Do Season and Environment Have a Role in the Incidence of Anterior Uveitis Attacks?

Intravital imaging of the human cornea reveals the differential effects of season on innate and adaptive immune cell morphodynamics

PURPOSE

While the external environment has been shown to shape the systemic human immune landscape, defining the in vivo immune status of peripheral tissues has remained a technical challenge. We recently developed functional in vivo confocal microscopy (Fun-IVCM) for dynamic, longitudinal imaging of corneal immune cells in living humans. This study investigated the effect of seasonal-driven environmental factors on the density, morphology and dynamic behavior of human corneal immune cell subsets.

DESIGN

Longitudinal, observational clinical study.

PARTICIPANTS

Sixteen healthy participants (18-40 years) attended two visits in distinct seasons in Melbourne, Australia (Visit 1: Spring/Summer: November-December 2021; Visit 2: Autumn/Winter: April-June 2022).

METHODS

Environmental data were collected over each period. Participants underwent ocular surface examinations and corneal Fun-IVCM (Heidelberg HRT-3, Rostock Corneal Module). Volume scans (80μm) were acquired at 5.5±1.5 minute intervals, for up to five timepoints. Time-lapse videos were created to analyze corneal immune cells, comprising epithelial T cells and dendritic cells (DCs), and stromal macrophages. Tear cytokines were analyzed using multiplex bead-based immunoassay.

MAIN OUTCOME MEASURES

Difference in the density, morphological and dynamic parameters of corneal immune cell subsets over the study periods.

RESULTS

Visit 1 was characterized by higher temperature, lower humidity, and higher air particulate and pollen levels than Visit 2. Clinical ocular surface parameters, and the density of immune cell subsets were similar across visits. At Visit 1 (Spring/Summer), corneal epithelial DCs were larger and more elongated, with a lower dendrite probing speed (0.38±0.21 vs 0.68±0.33μm/min, p<0.001) relative to Visit 2; stromal macrophages were more circular and had less dynamic activity (Visit 1: 7.2±1.9 vs Visit 2: 10.3±3.7 'dancing index', p<0.001). T cell morphology and dynamics were unchanged across periods. Basal tear levels of IL-2 and CXCL10 were lower during Spring/Summer.

CONCLUSION

This novel study shows that the in vivo morphodynamics of innate corneal immune cells (DCs, macrophages) are modified by environmental factors, but such effects are not evident for adaptive immune cells (T cells). The cornea is a potential non-invasive, in vivo 'window' to season-dependent changes to the human immune system, with capacity to yield new insight into environmental influences on immune regulation.

Uveitis Onset and Flare-Up: Does the Time of Year Matter?

PURPOSE

This retrospective chart review tests the hypothesis that initial presentation and flare-up of non-infectious anterior, intermediate, and posterior uveitis varies by month, temperature season, and calendar season among the patient population in Connecticut.

METHODS

The medical records of all adult patients presenting with a chief concern or diagnosis of "uveitis" at a university-based clinic between March 2013 and February 2019 and a community-based clinic between January 2016 and February 2019 in Connecticut were reviewed. Ongoing, chronic uveitis and infectious/traumatic uveitis were excluded. Patient age, sex, comorbid autoimmune conditions, time of onset, and anatomical location of uveitis was collected. χ 2 testing evaluated variation in uveitis presentation based on month, calendar season, and temperature.

RESULTS

353 cases of endogenous uveitis were identified among 272 patients. There was no significant variation by month, calendar season, or temperature across the entire population. There was no significant variation by temperature when assessing anterior uveitis, intermediate uveitis, posterior uveitis, and panuveitis cases separately. Though flare-ups did not show any significant seasonal trends, there was significant variation by temperature for new uveitis episodes. Uveitis episodes in patients with autoimmune conditions were shown to have significant variation by temperature. Uveitis episodes in HLA-B27 positive patients were found to have significant variation by both temperature and month.

CONCLUSION

While variation by month, calendar season, or temperature is not present for all uveitis patients, a subset of patients with comorbid autoimmune conditions, specifically HLA-B27 positive, experience temperature variations with increasing incidence of flare-ups in transitional months in Connecticut.

An Update on the Epidemiology of Uveitis in an Urban Setting in Northern Madrid, Spain

PURPOSE

To describe the incidence, prevalence and etiologies of uveitis in Madrid, Spain.

METHODS

A retrospective cross-sectional study was performed in a single hospital. All consecutive cases of uveitis that attended the Hospital during year 2019 were included. Mean incidence and prevalence were calculated.

RESULTS

Three hundred and one cases were included. Of these, 127 were incident. This represents an incidence of 21.24 new cases per 100,000 persons/year, and a prevalence was 50.43 cases per 100,000 persons. Mean age was 56.89 ± 18.78 years, and 159 were women (52.8%). Sixty-two cases were infectious (20.6%). Age (p = .005), initial visual acuity (p = .001) and cystoid macular oedema (CMO; p = .010) were found to be independent predictors of the final best corrected visual acuity (BCVA) in patients with uveitis.

CONCLUSIONS

Uveitis affects approximately 1 in 1800 persons in northern Madrid. Younger age, better initial visual acuities and the presence of CMO predicted better final BCVA.

Emerging roles of air pollution and meteorological factors in autoimmune eye diseases

Autoimmune eye diseases (AEDs), a collection of autoimmune inflammatory ocular conditions resulting from the dysregulation of immune system at the ocular level, can target both intraocular and periorbital structures leading to severe visual deficit and blindness globally. The roles of air pollution and meteorological factors in the initiation and progression of AEDs have been increasingly attractive, among which the systemic and local mechanisms are both involved in. Exposure to excessive air pollution and extreme meteorological conditions including PM2.5/PM0.1, environmental tobacco smoke, insufficient sunshine, and high temperature, etc., can disturb Th17/Treg balance, regulate macrophage polarization, activate neutrophils, induce systemic inflammation and oxidative stress, decrease retinal blood flow, promote tissue fibrosis, activate sympathetic nervous system, adversely affect nutrients synthetization, as well as induce heat stress, therefore may together deteriorate AEDs. The crosstalk among inflammation, oxidative stress and dysregulated immune system appeared to be prominent. In the present review, we will concern and summarize the potential mechanisms underlying linkages of air pollution and meteorological factors to ocular autoimmune and inflammatory responses. Moreover, we concentrate on the specific roles of air pollutants and meteorological factors in several major AEDs including uveitis, Graves' ophthalmopathy (GO), ocular allergic disease (OAD), glaucoma, diabetic retinopathy (DR), etc.

Seasonal Patterns of Vogt-Koyanagi-Harada Disease

PURPOSE

To identify the relationship between the incidence of Vogt-Koyanagi-Harada (VKH) disease and seasonality.

METHODS

A retrospective cohort study was performed, including patients with a confirmed diagnosis of VKH whose month of disease onset was available. Information on patients was entered retrospectively into a database and analyzed according to the month and season.

RESULTS

Twenty-four patients who met the inclusion criteria were included in the analysis. There was a statistically significant deviation from expected values in the incidences of VKH per season (P = .043). The most common season for the onset of VKH was fall, with 50% of the patients presenting in this season, while spring was the least common season for VKH presentation, with 12.5% of the patients presenting in this season.

CONCLUSION

Our study suggests that the onset of VKH in Puerto Rico follows a seasonal pattern, with most cases occurring during the fall.

The impact of air pollution and climate change on eye health: a global review

Climate change has important implications on human health, affecting almost every system in the body. Multiple studies have raised the possibility of climate change impacting eye health. In this review, we aimed to summarize current literature on the impact of air pollution and climate change on eye health. We performed a search in four different databases, including Medline, Scopus, Cochrane, and Web of Sciences databases. The search strategy combined terms regarding eye health and environmental/climate changes. The outcome of interest included all eye conditions. The search yielded 2,051 unique articles. After applying inclusion and exclusion criteria, 61 articles were included in this systematic review with data covering 2,620,030 participants. Most studies originated from China, India, South Korea, and USA. Climate change adversely affected different eye conditions, with ocular surface diseases (e.g., conjunctivitis and dry eye) being most affected. Moreover, higher particulate matter (PM) was the most widely assessed pollutant and was adversely associated with the majority of eye conditions, increasing the burden on patients and healthcare providers. We found a low frequency of publications related to the delivery of eye care and its impact on climate change in countries with high air pollution and climate change burden.

Association between meteorological factors and hospital admissions for uveitis in Hefei, China: a time-series study

Meteorological variables are regarded as risk factors for inflammatory diseases, but their associations with uveitis, one of the leading causes accounting for blindness worldwide with an estimated prevalence of 38-714 cases/100,000 person-years, have not been thoroughly investigated. The present study explored the short-term association between meteorological variables and hospital admissions for uveitis in Hefei City, China. Daily data on uveitis hospital admissions and meteorological variables including mean temperature (MT) (°C), diurnal temperature range (DTR) (°C), and relative humidity (RH) (%), from 2014 to 2020, were collected. A time-series study using generalized linear model combined with distributed lag non-linear model was applied. Totally, 1911 admissions for uveitis including 894 first admissions and 1017 readmissions were reported during the study period. The associations of high percentile of MT (75th, 24.5℃) and low percentile of DTR (25th, 5.4℃) with uveitis admissions were observed to be statistically significant from lag9 (RR = 1.041, 95%CI: 1.002-1.081) to lag11 (RR = 1.053, 95%CI: 1.003-1.104) and lag4 (RR = 1.053, 95%CI: 1.019-1.088) to lag5 (RR = 1.052, 95%CI: 1.020-1.085), respectively. Moreover, a significant association between low percentile of RH (1th, 44%) and uveitis admissions appeared at lag0-8 (RR = 1.869, 95%CI: 1.017-3.434) and lasted until lag0-13 (RR = 2.539, 95%CI: 1.102-5.850) in the cumulative lag structure. Subgroup analyses indicated that males and the young seemed to be more sensitive to high MT exposure, while females appeared to be more vulnerable to low DTR exposure. Interestingly, both the young and the elderly are susceptible to low DTR and low RH exposure. Furthermore, high MT and low DTR exposure were associated with increased risk of first admission for uveitis. In summary, exposure to high-value of MT and low-value of DTR and RH may increase the hospital admissions for uveitis, especially for the status of first admission.

INCIDENCE OF HERPES SIMPLEX VIRUS KERATITIS AND OTHER OCULAR DISEASE: GLOBAL REVIEW AND ESTIMATES

Purpose: We aimed to review available data on the incidence of herpes simplex virus (HSV) keratitis and other HSV ocular disease and to estimate the global burden of HSV ocular disease. Methods: We searched Medline and Embase databases to October 2020 for studies reporting on the incidence of HSV ocular disease. Study quality was evaluated using a four-point checklist. Pooled estimates were applied to 2016 population data to estimate global HSV ocular disease burden. Numbers with uniocular vision impairment (any visual acuity <6/12) were estimated by applying published risks to case numbers. Results: Fourteen studies had incidence data; seven met our quality criteria. In 2016, an estimated 1.7 (95% confidence interval, 95% CI 1.0–3.0) million people had HSV keratitis, based on a pooled incidence of 24.0 (95% CI 14.0–41.0; N = 2; I² = 97.7%) per 100,000 person-years. The majority had epithelial keratitis (pooled incidence 16.1 per 100,000; 95% CI 11.6–22.3; N = 3; I² = 92.6%). Available studies were few and limited to the USA and Europe. Data were even more limited for HSV uveitis and retinitis, although these conditions may collectively contribute a further >0.1 million cases. Based on global incidence, some 230,000 people may have newly acquired uniocular vision impairment associated with HSV keratitis in 2016. Conclusion: Over 1.8 million people may have herpetic eye disease annually. Preventing HSV infection could therefore have an important impact on eye health. Herpetic eye disease burden is likely to have been underestimated, as many settings outside of the USA and Europe have higher HSV-1 prevalence and poorer access to treatment.

Association between temperature changes and uveitis onset in mainland China

BACKGROUND

Some uveitis subtypes show seasonal patterns. Whether these patterns are caused by seasonally varying temperatures or by other climatic factors remains unknown. This ecological research aimed to quantify the association between climate variability and uveitis onset.

METHODS

We combined data from the largest database of uveitis cases with surface climate data to construct panel data. We used choropleth maps to visually assess spatial uveitis variations.

RESULTS

Among 12 721 reports of uveitis originating from 31 provinces of mainland China from 2006 to 2017, we found that a 1°C increase in monthly temperature was associated with a rise in approximately 2 uveitis reports per 1000 individuals (95% CI 0.00059 to 0.0029). This association was present across all provinces, ranging in effect size from 0.0011 to 0.072 (95% CI 0.00037 to 0.10). A clear 0-3 months of cumulative lagging effect was noted across all types of uveitis, with the strongest effect for non-infectious uveitis (0.0067, 95% CI 0.0041 to 0.013). Stratified by age and sex, we found that men and people aged 20-50 years were more affected by temperature variations. Our model predicts that China might experience an increase in uveitis cases due to future global warming.

CONCLUSION

Our study is the largest-ever investigation of the association between uveitis and climate and, for the first time, provides evidence that rising temperature can affect large-scale uveitis onset. These results may help promote and implement policies to mitigate future temperature increases and the burden of disease caused by global warming.