Aqueous Deficient Dry Eye Disease Research Articles

Confocal Microscopy of the Cornea in Aqueous-Deficient Dry Eye Disease-A Literature Review.

In vivo confocal microscopy (IVCM) is a vital tool in studying dry eye disease (DED), providing insights into morphological changes at ocular surface unit levels. This review presents the main differences in corneal structure between aqueous-deficient dry eye disease (AD-DED) and normal eyes. A comprehensive search of PubMed, Web of Science, Embase, and MEDLINE databases from January 2000 to December 2023 was conducted. The study selection process, as well as data selection and examination, were independently performed by two members of the review team. The review reveals a consistent decrease in corneal surface epithelial cell density in AD-DED cases compared to a control group, but conflicting data on basal epithelial cell density. Notably, the abnormal hyperreflectivity of keratocytes in patients with Sjogren's syndrome was recorded, and there was a significant keratocyte density in AD-DED subjects compared to evaporative DED and control groups. Studies also found a decrease in sub-basal nerve density, increased tortuosity, and the fragmentation of nerve fibers. Dendritic cell density and dendritic cell dendrites increase in AD-DED patients compared to healthy subjects. IVCM is a powerful tool for enhancing our understanding of the pathophysiological mechanisms underlying DED. However, the review underscores the urgent need to standardize the terminology, analysis, and units used for accurate interpretation, a crucial step in advancing our knowledge of DED.

Rosmarinic acid-grafted gelatin nanogels for efficient diquafosol delivery in dry eye disease therapy

Dry eye disease (DED) is a prevalent ocular disorder characterized by unstable tear film condition with loss of aqueous or mucin, excessive oxidative stress, and inflammation, leading to discomfort and potential damage to the ocular surface. Current DED therapies have shown restricted therapeutic effects such as frequent dosing and temporary relief with potential unwanted side effects, urgently necessitating the development of innovative efficient therapeutic approaches. Herein, we developed rosmarinic acid (RosA) conjugated gelatin nanogels loading diquafosol sodium (DQS), DRGNG, for simultaneous ROS-scavenging and mucin-secreting DED treatment. Mechanically, DRGNG suppressed the ROS production, reduced inflammatory factors, and prompted mucin secretion in vitro and in vivo. The whole transcriptome RNA sequencing in vitro further provided a detailed analysis of the upregulation of anti-oxidant, anti-inflammatory, and mucin-promotion pathways. Therapeutically, both in evaporative DED and aqueous deficient DED models, the dual-functional DRGNG could prolong the retention time at the ocular surface, efficiently suppress the oxidative stress response, reverse ocular surface morphology, and recover tear film homeostasis, thus alleviating the DED when the dosage is halved compared to the commercial Diquas®. Our findings contribute to developing innovative therapies for DED and offer insights into the broader applications of nanogels in ocular drug delivery and oxidative stress-related conditions.

Interleukin-1β activates matrix metalloproteinase-2 to alter lacrimal gland myoepithelial cell structure and function.

The aim of the present study is to investigate the role of c-Jun N-terminal kinase (JNK) and matrix metalloproteinase-2 (MMP-2) in mediating the effects of interleukin-1β (IL-1β) on the function of lacrimal gland myoepithelial cells (MECs). MECs isolated from an α-smooth muscle actin-green fluorescent protein (SMA-GFP) transgenic mouse were treated with IL-1β alone or in the presence of SP600125, a JNK inhibitor, or ARP100, an MMP-2 inhibitor. The GFP intensity and the cell size/area were measured, and on day 7, the SMA, calponin, and pro-MMP-2 protein levels and the MEC contraction were assessed. At baseline, the control and treated cells showed no differences in GFP intensity or cell size. Starting on day 2 and continuing on days 4 and 7, the GFP intensity and cell size were significantly lower in the IL-1β-treated samples, and these effects were alleviated following inhibition of either JNK or MMP-2. Compared with the control, the levels of SMA and calponin were lower in the IL-1β-treated samples, and both the JNK and MMP-2 inhibitors reversed this trend. The pro-MMP-2 protein level was elevated in the IL-1β-treated samples, and this effect was abolished by the JNK inhibitor. Finally, oxytocin-induced MEC contraction was diminished in the IL-1β-treated samples, and both the JNK and MMP-2 inhibitors reversed this effect. Our data suggest that IL-1β uses the JNK/MMP-2 pathways to alter MEC functions, which might account for the diminished tears associated with aqueous-deficient dry eye disease.

Immediate and Delayed Effects of Punctal Plug Insertion on Tear Meniscus Height in Severe Aqueous-Deficient Dry Eye.

The aim of this study was to assess the immediate and delayed effects of tear punctal occlusion with punctal plugs on tear meniscus height (TMH) in severe aqueous-deficient dry eye (ADDE) disease. Consecutive patients with severe ADDE related to Sjögren syndrome or ocular graft-versus-host disease underwent inferior and superior occlusion with punctal plugs. TMH was measured using the LacryDiag ocular surface analyzer platform before, 10 minutes, and at least 1 month after punctal occlusion. The corneal fluorescein staining (CFS) score was graded with the Oxford scale (from 0 to 5). Ocular symptoms were graded with a visual analog scale (from 1 to 10). We included 24 eyes of 24 patients (mean age 61 ± 9 years; mean follow-up 7 ± 5 months). The mean TMH was 0.19 ± 0.06 mm at baseline and increased significantly to 0.41 ± 0.13 mm (P < 0.001) and 0.46 ± 0.17 mm (P < 0.001) at 10 minutes after punctal plug insertion and at the end of follow-up, respectively. The median CFS score decreased from 3 ± 1 before plug insertion to 1 ± 2 at the end of follow-up (P < 0.001). Many patients (67%; n = 16) reported subjective improvement of symptoms. TMH was negatively correlated with the CFS score and visual analog scale score assessing symptoms. Upper and lower punctal occlusion increased TMH in patients with severe ADDE as soon as 10 minutes after plug insertion. TMH remained stable over time, which led to the relief of symptoms and reduced corneal staining.

Diagnostic Performance of the Tear Meniscus Osmolarity Measurement for Dry Eye Disease in Rheumatoid Arthritis Patients.

The aim of our study was to evaluate the diagnostic capacity of the tear meniscus osmolarity measurement for dry eye disease (DED) in patients with rheumatoid arthritis (RA), using a portable osmometer based on electrical impedance and an integrated circuit technology (TearLab® (Escondido, CA, USA)). We included 101 RA patients, 81 patients with DED and 20 without DED (controls). We measured tear osmolarity and assessed other clinical diagnostic tests as suggested by the TFOS DEWS II composite reference standard diagnostic criteria for DED using Ocular Surface Disease Index (OSDI), Five-item Dry Eye Questionnaire (DEQ-5), fluorescein tear break-up time (F-TUBT), ocular surface staining (SICCA score), and other clinical parameters to classify DED subtypes. We analyzed the agreement between osmolarity and the TFOS DEWS II composite reference standard for DED diagnosis. We conducted receiver operating characteristic (ROC) curve analyses using the DED variable and its subtypes as dependent variables and the continuous variable for osmolarity or the inter-eye difference in osmolarity as independent variable. Sensitivity, specificity, and area under the curve for all potential cut-off points were obtained and reported from ROC curves. We found that tear meniscus osmolarity had a low diagnostic capacity for DED (AUC = 0.57). Tear meniscus osmolarity measurement had a sensitivity of 35% and a specificity of 80% with a kappa level of agreement of 0.08 compared to the TFOS DEWS II composite reference standard. The low diagnostic capacity of the tear meniscus osmolarity was similar for aqueous-deficient DED and for evaporative DED, being only fair for severe DED with a 57% sensitivity and 80% specificity and a kappa level of agreement of 0.36. Our findings suggest that in patients with RA, tear meniscus osmolarity measured by the TearLab® showed low sensitivity, low specificity, and limited agreement with the TFOS DEWS II composite reference standard for DED diagnosis.

Role of topical and systemic immunosuppression in aqueous-deficient dry eye disease.

Immunosuppression in aqueous-deficient dry eye disease (ADDE) is required not only to improve the symptoms and signs but also to prevent further progression of the disease and its sight-threatening sequelae. This immunomodulation can be achieved through topical and/or systemic medications, and the choice of one drug over the other is determined by the underlying systemic disease. These immunosuppressive agents require a minimum of 6-8 weeks to achieve their beneficial effect, and during this time, the patient is usually placed on topical corticosteroids. Antimetabolites such as methotrexate, azathioprine, and mycophenolate mofetil, along with calcineurin inhibitors, are commonly used as first-line medications. The latter have a pivotal role in immunomodulation since T cells contribute significantly to the pathogenesis of ocular surface inflammation in dry eye disease. Alkylating agents are largely limited to controlling acute exacerbations with pulse doses of cyclophosphamide. Biologic agents, such as rituximab, are particularly useful in patients with refractory disease. Each group of drugs has its own side-effect profiles and requires a stringent monitoring schedule that must be followed to prevent systemic morbidity. A customized combination of topical and systemic medications is usually required to achieve adequate control, and this review aims to help the clinician choose the most appropriate modality and monitoring regimen for a given case of ADDE.

Dry eye disease and risk factors for corneal complications in chronic ocular graft-versus-host disease.

The current study was carried out to evaluate the clinical features and management outcomes of dry eye disease (DED) in chronic ocular GvHD following allogenic hematopoietic stem cell transplantation (HSCT). A retrospective review of consecutive patients diagnosed with chronic ocular GvHD between 2011 and 2020 was performed at a tertiary eye care network. Multi-variate regression analysis was carried out for identifying risk factors associated with progressive disease. A total of 34 patients (68 eyes) with a median age of 33 years [inter-quartile range (IQR) 23-40.5] were studied. The most common indication for HSCT was acute lymphocytic leukemia (26%). Ocular GvHD developed at a median of 2 years (IQR 1-5.5 years) after HSCT. Aqueous tear deficiency was present in 71% of the eyes, of which 84% had a Schirmer value of <5 mm. The median visual acuity at presentation and that after a median follow-up of 6.9 months were comparable at 0.1 log minimum angle of resolution (logMAR) (P = 0.97). Topical immunosuppression was required in 88% of cases, and with this, improvement in corneal (53%, P = 0.003) and conjunctival staining scores (45%, P = 0.43) was noted. A progressive disease was present in 32% with persistent epithelial defects being the most common complication. Grade 2 conjunctival hyperemia [odds ratio (OR): 2.6; P = 0.01] and Schirmer's value <5 mm (OR: 2.7; P = 0.03) were found to be associated with progressive disease. Aqueous deficient DED is the most common ocular manifestation of chronic ocular GvHD, and the risk of the disease progression is greater in eyes with conjunctival hyperemia and severe aqueous deficiency. Awareness among ophthalmologists of this entity is essential for its timely detection and optimal management.

Commentary on: Aqueous-deficient dry eye and systemic disease - More than meets the eye.

Commentary on: Aqueous-deficient dry eye and systemic disease - More than meets the eye.

Contact lenses in dry eye disease and associated ocular surface disorders.

Dry eye disease (DED) is prevalent in all age groups and is known to cause chronic ocular discomfort and pain, and greatly affects the quality of life. Patients with ocular surface disease (OSD) may also have reduced tear secretion due to lacrimal gland damage, thus leading to aqueous deficient DED. Even with conventional management modalities such as lubricating eyedrops, topical corticosteroids, autologous serum eyedrops, or punctal plugs, many patients continue to suffer from debilitating symptoms. Contact lenses are increasingly being used in OSD providing surface hydration, protection from environmental insults, mechanical damage from abnormal lids, and as a modality for constant drug delivery to the ocular surface. This review describes the role of soft lenses and rigid gas-permeable scleral lenses in the management of DED associated with OSD. The efficacy of contact lenses, lens selection, and optimal lens fit are reviewed for specific indications.

Ultrasound-Guided Transcutaneous Injection in the Lacrimal Gland: A Description of Sonoanatomy and Technique.

Purpose: To develop a method of injecting a volume up to 50% of the lacrimal gland (LG) volume while minimizing patient discomfort and maximizing accurate drug delivery. Herein we describe a series of ultrasound (US)-guided transcutaneous injections in the LG and discuss the safety and feasibility of this technique. Methods: Ultrasonography was performed in 40 patients with aqueous deficient dry eye disease using a GE Logic E10 (Milwaukee, Wisconsin, USA) US machine with a 6-24 MHz transducer. US was performed by 2 medical experts in ultrasonography. We recorded the injection and observed an enlargement of the LG ensuring delivery within the LG before the needle was removed. Assessment of injection-related adverse event was performed immediately after the injection. Results: The position of the injection needle within the LG was documented in all 40 patients. Injection of the stem cells and vehicle (N = 20) or solely vehicle (N = 20) led to an enlargement of the glandular structures in all cases. No serious adverse reactions related to the injections were observed. Conclusion: US-guided injection into the LG enables injection on a closed eye causing minimum patient discomfort and maximum certainty of accurate drug delivery. US can provide real-time images and may be used to safely guide the needle ensuring correct placement and injection within the gland capsule. This reduces the risk of injury to the eye and adjacent structures and makes a precise transcutaneous injection possible. Clinical Trial Registration number: NCT04615455.

Expression of Androgen and Estrogen Receptors in the Human Lacrimal Gland

Lacrimal gland dysfunction causes dry eye disease (DED) due to decreased tear production. Aqueous-deficient DED is more prevalent in women, suggesting that sexual dimorphism of the human lacrimal gland could be a potential cause. Sex steroid hormones are a key factor in the development of sexual dimorphism. This study aimed to quantify estrogen receptor (ER) and androgen receptor (AR) expression in the human lacrimal gland and compare it between sexes. RNA was isolated from 35 human lacrimal gland tissue samples collected from 19 cornea donors. AR, ERα, and ERβ mRNA was identified in all samples, and their expression was quantified using qPCR. Immunohistochemical staining was performed on selected samples to evaluate protein expression of the receptors. ERα mRNA expression was significantly higher than the expression of AR and ERβ. No difference in sex steroid hormone (SSH) receptor mRNA expression was observed between sexes, and no correlation was observed with age. If ERα protein expression is found to be concordant with mRNA expression, it should be investigated further as a potential target for hormone therapy of DED. Further research is needed to elucidate the role of sex steroid hormone receptors in sex-related differences of lacrimal gland structure and disease.

Systemic Lupus Erythematosus and Risk of Dry Eye Disease and Corneal Surface Damage: A Population-Based Cohort Study.

Systemic lupus erythematosus (SLE) potentially involves multiple parts of the ocular system, including the lacrimal glands and the cornea. The present study sought to assess the risk of aqueous-deficient dry eye disease (DED) and corneal surface damage in patients with SLE. We conducted a population-based cohort study using Taiwan's National Health Insurance research database to compare the risks of DED and corneal surface damage between subjects with and without SLE. Proportional hazard regression analyses were used to calculate the adjusted hazard ratio (aHR) and 95% confidence interval (CI) for the study outcomes. The propensity score matching procedure generated 5083 matched pairs with 78,817 person-years of follow-up for analyses. The incidence of DED was 31.90 and 7.66 per 1000 person-years in patients with and without SLE, respectively. After adjusting for covariates, SLE was significantly associated with DED (aHR: 3.30, 95% CI: 2.88-3.78, p < 0.0001) and secondary Sjögren's syndrome (aHR: 9.03, 95% CI: 6.86-11.88, p < 0.0001). Subgroup analyses demonstrated that the increased risk of DED was augmented among patients with age < 65 years and female sex. In addition, patients with SLE had a higher risk of corneal surface damage (aHR: 1.81, 95% CI: 1.35-2.41, p < 0.0001) compared to control subjects, including recurrent corneal erosion (aHR: 2.98, 95% CI: 1.63-5.46, p = 0.0004) and corneal scar (aHR: 2.23, 95% CI: 1.08-4.61, p = 0.0302). In this 12-year nationwide cohort study, we found that SLE was associated with increased risks of DED and corneal surface damage. Regular ophthalmology surveillance should be considered to prevent sight-threatening sequelae among patients with SLE.

A comparative review of evaporative dry eye disease and meibomian gland dysfunction in dogs and humans.

Dry eye disease is a complex ophthalmic disorder that consists of two main subtypes, aqueous deficient dry eye (ADDE) and evaporative dry eye disease (EDED). Due to the complex underlying physiology, human dry eye disease can be difficult to model in laboratory animal species. Thus, the identification and characterization of a spontaneous large animal model of dry eye disease is desirable. Dogs have been described as an ideal spontaneous model of ADDE due to the similar pathophysiology between dogs and humans. Recently, EDED and meibomian gland dysfunction (MGD) have been increasingly recognized and reported in dogs. These reports on EDED and MGD in dogs have identified similarities in pathophysiology, clinical presentations, and diagnostic parameters to humans with the comparable disorders. Additionally, the tests that are used to diagnose EDED and MGD in humans are more easily applicable to dogs than to laboratory species due to the comparable globe sizes between dogs and humans. The reported response of dogs to EDED and MGD therapies are similar to humans, suggesting that they would be a valuable preclinical model for the development of additional therapeutics. Further research and clinical awareness of EDED and MGD in dogs would increase their ability to be utilized as a preclinical model, improving the positive predictive value of therapeutics for EDED and MGD in both humans and dogs.

Лечение синдрома сухого глаза, комплексный подход

Dry eye disease (DED) is a chronic condition of the ocular surface characterized by failure to produce sufficient amounts or optimal quality of tears to moisturize the eyes. Worldwide, ocular lubricants are used in the initial management of DED, but they do not address the underlying causes of the disease. Overall, current therapies either reduce ocular surface inflammation or stabilize the tear film, but currently, it is still not clear which medication is best for those who has aqueous deficient DED or evaporative DED. DED is on the spectrum of chronic inflammatory disorders, thus lifestyle changes, nutritional status assessment and correction along with medications aimed to reduce inflammation could be an effective strategy. «Holistic», personalized approach, might give the way for a new generation of clinical studies to provide more effective solutions for management of DED. Keywords: Dry eye, cornea, ocular surface, nutrition

Role of stem cells in regenerative treatment of dry eye disease caused by lacrimal gland dysfunction.

An ageing population and increased screen use in younger people have contributed to a rise in incidence of dry eye disease (DED). Quality of life can be significantly affected by DED, with patients experiencing eye dryness, burning, pain and sensitivity to light. If left untreated, DED may progress to cause lasting damage to the delicate cell layers of the ocular surface. The aqueous-deficient form of DED is characterized by decreased tear volume. This can occur through underlying disease or damage to the lacrimal gland (LG), which results in increased inflammation at the ocular surface and decreased tear secretion. Regenerative therapy for treatment of aqueous-deficient DED would ideally restore LG function without causing adverse side effects and be feasible in terms of cost, production and practical application in the clinic. In this review, we evaluate research directed at the development of clinical procedures for regeneration of the LG using various stem cell types and their products. We also discuss work identifying potential therapeutic targets that may alter pathways to effect healing and ameliorate development of DED. Finally, we discuss shortcomings and recommend future avenues for research. These include determination of the best tissue of origin for mesenchymal cells and transference of knowledge gleaned from animal studies to clinical investigations.

Contact Lenses Loaded with Melatonin Analogs: A Promising Therapeutic Tool against Dry Eye Disease.

Melatonin analogs topically administered evoke a potent tear secretagogue effect in rabbits. This route of drug administration requires high drug concentration and frequent dosing due to its reduced ocular surface retention. Therefore, contact lenses (CLs) have emerged as an alternative drug-delivery system that prolongs drug retention in the cornea, improving its therapeutic performance. This study explores the in vitro ability of five commercially available hydrogel CLs to act as a delivery system for melatonin analogs and the in vivo secretagogue effect of melatonin analog-loaded CLs. We soaked CLs with melatonin or melatonin analog solutions (1 mM) for 12 h. Spectroscopic assays showed that IIK7-loaded CLs led to the inadequate delivery of this compound. Conventional hydrogel lenses loaded with agomelatine released more agomelatine than silicone ones (16–33% more). In contrast, the CLs of silicone materials are more effective as a delivery system of 5-MCA-NAT than CLs of conventional materials (24–29%). The adaptation of CLs loaded with agomelatine or 5-MCA-NAT in rabbits triggered a higher tear secretion than the corresponding eye drops (78% and 59% more, respectively). These data suggest that CLs preloaded with melatonin analogs could be an adequate strategy to combat aqueous tear deficient dry eye disease.

Title: P2x7 Receptor Activation and Estrogen Status Drive Neuroinflammatory Mechanisms in a Rat Model for Dry Eye.

Dry eye disease (DED) is recognized as a chronic inflammatory condition with an increase in tear osmolarity and loss of tear film integrity. DED is often accompanied by adverse ocular symptoms which are more prevalent in females than males. The basis for ocular hyperalgesia in DED remains uncertain; however, both peripheral and central neural mechanisms are implicated. A model for aqueous deficient DED, exorbital gland excision, was used to determine if activation of the purinergic receptor subtype 7, P2X7R, expressed by non-neural cells in peripheral and central trigeminal nerve pathways, contributed to persistent ocular hyperalgesia. Densitometry of trigeminal brainstem sections revealed increases in P2X7R, the myeloid cell marker Iba1, and the inflammasome, NLRP3, of estradiol-treated DED females compared to estradiol-treated sham females, while expression in DED males and DED females not given estradiol displayed minor changes. No evidence of immune cell infiltration into the trigeminal brainstem was seen in DED rats; however, markers for microglia activation (Iba1) were increased in all groups. Isolated microglia expressed increased levels of P2X7R and P2X4R, IL-1β (Ιnterleukin-1β), NLRP3, and iNOS (nitric oxide synthase). Further, estradiol-treated DED females displayed greater increases in P2X7R, IL-1β and NLRP3 expression compared to untreated DED females. Orbicularis oculi muscle activity (OOemg) evoked by ocular instillation of hypertonic saline (HS) was recorded as a surrogate measure of ocular hyperalgesia and was markedly enhanced in all DED groups compared to sham rats. Systemic minocycline reduced HS-evoked OOemg in all DED groups compared to sham rats. Local microinjection in the caudal trigeminal brainstem of an antagonist for P2X7R (A804598) greatly reduced HS-evoked OOemg activity in all DE groups, while responses in sham groups were not affected. Intra-trigeminal ganglion injection of siRNA for P2X7R significantly reduced HS-evoked OOemg activity in all DED groups, while evoked responses in sham animals were not affected. These results indicated that activation of P2X7R at central and peripheral sites in trigeminal pain pathways contributed to an increase in ocular hyperalgesia and microglia activation in DED males and females. Estrogen treatment in females further amplified ocular hyperalgesia and neuroimmune responses in this model for aqueous deficient DED.

Clinical outcomes and satisfaction of autologous serum tears treatment for ocular surface diseases

AbstractPurposeTo evaluate clinical outcomes and patient‐reported satisfaction of autologous serum tears for ocular surface diseases.MethodsWe retrospectively analyzed the clinical charts of 40 patients that were treated with 20% autologous serum tears for at least 3 months. We retrieved data for the Ocular Surface Disease Index (OSDI) questionnaire, fluorescein staining, corrected distance visual acuity (CDVA), and evidence of epithelial defects or corneal ulcers. We compared data from the initial visit to 3 months after autologous serum tears prescription. Concurrently with the study, we obtained patient‐reported satisfaction with the Treatment Satisfaction Questionnaire for Medication (TSQM).ResultsThe mean age was 59.3 (SD 15.2), 70% were female; 60% had aqueous deficient or mixed dry eye disease, 20% had neurotrophic keratopathy, and 20% had a persistent epithelial defect of different etiologies. OSDI improved from 32.7 ± 18.1 to 9.1 ± 7.7 (p &lt; 0.001). At baseline, 92.5% of patients had a grade 2 score or higher in the Oxford staining score, whereas after treatment, 32.5% had a grade 2 score or higher (p &lt; 0.001). The median of CDVA was 0.5 (0.2, 0.8) at baseline and 0.3 (0.2, 0.6) after treatment (p = 0.006). At baseline, 25% of patients had an epithelial defect or aseptic corneal ulcer, all resolved after treatment. The mean TSQM were 89.3 for global satisfaction, 84.8 for efficacy, and 68.5 for the convenience. No side effects were reported.ConclusionsAutologous serum tears improved the signs and symptoms of ocular surface diseases. Patients showed a high degree of satisfaction with the treatment.

Once-Daily Topical Phosphosulindac Is Efficacious in the Treatment of Dry Eye Disease: Studies in Rabbit Models of Its Main Clinical Subtypes.

Purpose: Dry eye disease (DED) is classified as aqueous deficient, evaporative, or mixed. We investigated the therapeutic effect of the novel anti-inflammatory drug phosphosulindac (PS) in rabbit models of DED encompassing its pathogenesis, and its transition to chronicity.Methods: We treated three rabbit models of DED with PS (hydrogel formulation) or vehicle topically applied 1 × /day. We induced aqueous-deficient DED (acute and chronic) by injecting Concanavalin A into lacrimal glands; evaporative DED by injecting into the upper eyelid inactivated Mycobacterium tuberculosis in complete Freund's adjuvant; and mixed DED through desiccative stress, induced by holding open the eye for 3 h. We determined corneal sensitivity, tear break-up time (TBUT), Schirmer's tear test (STT), tear osmolality, and fluorescein staining of the ocular surface.Results: PS reversed all abnormal DED parameters. In acute DED, PS dose dependently normalized corneal sensitivity and tear osmolality; and improved TBUT, STT, and fluorescein staining. PS normalized corneal sensitivity and improved all other parameters in chronic aqueous-deficient DED. In evaporative DED, PS normalized corneal sensitivity and improved TBUT and fluorescein staining (osmolality and STT were not significantly changed in this model). In the desiccative stress model, PS improved TBUT and fluorescein staining but had no effect on STT or tear osmolality.Conclusions: PS rapidly reversed almost all DED parameters in its three subtypes. The normalization of the suppressed corneal sensitivity suggests the possibility of marked symptomatic relief by PS. The hydrogel formulation allows once-daily dosing. PS merits further development as a potential treatment for DED.

Alterations in corneal nerves in different subtypes of dry eye disease: An in vivo confocal microscopy study

PurposeTo evaluate corneal subbasal nerve alterations in evaporative and aqueous-deficient dry eye disease (DED) as compared to controls. MethodsIn this retrospective, cross-sectional, controlled study, eyes with a tear break-up time of less than 10 s were classified as DED. Those with an anesthetized Schirmer's strip of less than 5 mm were classified as aqueous-deficient DED. Three representative in vivo confocal microscopy images were graded for each subject for total, main, and branch nerve density and numbers. ResultsCompared to 42 healthy subjects (42 eyes), the 70 patients with DED (139 eyes) showed lower total (18,579.0 ± 687.7 μm/mm2 vs. 21,014.7 ± 706.5, p = 0.026) and main (7,718.9 ± 273.9 vs. 9,561.4 ± 369.8, p < 0.001) nerve density, as well as lower total (15.5 ± 0.7/frame vs. 20.5 ± 1.3, p = 0.001), main (3.0 ± 0.1 vs. 3.8 ± 0.2, p = 0.001) and branch (12.5 ± 0.7 vs. 16.5 ± 1.2, p = 0.004) nerve numbers. Compared to the evaporative DED group, the aqueous-deficient DED group showed reduced total nerve density (19,969.9 ± 830.7 vs. 15,942.2 ± 1,135.7, p = 0.006), branch nerve density (11,964.9 ± 749.8 vs. 8,765.9 ± 798.5, p = 0.006), total nerves number (16.9 ± 0.8/frame vs. 13.0 ± 1.2, p = 0.002), and branch nerve number (13.8 ± 0.8 vs. 10.2 ± 1.1, p = 0.002). ConclusionsPatients with DED demonstrate compromised corneal subbasal nerves, which is more pronounced in aqueous-deficient DED. This suggests a role for neurosensory abnormalities in the pathophysiology of DED.