics, envisaging contributions of this unconventional body fluid to individualized approaches in biomedicine.

Efficacy and Safety of Artificial Tears Containing Lipidure and Hypromellose for the Treatment of Moderate Dry Eye Disease in Contact Lens Wearers

Purpose: Dry eye disease (DED) involves up to 50% of the global population. The present study compared efficacy, tolerability and safety of the novel Respilac artificial tears containing Lipidure and hypromellose (HPMC) to the widely used Nextal artificial tears, HPMC-based, for the treatment of moderate DED in contact lenses (CL) wearers.Methods: In a prospective, single-center, randomized investigation, 30 patients aged ≥18 years, diagnosed with moderate DED and wearing CL were randomly assigned to Respilac (n=15) or to Nextal group (n=15). Patients self-administrated one drop of Respilac or Nextal in both eyes 3-times daily for 21 days. Changes in endpoints (Visual Analogue Scale (VAS) score for ocular tolerability, Symptom Assessment iN Dry Eye (SANDE) score, Non-Invasive First Break-Up Time (NIF-BUT) results, Tear analysis value, Meibography results, CL tolerability results were investigated, comparing treatment groups and time-points evaluations. Adverse events (AEs) were also recorded and evaluated.Results: VAS scores decreased with time (p<0.001) in both groups showing no statistically significant difference among them (p=0.13). Improvements were also detected, from screening to end-of-treatment, by SANDE scores for severity and frequency (p<0.001) and by Tear analysis results (p<0.001) with no observed difference between Nextal and Respilac arm. NIF-BUT, Meibography and CL tolerability values showed to be non-significantly affected by treatment nor by time. No AEs were detected.Conclusion: According to the study results, Respilac showed to be effective, safe and well-tolerated for the treatment of moderate DED in CL wearers. Lipidure-based ophthalmic solution resulted not inferior to the currently used Nextal.

Evaluation of dry eye subtypes and characteristics using conventional assessments and dynamic tear interferometry

Background/aimsTo evaluate subtypes and characteristics of dry eye (DE) using conventional tests and dynamic tear interferometry, and to investigate determinants of disease severity in each DE subtype.Methods309 patients diagnosed with DE and 69 healthy controls were prospectively enrolled. All eyes were evaluated using Ocular Surface Disease Index (OSDI), Schirmer’s test I (ST1) and Meibomian gland dysfunction (MGD) grade were analysed. The tear interferometric pattern and lipid layer thickness were determined using DR-1α and LipiView II, respectively.ResultsDynamic interferometric analysis revealed 56.6% of patients with DE exhibited Jupiter patterns, indicative of aqueous-deficiency, while 43.4% exhibited crystal patterns, indicative of lipid deficiency. These findings were in accordance with classification based on ST1 scores and MGD grade. Conventional assessment indicated 286 patients exhibited evidence of evaporative DE (EDE) due to MGD, while only 11 exhibited signs of pure aqueous-deficient DE (pure ADDE, only ST1 ≤5 mm). Interestingly, of 286 patients with EDE, 144 were categorised into the mixed-ADDE/EDE group, in which ST1 was identified as a strong negative determinant of OSDI. In contrast, 72.2% of patients with mixed-ADDE/EDE exhibited Jupiter patterns (Jupiter mixed), while 27.8% exhibited crystal patterns (crystal mixed). OSDI values were significantly higher in the crystal-mixed group than in the Jupiter mixed, in which OSDI scores were independently associated with ST1 values only.ConclusionsOur findings indicate that majority of EDE patients also exhibit aqueous deficiency, which can aggravate symptoms even in patients with lipid-deficient mixed-ADDE/EDE. Conventional assessments should be combined with interferometric tear analysis to determine the most appropriate treatment for each DE patient.

Tear fluid collection methods: Review of current techniques

Tear fluid, composed of lipid, aqueous, and mucin layers, contains electrolytes, water, proteins, peptides, and glycoproteins. Its components may serve as diagnostic indicators of local and systemic diseases. The aim of the study was to conduct literature review in order to identify the current methods of tear collection. The most commonly used method which was relatively easy to perform and allowed to obtain sufficient tear volume for further chemical and physical analysis was selected through PubMed database search for the following keywords: tear sampling, human tears, chemical analysis of tears, physical tear analysis, animal tear sampling. Final criteria of articles selection were: human tears, tear sample collection, chemical and physical analysis of tears. Time of publication of the articles not older than 1995. The analysis of 70 articles revealed that the most common tear fluid collection methods are Schirmer tear strips and capillary tubes. Thus, we recommend the use of Schirmer strips and microcapillary tubes as the cheapest and easiest methods for sampling of tear fluid for further chemical analysis.

Ocular surface manifestation of COVID-19 and tear film analysis

To evaluate the ocular manifestation in patients hospitalized with coronavirus disease 2019 (COVID-19) and to search for the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in tears. This study was conducted in 29 hospitalized patients who were admitted to the COVID center at the Policlinic Hospital of the University of Messina, Italy. All patients underwent an ophthalmologic assessment comprising a Standardized Patient Evaluation of Eye Dryness (SPEED) questionnaire, anterior segment, and the ocular surface examination of both eyes using a portable slit lamp. The Schirmer I test was performed, and the filter paper strip was used to search for the presence of SARS-CoV-2 on the ocular surface by real-time quantitative polymerase chain reaction (RT-qPCR). A total of 10 patients reported ocular symptoms; in particular, four reported eye burning, three reported foreign body sensation, and three reported tearing. Moreover, seven patients presented conjunctival hyperemia and/or chemosis, eleven patients presented blepharitis signs such as lid margin hyperemia and/or telangiectasia, crusted eyelashes, and meibomian orifices alterations. Tear analysis did not reveal the presence of SARS-CoV-2. Ocular symptoms are common in patients with COVID-19; although, tear analysis did not reveal the presence of SARS-CoV-2.

Ocular surface manifestation of COVID-19 and tear film analysis

Purpose: To evaluate the ocular manifestation in patients hospitalized with coronavirus disease 2019 (COVID-19) and to search for the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in tears.Methods: This study was conducted in 29 hospitalized patients who were admitted to the COVID center at the Policlinic Hospital of the University of Messina, Italy.All patients underwent an ophthalmologic assessment comprising a Standardized Patient Evaluation of Eye Dryness (SPEED) questionnaire, anterior segment, and the ocular surface examination of both eyes using a portable slit lamp.The Schirmer I test was performed, and the filter paper strip was used to search for the presence of SARS-CoV-2 on the ocular surface by real-time quantitative polymerase chain reaction (RT-qPCR).Results: A total of 10 patients reported ocular symptoms; in particular, four reported eye burning, three reported foreign body sensation, and three reported tearing. Moreover, seven patients presented conjunctival hyperemia and/or chemosis, eleven patients presented blepharitis signs such as lid margin hyperemia and/or telangiectasia, crusted eyelashes, and meibomian orifices alterations. Tear analysis did not reveal the presence of SARS-CoV-2.Conclusion: Ocular symptoms are common in patients with COVID-19; although, tear analysis did not reveal the presence of SARS-CoV-2.

Integration of paper microfluidic sensors into contact lenses for tear fluid analysis

Paper microfluidic sensors were integrated into laser-inscribed contact lenses to provide an in situ platform for tear analysis with smartphone readouts.

Pterygium Pathology: A Prospective Case-Control Study on Tear Film Cytokine Levels

Pterygium is a common eye disease, linked to an increased exposure to UV radiation and dry environments. The associated pathology culminates in visual impairment and, in some rare cases, blindness. However, there remains a lot of uncertainty concerning the pathogenesis of this fibrovascular lesion. As the composition of the tear film provides a reflection into the pathological changes at the ocular surface, tear analysis represents an ideal approach to gain insight in the progression of disease following pterygiectomy. This study enrolled 19 patients and age/gender-matched healthy controls. Tear film levels of interleukin- (IL-) 6, IL-8, and vascular endothelial growth factor (VEGF) were investigated over time, and preoperative concentrations were linked to corneal neovascularization and pterygium size. Diminished tear film levels were found in unilateral patients who show no clinical signs of pterygium recurrence over a period of one year. Hence, our results highlight the potential of using the course of IL-6, IL-8, and VEGF levels in tears as biomarkers for recovery. In addition, when focusing on the affected eyes (i.e., primary and recurrent pterygium), we detected fold changes in preoperative cytokine concentrations to correspond with disease severity. As our proposed biomarkers did not reveal a linear relationship with corneal neovascularization nor the invasive behaviour of pterygium, no exact role in the pterygium pathology could be established. Hence, our data point to these factors being contributors rather than decisive players in the pathological processes.