Climatic droplet keratopathy: an old disease in new clothes

Integrated analysis of microRNA expression in tears of Kazakh patients with climatic droplet keratopathy in Xinjiang, China

Climatic droplet keratopathy (CDK) is a corneal diseases, which is characterized by increased oil-like deposits on the anterior elastic lamina and anterior stromal layer. Severe CDK can even cause blindness, with no specific available treatment. Besides. CDK is poorly understood in terms of its pathogenic mechanisms. Thus, to determine potential biomarkers for CDK, we analyzed the microRNA expression profile in tear samples from CDK patients and investigated their putative roles in the pathogenesis of CDK. Herein, miRNA sequencing and following bioinformatics analysis was performed to explore the roles of their target genes in CDK. A total of 67 differentially expressed miRNAs were identified, of which 25 were upregulated and 42 were downregulated. qPCR verification showed that among the up- and down-regulated miRNAs, expression of five and six, respectively, was most significantly different.The target genes of the differentially expressed miRNAs are involved in the FoxO signaling pathway, tumor necrosis factor (TNF) signaling pathway, and steroid hormone biosynthesis. Protein-protein interaction network analyses identified 20 hub genes, including PTEN, GSK3B, and SMAD3. In conclusion, the panel of differentially expressed miRNAs identified may have potential utility as early diagnostic biomarkers for CDK. Moreover, the TNF signaling pathway is a new potential target in CDK for the development of treatments.

TFOS Lifestyle Report: Impact of environmental conditions on the ocular surface

Environmental risk factors that have an impact on the ocular surface were reviewed and associations with age and sex, race/ethnicity, geographical area, seasonality, prevalence and possible interactions between risk factors are reviewed. Environmental factors can be (a) climate-related: temperature, humidity, wind speed, altitude, dew point, ultraviolet light, and allergen or (b) outdoor and indoor pollution: gases, particulate matter, and other sources of airborne pollutants. Temperature affects ocular surface homeostasis directly and indirectly, precipitating ocular surface diseases and/or symptoms, including trachoma. Humidity is negatively associated with dry eye disease. There is little data on wind speed and dewpoint. High altitude and ultraviolet light exposure are associated with pterygium, ocular surface degenerations and neoplastic disease. Pollution is associated with dry eye disease and conjunctivitis. Primary Sjögren syndrome is associated with exposure to chemical solvents. Living within a potential zone of active volcanic eruption is associated with eye irritation. Indoor pollution, "sick" building or house can also be associated with eye irritation. Most ocular surface conditions are multifactorial, and several environmental factors may contribute to specific diseases. A systematic review was conducted to answer the following research question: "What are the associations between outdoor environment pollution and signs or symptoms of dry eye disease in humans?" Dry eye disease is associated with air pollution (from NO2) and soil pollution (from chromium), but not from air pollution from CO or PM10. Future research should adequately account for confounders, follow up over time, and report results separately for ocular surface findings, including signs and symptoms.

miR-1273h-5p protects the human corneal epithelium against UVR-induced oxidative stress and apoptosis: Role of miR-1273h-5p in climatic droplet keratopathy

Climatic droplet keratopathy (CDK) is characterized by an increased number of oil-like deposits on the most anterior corneal layers, which affect vision and can cause blindness. Environmental ultraviolet radiation (UVR) exposure is a major risk factor, but the underlying mechanism of CDK pathogenesis is unclear. Increasing evidence has demonstrated that miRNAs participate in the cross-talk with oxidative stress. We aimed to explore whether certain miRNAs are involved in the pathogenesis of CDK. We performed miRNA sequencing of tears from patients with CDK and healthy individuals from Tacheng region of Xinjiang and conducted bioinformatic analysis of key miRNAs. We also evaluated viability, migration, and apoptosis of human corneal epithelial cells (HCECs) subjected to UVR treatment. miR-1273h-5p expression was abnormally downregulated in the tears of patients with CDK. miR-1273h-5p promoted cell proliferation and migration and inhibited UVR-induced mitochondrial apoptosis. miR-1273h-5p protected HCECs against UVR-induced oxidative damage by reducing the accumulation of reactive oxygen species and inhibiting mitochondrial apoptosis via the activation of the Nrf2 pathway. Thus, our results suggest that miR-1273h-5p protects the corneal epithelium against UVR-induced oxidative stress damage.

Prevalence and associated factors for climatic droplet keratopathy in Kazakhs adults: a cross-sectional study in Tacheng, Xinjiang, China

Background

Investigation of the prevalence of climatic droplet keratopathy (CDK) in Tacheng, Xinjiang, China.

Methods

A total of 1030 participants, in their 40s or older, from the Kazakh ethnic group in Tacheng, were randomly sampled by stratification method. Ophthalmic examinations and surveys were carried out on these participants. Factors associated with CDK were analyzed with logistic regression models.

Results

CDK was found in 66 (6.4%; 95% confidence interval [CI]: 4.9–7.9%) Kazakh individuals.

After multiple regression model analysis, it demonstrated that age (< 0.001), exposure time (< 0.001), exposure protection (< 0.001), and vegetable intake (< 0.001) were of correlation with CDK, of which age (OR = 1.21[CI]: 1.16–1.27) and long-term outdoor exposure (OR = 2.42[CI]: 1.26–4.67) were the risk factors, and that vegetable intake (OR = 0.29[CI]: 0.14–0.59) and wearing a hat (OR = 0.24[CI]: 0.10–0.56) were protective factors.

Conclusions

This study has revealed the risk and protective factors of CDK, providing a new insight on related research.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-02065-4.

Prevalence of Solar Keratopathy, Pterygium and Cataract in the Islands of Northern Red Sea Zone, Eritrea: Cross-Sectional Study, 2021

Background

Everybody is exposed to ultraviolet radiation and the natural source of ultraviolet radiation is sunlight. The objective of this study was to determine the prevalence of solar keratopathy, pterygium and cataract and further to evaluate other factors that cause blindness to the inhabitants of the Northern Red Sea Zone islands of Eritrea.

Methods

It was a community-based cross-sectional study of all people aged 40 years and above, with a census sampling method. Study participants were screened for presence of solar keratopathy and other ocular diseases, and data were collected by a checklist from March 20 to April 20, 2021. Data were entered on an Excel sheet and transported to SPSS version 21. Results were presented with frequencies and percentages and chi-squared bivariable analysis was carried. P-value less than 0.05 was considered significant.

Results

The prevalence of solar keratopathy and cataract was 19.6% and 15.8%, respectively. Pterygium (40%) and pinguecula (32.1%) were also commonly found in the community. Participants aged 70 years and above (P<0.001), fishermen (P<0.001), housewife (P<0.001) and females (P<0.001) had a higher rate of blindness. The prevalence of solar keratopathy was higher with increased age and work experience (P<0.001). Fishermen and housewives had higher rates of solar keratopathy (44.6%) and cataract (30.2%), respectively, (P<0.001). Respondents aged 40 to 49 years had the highest prevalence of pterygium (44.1%) and pinguecula (39.1%) (P<0.001).

Conclusion

The prevalence of solar keratopathy, cataract, pterygium and pinguecula was high in the community. Fishermen with increased work experience were having the highest prevalence of blindness and solar keratopathy. Age, occupation, work experience, sex, vision problems and history of eye operations had showed significant association with visual acuity, solar keratopathy, cataract, pterygium, and pinguecula. Community awareness about the preventive aspects of these diseases is highly recommended.

UV-B-Induced Inflammasome Activation Can Be Prevented by Cis-Urocanic Acid in Human Corneal Epithelial Cells

Purpose

The cornea is continually exposed to highly energetic solar UV-B (280-320 nm). Our aim was to investigate whether UV-B triggers the activation of NLRP3 inflammasomes and the production of IL-1β and/or IL-18 in human corneal epithelial (HCE) cells. Additionally, we studied the capability of cis-urocanic acid (cis-UCA) to prevent inflammasome activation or alleviate inflammation through other signaling pathways.

Methods

HCE-2 cell line and primary HCE cells were primed using lipopolysaccharide or TNF-α. Thereafter, cells were exposed to UV-B before or after the addition of cis-UCA or caspase-1 inhibitor. Caspase-1 activity was measured from cell lysates by an enzymatic assay. IL-1β, IL-18, IL-6, IL-8, and NLRP3 levels were detected using the ELISA method from cell culture media. Additionally, intracellular NLRP3 levels were determined by the Western blot technique, and cytotoxicity was measured by the LDH assay.

Results

UV-B exposure significantly increased caspase-1 activity in TNF-α-primed HCE cells. This result was consistent with the concurrently induced IL-1β secretion. Both caspase-1 activity and release of IL-1β were reduced by cis-UCA. Additionally, UV-B stimulated the caspase-1-independent production of IL-18, an effect also reduced by cis-UCA. Cis-UCA decreased the release of IL-6, IL-8, and LDH in a time-dependent manner when administered to HCE-2 cells after UV-B exposure.

Conclusions

Our findings demonstrate that UV-B activates inflammasomes in HCE cells. Cis-UCA can prevent the secretion of IL-1β and IL-18 and therapeutically reduces the levels of IL-6, IL-8, and LDH in UV-B-stressed HCE cells.

Advanced spheroidal degeneration

Spheroidal degeneration, involving the cornea and/or the conjunctiva, is characterized by amber-colored homogeneous, translucent spherules in the corneal stroma, Bowman's membrane, and subepithelium. The condition has a higher prevalence in areas with extreme temperatures, low humidity, high wind, and presence of sand. We report the case of a 46-year-old man with a 10-year history of gradual progressive diminution of vision, severe blepharospasm, and photophobia. Examination revealed bilateral plaques of amber-colored nodules covering about half of the cornea. Superficial keratectomy was performed for the lesions in both eyes, leaving an epithelial defect overlying a plane of opaque cornea. Histopathology showed amorphous protein in the anterior stroma, confirming the clinical diagnosis of advanced grade 4 spheroidal degeneration. Visual acuity and other symptoms dramatically improved, and the patient was scheduled for keratoplasty.

Prevalence of spheroidal degeneration of cornea and its association with other eye diseases in tribes of Western Rajasthan

PURPOSE

To determine the prevalence of spheroidal degeneration of cornea (SDC) and its association with other eye diseases in the tribes of South-West Rajasthan.

METHODS

A total of 5012 patients were examined on slit lamp for the diagnosis of SDC. Diagnosis of SDC was made based on presence of amber granules in the superficial stroma of peripheral interpalpebral cornea with increasing opacification, coalescence and central spread or nodular and hazy surrounding stroma and divided in three stages.

RESULTS

The prevalence of SDC was 10.7%. Around 55% of the total of 535 cases examined were found to have Stage I followed by Stage II (32%) and Stage III (13%). The prevalence is greatest in both men and women over 70 years of age. The severity of SDC is greater in men. SDC was significantly associated with pterygium and pseudocapsular exfoliation.

CONCLUSION

Extreme temperature, low humidity, dust, high wind, and microtrauma caused by sand particles are the probable etiologies for higher prevalence of this kind of degeneration in this region.

Phospholipidomic Studies in Human Cornea From Climatic Droplet Keratopathy

Climatic droplet keratopathy (CDK) is an acquired degenerative disease predominantly affecting males over 40 years old. It results in progressive corneal opacities usually affecting both eyes. CDK is multifactorial and its etiology remains unknown. Our recent findings are consistent with CDK pathology being driven by environmental factors with oxidative stress playing an important role (e.g.,, contributing to lipid peroxidation) rather than climate factors. The changes in corneal lipid composition affected by environmental factors remain understudied. The purpose of this study was to systematically investigate phospholipids profile (phosphatidylcholine [PC] and phosphatidylserine [PS]) in corneas from CDK patients using tandem mass spectrometry. Samples from CDK areas and from non-affected areas were obtained from patients diagnosed with CDK who underwent cataract surgery, were subjected to lipid extraction using a modified Bligh and Dyer method; protein concentrations were determined using the Bradford's method. Lipids were identified and subjected to ratiometric quantification using TSQ Quantum Access Max triple quadrupole mass spectrometer, using appropriate class specific lipid standards. All phospholipid classes showed lower total amounts in affected areas compared to control areas from CDK's corneas. Comparative profiles of two phospholipid classes (PC, PS) between CDK areas and control areas showed several common species between them. We also found a few unique lipids that were absent in CDK areas compared to controls and vice versa. Lower amount of phospholipids in CDK areas compared to control areas could be attributed to the lipid peroxidation in the affected corneal regions as a consequence of increased oxidative stress. J. Cell. Biochem. 118: 3920-3931, 2017. © 2017 Wiley Periodicals, Inc.

Damaging Effects of Ultraviolet Radiation on the Cornea

The cornea sits at the anterior aspect of the eye and, like the skin, is highly exposed to ultraviolet radiation (UVR). The cornea blocks a significant proportion of UVB from reaching the posterior structures of the eye. However, UVA can penetrate the full thickness of the cornea, even reaching the anterior portion of the lens. Epidemiological data indicate that UVR is a contributing factor for a multitude of diseases of the cornea including pterygium, photokeratitis, climatic droplet keratopathy and ocular surface squamous neoplasia (OSSN), although the pathogenic mechanisms of each require further elucidation. UVR is a well-known genotoxic agent, and its effects have been well characterized in organs such as the skin. However, we are only beginning to identify its effects on the cornea, such as the UVR signature C → T and CC → TT transversions identified by sequencing and increased proliferative and shedding rates in response to UVR exposure. Alarmingly, a single low-dose exposure of UVR to the cornea is sufficient to elicit genetic, molecular and cellular changes, supporting the consideration of using protective measures, such as wearing sunglasses when outdoors. The aim of this review was to describe the adverse effects of UVR on the cornea.

Climatic Droplet Keratopathy in Argentina: Involvement of Environmental Agents in Its Genesis Which Would Open the Prospect for New Therapeutic Interventions

Climatic droplet keratopathy (CDK) is a degenerative corneal disease of unknown etiology. We described CDK for the first time in Latin America in the Argentinean Patagonia (El Cuy). A deeper knowledge of CDK pathogenic mechanisms will provide new therapeutic strategies. For that reason we investigated the prevalence of CDK in El Cuy and its existence in other 3 provinces with similar climate. Patients eyes were examined, habits throughout lives were inquired about, and serum ascorbate (sAA) was determined. All individuals work outdoors for most of the day. All regions had normal O₃ levels. Individuals from regions 1, 2, and 3 had very low consumption of vegetables/fruits and low sAA levels. Conversely, region 4 individuals had balanced diet and higher sAA concentrations. CDK was only found in region 3 where individuals had partial deficiency of sAA and did not use eye protection. No CDK was found in regions 1 and 2 where individuals had similar work activities and dietary habits to those in region 3 but wear eye protection. No disease was found in region 4 where individuals work outdoors, have balanced diet, and use eye protection. To summarize, the CDK existence was related not only to climate but also to the dietary habits and lack of protection from sunlight.

Effects produced by different types of laser in cornea of Guinea pigs: Identification of a laser capable of producing superficial lesions without leaving scars

PURPOSE

Climatic droplets keratopathy (CDK) is closely associated with superficial corneal erosions and lack of protective mechanisms against the harmful effects of ultraviolet radiation (UVR) during a prolonged period of time. One of the difficulties in studying the pathogenic mechanisms involved in this human disease is the lack of an experimental animal model. In this paper, a study is conducted on the effects of 4 types of lasers at various powers and time conditions on the normal guinea pig corneas in order to select only one laser condition that reversibly injures the epithelium and superficial stroma, without leaving scarring.

METHODS

Damage was induced in the cornea of Guinea pigs using different powers and exposure times of 4 types of laser: argon, CO2, diode and Nd-Yag, and any injuries were evaluated by biomicroscopy (BM) and optical microscopy. Corneas from other normal animals were exposed to argon laser (350 mW, 0.3s, 50 μm of diameter), and the induced alterations were studied at different times using BM, optical coherence tomography (OCT) and transmission electron microscopy (TEM).

RESULTS

Only argon laser at 350 mW, 0.3s, 50 μm of diameter produced epithelium and superficial stroma lesions. Some leukomas were observed by BM, and they disappeared by day 15. Corneal thickness measured by OCT decreased in the eyes treated with argon laser during the first week. Using TEM, different ultra structural alterations in corneal epithelium and stroma were observed during the early days, which disappeared by day 15.

CONCLUSIONS

It was possible to develop reproducible corneal epithelium and anterior stroma injuries using Argon laser at 350 mW, 0.3s, 50 μm of diameter. In vivo and in vitro studies showed that injured corneas with these laser conditions did not leave irreversible microscopic or ultra structural alterations. This protocol of corneal erosion combined with exposure to UVR and partial deficiency of ascorbate in the diets of the animals for an extended period of time has been used in order to try to develop an experimental model of CDK.