Ocular surface diabetic disease: A neurogenic condition?

Association of polymorphism of NLRP3, ICAM-1, PTPN22, INS genes in childhood onset type 1 diabetes in a Pakistani population

BACKGROUND

Type 1 diabetes (T1D) is an organ-specific autoimmune disorder characterized by the destruction of pancreatic β cells, leading to absolute insulin deficiency. The genes NLRP3, ICAM-1, PTPN22, and INS are reportedly associated with T1D in other populations. However, the genetic pattern of T1D in the Pakistani population is not clear. This study aimed to find the association of polymorphisms in the PTPN22, INS, NLRP3, and ICAM-1 genes with T1D susceptibility in the Pakistani population.

METHODOLOGY

This case-control study includes 100 T1D patients (3-14 years), recruited randomly from the pediatric endocrinology department of Fatima Memorial Hospital, Lahore, Pakistan and 100 age-matched healthy controls were selected from different localities of the same population. The polymorphisms in PTPN22 (rs601, rs33996649, rs2488457), INS (rs80356664), NLRP3 (rs10754558, rs35829419), and ICAM-1 (rs1799969, rs5498) genes were genotyped by Sanger sequencing. The genotypic and allelic frequencies, haplotypes, and linkage disequilibrium were computed using the genetic toolset PLINK to investigate their relationship to T1D.

RESULTS

The results indicate that the occurrence of the GT genotype of the rs33996649 variant is significantly higher in children with T1D compared to a control group of healthy individuals (P = 0.001, OR: 2.0, 95% CI = 0.15-0.45). Furthermore, the CT genotype of rs2488457 was notably associated with T1D patients (P = 0.007, OR: 2.8, 95% CI = 0.56-0.67). The CG genotype of rs80356664 showed a slight association with T1D (P = 0.03, OR: 1.9, 95% CI = 0.35-0.59). The prevalence of the AT genotype of rs10754558 showed a strong association with T1D (P = 0.005, OR: 3.4, 95% CI = 0.45-0.69). The TG genotype of rs5498 was also strongly associated with T1D (P = 0.009, OR: 2.8, 95% CI = 0.75-0.89).

CONCLUSION

The present study provides evidence that SNPs in the PTPN22, INS, NLRP3, and ICAM-1 genes are associated with the development of T1D. Further research is needed to explore their potential use in genetic screening and personalized medication.

Tear neuropeptide Y as a non-invasive marker of peripheral microvascular complications in type 1 diabetes

AIMS

To investigate tear neuropeptide Y (NPY) and substance P concentrations in individuals with type 1 diabetes, comparing those with and without both diabetic retinopathy (DR) and peripheral neuropathy.

METHODS

This cross-sectional study involved 41 participants with type 1 diabetes and none to moderate DR, and 22 healthy controls. Assessments included clinical ocular surface parameters, quantification of corneal nerve attributes (based on in vivo confocal microscopy imaging), DR grading, and evaluation for small and large fibre neuropathy. Concentrations of NPY and substance P in tear samples were measured using enzyme-linked immunosorbent assay.

RESULTS

Mean (± standard deviation) tear NPY concentrations in participants with type 1 diabetes and length-dependent small fibre neuropathy (SFN) was lower than in controls (10.84 ± 4.10 ng/mL vs 14.72 ± 3.12 ng/mL; p=0.004), but not significantly different from type 1 diabetes participants without SFN (13.39 ± 4.66 ng/mL; p=0.11). Tear NPY levels were lower in individuals with type 1 diabetes and mild/moderate non-proliferative DR (10.44 ± 3.46 ng/mL) compared to none/minimal DR (13.79 ± 4.76 ng/mL; p=0.0005) and controls. In separate linear regression models, both the presence of SFN (β = -0.75, p=0.02) and the presence of mild/moderate DR (β = -0.84, p=0.009) were significantly associated with tear NPY levels relative to controls, after adjusting for participant age, sex, and dry eye disease. There were no inter-group differences for tear substance P concentrations.

CONCLUSIONS

Tear NPY has potential utility as an indicator of peripheral microvascular complications associated with type 1 diabetes.

Prophylactic Therapy for Long-Term Ocular Discomfort After Cataract Surgery

PURPOSE

The cataract surgery dissatisfaction rate is 20% to 35% due to ocular surface discomfort. We investigate the ocular surface discomfort after surgical failure as a consequence of age-related parainflammation. We also aim to prevent it by immune-modulating prophylactic management.

METHODS

Monocentric clinical trial realized in a teaching hospital. Prospective, randomized, open-label, unmasked clinical trial. One hundred patients diagnosed with cataracts underwent phacoemulsification surgery. Groups A (<65 years; n = 25) and B (>75 years; n = 25) received surgery only. Groups C and D (both >75 years and both n = 25) used cyclosporine A 0.1% cationic emulsion (CE) eye drops or CE lubricating eye drops (both twice daily), respectively, for 30 days before surgery. Patients were followed up 90 days after surgery. The primary outcome was postoperative ocular surface failure; secondary outcomes examined the influence of prophylactic cyclosporine A 0.1% CE therapy on ocular surface outcomes.

RESULTS

Group B demonstrated greater severity regarding ocular surface signs and symptoms throughout the study period, versus all other groups. Signs/symptoms were typically lower in Group A. Group C achieved significant reductions in conjunctival Symptom Assessment in Dry Eye values ( P < 0.05), conjunctival hyperemia severity ( P < 0.01), and meibomian gland dysfunction ( P < 0.001) at Day 45, versus Group B, and tear break-up time was increased ( P < 0.001). Ocular surface inflammatory marker transcription (HLADR, intercellular adhesion molecule 1 [ICAM-1], and interleukin 6 [IL-6]) was significantly downregulated in Group C, versus Group B, at 90 days ( P < 0.05).

CONCLUSIONS

Cataract surgery induced ocular surface system failure with a clinically significant persistent inflammatory status (InflammAging) in patients older than 75 years. Prophylactic cyclosporine A 0.1% CE eye drops were associated with improved ocular surface homeostasis and reductions in inflammatory markers.

Effects of Diabetes Mellitus on Corneal Immune Cell Activation and the Development of Keratopathy

Diabetes mellitus (DM) is one of the most prevalent diseases globally, and its prevalence is rapidly increasing. Most patients with a long-term history of DM present with some degree of keratopathy (DK). Despite its high incidence, the underlying inflammatory mechanism of DK has not been elucidated yet. For further insights into the underlying immunopathologic processes, we utilized streptozotocin-induced mice to model type 1 DM (T1D) and B6.Cg-Lepob/J mice to model type 2 DM (T2D). We evaluated the animals for the development of clinical manifestations of DK. Four weeks post-induction, the total frequencies of corneal CD45+CD11b+Ly-6G- myeloid cells, with enhanced gene and protein expression levels for the proinflammatory cytokines TNF-α and IL-1β, were higher in both T1D and T2D animals. Additionally, the frequencies of myeloid cells/mm2 in the sub-basal neural plexus (SBNP) were significantly higher in T1D and T2D compared to non-diabetic mice. DK clinical manifestations were observed four weeks post-induction, including significantly lower tear production, corneal sensitivity, and epitheliopathy. Nerve density in the SBNP and intraepithelial terminal endings per 40x field were lower in both models compared to the normal controls. The findings of this study indicate that DM alters the immune quiescent state of the cornea during disease onset, which may be associated with the progressive development of the clinical manifestations of DK.

High-throughput sequencing reveals differences in microbial community structure and diversity in the conjunctival tissue of healthy and type 2 diabetic mice

BACKGROUND

To investigate the differences in bacterial and fungal community structure and diversity in conjunctival tissue of healthy and diabetic mice.

METHODS

RNA-seq assays and high-throughput sequencing of bacterial 16 S rDNA and fungal internal transcribed spacer (ITS) gene sequences were used to identify differentially expressed host genes and fungal composition profiles in conjunctival tissues of diabetic BKS-db/db mice and BKS (control) mice. Functional enrichment analysis of differentially expressed genes and the correlation between the relative abundance of bacterial and fungal taxa in the intestinal mucosa were also performed.

RESULTS

Totally, 449 differential up-regulated genes and 1,006 down-regulated genes were identified in the conjunctival tissues of diabetic mice. The differentially expressed genes were mainly enriched in metabolism-related functions and pathways. A decrease in conjunctival bacterial species diversity and abundance in diabetic mice compared to control mice. In contrast, fungal species richness and diversity were not affected by diabetes. The microbial colonies were mainly associated with cellular process pathways regulating carbohydrate and lipid metabolism, as well as cell growth and death. Additionally, some interactions between bacteria and fungi at different taxonomic levels were also observed.

CONCLUSION

The present study revealed significant differences in the abundance and composition of bacterial and fungal communities in the conjunctival tissue of diabetic mice compared to control mice. The study also highlighted interactions between bacteria and fungi at different taxonomic levels. These findings may have implications for the diagnosis and treatment of diabetes.

Electroacupuncture regulates the P2X7R-NLRP3 inflammatory cascade to relieve decreased sensation on ocular surface of type 2 diabetic rats with dry eye

Dry eye (DE) is a prevalent ocular surface disease in patients with type 2 diabetes (T2DM). However, current medications are ineffective against decreased sensation on the ocular surface. While electroacupuncture (EA) effectively alleviates decreased sensation on ocular surface of DE in patients with T2DM, the neuroprotective mechanism remains unclear. This study explored the pathogenesis and therapeutic targets of T2DM-associated DE through bioinformatics analysis. It further investigated the underlying mechanism by which EA improves decreased sensation on the ocular surface of DE in rats with T2DM. Bioinformatic analysis was applied to annotate the potential pathogenesis of T2DM DE. T2DM and DE was induced in male rats. Following treatment with EA and fluorometholone, comprehensive metrics were assessed. Additionally, the expression patterns of key markers were studied. Key targets such as NLRP3, Caspase-1, and NOD-like receptor signaling may be involved in the pathogenesis of T2DM DE. EA treatment improved ocular measures. Furthermore, EA potently downregulated P2X7R, NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), and Caspase-1 expression within the trigeminal ganglion and spinal trigeminal nucleus caudalis. Targeted P2X7R antagonist (A-438079) and agonist (BzATP) employed as controls to decipher the biochemistry of the therapeutic effects of EA showed an anti-inflammatory effect with A-438079, while BzATP blocked the anti-inflammatory effect of EA. EA relieved DE symptoms and attenuated inflammatory damage to sensory nerve pathways in T2DM rats with DE. These findings suggest a crucial role of EA inhibition of the P2X7R-NLRP3 inflammatory cascade to provide these benefits.

Ocular Surface Disease as Extraesophageal Gastroesophageal Reflux Disease Manifestation: A Specific Therapeutic Strategy

PURPOSE

Gastroesophageal reflux disease (GERD) and laryngopharyngeal reflux (LPR) are common gastrointestinal disorders with extraesophageal manifestations (EGERD). Studies showed a correlation between GERD/LPR and ocular discomfort. Our aim was to report the prevalence of ocular involvement in patients with GERD/LPR, describe clinical and biomolecular manifestations, and provide a treatment strategy for this novel EGERD comorbidity.

METHODS

Fifty-three patients with LPR and 25 healthy controls were enrolled in this masked randomized controlled study. Fifteen naive patients with LPR were treated with magnesium alginate eye drops and oral therapy (magnesium alginate and simethicone tablets) with a 1-month follow-up. Clinical ocular surface evaluation, Ocular Surface Disease Index questionnaire, tear sampling, and conjunctival imprints were performed. Tear pepsin levels were quantified by ELISA. Imprints were processed for human leukocyte antigen-DR isotype (HLA-DR) immunodetection and for HLA-DR, IL8, mucin 5AC (MUC5AC), nicotine adenine dinucleotide phosphate (NADPH), vasoactive intestinal peptide (VIP), and neuropeptide Y (NPY) transcript expression (PCR).

RESULTS

Patients with LPR had significantly increased Ocular Surface Disease Index ( P < 0.05), reduced T-BUT ( P < 0.05), and higher meibomian gland dysfunction ( P < 0.001) compared with controls. After treatment, tear break-up time (T-BUT) and meibomian gland dysfunction scores improved to normal values. Pepsin concentration increased in patients with EGERD ( P = 0.01) and decreased with topical treatment ( P = 0.0025), significantly. HLA-DR, IL8, and NADPH transcripts were significantly increased in the untreated versus controls and comparable significant values were obtained after treatment ( P < 0.05). MUC5AC expression significantly increased with treatment ( P = 0.005). VIP transcripts were significantly higher in EGERD than in controls and decreased with the topical treatment ( P < 0.05). No significant changes were observed in NPY.

CONCLUSIONS

We report an increase in prevalence of ocular discomfort in patients with GERD/LPR. The observations of VIP and NPY transcripts demonstrate the potential neurogenic nature of the inflammatory state. Restoration of the ocular surface parameters suggests the potential usefulness of topical alginate therapy.

The Role of Insulin-like Growth Factor (IGF) System in the Corneal Epithelium Homeostasis-From Limbal Epithelial Stem Cells to Therapeutic Applications

The corneal epithelium, comprising three layers of cells, represents the outermost portion of the eye and functions as a vital protective barrier while concurrently serving as a critical refractive structure. Maintaining its homeostasis involves a complex regenerative process facilitated by the functions of the lacrimal gland, tear film, and corneal nerves. Crucially, limbal epithelial stem cells located in the limbus (transitional zone between the cornea and the conjunctiva) are instrumental for the corneal epithelium integrity by replenishing and renewing cells. Re-epithelialization failure results in persistent defects, often associated with various ocular conditions including diabetic keratopathy. The insulin-like growth factor (IGF) system is a sophisticated network of insulin and other proteins essential for numerous physiological processes. This review examines its role in maintaining the corneal epithelium homeostasis, with a special focus on the interplay with corneal limbal stem cells and the potential therapeutic applications of the system components.

Diabetic corneal neuropathy and its relation to the severity of retinopathy in patients with type 2 diabetes mellitus: an in vivo confocal microscopy study

PURPOSE

To investigate corneal neuropathy and corneal nerve alterations in type 2 diabetes mellitus (DM) patients with different diabetic retinopathy (DR) status.

METHODS

A total of 87 eyes of 87 patients with DM and 28 eyes of 28 healthy control subjects were included in the study. DM patients were further classified into 3 groups: patients without DR (NDR), patients with non-proliferative DR (NPDR), and patients with proliferative DR (PDR). PDR patients were classified into 2 groups regarding having undergone retinal argon laser photocoagulation treatment (ALP). Ocular surface disease index score (OSDI), average tear break-up time (A-BUT), corneal sensitivity and cornea nerve fiber length (CNFL), cornea nerve fiber density (CNFD), and cornea nerve branch density (CNBD) of the cornea subbasal nerve plexus (SBNP) were measured using in vivo confocal microscopy (IVCM).

RESULTS

OSDI scores increased and A-BUT decreased in DM patients compared to the control group, but no significant difference was found between DM patient groups. Corneal sensitivity decreased in DM patients who developed DR, compared to both the controls and the NDR group. CNFD and CNFL decreased in NPDR and PDR patients compared to controls. CNFD and CNBD decreased in patients who had developed PDR, compared to all three groups. All IVCM parameters decreased with DR progression.

CONCLUSION

IVCM can detect early structural corneal nerve changes in diabetic patients. The presence of DM affects ocular surface parameters, especially in long-term DM patients. Corneal sensitivity loss is increased with the presence of DR. All IVCM parameters decrease with DR development and its progression.

One Soul and Several Faces of Evaporative Dry Eye Disease

The ocular surface system interacts with, reacts with, and adapts to the daily continuous insults, trauma, and stimuli caused by direct exposure to the atmosphere and environment. Several tissue and para-inflammatory mechanisms interact to guarantee such an ultimate function, hence maintaining its healthy homeostatic equilibrium. Evaporation seriously affects the homeostasis of the system, thereby becoming a critical trigger in the pathogenesis of the vicious cycle of dry eye disease (DED). Tear film lipid composition, distribution, spreading, and efficiency are crucial factors in controlling water evaporation, and are involved in the onset of the hyperosmolar and inflammatory cascades of DED. The structure of tear film lipids, and subsequently the tear film, have a considerable impact on tears' properties and main functions, leading to a peculiar clinical picture and specific management.

Comparison of Subjective Responses to Cyclosporine 0.05% Versus Lifitegrast 5.0% in Individuals With Dry Eye Disease

PURPOSE

The aim of the study was to examine subjective responses to cyclosporine A (CsA) 0.05% versus lifitegrast 5% in individuals with dry eye disease.

METHODS

This study was a retrospective review of individuals with clinically diagnosed dry eye disease treated with both CsA 0.05% and lifitegrast 5% over the course of their disease. Information collected included demographics, comorbidities, and dry eye disease signs. Treatment preferences were noted as mild or strong for a particular medication, no preference, or unable to tolerate either medication. The primary outcome measure was patient-reported medication preference. The secondary outcome measure was an examination of individual and eye factors that related to medication preference.

RESULTS

Sixty-four individuals (mean age 66.73 ± 13.17 years; 82.8% male, 71.9% White, 29.7% Hispanic) used both CsA and lifitegrast over the course of their disease. Of those, 33 preferred CsA (12.5% mildly and 39.1% strongly), 14 preferred lifitegrast (3.1% mildly and 18.8% strongly), 12 had no preference (18.8%), and 5 could not tolerate either medication (7.8%) due to side effects. No demographic characteristics, comorbidities, or ocular surface findings correlated with medication preference.

CONCLUSIONS

In individuals who used both CsA 0.05% and lifitegrast 5% over the course of their disease, a higher frequency of individuals preferred CsA. No clinical factors correlated with medication preference.

The role of the JAK/STAT3 signaling pathway in acquired corneal diseases

Acquired corneal diseases such as dry eye disease (DED), keratitis and corneal alkali burns are significant contributors to vision impairment worldwide, and more effective and innovative therapies are urgently needed. The Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signaling pathway plays an indispensable role in cell metabolism, inflammation and the immune response. Studies have shown that regulators of this pathway are extensively expressed in the cornea, inducing significant activation of JAK/STAT3 signaling in specific acquired corneal diseases. The activation of JAK/STAT3 signaling contributes to various pathophysiological processes in the cornea, including inflammation, neovascularization, fibrosis, and wound healing. In the context of DED, the hypertonic environment activates JAK/STAT3 signaling to stimulate corneal inflammation. Inflammation and injury progression in infectious keratitis can also be modulated by JAK/STAT3 signaling. Furthermore, JAK/STAT3 signaling is involved in every stage of corneal repair after alkali burns, including acute inflammation, angiogenesis and fibrosis. Treatments modulating JAK/STAT3 signaling have shown promising results in attenuating corneal damage, indicating its potential as a novel therapeutic target. Thus, this review emphasizes the multiple roles of the JAK/STAT3 signaling pathway in common acquired corneal disorders and summarizes the current achievements of JAK/STAT3-targeting therapy to provide new insights into future applications.

Impact of Peripheral and Corneal Neuropathy on Markers of Ocular Surface Discomfort in Diabetic Chronic Kidney Disease

SIGNIFICANCE

There is a reduction in corneal nerve fiber density and length in type 2 diabetes mellitus with chronic kidney disease compared with type 2 diabetes mellitus alone; however, this difference does not result in worse ocular surface discomfort or dry eye disease.

PURPOSE

This study aimed to determine the clinical impact of corneal nerve loss on ocular surface discomfort and markers of ocular surface homeostasis in people with type 2 diabetes mellitus without chronic kidney disease (T2DM-no CKD) and those with type 2 diabetes mellitus with concurrent chronic kidney disease (T2DM-CKD).

METHODS

Participants were classified based on estimated glomerular filtration rates into two groups: T2DM-CKD (n = 27) and T2DM-no CKD (n = 28).

RESULTS

There was a significant difference between the T2DM-CKD and T2DM-no CKD groups in corneal nerve fiber density (14.9 ± 8.6 and 21.1 ± 7.1 no./mm 2 , respectively; P = .005) and corneal nerve fiber length (10.0 ± 4.6 and 12.3 ± 3.7 mm/mm 2 , respectively; P = .04). Fluorescein tear breakup time was significantly reduced in T2DM-CKD compared with T2DM-no CKD (8.1 ± 4.4 and 10.7 ± 3.8 seconds, respectively; P = .01), whereas ocular surface staining was not significantly different (3.5 ± 1.7 and 2.7 ± 2.3 scores, respectively; P = .12). In terms of ocular surface discomfort, there were no significant differences in the ocular discomfort score scores (12.5 ± 11.1 and 13.6 ± 12.1, respectively; P = .81) and Ocular Pain Assessment Survey scores (3.3 ± 5.4 and 4.3 ± 6.1, respectively; P = .37) between the T2DM-CKD and T2DM-no CKD.

CONCLUSIONS

The current study demonstrated that corneal nerve loss is greater in T2DM-CKD than in T2DM-no CKD. However, these changes do not impact ocular surface discomfort or markers of ocular surface homeostasis.

A Narrative Review of STAT Proteins in Diabetic Retinopathy: From Mechanisms to Therapeutic Prospects

Diabetic retinopathy (DR), a blinding disease, is one of the high-incidence chronic complications of diabetes. However, the current treatment for DR is mainly based on advanced pathological changes, which cannot reverse pre-existing retinal tissue damage and visual impairment. Signal transducer and activator of transcription (STAT) proteins are essential in DR through early and late stages. They participate in the early stage of DR through multiple mechanisms and have a strong proangiogenic effect in the late stage. Inhibiting STAT proteins activity has also achieved a significant effect in reversing the pathological changes of DR. Thus, STAT proteins are expected to be an effective therapeutic target in the early stage of DR and can make up for inadequate late treatment. This review introduces the structure, signal transduction mode, and biological functions of STAT proteins in detail and focuses on their role in the mechanism of DR. We also summarize the current research on STAT-related biological agents in DR, aiming to provide a theoretical basis for the treatment of DR.

Immunomodulatory Role of Neuropeptides in the Cornea

The transparency of the cornea along with its dense sensory innervation and resident leukocyte populations make it an ideal tissue to study interactions between the nervous and immune systems. The cornea is the most densely innervated tissue of the body and possesses both immune and vascular privilege, in part due to its unique repertoire of resident immune cells. Corneal nerves produce various neuropeptides that have a wide range of functions on immune cells. As research in this area expands, further insights are made into the role of neuropeptides and their immunomodulatory functions in the healthy and diseased cornea. Much remains to be known regarding the details of neuropeptide signaling and how it contributes to pathophysiology, which is likely due to complex interactions among neuropeptides, receptor isoform-specific signaling events, and the inflammatory microenvironment in disease. However, progress in this area has led to an increase in studies that have begun modulating neuropeptide activity for the treatment of corneal diseases with promising results, necessitating the need for a comprehensive review of the literature. This review focuses on the role of neuropeptides in maintaining the homeostasis of the ocular surface, alterations in disease settings, and the possible therapeutic potential of targeting these systems.

Tear film and ocular surface neuropeptides: Characteristics, synthesis, signaling and implications for ocular surface and systemic diseases

Ocular surface neuropeptides are vital molecules primarily involved in maintaining ocular surface integrity and homeostasis. They also serve as communication channels between the nervous system and the immune system, maintaining the homeostasis of the ocular surface. Tear film and ocular surface neuropeptides have a role in disease often due to abnormalities in their synthesis (either high or low production), signaling through defective receptors, or both. This creates imbalances in otherwise normal physiological processes. They have been observed to be altered in many ocular surface and systemic diseases including dry eye disease, ocular allergy, keratoconus, LASIK-induced dry eye, pterygium, neurotrophic keratitis, corneal graft rejection, microbial keratitis, headaches and diabetes. This review examines the characteristics of neuropeptides, their synthesis and their signaling through G-protein coupled receptors. The review also explores the types of neuropeptides within the tears and ocular surface, and how they change in ocular and systemic diseases.

[Modern capabilities in diagnosis and treatment of neurotrophic keratopathy]

In recent years, the problem of diagnosing and treating neurotrophic keratopathy (NK) has become relevant in view of its prevalence reaching 1.6-11.0 per 10000 people. While previously it was associated only with neuroparalytic keratitis, at present the violation of sensitive and trophic innervation of the cornea with the development of characteristic keratopathy is observed in many diseases and injuries of the organ of vision. Diagnosis of NK is based on anamnestic information and assessment of clinical and functional parameters: determination of the stability of the tear film, tear production and assessment of staining of the ocular surface with vital dyes. The main role in the diagnosis of NK belongs to corneal sensitivity determined with the Cochet-Bonnet esthesiometer. Treatment of NK is designed to restore or increase corneal sensitivity and involves tear replacement therapy, instillations of preparations derived from patient's own blood, anti-inflammatory, metabolic and antibacterial therapy. However, instillations of human erve growth factor (NGF) - the drug Cenegermin (registered in Europe in 2017 at a dose of 20 μg/ml under the name Oxervate), a recombinant form of human rhNGF from Escherichia coli bacteria - exhibit the highest pathogenetic orientation. Its «target» is the affected nerve fibers (specific receptors for their growth factor), which makes it possible to eliminate the violation of reparative processes in neural and epithelial cells. A high and long-term clinical efficacy of a course of six (with an interval of 2 hours) instillations of the drug for 8 weeks in the treatment of children and adults with NK has been established. Among the pathogenetically justified methods of surgical treatment, there is the so-called surgical neurotization of the cornea involving the contralateral supraorbital, supratrochlear, great auricular and other nerves, which has a long-term clinical effect.

Ocular Surface Failure in Urban Syndrome

BACKGROUND

Nowadays, the continuous increase in air pollution has significantly changed air quality, leading to the onset of the so-called urban syndrome (US), an allergic-like conjunctivitis triggered by pollutants. These patients are characterized by persistent dysregulation of ocular surface para-inflammation, causing chronic low-grade inflammation and ocular discomfort, with significant consequences for occupational health and job productivity prospects. This study aims to investigate the effects of topical glycerophosphoinositol (GPI) eye drops on the signs and symptoms of US.

METHODS

A multicenter prospective open interventional study was performed. Patients affected by US, enrolled from occupational medicine clinics, were treated with eye drops containing 0.001% GPI in 0.2% HA vehicle three times a day. Ocular surface disease index (OSDI), tear break-up time (T-BUT), Schirmer test, Oxford score, hyperemia and ocular surface symptoms were recorded at patient enrolment (T0), after 1 week (T1) and after 1 month (T2) of treatment.

RESULTS

A total of 113 consecutive patients (226 eyes) were included. OSDI score displayed a significant improvement after one week (T0: 39.9 ± 19, T1: 20.8 ± 17.9, T2: 18.4 ± 15.6, p < 0.0001); T-BUT (T0: 5.2 ± 2, T1: 7.7 ± 2.2, T2: 9.7 ± 1.8, p < 0.0001) and Schirmer Test (T0: 6.6 ± 2.4, T1: 9.7 ± 2.7, T2: 12.6 ± 2.6, p < 0.0001) progressively improved from T0 to T2.

CONCLUSIONS

trice-daily topic instillation of 0.001% GPI in 0.02% HA vehicle resulted an effective and well tolerated treatment in US patients.

Sex Hormones Related Ocular Dryness in Breast Cancer Women

Background: Dry eye syndrome (DES) is strictly connected to systemic and topical sex hormones. Breast cancer treatment, the subsequent hormonal therapy, the subsequent hyperandrogenism and the early sudden menopause, may be responsible for ocular surface system failure and its clinical manifestation as dry eye disease. This local dryness is part of the breast cancer iatrogenic dryness, which affects overall mucosal tissue in the fragile population of those with breast cancer. Methods: A literature review regarding the role of sex hormone changes and systemic hormonal replacement treatments (SHRT) in DES available on PubMed and Web of Science was made without any restriction of language. Results: Androgens exert their role on the ocular surface supporting meibomian gland function and exerting a pro-sebaceous effect. Estrogen seems to show a pro/inflammatory role on the ocular surface, while SHRT effects on dry eye are still not well defined, determining apparently contradictory consequences on the ocular surface homeostasis. The role of sex hormones on dry eye pathogenesis is most likely the result of a strict crosstalk between the protective androgens effects and the androgen-modulating effects of estrogens on the meibomian glands. Conclusions: Patients with a pathological or iatrogenic hormonal imbalance, such as in the case of breast cancer, should be assessed for dry eye disease, as well as systemic dryness, in order to restore their social and personal quality of life.

The two-faced effects of nerves and neuropeptides in corneal diseases

Corneal nerves are instrumental to maintain cornea integrity through regulation of key physiological functions such as tear secretion, blink reflex, and neuropeptide turnover. Corneal nerve injury/stimulation can follow many insults including mechanical/chemical trauma, infections and surgeries. Nerve disruption initiates a process named neurogenic inflammation which leads to edema, pain, and recruitment and activation of leukocytes. Interestingly, leukocyte influx in the cornea can further damage nerves by releasing inflammatory mediators-including neuropeptides. The clinical outcome of neuroinflammation can be beneficial or detrimental to corneal integrity. On one side, it ensures prompt wound healing and prevents infections. On the other, prolonged and/or deranged neuroinflammation can permanently disrupt corneal integrity and impair vision. The cornea is an ideal site to study peripheral neuroinflammation and neurogenic inflammation since it receives the highest density of sensory nerves of the entire body. We will review the corneal nerve anatomy and neurochemistry, discuss the beneficial and detrimental effects of neurogenic inflammation in corneal wound healing, inflammatory processes, and pain. We will also examine the emerging remote impact of corneal nerve disruption on the trigeminal ganglion and the brain, highlighting the key role of neuropeptide Substance P. Finally, we will discuss the clinical relevance of such neuroinflammatory network in the context of severe and highly prevalent ocular diseases, including potential treatments.

An Analysis of the Areas Occupied by Vessels in the Ocular Surface of Diabetic Patients: An Application of a Nonparametric Tilted Additive Model

(1) Background: As diabetes melllitus (DM) can affect the microvasculature, this study evaluates different clinical parameters and the vascular density of ocular surface microvasculature in diabetic patients. (2) Methods: In this cross-sectional study, red-free conjunctival photographs of diabetic individuals aged 30-60 were taken under defined conditions and analyzed using a Radon transform-based algorithm for vascular segmentation. The Areas Occupied by Vessels (AOV) images of different diameters were calculated. To establish the sum of AOV of different sized vessels. We adopt a novel approach to investigate the association between clinical characteristics as the predictors and AOV as the outcome, that is Tilted Additive Model (TAM). We use a tilted nonparametric regression estimator to estimate the nonlinear effect of predictors on the outcome in the additive setting for the first time. (3) Results: The results show Age (p-value = 0.019) and Mean Arterial Pressure (MAP) have a significant linear effect on AOV (p-value = 0.034). We also find a nonlinear association between Body Mass Index (BMI), daily Urinary Protein Excretion (UPE), Hemoglobin A1C, and Blood Urea Nitrogen (BUN) with AOV. (4) Conclusions: As many predictors do not have a linear relationship with the outcome, we conclude that the TAM will help better elucidate the effect of the different predictors. The highest level of AOV can be seen at Hemoglobin A1C of 9% and AOV increases when the daily UPE exceeds 600 mg. These effects need to be considered in future studies of ocular surface vessels of diabetic patients.

Corneal neurotization for neurotrophic keratopathy: Review of surgical techniques and outcomes

Neurotrophic keratopathy is a degenerative disease in which damage to the corneal nerves leads to corneal hypoesthesia. Injuries to neurotrophic corneas are notoriously difficult to treat and have traditionally been approached with supportive management. However, recent progress in the field of corneal neurotization has given new direction for addressing nerve loss directly by stimulating new nerve growth onto the cornea from nearby sensory nerves transferred to the perilimbal region. Herein, we review the surgical techniques utilized in corneal neurotization, including direct transfers and the use of nerve grafts. Considerations in surgical approach, as well as factors that influence prognosis and outcomes of the surgical intervention are also discussed.