Tear fluid biomarkers in ocular and systemic disease: potential use for predictive, preventive and personalised medicine

In the field of predictive, preventive and personalised medicine, researchers are keen to identify novel and reliable ways to predict and diagnose disease, as well as to monitor patient response to therapeutic agents. In the last decade alone, the sensitivity of profiling technologies has undergone huge improvements in detection sensitivity, thus allowing quantification of minute samples, for example body fluids that were previously difficult to assay. As a consequence, there has been a huge increase in tear fluid investigation, predominantly in the field of ocular surface disease. As tears are a more accessible and less complex body fluid (than serum or plasma) and sampling is much less invasive, research is starting to focus on how disease processes affect the proteomic, lipidomic and metabolomic composition of the tear film. By determining compositional changes to tear profiles, crucial pathways in disease progression may be identified, allowing for more predictive and personalised therapy of the individual. This article will provide an overview of the various putative tear fluid biomarkers that have been identified to date, ranging from ocular surface disease and retinopathies to cancer and multiple sclerosis. Putative tear fluid biomarkers of ocular disorders, as well as the more recent field of systemic disease biomarkers, will be shown

Disruption of TGF-β Signaling Improves Ocular Surface Epithelial Disease in Experimental Autoimmune Keratoconjunctivitis Sicca

TGF-β is a pleiotropic cytokine that can have pro- or anti-inflammatory effects depending on the context. Elevated levels of bioactive TGF-β1 in tears and elevated TGF-β1mRNA transcripts in conjunctiva and minor salivary glands of human Sjögren's Syndrome patients has also been reported. The purpose of this study was to evaluate the response to desiccating stress (DS), an experimental model of dry eye, in dominant-negative TGF-β type II receptor (CD4-DNTGFβRII) mice. These mice have a truncated TGF-β receptor in CD4(+) T cells, rendering them unresponsive to TGF-β.DS was induced by subcutaneous injection of scopolamine and exposure to a drafty low humidity environment in CD4-DNTGFβRII and wild-type (WT) mice, aged 14 weeks, for 5 days. Nonstressed (NS) mice served as controls. Parameters of ocular surface disease included corneal smoothness, corneal barrier function and conjunctival goblet cell density. NS CD4-DNTGFβRII at 14 weeks of age mice exhibited a spontaneous dry eye phenotype; however, DS improved their corneal barrier function and corneal surface irregularity, increased their number of PAS+ GC, and lowered CD4(+) T cell infiltration in conjunctiva. In contrast to WT, CD4-DNTGFβRII mice did not generate a Th-17 and Th-1 response, and they failed to upregulate MMP-9, IL-23, IL-17A, RORγT, IFN-γ and T-bet mRNA transcripts in conjunctiva. RAG1KO recipients of adoptively transferred CD4+T cells isolated from DS5 CD4-DNTGFβRII showed milder dry eye phenotype and less conjunctival inflammation than recipients of WT control.Our results showed that disruption of TGF-β signaling in CD4(+) T cells causes paradoxical improvement of dry eye disease in mice subjected to desiccating stress

Paper-based microfluidic system for tear electrolyte analysis

The analysis of tear constituents at point-of-care settings has a potential for early diagnosis of ocular disorders such as dry eye disease, low-cost screening, and surveillance of at-risk subjects. However, current minimally-invasive rapid tear analysis systems for point-of-care settings have been limited to assessment of osmolarity or inflammatory markers and cannot differentiate between dry eye subclassifications. Here, we demonstrate a portable microfluidic system that allows quantitative analysis of electrolytes in the tear fluid that is suited for point-of-care settings. The microfluidic system consists of a capillary tube for sample collection, a reservoir for sample dilution, and a paper-based microfluidic device for electrolyte analysis. The sensing regions are functionalized with fluorescent crown ethers, o-acetanisidide, and seminaphtorhodafluor that are sensitive to mono- and divalent electrolytes, and their fluorescence outputs are measured with a smartphone readout device. The measured sensitivity values of Na(+), K(+), Ca(2+) ions and pH in artificial tear fluid were matched with the known ion concentrations within the physiological range. The microfluidic system was tested with samples having different ionic concentrations, demonstrating the feasibility for the detection of early-stage dry eye, differential diagnosis of dry eye sub-types, and their severity staging

Efficacy of cultivated corneal epithelial stem cells for ocular surface reconstruction

Pinnita Prabhasawat,1 Pattama Ekpo,2 Mongkol Uiprasertkul,3 Suksri Chotikavanich,1 Nattaporn Tesavibul11Department of Ophthalmology, 2Department of Immunology, 3Department of Pathology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, ThailandPurpose: To investigate the clinical outcomes of cultivated corneal limbal epithelial transplantation (CLET) using human amniotic membrane for corneal limbal stem-cell deficiency.Methods: Prospective, noncomparative case series. Eighteen patients (19 eyes) with severe ocular surface diseases were chosen to undergo CLET using human amniotic membrane. Twelve eyes received auto-CLET, and seven eyes received allo-CLET. Clinical outcomes of corneal surface epithelialization, conjunctivalization, inflammation, visual acuity, graft status, and complications were observed.Results: Corneal epithelium cultivated on amniotic membrane (two to four layers) was positive for molecular markers p63, ABCG2, CK3, and CK12. The mean patient age was 44.7 ± 15.2 years. A successful clinical outcome, defined as corneal epithelialization without central conjunctivalization or severe inflammation, was obtained in 14 (73.7%) of 19 eyes (mean follow-up 26.1 ± 13.5 months; range 6–47). A histopathologic success, defined as absence of goblet cells at the central cornea, was achieved in 12 (63.2%) eyes. Clinical failures occurred in five (26.3%) of 19 eyes, and histopathologic failures occurred in seven (36.8%) of 19 eyes. Survival analysis at 1 year showed that the clinical success rate was 77.9% and the pathological success rate was 72.3%. Fourteen of 19 (73.7%) eyes had visual acuity improvements after CLET. Six cases underwent penetrating keratoplasty; five of these grafts remained clear after 20.4 ± 6.9 months (range, 12–31) of follow-up. Complications included infectious keratitis (three cases) and recurrent symblepharon (one case). All complicated cases had lid abnormalities. Factors affecting the final clinical outcomes were lid abnormalities, abnormal corneal stromal beds, and complications.Conclusion: CLET can successfully restore ocular surface damage in most cases with corneal limbal stem cell deficiency.Keywords: limbal deficiency, limbal transplantation, corneal epithelial stem-cell transplantation, cultivated corneal epithelial stem cell

A 5-year retrospective record review of hospital-based low-vision rehabilitation in Thailand

Suksri Chotikavanich, Nacha Chanvarapha, Siriwan Loket, Rungtip Yingyong, Somthin Dongngam, Waree Nujoi, Prapasson Sangsre, Krissana Maneephagaphan, Ketsara Rungsiri, Wichuda Krutthong Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand Purpose: To investigate the quality-of-life-related goals of low-vision patients, the causes of visual impairment, and the low-vision rehabilitation services at a Thai national tertiary referral center. Subjects and methods: A review was conducted on the medical records of patients attending the Low Vision Rehabilitation Clinic, Siriraj Hospital, Bangkok, Thailand, between 2012 and 2016. Results: A total of 992 patient records were included, comprising of 760 adults (aged over 15 years) and 232 children (aged ≤15), with a mean age of 52.2 and 5.4 years, respectively. The retina was the most common anatomic site of visual impairment. Among the adults, the most common ocular condition was retinitis pigmentosa (28.3%), followed by age-related macular degeneration (10.3%), glaucoma (10.0%), and diabetic retinopathy (9.6%). As for the children, the most common ocular conditions were cortical visual impairment (17.7%), optic nerve hypoplasia (13.4%), and retinopathy of prematurity (9.5%). More patients had low vision (a visual acuity of <6/18–3/60) than blindness (a visual acuity below 3/60). The most commonly stated goals among the adults were reading, writing, and performing near tasks (34.7%), and independent mobility (21.3%), whereas for children, the most frequently indicated goal was visual and developmental stimulation (38.4%). The services most often provided for the adults were the prescribing of visual aid devices (51.8%) and orientation and mobility training (40.7%), while the children most often received visual and developmental stimulation provided by a multidisciplinary team (33.8%). The Thai Government’s Universal Health Care Coverage scheme was the most commonly used medical insurance. Conclusion: Data from this study can be used to improve low-vision patient care and rehabilitation services, and as input to the further development of national health care policies for low-vision patients. Keywords: Thailand, low vision, vision rehabilitation, visual impairmen

A 5-year retrospective record review of hospital-based low-vision rehabilitation in Thailand

Suksri Chotikavanich, Nacha Chanvarapha, Siriwan Loket, Rungtip Yingyong, Somthin Dongngam, Waree Nujoi, Prapasson Sangsre, Krissana Maneephagaphan, Ketsara Rungsiri, Wichuda Krutthong Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand Purpose: To investigate the quality-of-life-related goals of low-vision patients, the causes of visual impairment, and the low-vision rehabilitation services at a Thai national tertiary referral center. Subjects and methods: A review was conducted on the medical records of patients attending the Low Vision Rehabilitation Clinic, Siriraj Hospital, Bangkok, Thailand, between 2012 and 2016. Results: A total of 992 patient records were included, comprising of 760 adults (aged over 15 years) and 232 children (aged ≤15), with a mean age of 52.2 and 5.4 years, respectively. The retina was the most common anatomic site of visual impairment. Among the adults, the most common ocular condition was retinitis pigmentosa (28.3%), followed by age-related macular degeneration (10.3%), glaucoma (10.0%), and diabetic retinopathy (9.6%). As for the children, the most common ocular conditions were cortical visual impairment (17.7%), optic nerve hypoplasia (13.4%), and retinopathy of prematurity (9.5%). More patients had low vision (a visual acuity of <6/18–3/60) than blindness (a visual acuity below 3/60). The most commonly stated goals among the adults were reading, writing, and performing near tasks (34.7%), and independent mobility (21.3%), whereas for children, the most frequently indicated goal was visual and developmental stimulation (38.4%). The services most often provided for the adults were the prescribing of visual aid devices (51.8%) and orientation and mobility training (40.7%), while the children most often received visual and developmental stimulation provided by a multidisciplinary team (33.8%). The Thai Government’s Universal Health Care Coverage scheme was the most commonly used medical insurance. Conclusion: Data from this study can be used to improve low-vision patient care and rehabilitation services, and as input to the further development of national health care policies for low-vision patients. Keywords: Thailand, low vision, vision rehabilitation, visual impairmen