Diabetes mellitus is associated with dry eye syndrome: a meta-analysis

Molecular mechanism of Wilms tumour 1-associated protein in diabetes-related dry eye disease by mediating m6A methylation modification of lncRNA NEAT1

Background: Dry eye disease (DED) is often secondary to diabetes mellitus (DM).Purpose: This study is to explore the action of Wilms tumor 1-associated protein (WTAP) in DM-DED via lncRNA NEAT1 m6A methylation.Methods: DM-DED mouse models were treated with sh-WTAP/sh-NEAT1, followed by assessment of corneal epithelial damage/histopathological changes. HCE-2 cells were exposed to hyperosmotic conditions to establish in vitro DED models and treated with oe-NEAT1/sh-NEAT1/sh-WTAP/nigericin (an NLRP3 inflammasome inducer). Cell viability/apoptosis were evaluated by CCK-8/TUNEL. Levels of WTAP/NEAT1/inflammatory factors/NLRP3 inflammasome- and apoptosis-related markers were determined. m6A modification was examined by MeRIP-qPCR and NEAT1 stability was also detected.Results: DM-DED mice exhibited up-regulated WTAP/NEAT1 expression and severe corneal damage, whereas WTAP/NEAT1 knockdown alleviated inflammation/corneal damage. In hyperosmolarity-induced HCE-2 cells, NEAT1 aggravated inflammation and apoptosis, while NEAT1 knockdown suppressed NLRP3 inflammasome activation and ameliorated cell injury. Hyperosmolarity-induced WTAP expression increased m6A modification and NEAT1 mRNA stability. WTAP mediated m6A methylation of NEAT1 and NLRP3 inflammasome activation in DM-DED mice.

Increased expression of neutrophil CD15 correlates with the severity of anterior ocular surface damage in type II diabetes mellitus

BACKGROUND

Diabetes mellitus is associated with increased risk of ocular surface diseases in elderly. We consider neutrophil CD15 as a potential marker of ocular surface damage in type II diabetes mellitus patients.

AIM

We aimed to evaluate expression of neutrophil CD15 and correlate it with results of conjunctival impression cytology and routine objective anterior ocular surface tests (TMH, NIBUT, LLT, MGD) in T2DM patients.

MATERIALS AND METHODS

We prospectively enrolled sixty type II diabetes mellitus patients (120 eyes) into a study group. The control group included forty (80 eyes) age- and sex-matched healthy individuals. All patients underwent comprehensive ophthalmological examination, and tear meniscus height test (TMH), noninvasive tear break-up time (NIBUT), lipid layer thickness measurement (LLT), Meibomian gland dysfunction evaluation (MGD), conjunctival impression cytology (CIC) and expression of CD15.

RESULTS

Abnormal Nelson's grades of squamous metaplasia (grades 2 and 3) were observed in 50% (60 eyes) of the study group, and 13.8 (11 eyes) of the control group. Fifteen patients with type II diabetes mellitus suffered from grade 3 squamous metaplasia. Nelson's grades of squamous metaplasia have shown a positive correlation with the level of CD15 expression either in the study and control groups (rs = 0.628, p = <0.0001; rs = 0.746, p < 0.0001; respectively).

CONCLUSIONS

The research shows significantly reduced values of routine objective ocular tests in type II diabetes mellitus patients in comparison to healthy participants older than 60 y.o. Increased CD15 in the peripheral blood is associated with the development of squamous metaplasia and may be used to evaluate the severity of ocular surface damage in type II diabetes mellitus patients.

Understanding Ocular Graft-Versus-Host Disease to Facilitate an Integrated Multidisciplinary Approach

Ocular Graft-versus-Host Disease (oGVHD) remains a challenging and potentially devastating complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT). It significantly impacts the quality of life of affected survivors, however, is often underrecognized particularly during the early stages. Targeting all providers in the HSCT community who see patients regularly and frequently for their post-allo-HSCT care, this review and opinion piece introduces the basic concepts of ocular surface pathophysiology, dissects the different stages of clinical presentation of oGVHD, explains why the current diagnostic criteria tend to capture the late disease stages, highlights the warning signs of early disease development, in hope to facilitate prompt referral of oGVHD suspects for ocular specialist care. In addition to introducing a comprehensive list of treatment options, this review emphasizes basic therapeutic strategy and options that are safe and effective to be initiated by any care provider. We believe in empowering the patients as well as the care providers beyond disciplinary boundaries, in order to provide the most cohesive and integrated care to our patients in a multidisciplinary approach.

Effects of Diquafosol Sodium Ophthalmic Solution on Tear Film Matrix Metallopeptidase-9 and Corneal Nerve Density in Patients with Type 2 Diabetic Dry Eye

Purpose: Diabetes mellitus has been associated with increased dry eye disease (DED) and exacerbates DED's pathology. This preliminary short-term study aimed to evaluate the effects of 3% Diquafosol Sodium ophthalmic solution (DQS) on ocular surface inflammation and corneal nerve density in diabetic dry eye (DDE) patients. Methods: In this perspective, participants used 1 drop of 3% DQS (Diquas; Santen Pharmaceutical Co., Ltd., Osaka, Japan) 6 times daily for 8 weeks. Non-invasive tear breakup time (NITBUT), tear film lipid layer (TFLL), conjunctival hyperemia [redness score (RS)], corneoconjunctival staining (CFS), corneal sensitivity (CS), Meibomian gland quality (MGQ) and Meibomian gland expressibility (MGEx), corneal nerve fiber density (CNFD), and Standard Patient Evaluation Eye Dryness (SPEED) questionnaire were assessed at baseline, at weeks 4, and up to 8 weeks. Matrix metalloproteinase-9 (MMP-9) of tear samples was measured at baseline and weeks 8. Results: The mean age was 61.27 ± 11.68 years. At baseline NITBUT = 5.89 ± 2.81 s, tear meniscus height = 0.17 ± 0.05 mm, TFLL = 2.74 ± 0.51, CFS = 4.35 ± 0.68, CS = 53.83 ± 9.63 mm, MMP-9 = 49.10 ± 10.42 ng/mL, RS = 1.65 ± 0.44, MGEx = 1.85 ± 0.72, MGQ = 2.65 ± 0.50, CNFD = 20.36 ± 8.20 no./mm2, and SPEED = 12.62 ± 3.91. At week 4, significant improvements were found in all parameters except RS (1.59 ± 0.46, P = 0.172) and CNFD (21.46 ± 8.41, P = 0.163). Finally, at week 8, all parameters had significant improvements. Conclusion: Preliminary short-term findings suggest that treatment of DDE patients with DQS was found to be safe and efficacious in improving dry eye parameters. In addition, inflammatory marker and corneal nerve density were significantly improved. This study was registered with ClinicalTrials.gov (NCT05193331).

Tear Fluid Progranulin as a Noninvasive Biomarker for the Monitoring of Corneal Innervation Changes in Patients With Type 2 Diabetes Mellitus

Purpose

This study aimed to investigate the expression levels of progranulin (PGRN) in the tears of patients with diabetic retinopathy (DR) versus healthy controls. Additionally, we sought to explore the correlation between PGRN levels and the severity of ocular surface complications in patients with diabetes.

Methods

In this prospective, single-visit, cross-sectional study, patients with DR (n = 48) and age-matched healthy controls (n = 22) were included and underwent dry eye examinations. Tear fluid was collected, and its components were analyzed using the Luminex assay. The subbasal nerve plexus of all participants was evaluated by in vivo confocal microscopy.

Results

Patients with DR exhibited more severe dry eye symptoms, along with a reduction in nerve fiber density, length, and branch density within the subbasal nerve plexus, accompanied by an increase in the number of dendritic cells. Tear PGRN levels were also significantly lower in patients with diabetes than in normal controls, and the levels of some inflammatory factors (TNF-α, IL-6, and MMP-9) were higher in patients with DR. Remarkably, the PGRN level significantly correlated with nerve fiber density (R = 0.48, P < 0.001), nerve fiber length (R = 0.65, P < 0.001), and nerve branch density (R = 0.69, P < 0.001).

Conclusions

Tear PGRN levels might reflect morphological changes in the corneal nerve plexus under diabetic conditions, suggesting that PGRN itself is a reliable indicator for predicting the advancement of neurotrophic keratopathy in patients with diabetes.

Translational Relevance

PGRN insufficiency on the ocular surface under diabetic conditions was found to be closely associated with nerve impairment, providing a novel perspective to discover the pathogenesis of diabetic complications, which could help in developing innovative therapeutic strategies.

Fosfenopril Attenuates Inflammatory Response in Diabetic Dry Eye Models by Inhibiting the TLR4/NF-κB/NLRP3 Signaling Pathway

Purpose

The purpose of this study was to investigate the involvement of the TLR4/NF-κB/NLRP3 signaling pathway and its underlying mechanism in diabetic dry eye.

Methods

Two models of diabetic dry eye were established in high glucose-induced human corneal epithelial (HCE-T) cells and streptozotocin (STZ)-induced C57BL/6 mice, and the TLR4 inhibitor fosfenopril (FOS) was utilized to suppress the TLR4/NF-κB/NLRP3 signaling pathway. The expression changes in TLR4, NF-κB, NLRP3, and IL-1β, and other factors were detected by Western blot and RT‒qPCR, the wound healing rate was evaluated by cell scratch assay, and the symptoms of diabetic mice were evaluated by corneal sodium fluorescein staining and tear secretion assay.

Results

In the diabetic dry eye model, the transcript levels of TLR4, NF-κB, NLRP3, and IL-1β were raised, and further application of FOS, a TLR4 inhibitor, downregulated the levels of these pathway factors. In addition, FOS was found to be effective in increasing the wound healing rate of high glucose-induced HCE-T cells, increasing tear production, and decreasing corneal fluorescence staining scores in diabetic mice, as measured by cell scratch assay, corneal sodium fluorescein staining assay, and tear production.

Conclusions

The current study found that the TLR4/NF-κB/NLRP3 signaling pathway regulates diabetic dry eye in an in vitro and in vivo model, and that FOS reduces the signs of dry eye in diabetic mice, providing a new treatment option for diabetic dry eye.

Assessment of the systemic immune-inflammation index in type 2 diabetic patients with and without dry eye disease: A case-control study

Background

The inflammation plays a role in the pathophysiology of type-2 diabetes progression, and the mechanism remains unclear. The systemic immune-inflammation index (SII) is a novel inflammatory marker for type 2 diabetes patients and integrates multiple indicators in complete blood counts and routine blood tests.

Aim

Since there is no international diagnostic standard for dry eye disease (DED), this study uses low-cost inflammatory blood biomarkers to investigate the correlation between SII and DM2-DED and determine the diagnosis indices of other biomarkers in DM2-DED.

Methodology

A case-control retrospective analysis of totel patients n = 293 randomly selected and categorized into four groups: DED, DM2, DM2-DED, and healthy subjects. Demographic and blood biomarker variables were classified as categorical and continuous variables. The platelet-to-lymphocyte ratio (PLR), lymphocytes-to-lymphocyte ratio, neutrophil-to-lymphocyte ratio (NLR), and SII were calculated platelet count multiply by NLR and analyzed for their correlation for all groups.

Results

Focusing on DM2-DED patients was more common in females, 59.6%, than in males, 40.2%. The mean ages were 60.7 ± 11.85 years, a statistically significant difference with all groups. In the study group DM2-DED, there was an increase in all blood markers compared to all remaining groups except PLR. Only neutrophil, hemoglobin A1c (HbA1c), and fasting blood sugar levels were statistically significant differences in DM2-DED patients (p > 0.001, p < 0.001, and p < 0.001, respectively) compared to all groups. There was a positive correlation between HbA1c and PLR, HbA1c and NLR, and HbA1c and SII (r = 0.037, p = 0.705; r = 0.031, p = 0.754; and r = 0.066, p < 0.501, respectively) in the DM2-DED group.

Conclusion

This study demonstrated that elevated SII values were linked to elevated HbA1c in DM2-DED patients. The potential of SII and HbA1c as early diagnostic indicators for ocular problems associated with diabetes mellitus is highlighted by their favorable connection in diagnosing DM2-DED.

Association of self-reported psychiatric and systemic risk factors in dry eye disease in adult Korean population

PURPOSE

To evaluate the association between dry eye disease (DED) and various psychiatric and systemic diseases in an adult Korean population aged 40 years or older.

METHODS

Population-based cross-sectional data of 6,732 participants aged ≥40 years was extracted from the Korea National Health and Nutrition Examination Survey 2017-2018 (KNHANES VII). Data including DED, demographic variables, behavioral factors, psychiatric conditions, and systemic diseases was analysed to determine the prevalence and psychiatric and systemic risk factors for DED.

RESULTS

The weighted prevalence of DED was 7.9 ± 0.4% (mean ± SE). Multivariate analysis showed that female sex and urban residence were associated with an increased risk of DED. The prevalence of DED was lower in patients aged ≥70 years than in those aged 40-69 years. Self-reported psychological conditions including perceived stress and depression were associated with the risk of DED. Self-reported Systemic conditions, such as rheumatoid arthritis, degenerative arthritis, osteoporosis, ischemic heart disease, and chronic renal failure had association with an increased risk of DED.

CONCLUSION

DED may be associated with several self-reported psychiatric and systemic conditions, which highlights the need for an integrated approach to manage these diseases for optimal treatment of DED.

A PEDF peptide mimetic effectively relieves dry eye in a diabetic murine model by restoring corneal nerve, barrier, and lacrimal gland function

PURPOSE

The study investigated effectiveness of a novel PEDF peptide mimetic to alleviate dry eye-like pathologies in a Type I diabetic mouse model established using streptozotocin.

METHODS

Mice were treated topically for 3-6 weeks with Ppx (a 17-mer PEDF mimetic) 2x/day or vehicle. Corneal sensitivity, tear film, epithelial and endothelial injury were measured using Cochet-Bonnet esthesiometer, phenol red cotton thread wetting, fluorescein sodium staining, and ZO1 expression, respectively. Inflammatory and parasympathetic nerve markers and activation of the MAPK/JNK pathways in the lacrimal glands were measured.

RESULTS

Diabetic mice exhibited features of dry eye including reduced corneal sensation and tear secretion and increased corneal epithelium injury, nerve degeneration, and edema. Ppx reversed these pathologies and restored ZO1 expression and morphological integrity of the endothelium. Upregulation of IL-1β and TNFα, increased activation of P-38, JNK, and ERK, and higher levels of M3ACHR in diabetic lacrimal glands were also reversed by the peptide treatment.

CONCLUSION

The study demonstrates that topical application of a synthetic PEDF mimetic effectively alleviates diabetes-induced dry eye by restoring corneal sensitivity, tear secretion, and endothelial barrier and lacrimal gland function. These findings have significant implications for the potential treatment of dry eye using a cost-effective and reproducible approach with minimal invasiveness and no obvious side effects.

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.

METHOD OF POVIDONE-IODINE APPLICATION AND ENDOPHTHALMITIS RISK

PURPOSE

To evaluate the proportion of patients developing endophthalmitis after intravitreal injection of anti-vascular endothelial growth factor agents according to the mode of povidone-iodine (PI) antisepsis.

METHODS

A retrospective review of the anti-vascular endothelial growth factor injections given in a 7-year period at a community-based retinal practice. Endophthalmitis was diagnosed to have occurred if an eye developed intraocular inflammation and was given antibiotics with or without supportive culture identification of an organism. As part of their habitual clinical practice, component physicians used 5% PI as two drops, one drop, or just a dot of PI administered with a cotton-tipped applicator to the site before injection.

RESULTS

There were 113,610 intravitreal injections administered and 23 cases were diagnosed with endophthalmitis over the 7-year period, for a rate of 1 case per 4,940 injections. The mode of PI antisepsis showed no significant relation to the rate of endophthalmitis ( P = 0.55, chi-square test). The proportion of endophthalmitis by physician demonstrated no significant difference ( P = 0.39, chi-square test).

CONCLUSION

The use of PI has been associated with decreased incidence of endophthalmitis, but the mode of application has not been standardized. The results of this study suggest that "more is not better" in PI antisepsis in endophthalmitis. Moreover, the toxicity of PI on the ocular surface is known to be dose-related.

Guideline for the Management of Diabetes Mellitus in the Elderly in China (2024 Edition)

With the deepening of aging in China, the prevalence of diabetes in older people has increased noticeably, and standardized diabetes management is critical for improving clinical outcomes of diabetes in older people. In 2021, the National Center of Gerontology, Chinese Society of Geriatrics, and Diabetes Professional Committee of Chinese Aging Well Association organized experts to write the first guideline for diabetes diagnosis and treatment in older people in China, the Guideline for the Management of Diabetes Mellitus in the Elderly in China (2021 Edition). The guideline emphasizes that older patients with diabetes are a highly heterogeneous group requiring comprehensive assessment and stratified and individualized management strategies. The guideline proposes simple treatments and de-intensified treatment strategies for older patients with diabetes. This edition of the guideline provides clinicians with practical and operable clinical guidance, thus greatly contributing to the comprehensive and full-cycle standardized management of older patients with diabetes in China and promoting the extensive development of clinical and basic research on diabetes in older people and related fields. In the past 3 years, evidence-based medicine for older patients with diabetes and related fields has further advanced, and new treatment concepts, drugs, and technologies have been developed. The guideline editorial committee promptly updated the first edition of the guideline and compiled the Guideline for the Management of Diabetes Mellitus in the Elderly in China (2024 Edition). More precise management paths for older patients with diabetes are proposed, for achieving continued standardization of the management of older Chinese patients with diabetes and improving their clinical outcomes.

Unique composition of ocular surface microbiome in the old patients with dry eye and diabetes mellitus in a community from Shanghai, China

BACKGROUND

This study investigates the variations in microbiome abundance and diversity on the ocular surfaces of diabetic patients suffering from dry eye within a community setting. The goal is to offer theoretical insights for the community-level prevention and treatment of dry eye in diabetic cohorts.

METHODS

Dry eye screening was performed in the Shanghai Cohort Study of Diabetic Eye Disease (SCODE) from July 15, 2021, to August 15, 2021, in the Xingjing community; this study included both a population with diabetes and a normal population. The population with diabetes included a dry eye group (DM-DE, n = 40) and a non-dry eye group (DM-NoDE, n = 39). The normal population included a dry eye group (NoDM-DE, n = 40) and a control group (control, n = 39). High-throughput sequencing of the 16 S rRNA V3-V4 region was performed on conjunctival swab from both eyes of each subject, and the composition of microbiome on the ocular surface of each group was analyzed.

RESULTS

Significant statistical differences were observed in both α and β diversity of the ocular surface microbiome among the diabetic dry eye, diabetic non-dry eye, non-diabetic dry eye, and normal control groups (P < 0.05).

CONCLUSIONS

The study revealed distinct microecological compositions on the ocular surfaces between the diabetic dry eye group and other studied groups. Firmicutes and Anoxybacillus were unique bacterial phyla and genera in the dry eye with DM group, while Actinobacteria and Corynebacterium were unique bacterial phyla and genera in the normal control group.

Prevalence and Risk Factors of Dry Eye Disease in Association With the Increased Use of Electronic Devices Among University Students in Western Saudi Arabia

AIM

Dry eye disease (DED) is a prevalent ocular condition that significantly impacts individuals' quality of life and performance. It is charac-terized by the instability of the tear film, which causes ocular surface inflamma-tion and damage that leads to ocular symptoms. However, this study aimed to determine the prevalence of DED and identify associated risk factors among university students in western Saudi Arabia.

METHODS

A total of 402 university students participated in this study. The sample size was determined using Raosoft software (Raosoft, Inc., Seattle, WA), considering an estimated student population of 20,000. Data were collected between January and March 2023 through an online questionnaire distributed to the participants. The questionnaire comprised three sections, covering general information, behaviors related to digital device (DD) use, and the validated Arabic version of the Ocular Surface Disease Index (OSDI) questionnaire. OSDI scores were calculated, and the severity of DED was categorized using established cutoff points.

RESULTS

Among the 402 university students who took part in the survey, the majority (63.2%) were aged between 21 and 25 years, with females representing the dominant gender (72.9%). Notably, 90.8% of participants reported using DDs at bedtime. Over 60% of students had been using DDs for more than 10 years, and approximately 61.7% reported having more than six hours of daily screen time. Mobile devices were the most commonly used electronic devices (67.2%), and TikTok emerged as the most frequently used application (35.6%). Based on the OSDI criteria, 21.1% of students had mild DED symptoms, 14.9% had moderate symptoms, and 38.6% had severe symptoms. Hence, the prevalence of students exhibiting positive DED symptoms was 74.6%, while 25.4% were negative.

Macrophage Migration Inhibitory Factor (MIF) is a Key Player in Dry Eye Disease

PURPOSE

To explore the role of the proinflammatory cytokine, macrophage migration inhibitory factor (MIF), in a murine model of dry eye disease (DED).

METHODS

The role of MIF on DED was determined using genetically MIF deficient mice and pharmacological inhibition of MIF. DED was induced with 0.5 mg of scopolamine via subcutaneous injection in wild type (WT) and mice lacking MIF (Mif-/-), three times a day for 21 days. DED signs, tear volume, ferning pattern and cytology impression were evaluated. Also, eye tissues were collected to determine transcripts of key inflammatory mediators and histopathological damage. In a second set of experiments, we neutralized MIF with ISO-1, an isozaxiline-derivative MIF tautomerase activity-inhibiting small molecule in WT mice, following an acute DED model for 10 days. ISO-1 was given starting on day 3 after DED induction and signs were evaluated, including a recovery phase in both experimental approaches.

RESULTS

When compared to WT, Mif-/- mice showed attenuated signs of DED like preserved mucin pattern and increased tear volume. Also, Mif-/- mice maintained conjunctival epithelial cells and less corneal damage, associated with lower levels of TNFα and IL-1β. At recovery phase, Mif-/- mice presented improved signs. Interestingly, in cornea and conjunctiva the absence of MIF selectively downregulated the transcription of inflammatory enzymes like inos and nox4 whereas displayed enhanced transcripts of il-4, il-13, tgfβ and cox2. Finally, pharmacological inhibition of MIF using ISO-1, replicated the above findings in the mouse model.

CONCLUSION

MIF is a central positive mediator of the inflammatory process in experimental DED, thus, targeting MIF could be used as a novel therapy in ocular surface inflammatory pathologies.

A protocol for a single center, randomized, controlled trial comparing the clinical efficacy of 3% diquafosol and 0.1% hyaluronic acid in diabetic patients with dry eye disease

BACKGROUND

The global prevalence of diabetes mellitus (DM) continues to rise and 70% of diabetic individuals have dry eye disease (DED) that leads to subsequent abnormalities of the corneal epithelium, corneal nerves, tear film, or corneal endothelium. In addition, persons with diabetes produce fewer tear secretions than healthy individuals. While several anti-inflammatory drug-based therapies for dry eye in diabetic individuals are currently being administered, their efficacy has not been studied in detail. Therefore, the aim of this study was to compare the effectiveness of 3% diquafosol (DQS) vs 0.1% hyaluronic acid (HA) eye drops in diabetic dry eye patients.

METHODS

This triple-blind randomized, control trial will include 202 diabetic-related DED and will be assigned to DQS (n = 101) and HA (n = 101) one drop, six times per day for 8 weeks. Tear film lipid layer, non-invasive breakup time, conjunctivocorneal staining score, corneal sensitivity, tear MMP-9 levels, meibomian gland expression and quality, tear meniscus height, corneal nerves, immune/inflammatory cell change, conjunctival hyperemia, and ocular surface disease index questionnaire score will be assessed and compared at baseline, week 4, and week 8.

DISCUSSION

This study will be a standardized, scientific, clinical trial designed to evaluate the therapeutic effects and safety of DQS and HA for diabetic dry eye treatment.

TRIAL REGISTRATION

ClinicalTrials.govNCT05682547. Registered on December 05, 2022.

Relationship between ocular surface pain and corneal nerve loss in dry eye diabetics: a cross-sectional study in Shenyang, China

BACKGROUND

Diabetes mellitus has been associated with increased dry eye disease (DED) and exacerbates DED pathology.

OBJECTIVE

To investigate the potential relationship between corneal nerve loss and ocular pain among diabetic patients with dry eye (DE).

DESIGN

A cross-sectional study.

SETTING

He Eye Specialist Hospital, Shenyang, China.

PARTICIPANTS

This study recruited 124 eyes of 62 diabetic patients diagnosed with DED between August and October 2022.

MAIN OUTCOME MEASURES

Best-corrected visual acuity, intraocular pressure, non-invasive tear breakup time, tear meniscus height, tear film lipid layer, conjunctival hyperaemia (redness score), conjunctivocorneal epithelial staining (CS score), central corneal sensitivity and vitro confocal corneal microscopy was assessed in all subjects. The Ocular Surface Disease Index Questionnaire assessed DE symptoms and ocular pain.

RESULTS

The study's final analysis included 26 patients (52 eyes) without ocular pain and 36 patients (72 eyes) with ocular pain. The corneal nerve fibre density (CNFD), corneal nerve branch density (CNBD) and corneal nerve fibre length (CNFL) in patients with ocular pain were significantly lower than those without (p<0.001, p=0.004, and p<0.001, respectively). CNFD, CNBD and CNFL negatively correlated with ocular pain (r=-0.385, r=-0.260, r=-0.358, respectively). Moreover, CNFD, CNBD and CNFL have a significant (p<0.05) positive correlation with corneal sensitivity (r=0.523, r=0.330, r=0.421, respectively).

CONCLUSIONS

Corneal nerve loss was associated with ocular pain and decreased corneal sensitivity in diabetic patients with DE. Further studies into the neurological role of ocular surface diseases can elaborate diagnostics, prognosis and treatment of diabetic patients with DE.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov (NCT05193331).

Prevalence and Determinants of Symptomatic Dry Eye Disease Among Adult Urban Residents of High-Altitude Areas of Southwest Saudi Arabia - A Survey

Purpose

To estimate the prevalence and determinants of Ocular Surface Disease Index (OSDI) score based dry eye disease (DED) among the adult urban population of four cities located at high altitudes in Southwest Saudi Arabia.

Methods

This cross-sectional survey was held in 2023. OSDI questionnaire was used to collect the responses of the adult participants. The score was further graded into none, mild, moderate, and severe DED to estimate age-sex-adjusted DED prevalence. The OSDI score was correlated to demographic (age group, gender, education, occupation, city) and risk factors like smoking and co-morbidities.

Results

Of the 401 adults, 388 (response rate of 97.8%) participated. The age-sex-adjusted prevalence of mild, moderate, and severe DED was 21.7%, 13.1%, and 32%, respectively. The median ODSI score was 22.9 [Interquartile range (IQR) 10.4; 47.9)]. The score was significantly higher in females (Mann-Whitney U-test P = 0.038), residents of Taif city (KW P = 0.05), those with primary/middle school education (Kruskal-Wallis P = 0.004), comorbidities like hypertension, asthma (KW P < 0.001) and risk factors like past refractive surgeries, arthritis (KW P = 0.013). Education status (P <0.001) [B = -9.0 95%] and presence of comorbidity (P = 0.022), [B = -0.823] were significant predictors of DED.

Conclusion

The prevalence of DED and severe grade was high. The level of education and presence of comorbidities significantly influenced DED in the adult urban Saudi population of cities at high altitudes.

TFOS Lifestyle: Impact of nutrition on the ocular surface

Nutrients, required by human bodies to perform life-sustaining functions, are obtained from the diet. They are broadly classified into macronutrients (carbohydrates, lipids, and proteins), micronutrients (vitamins and minerals) and water. All nutrients serve as a source of energy, provide structural support to the body and/or regulate the chemical processes of the body. Food and drinks also consist of non-nutrients that may be beneficial (e.g., antioxidants) or harmful (e.g., dyes or preservatives added to processed foods) to the body and the ocular surface. There is also a complex interplay between systemic disorders and an individual's nutritional status. Changes in the gut microbiome may lead to alterations at the ocular surface. Poor nutrition may exacerbate select systemic conditions. Similarly, certain systemic conditions may affect the uptake, processing and distribution of nutrients by the body. These disorders may lead to deficiencies in micro- and macro-nutrients that are important in maintaining ocular surface health. Medications used to treat these conditions may also cause ocular surface changes. The prevalence of nutrition-related chronic diseases is climbing worldwide. This report sought to review the evidence supporting the impact of nutrition on the ocular surface, either directly or as a consequence of the chronic diseases that result. To address a key question, a systematic review investigated the effects of intentional food restriction on ocular surface health; of the 25 included studies, most investigated Ramadan fasting (56%), followed by bariatric surgery (16%), anorexia nervosa (16%), but none were judged to be of high quality, with no randomized-controlled trials.

Tear Fluid Biomarkers and Quality of Life in People with Type 2 Diabetes and Dry Eye Disease

Dry eye disease (DED) can be extremely distressing and is common in type 2 diabetes (T2D). To investigate potential biomarkers of DED in T2D, panels of proteins in tears, alongside clinical signs and symptoms of DED, were assessed. Patients were classified into four groups: T2D + DED (n = 47), T2D-only (n = 41), DED-only (n = 17) and healthy controls (n = 17). All patients underwent the Ocular Surface Disease Index (OSDI) and Dry Eye-Related Quality of Life (DEQS) questionnaires, tear evaporation rate (TER), fluorescein tear break-up time (fTBUT), corneal fluorescein staining (CFS) and Schirmer 1 test assessments. Six metabolic proteins and 14 inflammatory cytokines were analyzed with multiplex bead analysis. Interleukin (IL)-6 and IL-8 concentrations in tears were significantly higher in the T2D + DED group, and these biomarkers were positively correlated with CFS. In addition, tear IL-6 was negatively correlated with fTBUT in the T2D + DED group. Clinical signs of DED in the T2D + DED group were similar to the DED-only group. The T2D + DED group had more patients with moderate and severe DED (versus the DED-only group), suggesting a different pathogenesis for DED in T2D versus DED-only. Therefore, IL-6 and IL-8 could potentially be diagnostic biomarkers of DED in T2D.

Screening marker genes of type 2 diabetes mellitus in mouse lacrimal gland by LASSO regression

Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance and a relative deficiency of insulin. This study aims to screen T2DM-related maker genes in the mouse extraorbital lacrimal gland (ELG) by LASSO regression.C57BLKS/J strain with leptin db/db homozygous mice (T2DM, n = 20) and wild-type mice (WT, n = 20) were used to collect data. The ELGs were collected for RNA sequencing. LASSO regression was conducted to screen marker genes with the training set. Five genes were selected from 689 differentially expressed genes by LASSO regression, including Synm, Elovl6, Glcci1, Tnks and Ptprt. Expression of Synm was downregulated in ELGs of T2DM mice. Elovl6, Glcci1, Tnks, and Ptprt were upregulated in T2DM mice. Area under receiver operating curve of the LASSO model was 1.000(1.000-1.000) and 0.980(0.929-1.000) in the training set and the test set, respectively. The C-index and the robust C-index of the LASSO model were 1.000 and 0.999, respectively, in the training set, and 1.000 and 0.978, respectively, in the test set. In the lacrimal gland of db/db mice, Synm, Elovl6, Glcci1, Tnks and Ptprt can be used as marker genes of T2DM. Abnormal expression of marker genes is related to lacrimal gland atrophy and dry eye in mice.

Wearable and Invisible Sensor Design for Eye-Motion Monitoring Based on Ferrofluid and Electromagnetic Sensing Technologies

For many human body diseases, treatments in the early stages are more efficient and safer than those in the later stages; therefore, detecting the early symptoms of a disease is crucial. One of the most significant early indicators for diseases is bio-mechanical motion. This paper provides a unique way of monitoring bio-mechanical eye motion based on electromagnetic sensing technology and a ferro-magnetic material, ferrofluid. The proposed monitoring method has the advantages of being inexpensive, non-invasive, sensor-invisible and extremely effective. Most of the medical devices are cumbersome and bulky, which makes them hard to apply for daily monitoring. However, the proposed eye-motion monitoring method is designed based on ferrofluid eye make-up and invisible sensors embedded inside the frame of glasses such that the system is wearable for daily monitoring. In addition, it has no influence on the appearance of the patient, which is beneficial for the mental health of some patients who do not want to attract public attention during treatment. The sensor responses are modelled using finite element simulation models, and wearable sensor systems are created. The designed frame of the glasses is manufactured based on 3-D printing technology. Experiments are conducted to monitor eye bio-mechanical motions, such as the frequency of eye blinking. Both the quick blinking behaviour with an overall frequency of around 1.1 Hz and the slow blinking behaviour with an overall frequency of around 0.4 Hz can be observed through experimentation. Simulations and measurements results show that the proposed sensor design can be employed for bio-mechanical eye-motion monitoring. In addition, the proposed system has the advantages of invisible sensor set-up and will not affect the appearance of the patient, which is not only convenient for the daily life of the patient but also beneficial for mental health.

Identifying Meibomian Gland Dysfunction Biomarkers in a Cohort of Patients Affected by DM Type II

(1) Background: Meibomian gland dysfunction (MGD) among patients with diabetes mellitus (DM) is a common manifestation of dry eye syndrome (DES). (2) Methods: The purpose of this study is to identify clinical parameters and biomarkers useful to improve the follow-up and the treatment of these patients. We have used an ocular surface disease index (OSDI) questionnaire, Schirmer test I/II, tear film break-up time (TF-BUT), fluorescein plus lissamine green staining, Marx's line (ML), and meibomian gland (MGs) morphology using Sirius^® Topographer (CSO, Costruzione Strumenti Oftalmici, Florence, Italy). Blood sample analysis included glucose, glycated hemoglobin, lipid profile, cortisol, dehydroepiandrosterone sulfate (DHEA-S), androstenedione (ASD) and testosterone. (3) Results: Cortisol and ASD were positively correlated with an increase of MG tortuosity, and an Increased level of triglycerides was associated with a reduction of MGs length. DHEAS levels lowered with age and were associated with ocular surface staining. (4) Conclusions: Future studies, perhaps including meibum lipid analysis and tear cytokine levels, may also further elucidate the connection between these parameters, MG architecture and function.

The effect of a-Lipoic acid (ALA) on oxidative stress, inflammation, and apoptosis in high glucose-induced human corneal epithelial cells

PURPOSE

Oxidative stress and inflammation had been proved to play important role in the progression of diabetic keratopathy (DK). The excessive accumulation of AGEs and their bond to AGE receptor (RAGE) in corneas that cause the formation of oxygen radicals and the release of inflammatory cytokines, induce cell apoptosis. Our current study was aimed to evaluate the effect of ALA on AGEs accumulation as well as to study the molecular mechanism of ALA against AGE-RAGE axis mediated oxidative stress, apoptosis, and inflammation in HG-induced HCECs, so as to provide cytological basis for the treatment of DK.

METHODS

HCECs were cultured in a variety concentration of glucose medium (5.5, 10, 25, 30, 40, and 50 mM) for 48 h. The cell proliferation was evaluated by CCK-8 assay. Apoptosis was investigated with the Annexin V- fluorescein isothiocyanate (V-FITC)/PI kit, while, the apoptotic cells were determined by flow cytometer and TUNEL cells apoptosis Kit. According to the results of cell proliferation and cell apoptosis, 25 mM glucose medium was used in the following HG experiment. The effect of ALA on HG-induced HCECs was evaluated. The HCECs were treated with 5.5 mM glucose (normal glucose group, NG group), 5.5 mM glucose + 22.5 mM mannitol (osmotic pressure control group, OP group), 25 mM glucose (high glucose group, HG group) and 25 mM glucose + ALA (HG + ALA group) for 24 and 48 h. The accumulation of intracellular AGEs was detected by ELISA kit. The RAGE, catalase (CAT), superoxide dismutase 2 (SOD2), cleaved cysteine-aspartic acid protease-3 (Cleaved caspase-3), Toll-like receptors 4 (TLR4), Nod-like receptor protein 3 (NLRP3) inflammasome, interleukin 1 beta (IL-1 ß), and interleukin 18 (IL-18) were quantified by RT-PCR, Western blotting, and Immunofluorescence, respectively. Reactive oxygen species (ROS) production was evaluated by fluorescence microscope and fluorescence microplate reader.

RESULTS

When the glucose medium was higher than 25 mM, cell proliferation was significantly inhibited and apoptosis ratio was increased (P < 0.001). In HG environment, ALA treatment alleviated the inhibition of HCECs in a dose-dependent manner, 25 μM ALA was the minimum effective dose. ALA could significantly reduce the intracellular accumulation of AGEs (P < 0.001), activate protein and genes expression of CAT and SOD2 (P < 0.001), and therefore inhibited ROS-induced oxidative stress and cells apoptosis. Besides, ALA could effectively down-regulate the protein and gene level of RAGE, TLR4, NLRP3, IL-1B, IL-18 (P < 0.05), and therefore alleviated AGEs-RAGE-TLR4-NLRP3 pathway-induced inflammation in HG-induced HCECs.

CONCLUSION

Our study indicated that ALA could be a desired treatment for DK due to its potential capacity of reducing accumulation of advanced glycation end products (AGEs) and down-regulating AGE-RAGE axis-mediated oxidative stress, cell apoptosis, and inflammation in high glucose (HG)-induced human corneal epithelial cells (HCECs), which may provide cytological basis for therapeutic targets that are ultimately of clinical benefit.

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.

Activation of Conjunctiva-Associated Lymphoid Tissue in Diabetic Patients

PURPOSE

To evaluate changes in conjunctiva-associated lymphoid tissues (CALTs) in patients with type 2 diabetic mellitus (T2DM).

METHODS

Thirty-two patients with T2DM and 32 healthy volunteers underwent comprehensive examinations. In vivo confocal microscopy and Image J were used to observe and evaluate the patients' CALT-related parameters. Conjunctival impression cytology (CIC) samples of the tarsal conjunctiva were collected from the patients, and CD4+ and CD8+ cells were evaluated by immunofluorescence staining.

RESULTS

The diabetes group showed higher diffuse lymphocyte density(p < .001), follicular density(p < .001) and parafollicular lymphocyte density(p < .001). The percentages of CD4+ cells (p < .001) and CD8+ cells (p < .001) in the diabetes group were higher than those in the control group. CALT-related parameters of the diabetic patients with diabetic retinopathy showed higher degrees of activation than those of the diabetic patients without diabetic retinopathy.

CONCLUSIONS

CALT activation is observed in patients with T2DM, and the activation is more obvious in patients with diabetic retinopathy.

TRIAL REGISTRATION NUMBER

Retrospectively registered, ChiCTR2100046030.

Tear inflammation related indexes after cataract surgery in elderly patients with type 2 diabetes mellitus

BACKGROUND

Quantitative studies on the changes in inflammation-related content in tears, especially the effect of diabetes, are lacking. In this study, we measured the preoperative and postoperative tear inflammatory mediator levels in cataract patients, focusing on the expression of inflammatory factors in postoperative cataracts in the diabetic, and investigated the effect of drugs on the control of postoperative inflammation.

AIM

To study the expression of inflammatory factors in elderly people with type 2 diabetes after cataract surgery.

METHODS

Patients with a mean age of 70.3 ± 6.3 years were divided into group A (composed of elderly patients with cataracts and type 2 diabetes, n = 20 eyes) and group B (patients with age-related cataract, n = 20 eyes). Their tears were collected before each operation and on days 1 and 3, and weeks 1, 2, 3, and 4 post-surgery. Saline (150 μL) was dropped into the conjunctival sac of the surgical eye, followed by oculogyration in four directions. The fluid in the conjunctival sac was extracted using a sterile syringe and stored in Eppendorf tubes at -80 °C until measurement. The expression levels of matrix metalloproteinase-2 (MMP-2), MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), TIMP-2, interleukin-6 (IL-6), and IL-20 in tear fluid were measured using enzyme-linked immunosorbent assays.

RESULTS

The postoperative expression levels of MMP-2, MMP-9, TIMP-2, IL-6, and IL-20 in group A were significantly higher than those in group B, whereas the concentration of TIMP-1 in group A remained lower than that in group B. The levels of MMP-2 and IL-6 in both groups continuously increased until the peak in the first postoperative week, and then gradually decreased over the next three weeks. Ultimately, MMP-2 declined to a lower level than that preoperatively at week 4, but IL-6 decreased to the same level as that preoperatively. The level of MMP-9 peaked in the first two weeks postoperative and then returned to the same level as 1-day post-operation. The concentration of TIMP-1 post-operation remained constant at a lower level than before surgery, and TIMP-2 Levels remained stable in both groups. IL-20 content started to increase in the third week after surgery.

CONCLUSION

Inflammatory factor levels in tears fluctuated before and post-operation, which indicated more severe postoperative inflammation in the first two weeks.

Keeping an eye on the diabetic foot: The connection between diabetic eye disease and wound healing in the lower extremity

Diabetic eye disease is strongly associated with the development of diabetic foot ulcers (DFUs). DFUs are a common and significant complication of diabetes mellitus (DM) that arise from a combination of micro- and macrovascular compromise. Hyperglycemia and associated metabolic dysfunction in DM lead to impaired wound healing, immune dysregulation, peripheral vascular disease, and diabetic neuropathy that predisposes the lower extremities to repetitive injury and progressive tissue damage that may ultimately necessitate amputation. Diabetic retinopathy (DR) is caused by cumulative damage to the retinal mic-rovasculature from hyperglycemia and other diabetes-associated factors. The severity of DR is closely associated with the development of DFUs and the need for lower extremity revascularization procedures and/or amputation. Like the lower extremity, the eye may also suffer end-organ damage from macrovascular compromise in the form of cranial neuropathies that impair its motility, cause optic neuropathy, or result in partial or complete blindness. Additionally, poor perfusion of the eye can cause ischemic retinopathy leading to the development of proliferative diabetic retinopathy or neovascular glaucoma, both serious, vision-threatening conditions. Finally, diabetic corneal ulcers and DFUs share many aspects of impaired wound healing resulting from neurovascular, sensory, and immunologic compromise. Notably, alterations in serum biomarkers, such as hemoglobin A1c, ceruloplasmin, creatinine, low-density lipoprotein, and high-density lipoprotein, are associated with both DR and DFUs. Monitoring these parameters can aid in prognosticating long-term outcomes and shed light on shared pathogenic mechanisms that lead to end-organ damage. The frequent co-occurrence of diabetic eye and foot problems mandate that patients affected by either condition undergo reciprocal comprehensive eye and foot evaluations in addition to optimizing diabetes management.

Risk of dry eye in headache patients: a systematic review and meta-analysis

OBJECTIVES

The objective of this meta-analysis was to identify whether headache increase the risk of dry eye disease (DED).

METHODS

PubMed, Web of Science, Cochrane Library and EMBASE databases were searched for relevant studies. The odds ratio (OR) of DED in all-cause headache was calculated via Stata software. To explore the source of heterogeneity, subgroup and sensitivity analyses were conducted. Funnel plots and Egger's test were performed to assess publication bias.

RESULTS

This meta-analysis included 11 studies. Pooled analysis indicated that all-cause headache was related to a higher risk of DED (OR = 1.586, 95% CI : 1.409-1.785, I² = 89.3%, p < .001). Migraine headache, tension headache and cluster headache were all related to a higher risk of DED (OR = 1.503, 95% CI: 1.369-1.650, I² = 81.8%, p < .001; OR = 1.610, 95% CI: 1.585-1.635, p < .001; OR = 2.120, 95% CI: 1.104-4.073, p = .024), respectively. The risk of DED in case-control studies was slightly higher than in cross-sectional studies and cohort study (OR = 1.707, 95% CI: 1.291-2.258, I² = 85.0%, p < .001; OR = 1.600, 95% CI: 1.590-1.610, I² = 0.0%, p < .001; OR = 1.440, 95% CI: 1.096-1.893, p = .009), respectively. Subgroup analysis in territory type showed that all-cause headache in America, Europe, Asia and Oceania were all related to a higher risk of DED.

CONCLUSIONS

This study indicates that headache is related to a higher risk of DED, especially in the migraine patients. These results suggest that headaches should be regarded as an independent risk factor for DED.KEY MESSAGESIn this meta-analysis, 11 studies (one cohort study, four case-control studies and six cross-sectional studies) covering 3,575,957 individuals were included.Pooled analysis indicated that all-cause headache was related to a higher risk of dry eye (OR = 1.586, 95% CI: 1.409-1.785, I² = 89.3%, p < .001).These results suggest that headaches should be regarded as an independent risk factor for dry eye.

The management of cataract surgery in diabetic patients

A cataract in the eye is a major cause of vision loss in diabetic patients, which occurs earlier and develops faster than non-diabetic patients, and often requires surgery for treatment. However, diabetic patients undergoing cataract surgery have a higher risk of intraoperative and postoperative complications than non-diabetic patients. For diabetic patients undergoing any surgery, careful perioperative assessment and management are required to reduce postoperative complications and improve surgical outcomes. Better understanding of their needs may guide perioperative practitioners to manage their care appropriately. This article presents recent evidence and guidance associated with the preoperative, intraoperative and postoperative management of diabetic patients undergoing cataract surgery and to inform perioperative practitioners of the challenges and potential complications to provide the best care and improve sight.

Predicting demographics from meibography using deep learning

This study introduces a deep learning approach to predicting demographic features from meibography images. A total of 689 meibography images with corresponding subject demographic data were used to develop a deep learning model for predicting gland morphology and demographics from images. The model achieved on average 77%, 76%, and 86% accuracies for predicting Meibomian gland morphological features, subject age, and ethnicity, respectively. The model was further analyzed to identify the most highly weighted gland morphological features used by the algorithm to predict demographic characteristics. The two most important gland morphological features for predicting age were the percent area of gland atrophy and the percentage of ghost glands. The two most important morphological features for predicting ethnicity were gland density and the percentage of ghost glands. The approach offers an alternative to traditional associative modeling to identify relationships between Meibomian gland morphological features and subject demographic characteristics. This deep learning methodology can currently predict demographic features from de-identified meibography images with better than 75% accuracy, a number which is highly likely to improve in future models using larger training datasets, which has significant implications for patient privacy in biomedical imaging.

Identified risk factors for dry eye syndrome: A systematic review and meta-analysis

A meta-analytic approach was used to identify potential risk factors for dry eye syndrome. PubMed, Embase, and the Cochrane library were systematically searched for studies investigated the risk factors for dry eye syndrome from their inception until September 2021. The odds ratio (OR) with 95% confidence interval (CI) was calculated using the random-effects model. Forty-eight studies comprising 493,630 individuals were included. Older age (OR: 1.82; P<0.001), female sex (OR: 1.56; P<0.001), other race (OR: 1.27; P<0.001), visual display terminal use (OR: 1.32; P<0.001), cataract surgery (OR: 1.80; P<0.001), contact lens wear (OR: 1.74; P<0.001), pterygium (OR: 1.85; P = 0.014), glaucoma (OR: 1.77; P = 0.007), eye surgery (OR: 1.65; P<0.001), depression (OR: 1.83; P<0.001), post-traumatic stress disorder (OR: 1.65; P<0.001), sleep apnea (OR: 1.57; P = 0.003), asthma (OR: 1.43; P<0.001), allergy (OR: 1.38; P<0.001), hypertension (OR: 1.12; P = 0.004), diabetes mellitus (OR: 1.15; P = 0.019), cardiovascular disease (OR: 1.20; P<0.001), stroke (OR: 1.32; P<0.001), rosacea (OR: 1.99; P = 0.001), thyroid disease (OR: 1.60; P<0.001), gout (OR: 1.40; P<0.001), migraines (OR: 1.53; P<0.001), arthritis (OR: 1.76; P<0.001), osteoporosis (OR: 1.36; P = 0.030), tumor (OR: 1.46; P<0.001), eczema (OR: 1.30; P<0.001), and systemic disease (OR: 1.45; P = 0.007) were associated with an increased risk of dry eye syndrome. This study reported risk factors for dry eye syndrome, and identified patients at high risk for dry eye syndrome.

Chronic Hyperglycemia Compromises Mitochondrial Function in Corneal Epithelial Cells: Implications for the Diabetic Cornea

Mitochondrial dysfunction is a major pathophysiological event leading to the onset of diabetic complications. This study investigated the temporal effects of hyperglycemia on mitochondrial metabolism in corneal epithelial cells. To accomplish this, human telomerase-immortalized corneal epithelial cells were cultured in a defined growth medium containing 6 mM glucose. To simulate hyperglycemia, cells were cultured in a medium containing 25 mM D-glucose, and control cells were cultured in mannitol. Using metabolic flux analysis, there was a hyperosmolar-mediated increase in mitochondrial respiration after 24 h. By day 5, there was a decrease in spare respiratory capacity in cells subject to high glucose that remained suppressed throughout the 14-day period. Although respiration remained high through day 9, glycolysis was decreased. Mitochondrial respiration was decreased by day 14. This was accompanied by the restoration of glycolysis to normoglycemic levels. These changes paralleled a decrease in mitochondrial polarization and cell cycle arrest. Together, these data show that chronic but not acute hyperglycemic stress leads to mitochondrial dysfunction. Moreover, the hyperglycemia-induced loss of spare respiratory capacity reduces the ability of corneal epithelial cells to respond to subsequent stress. Compromised mitochondrial function represents a previously unexplored mechanism that likely contributes to corneal complications in diabetes.

Association of Meibomian Gland Dysfunction with Oral Statin Use

This retrospective cross-sectional study aimed to determine the association of oral statin use, dry eye disease (DED), and meibomian gland dysfunction (MGD). A total of 93 subjects were included and divided into two groups: statin users (n = 45) and nonstatin users (n = 47). Significant differences were observed in the total cholesterol (p = 0.013), low-density lipoprotein (LDL) (p = 0.005), and meiboscore (p = 0.000) levels between the two groups. For stratified analysis, the statin group was divided into subgroups according to the type or dose of statin and total duration of statin use. However, there were no differences in clinical features between the subgroups. In multiple regression analysis, meiboscore was significantly associated with age (slope = 0.05, p = 0.00) and statin use (slope = −1.19, p = 0.00), with an R² of 0.44. Thus, older adults and participants who do not use statin appeared to have higher scores. In conclusion, although the mechanism is unclear, statins may exert a protective effect on the meibomian gland. Further lipidomic studies are required to determine the pharmacological effects of statins on the meibomian gland and other meibum components.

Acupuncture for patients with type 2 diabetes mellitus with dry eye: protocol for a systematic review and meta-analysis

INTRODUCTION

The global incidence of patients with type 2 diabetes mellitus (T2DM) with dry eye is increasing annually, which imposes additional healthcare costs and financial burden on families and societies. In clinical practice, artificial tears are often used for symptomatic treatment, but these can only relieve the symptoms of discomfort. Acupuncture is a widely used alternative therapy. Indeed, randomised trials have found that acupuncture confers a definite therapeutic effect on patients with T2DM with dry eye. However, systematic reviews on the effectiveness and safety of acupuncture are lacking, therefore this systematic review aims to evaluate the effectiveness and safety of acupuncture for T2DM with dry eye.

METHODS AND ANALYSIS

Four English databases (PubMed, Cochrane Library, Embase and Ovid), three Chinese databases (China National Knowledge Infrastructure, Wanfang, Chonqing VIP Information), three Japanese databases (Japan Science, Technology Agency and Japan Medical Abstracts Society) and three Korean databases (Korean Medical database, Oriental Medicine Advanced Searching Integrated System and Research Information Service System) will be searched for reports published between 1 January 2007 and 1 October 2021. Only randomised controlled trials will be included, and language or publication dates will not be restricted. Two researchers will independently extract, manage and analyse data. The primary outcomes will include Schirmer's I test, breakup time, corneal fluorescein staining and ocular surface disease index scores. Secondary results will include visual analogue scale scores for ocular symptoms and any adverse events related to acupuncture. We will use Review Manager V.5.4 for the meta-analysis. The risk of bias will be independently assessed using Cochrane's 'risk of bias' tool.

ETHICS AND DISSEMINATION

Ethical approval will not be required since raw data will not be collected or generated. Our findings will be disseminated through peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42021271891.

Evaluation of Ocular Surface Characteristics in Dry Eye Disease With and Without Soft Contact Lens Wear: A Comparative Study

OBJECTIVES

To investigate ocular surface alterations and in vivo confocal microscopic characteristics of the cornea in dry eye disease (DED) with contact lens wear (CLW).

METHODS

Sixty participants were divided into three groups: DED with CLW (n=20), DED without CLW (n=20), and normal control (n=20). Ocular surface parameters were evaluated. Basal tears and in vivo confocal microscopy images of the cornea were collected. Multiplex bead analysis was used to assess interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α, nerve growth factor (NGF), and substance P (SP) in tears. Nerve morphology and dendritic cell density in corneal subbasal nerve images were calculated.

RESULTS

The DED with CLW group showed significantly higher ocular surface staining scores (P=0.022) and higher levels of IL-1β, NGF, and SP in tears (P=0.014, P=0.004 and P=0.025) than the DED without CLW group. Corneal dendritic cell density in the DED with CLW group was significantly higher than that in the normal controls (P=0.001) and DED without CLW group (P=0.043). Tear cytokine levels of IL-1β, NGF, and SP were correlated with ocular surface parameters in the DED with CLW group. Moreover, the years of CLW were positively correlated with corneal dendritic cell density (r=0.527, P=0.017) and negatively correlated with corneal nerve density (r=-0.511, P=0.021).

CONCLUSIONS

Patients with DED with CLW showed greater epithelial damage, elevated inflammatory cytokines and neuromediators in tears, and higher corneal dendritic cell density than patients with DED without CLW. The immune and nervous systems may be involved in contact lens-related DED.

A Cross-Sectional Study of Ocular Changes in Children and Adolescents with Diabetes Mellitus in Selected Health Facilities in Ghana

BACKGROUND

The main objective of the study was to determine the prevalence of diabetic retinopathy (DR), other diabetes-related ocular changes (e.g., cataracts, corneal ulceration), and non-diabetic ocular disease in Ghanaian children and adolescents. The second objective was to evaluate the relationship between these conditions and age at diagnosis, current age, diabetes mellitus (DM) duration, and participant's sex.

METHODS

A cross-sectional study, undertaken by a multidisciplinary team, included a cohort of children and adolescents (4-19 years) with DM recruited from selected health facilities in Ghana, from March 2016 to September 2019, after written informed consent or assent. The cohort will be followed up for 3 years to determine the natural course of the ocular changes, reported later. Participants were examined for all microvascular and macrovascular complications, non-diabetic ocular disease, anthropometric measurements, laboratory characteristics and quality of life issues. Full ocular examination was also undertaken. Statistical Package for Social Sciences (SPSS Version 25.0) was used for the data analysis. Continuous and categorical variables were presented as mean and standard deviation (SD), median (interquartile range) and as percentages (%), respectively. T-test and Mann-Whitney U test were used in establishing associations.

RESULTS

A total of 58 participants were recruited. DR was detected in only 1 out of 58 (1.7%) participants at baseline. Cataracts were the most common ocular finding, detected in 42 (72%) at baseline. Other anterior segment changes observed included blepharitis 46 (79.3%) and tear film instability 38 (65.5%). There was a significant positive association between duration of the DM and the risk of cataract (p = 0.027). Participants' age at diagnosis was significantly associated with the presence of prominent corneal nerves (p = 0.004).

CONCLUSIONS

DR was uncommon in this cohort of young persons with DM in Ghana. Cataracts, blepharitis and refractive errors were ocular changes commonly observed. All young persons with diabetes should undergo regular eye examination in all clinics where follow-up care is provided.

Effect of Repeated Topical Povidone-Iodine and Antibiotic Applications on Meibomian Glands and Ocular Surface Parameters in Patients With Repeated Intravitreal Injections

OBJECTIVES

To assess whether meibomian glands and ocular surface parameters are affected by repeated topical povidone-iodine and antibiotic applications in patients with repeated intravitreal injections.

METHODS

Forty-five patients with at least three previous intravitreal injections and 28 healthy controls were included in the study. In the injection group, 21 patients had age-related macular degeneration and 24 patients had diabetic macular edema. For each participant, infrared meibography for the upper and lower eyelids and noninvasive tear break-up time calculation were performed with a corneal topographer. Fluorescein tear break-up time and ocular surface disease index (OSDI) scores were also obtained. Noninvasive tear break-up time, fluorescein tear break-up time, and OSDI scores were recorded for each participant and compared between the injection and control groups. These parameters were also compared as a subgroup analysis between patients with age-related macular degeneration (AMD) and diabetic macular edema (DME).

RESULTS

Upper lid meibomian gland loss, lower lid meibomian gland loss ratios, and OSDI scores were significantly higher in the intravitreal injection group compared with the control group (P=0.004, P<0.001, P<0.001, respectively). Fluorescein tear break-up time and noninvasive tear break-up time were significantly lower in the intravitreal injection group compared with the control group (P<0.001, P<0.001). There was no significant difference between the AMD and DME groups for these parameters.

CONCLUSION

This study showed for the first time that meibomian gland losses were significantly increased by repeated povidone-iodine and antibiotic applications in patients with repeated intravitreal injections. Ocular surface parameters were altered with higher ocular surface symptoms in those patients.

Association Between Dry Eye Syndrome and Osteoarthritis Severity: A Nationwide Cross-Sectional Study (KNHANES V)

OBJECTIVE

Recently, several researchers reported an association between osteoarthritis and dry eye syndrome (DES) and suggested that they may be related to central sensitization. We investigated the association between DES, osteoarthritis pain, and radiographic severity.

DESIGN

A nationwide, cross-sectional study.

SETTING

The Fifth Korean National Health and Nutrition Examination Survey.

SUBJECTS

8,664 participants in this survey.

METHODS

Osteoarthritis-associated radiographic changes were evaluated by trained radiologists. Multivariable logistic regression was performed to examine the relationship between osteoarthritis pain, radiographic severity, and DES. The odds ratios (ORs) of DES were analyzed in accordance with the presence of osteoarthritis-associated factors.

RESULTS

Radiographic knee osteoarthritis was significantly associated with lower ORs for DES (OR = 0.80, P = 0.046, for diagnosed/self-reported DES; OR = 0.84, P = 0.034, for symptoms of DES). Knee pain or stiffness was significantly associated with higher ORs for DES (OR = 1.28, P = 0.020, for diagnosed/self-reported DES; OR = 1.29, P = 0.003, for symptoms of DES). In patients with symptomatic osteoarthritis, DES was not significantly associated with radiographic severity of osteoarthritis. In patients with nonsymptomatic radiographic osteoarthritis, DES was inversely related with radiographic severity (Ptrend = 0.012 for diagnosed/self-reported DES; Ptrend < 0.001 for symptoms of DES).

CONCLUSIONS

Radiographic osteoarthritis showed a significant association with decreased DES. Patients with less pain and severe radiographic OA were more likely to have less DES. Our results suggest that the degree of pain caused by osteoarthritis and central sensitization may be closely associated with DES.

Association Between Migraine and Dry Eye: A Systematic Review and Metaanalysis

PURPOSE

The purpose of this study was to assess whether migraine might be associated with the increased risk of dry eye disease and to determine the strength of the association between migraine and dry eye disease.

METHODS

We searched EMBASE, PubMed, Web of Science databases and China National Knowledge Infrastructure, WanFang, and VIP databases for studies that investigated the association between dry eye and migraine from inception to September 8, 2020. Relevant data were extracted by 2 investigators independently. Publication bias and heterogeneity were evaluated. Odds ratio (OR) and 95% confidence interval (CI) were computed by metaanalysis using random-effects models.

RESULTS

Of the 565 studies identified, 7 studies met the inclusion criteria and were included in this metaanalysis. Patients with migraine had significantly higher morbidity of dry eye compared with the control group (OR = 1.55; 95% CI = 1.32-1.82; P < 0.001). Subgroup analysis showed that the association between dry eye and migraine was stronger in hospital-based studies (OR = 1.97, P = 0.036) than population-based studies (OR = 1.42, P < 0.001). In addition, differences in geographic location and diagnostic criteria have no effect on the results.

CONCLUSIONS

There was a significant association between dry eye and migraine. Patients with migraine are more prone to suffer from dry eye than subjects without migraine, and the association strength varies among populations studied.

Validation of the Arabic version of the Ocular Surface Disease Index Questionnaire

AIM

To develop an Arabic version of the ocular surface disease index (OSDI) and to assess its reliability and validity.

METHODS

A cross sectional study was carried out to validate the Arabic version of the OSDI questionnaire. Initially, forward-backward translation was used to translate the English version of OSDI into Arabic. The translated questionnaire was tested for equivalence and cultural adaptability. Totally 200 subjects were then recruited from a non-clinical population and asked to complete the Arabic version of the OSDI (ARB-OSDI). The reliability of the questionnaire was assessed using Cronbach's-α. A subgroup of 30 participants was asked to complete the questionnaire on two occasions to test the test-retest reliability.

RESULTS

A total of 200 participants were enrolled in the study. The average age of the study participants was 31.21±13.2y and 57% were male. An acceptable internal consistency level for the ARB-OSDI questionnaire measured by Cronbach's-α was revealed. All questions showed good internal consistency. Test-retest reliability analysis revealed good stability (interclass correlation coefficient, r=0.832, P<0.001). The construct validity for the questionnaire was also high.

CONCLUSION

The ARB-OSDI questionnaire shows very good psychometric properties (acceptable internal consistency and test-retest reliability). That makes the questionnaire a valid potential tool to use in Arabic-speaking countries to monitor symptoms of dry eye disease in a larger population.

The Association Between Risk Factors for Metabolic Syndrome and Meibomian Gland Disease in a Dry Eye Cohort

Purpose

Risk factors for metabolic syndrome include abdominal obesity, insulin resistance, hypertension, high triglycerides and/or low high-density lipoprotein cholesterol, and hyperglycemia. Risk factors for metabolic syndrome have been associated with dry eye disease; however, their association with meibomian gland disease (MGD), a subtype of dry eye, is unclear. In the present study, we investigated risk factors for metabolic syndrome in a dry eye cohort with and without MGD.

Methods

This retrospective case-control study evaluated electronic medical records at a major urban outpatient medical center to identify patients with a known diagnosis of dry eye disease with and without MGD. Males and females were matched for age, smoking status, race, ethnicity, and body mass index (BMI). Patient demographics, anthropometric measurements, medical history, clinical findings, and serologies were analyzed. A diagnosis of MGD was based on clinical signs noted in the medical record.

Results

MGD was not associated with BMI, smoking, type 2 diabetes mellitus, hypertension or hyperlipidemia in this dry eye cohort. MGD was associated with male sex and increasing age. While increasing age was weakly correlated with decreased low density lipoprotein cholesterol and non-high density lipoprotein cholesterol, serum lipid levels were not associated with MGD.

Conclusion

Importantly, we found that risk factors for metabolic syndrome are not specifically associated with an increase in MGD when compared to non-MGD dry eye subjects. While risk factors for metabolic syndrome are associated with dry eye disease, they likely reflect a chronic systemic state of low-grade inflammation that negatively impacts the function of both lacrimal and meibomian glands.

Eye disorders other than diabetic retinopathy in patients with diabetes

AIM

While diabetic retinopathy is the most specific complication of chronic hyperglycaemia, numerous other ocular conditions also can involve the eyes of people with diabetes. Cataract, glaucoma, age-related macular degeneration, retinal vascular occlusion, and acute ischaemic optic neuropathy combine to impair vision in people with diabetes, especially when they are old. This report provides a critical analysis and an overview of the current knowledge of the main ocular disorders (excluding diabetic retinopathy) and their association in patients with diabetes.

METHODS

A literature search strategy was conducted for all English-language literature with a systematic review of key references until 2021.

RESULTS

Patients with diabetes have a high-to-moderate increased risk for most of the usual ocular disorders we reviewed with the exception of age-related macular degeneration. Exposure to chronic hyperglycaemia promotes the development of many eye disorders while acute glucose changes are involved in refractive disorders, diabetic papillopathy and acute cataract.

CONCLUSION

Diabetes, beyond diabetic retinopathy, increases the risk of numerous eye disorders leading to low vision with implications for daily diabetes management. Even in the absence of clearly demonstrated benefit from glucose control in all eye conditions, achieving good glycaemic control and adherence to diabetes treatment will likely help avoid an additional risk of visual impairment in people with diabetes. In perspective, interesting findings suggesting a preventive effect of metformin use on age-related macular degeneration occurrence justify further studies.

Dry Eye and Phacoemulsification Cataract Surgery: A Systematic Review and Meta-Analysis

Purpose: To evaluate whether dry eye deteriorates after phacoemulsification cataract surgery, and to explore the influential factors.

Methods: Studies published before February 2020 indexed on PubMed and the Cochrane Central Register of Controlled Trials were retrieved. A meta-analysis, including meta-regression, a sensitivity analysis, and a subgroup analysis, were performed.

Results: Twenty studies with 2,247 eyes were included in the meta-analysis, dry eye-related parameters were investigated preoperatively and 1 month postoperatively. Patients with pre-existing meibomian gland dysfunction (MGD) had worsened subjective symptoms of dry eye (1.31, 95% confidence interval (CI) [0.66, 1.95], P < 0.0001), a reduced tear break-up time (BUT) (−2.27, 95% CI [−2.66, −1.88], P < 0.0001), and a worse corneal fluorescein staining (CFS) score (0.75, 95% CI [0.5, 1.0], P < 0.0001) after phacoemulsification cataract surgery, whereas in the general population, the subjective symptoms score and CFS remained unchanged and BUT decreased slightly after surgery. Patients without diabetes showed significantly reduced total tear secretion after phacoemulsification cataract surgery (−1.25, 95% CI [−1.62, −0.88], P < 0.0001).

Conclusion: Dry eye generally remained unchanged 1 month after phacoemulsification cataract surgery. Notably, worsened symptoms and signs of dry eye were observed more frequently in patients with pre-existing MGD. Patients without diabetes were more susceptible to reduced tearing postoperatively.

Clinical Trial Registration: Identifier: PERSPERO (2020: CRD42020203316).

Hyperglycemia-induced severe mitochondrial bioenergetic deficit of lacrimal gland contributes to the early onset of dry eye in diabetic mice

Dry eye and diabetic keratopathy represent the major diabetic complications in ocular surface. Here we found that diabetic mice exhibited the early onset of reduced tear secretion and lacrimal gland weight compared to the symptoms of diabetic keratopathy. Considering to the high bioenergetic needs in lacrimal gland and cornea, we hypothesized that hyperglycemia may cause different severity of mitochondrial bioenergetic deficit between them. Through the measurement of oxygen consumption rate (OCR) and basal extracellular acidification rate (ECAR), we found the apparent alterations of mitochondrial bioenergetic profiles in diabetic lacrimal gland and cornea, accompanied with the mtDNA damage and copy number reduction, as well as the reduced glutathione content. Comparative analysis revealed that mouse lacrimal gland cells exhibited 2-3 folds higher of basal, ATP production, maximal OCR and basal ECAR than corneal epithelial cells in normoglycemia. However, the differences were slightly significant or even not detected in hyperglycemia. Accordingly, the mitochondrial bioenergetic metabolism of lacrimal gland was more compromised than that of corneal epithelium in diabetic mice. Through the administration of mitochondrial-targeted antioxidant SkQ1, the severity of dry eye and diabetic keratopathy was significantly attenuated with the improved mitochondrial function. These results indicate that the susceptibility of mitochondrial bioenergetic deficit in diabetic lacrimal gland may contribute to the early onset of dry eye, while mitochondria-targeted antioxidant possesses therapeutic potential for diabetic dry eye and keratopathy.

Light cycle phase advance as a model for jet lag reprograms the circadian rhythms of murine extraorbital lacrimal glands

PURPOSE

Jet lag causes a disruption in physiological rhythms in humans. This study aims to explore the extent to which jet lag affects the circadian rhythmicity in the lacrimal glands.

METHODS

C57BL/6J mice were subjected to a 12-h light/12-h dark (LD) cycle and an 8-h advanced LD schedule as a model for jet lag. On day 5 after the LD advance, the extraorbital lacrimal glands (ELGs) were collected at 3-h intervals during a 24-h cycle. Total mRNA was extracted from normal and advanced LD-treated ELGs and assayed using high-throughput RNA sequencing. The rhythmic transcripts were identified, analyzed, and visualized by bioinformatics techniques. Finally, (i) animal behavior; (ii) the mass, cell size, and secretion response of ELGs; and (iii) circadian migration of immune cells to ELGs were also assayed.

RESULTS

Jet lag treatment drastically altered the phase and composition of the rhythmic transcripts compared to that of normal ELGs. The key biological processes, signaling pathways, and protein-protein association networks were also dramatically altered in a spatiotemporal pattern. Furthermore, the circadian migration of neutrophils, T cells, B cells, and macrophages to the ELGs increased and shifted later by 6-h. Finally, the circadian rhythms of the ELGs with respect to mass, cell size, and secretion response were also impaired in jet lag-treated animals.

CONCLUSIONS

Jet lag impairs the circadian rhythm of the transcriptomic profile, structure, and secretion function of the lacrimal glands. This information provides novel insight into the negative effects of jet lag on ELGs.

Association of dry eye disease and sun exposure in geographically diverse adult (≥40 years) populations of India: The SEED (sun exposure, environment and dry eye disease) study - Second report of the ICMR-EYE SEE study group

PURPOSE

To estimate the prevalence and determine risk factors for dry eye disease (DED) in geographically diverse regions of India.

METHOD

A population based cross-sectional study was conducted on people aged ≥40 years in plain, hilly and coastal areas. Dry eye assessment by objective [tear film break-up time (TBUT), Schirmer I, corneal staining] and subjective [Ocular Surface Disease Index (OSDI)] parameters was performed with questionnaire-based assessment of exposure to sunlight, cigarette smoke, indoor smoke. The prevalence of DED with age, sex, occupation, location, smoking, exposure to sunlight, indoor smoke, diabetes, hypertension, was subjected to logistic regression analysis.

RESULTS

9,735 people (age 54.5 ± 0.1 years; range 40-99, males 45.5%) were included. The prevalence of DED was 26.2%, was higher in plains (41.3%) compared to hilly (24.0%) and coastal area (9.9%) (p < 0.001) and increased with age (p < 0.001), female gender (p < 0.001), smoking (p < 0.001), indoor smoke (p < 0.001), diabetes (p-0.02), hypertension (0.001), occupations with predominant outdoor activity (p-0.013) and increasing exposure to sunlight (trend). Multi-logistic regression showed a positive association with female sex (OR-1.2, CI-1.01, 1.4), exposure to indoor smoke (OR-1.3, CI-1.1, 1.5), smoking (OR-1.2; CI-1.03, 1.3), prolonged exposure to sunlight (OR-1.8, CI-1.5, 2.2), hypertension (OR 1.3, CI-1.2, 1.4), diabetes (OR-1.2, CI-1, 1.5) and negative association with region - hilly (OR-0.5, CI-0.4, 0.6) and coastal (OR-0.2; CI-0.1, 0.2), and BMI (OR-0.8, CI-0.7, 0.9).

CONCLUSION

DED is common in population ≥40 years of age. Its prevalence is affected by extrinsic (geographic location, exposure to sunlight, smoking, indoor smoke) and intrinsic (age, sex, hypertension, diabetes, BMI) factors.