Association between ultraviolet radiation exposure dose and cataract in Han people living in China and Taiwan: A cross-sectional study

Association of nuclear cataract prevalence with UV radiation and heat load in lens of older people -five city study

Epidemiological studies have reported that the frequency of nuclear cataracts (NUCs) is high among the elderly and in tropical countries. Ultraviolet (UV) irradiation and lens temperature are considered as key physical contributors, although their precise quantification is difficult. The aim of this study is to investigate the association of NUC prevalence with UV irradiation and heat load. First, we assessed the lens temperature using thermodynamic modeling considering the thermophysiological response. We then conducted a multivariate linear regression analysis for the epidemiological analysis of NUC prevalence across five cities. A strong correlation was observed between NUC prevalence and the combined effects of UV irradiation and cumulative equivalent minutes at 43 °C (CEM43°C) derived from the computed lens temperature (adjusted R2 = 0.933, p < 0.0001). Heat load significantly contributed to the prevalence at 52%, surpassing the contributions of UV irradiation (31%) and the decline in DNA repair capacity in the lens (17%). These results suggested that both UV radiation and heat load are associated with NUC, with heat load contributing more. Our findings provided important implications for future interventions, particularly in the context of global warming.

Upregulation of EphA2 is associated with apoptosis in response to H2O2 and UV radiation-induced cataracts

In this article, we examine the role of erythropoietin-producing hepatocellular receptor A2 (EphA2) in the apoptosis of lens epithelial cells (LECs) in H2O2 and UV radiation-induced cataracts. We treated SRA01/04 cells with H2O2 or ultraviolet (UV) radiation to create a cataract cell model. We constructed a cataract lens model by exposing mice to UV radiation. We used CCK8 assays, Annexin V-FITC analysis, and immunohistochemical staining to explore proliferation and apoptosis of the cataract model. Thereafter, we used quantitative real-time PCR (qPCR) analysis, Western blot assays, and immunofluorescence to determine gene and protein expression levels. We also employed Crispr/Cas9 gene editing to create an EphA2 knockout in SRA01/04 cells. Results: H2O2 or UV radiation induced SRA01/04 cells showed EphA2 gene upregulation. CCK8 and apoptosis assays showed that EphA2 over-expression (OE) reduced epithelial cell apoptosis, but knockout of EphA2 induced it in response to H2O2 and UV radiation, respectively. Mutation of the EphA2 protein kinase domain (c.2003G > A, p. G668D) had a limited effect on cell apoptosis. In vivo, the EphA2 protein level increased in the lenses of UV-treated mice. Our results showed that EphA2 was upregulated in SRA01/04 cells in response to H2O2 and UV radiation. Mutation of the EphA2 protein kinase domain (c.2003G > A, p. G668D) had a limited effect on H2O2 and UV radiation-induced cell apoptosis. We confirmed this change with an experiment on UV-treated mice. The present study established a novel association between EphA2 and LEC apoptosis.

Associations Among Outdoor Time, Skin Tanning, and the Risk of Surgically Treated Cataract for Australians 45 to 65 Years of Age

Purpose

To investigate the association between outdoor time and the risk of cataract surgery in a large Australian population.

Methods

This was a population-based prospective cohort study with 137,133 participants 45 to 65 years of age and without prior history of cataract surgery from the 45 and Up Study. Outdoor hours per day on weekdays and weekends, as well as tanning with repeated sun exposure, were assessed by a self-administered baseline questionnaire. Cataract surgery events were confirmed by the Medicare Benefits Schedule from baseline until the end of follow-up in 2016.

Results

During a mean follow-up of 9 years, 14,338 participants received cataract surgery with a corresponding incidence of 10.5%. Multiple Cox regression analysis showed that more outdoor hours on weekends (P trend < 0.001) and the ability to get tanned by repeated sun exposure (P trend = 0.041) were significantly associated with a lower risk of cataract surgery, whereas more outdoor hours on weekdays were nominally significantly associated (P trend = 0.055). Participants who spent 10+ hours outdoors on weekends had 9% decreased risk compared with those who spent ≤2 hours outdoors. In addition, compared to participants who got very tanned by repeated sun exposure, those less likely to get tanned had a 5% to 7% increased risk of cataract surgery.

Conclusions

In this large Australian cohort 45 to 65 years of age, more outdoor time and ease of tanning with sun exposure were associated with a lower incidence of cataract surgery.

Translational Relevance

With proper sun protection, more outdoor time may lead to a lower risk of severe cataracts requiring surgery.

Analyzing Effect of Waterclefts on Visual Functions Via Optical Simulations

Purpose

To investigate the impact of the size and location of waterclefts (WC), which are one of several cataract subtypes, on visual function by optical simulation analysis.

Methods

An optical simulation software (CODE V) was used to develop a schematic eye model and several sizes of WC central and peripheral types that were located below the anterior and posterior subcapsules of the crystalline lens, and analyses of refraction, higher-order aberrations (HOA), and the modulation transfer function (MTF) were performed.

Results

An increase in the WC size increased the refraction and HOA and decreased the MTF. The impact of the WC below the posterior subcapsule on the visual function was more enhanced than that below the anterior subcapsule. Large WC demonstrated a remarkable hyperopic shift in refractive power as well as an increase in HOA. The MTF decreased slightly with increasing WC size at a spatial frequency of 20 cycles/mm, and it decreased remarkably at 60 cycles/mm.

Conclusions

The impact on the visual function increased with increasing WC size. It was revealed that eyes with WC below the posterior subcapsule are more hyperopic than those with WC below the anterior subcapsule, and the former have a higher HOA and lower MTF than the latter.

Association between age-related cataract and blepharoptosis in Korean adults: a population-based study

Cataract and blepharoptosis are both commonly encountered ophthalmic problems in older adults. Since they share similar risk factors, it is plausible that there may be an association between the two conditions. We examined data from the Korean National Health and Nutrition Examination Survey (KNHANES) 2010–2012 to determine if there is an association between age-related cataract and blepharoptosis. Multivariable adjusted logistic regression analysis was conducted to examine the odds ratio (OR) and 95% confidence interval (CI) for association of each specific type of cataract with presence of blepharoptosis. Of the 10,387 eligible participants, 4782 (46.0%) had cataract and 1419 (15.8%) had blepharoptosis. There were more participants with blepharoptosis in the cataract group, compared with those in the no cataract group. After adjusting for potential confounders, participants with blepharoptosis had a higher risk of total cataract (OR: 1.557, 95% CI 1.201–2.019) and nuclear subtype cataract (OR: 1.305, 95% CI 1.050–1.620). Blepharoptosis was associated with significantly higher odds of cataract in obese participants when compared with non-obese participants (p for interaction = 0.0236). Our study revealed a positive association between age-related cataract and blepharoptosis; it suggests that thorough ophthalmic assessment is needed when assessing patients who are planning cataract or blepharoptosis surgery.

Mitotic Activation Around Wound Edges and Epithelialization Repair in UVB-Induced Capsular Cataracts

Purpose

Ultraviolet B (UVB) has been well documented to induce capsular cataracts; however, the mechanism of the lens epithelial cell-mediated repair process after UVB irradiation is not fully understood. The purpose of this study was to better understand lens epithelial cell repair after UVB-induced epithelium damage.

Method

C57BL/6J mice were irradiated by various doses of UVB. Lens morphology and lens capsule opacity were monitored by slit lamp, darkfield microscopy, and phase-contrast microscopy. Lens epithelial cell mitotic activation and cell apoptosis were measured by immunohistochemistry. Lens epithelial ultrastructure was analyzed by transmission electron microscopy.

Results

UVB irradiation above a dose of 2.87 kJ/m2 triggered lens epithelial cell apoptosis and subcapsular cataract formation, with a ring-shaped structure composed of multilayered epithelial cell clusters manifesting a dense ring-shaped capsular cataract. The epithelial cells immediately outside the edge of the ring-shaped aggregates transitioned to mitotically active cells and performed wound healing through the epithelialization process. However, repairs ceased when lens epithelial cells made direct contact, and scar-like tissue in the center of the anterior capsule remained even by 6 months after UVB irradiation.

Conclusions

Our present study demonstrates that normally quiescent lens epithelial cells can be reactivated for epithelialization repair in response to UV-induced damage.

Correlation of Sunlight Exposure and Different Morphological Types of Age-Related Cataract

Purpose

The previous lab and clinical studies of the correlation between the ultraviolet B and age-related cataract (ARC) did not reach in the universal agreement, especially in different morphological types of ARC. It is important to systemically summarize those previous data of epidemiological studies, which might penetrate the relevance between three morphological types of ARC, cortical, nuclear, and posterior capsular (PSC), with sunlight exposure.

Methods

PubMed, Web of Science, CNKI, Embase, and Cochrane were searched online. Data were extracted and recalculated, and quality check was performed by hand. Review Manager was used to perform the fixed effects meta-analysis on ARC and its morphological types. The highest exposed dose group was defined as the exposed group, and the lowest dose group as the control group as possible.

Results

Finally, the number of analyzed studies was 31: 20 for ARC and twelve, eleven, and nine for the morphological types cortical, nuclear, and PSC, respectively. The pooled OR for ARC was 1.15 (range 1.00~43.78, 95% CI 1.09 to 1.21). The cortical cataract revealed a slightly higher risk, and pooled OR was 1.03 (range 0.67~2.91, 95% CI 1.02 to 1.03). But the pooled OR for nuclear and PSC were 1.00 (range 0.50~5.35, 95% CI 1.00 to 1.00) and 0.99 (range 0.57~1.87, 95% CI 0.95 to 1.01), respectively.

Conclusions

The systemic analysis of epidemiological articles reported till now reveals a significantly increased risk of ARC for those exposed with more sunlight, especially the morphological type of cortical cataract.

The elevated risk of sight-threatening cataract in diabetes with retinopathy: a retrospective population-based cohort study

Background

The effect of diabetic retinopathy (DR) on the development of sight-threatening cataracts was assessed using the National Health Insurance Research Database of Taiwan.

Methods

Patients diagnosed with diabetes mellitus (DM) and DR were enrolled in the study group. Age- and sex-matched DM individuals without DR and patients without DM served as the DM control group and non-DM control group, respectively, both with 1:4 ratios. The outcome was set as the performance of cataract surgery. Cox proportional hazard regression was used to calculate the adjusted hazard ratio (aHR) of DR considering multiple factors underlying cataract formation.

Results

A total of 3297 DR patients, 13,188 DM control patients and 13,188 non-DM control subjects were enrolled. The study group included 919 events of sight-threatening cataracts (27.87%), the DM control group included 1108 events (8.40%), and the non-DM control group included 957 events (7.26%). A multivariable analysis indicated that the study group presented a higher aHR of cataract surgery (2.93, 95% CI: 2.60–3.30) and a higher cumulative probability of cataract surgery than both the DM control and non-DM control groups (both log rank P < 0.001). In addition, both the proliferative DR (3.90, 95% CI: 3.42–4.45) and nonproliferative DR (2.35, 95% CI: 2.08–2.65) subgroups showed a higher aHR of cataract surgery than the DM control group.

Conclusion

The presence of DR increases the risk of sight-threatening cataracts that warrant surgery, and the effect is prominent among patients with both proliferative DR and nonproliferative DR.

Relationship between practices of eye protection against solar ultraviolet radiation and cataract in a rural area

BACKGROUND

Cataract is a public health concern worldwide that differentially affects rural residents of outlying islands where ultraviolet radiation (UVR) may have greater penetration because of less shading.

OBJECTIVES

To assess the relationships between attitudes and practices of eye protection and eye diseases for residents of an offshore island of Taiwan.

METHODS

Questionnaire survey was administered to local residents (age > 50 years) regarding socio-demographic information, attitudes/practices of eye protection under sun exposure and eye diseases.

RESULTS

A total of 816 participants (response rate 90.7%, 816/900) completed the questionnaires. Mean age was 63.7 (+ 10.8) years. Among these participants, 44.4%, 15.1% and 8.3% had cataract, dry eye and glaucoma, respectively. Although 86.3% and 88.2% of participants agreed that they should avoid outdoor activities and wear glasses/broad-brimmed hats in harsh daylight, 69.4% and 48.3% of participants never/rarely used glasses or hats/umbrellas in harsh daylight, respectively. Predictors of less practices of eye protection against solar UVR included residents who were male, with lower education level, with longer residence and lack of commercial health insurance. Multivariate logistic regression revealed that practices of eye protection under sun exposure were significantly associated with less cataract, but not glaucoma or dry eye. Participants who did not wear glasses, broad-brimmed hats/use umbrellas or both in harsh sunlight (almost) every time were respectively associated with a 57% (P = 0.028), 45% (P = 0.027) or 70% (P = 0.026) increase of cataract than those who did in harsh sunlight (almost) every time.

CONCLUSIONS

Practices of eye protection under sun exposure is associated with lower risk of cataract.

Association among pterygium, cataracts, and cumulative ocular ultraviolet exposure: A cross-sectional study in Han people in China and Taiwan

Purpose

Pterygium is an ocular surface disorder mainly caused by ultraviolet (UV) light exposure. This study explored the relationships between six cataract types with pterygium and UV exposure.

Methods

We have previously studied cataracts in residents of three regions in China and Taiwan with different UV intensities. From that study, we identified 1,547 subjects with information on the presence or absence of pterygium. Pterygium severity was graded by corneal progress rate. Cataracts were graded by classification systems as three main types (cortical, nuclear, posterior subcapsular) and three subtypes (retrodots, waterclefts, fiber folds) with high prevalence in middle-aged and elderly people. We calculated the cumulative ocular UV exposure (COUV) based on subject data and National Aeronautics and Space Administration data on UV intensities and used logistic regression to calculate odds ratios for the associations of COUV, cataract, and pterygium.

Results

We found an overall pterygium prevalence of 23.3%, with significant variation among the three regions. Four cataract types (cortical, nuclear, posterior subcapsular, and retrodots) were significantly associated with the presence of pterygium.

Conclusions

There was a significant association between COUV and pterygium, indicating that COUV is associated with the risk of pterygium development and that pterygium is useful as an index of UV exposure. Furthermore, the type of cataract in eyes with pterygium may indicate the level of UV exposure.

Effect of a Lens Protein in Low-Temperature Culture of Novel Immortalized Human Lens Epithelial Cells (iHLEC-NY2)

The prevalence of nuclear cataracts was observed to be significantly higher among residents of tropical and subtropical regions compared to those of temperate and subarctic regions. We hypothesized that elevated environmental temperatures may pose a risk of nuclear cataract development. The results of our in silico simulation revealed that in temperate and tropical regions, the human lens temperature ranges from 35.0 °C to 37.5 °C depending on the environmental temperature. The medium temperature changes during the replacement regularly in the cell culture experiment were carefully monitored using a sensor connected to a thermometer and showed a decrease of 1.9 °C, 3.0 °C, 1.7 °C, and 0.1 °C, after 5 min when setting the temperature of the heat plate device at 35.0 °C, 37.5 °C, 40.0 °C, and 42.5 °C, respectively. In the newly created immortalized human lens epithelial cell line clone NY2 (iHLEC-NY2), the amounts of RNA synthesis of αA crystallin, protein expression, and amyloid β (Aβ)1-40 secreted into the medium were increased at the culture temperature of 37.5 °C compared to 35.0 °C. In short-term culture experiments, the secretion of Aβ1-40 observed in cataracts was increased at 37.5 °C compared to 35.0 °C, suggesting that the long-term exposure to a high-temperature environment may increase the risk of cataracts.

Protective effects of calbindin‑D28K on the UVB radiation‑induced apoptosis of human lens epithelial cells

Calbindin-D28K (Calb1) may protect human lens epithelial cells (HLECs) from apoptosis, which is a process resulting in individual cell death. The protective effects of Calb1 may be attributed to buffering high concentrations of Ca²⁺. The present study investigated the mechanisms through which Calb1 protects SRA01/04 cells (a human lens epithelial cell line) against apoptosis induced by ultraviolet B (UVB) exposure. Cells transfected with a lentivirus overexpressing Calb1 and control cells were treated with 40 µW/cm² irradiation for 15 min and then cultured for 24 h. The changes in intracellular Ca²⁺ were detected by colorimetry, and the protein expression levels of Bad, Bcl-2 and caspase-12 were measured by western blot analysis. The intracellular Ca²⁺ concentration of control HLECs increased significantly following UVB irradiation, whereas in Calb1-overexpressing cells, the Ca²⁺ levels remained steady. In the control cells, the expression of Bad and caspase-12 was upregulated, and that of Bcl-2 was down-regulated. Notably, during UVB radiation-induced apoptosis, the overexpression of Calb1 inhibited cell death, resulting in the decreased expression of Bad and caspase-12, and in the upregulated expression of Bcl-2. These results suggested that Calb1 inhibited the upregulation of genes involved in apoptosis. The siRNA-mediated knockdown of Calb1 resulted in increased rates of UVB radiation-induced apoptosis, the increased expression of Bad and caspase-12, and the decreased expression of Bcl-2, further demonstrating that Calb1 may mediate UVB radiation-mediated apoptosis by regulating Ca²⁺. On the whole, the findings of the present study indicate that UVB exposure can lead to an imbalance in the intracellular Ca²⁺ homeostasis in HLECs and that Calb1 protein exerts a negative effect on the expression of pro-apoptotic genes in HLECs. Calb1 may thus inhibit the UVB radiation-induced apoptosis of HLECs by regulating Ca²⁺.

Visual Function and Functional Decline in Patients With Waterclefts

Purpose

To investigate visual function in eyes with three subtypes of waterclefts (WCs).

Methods

Of patients in Kanazawa Medical University Hospital (2013-2017) and participants of Monzen Eye Study (2013-2016), 77 transparent lenses, mean age 66.7 years, and 70 eyes with only WC opacity of 70 patients, mean age 68.1 years, divided into peripheral-, central-, and total-type WC groups, were analyzed. Opacity was classified by one ophthalmologist using slit-lamp microscopy. Corrected-distance visual acuity (CDVA), contrast visual acuity (CVA), spherical equivalent (SE), astigmatism values, corneal refractive power (CP), axial length (AL), straylight, backward light scattering (BLS), and higher order aberrations (HOA) were measured and lenticular refractive power (LP) was calculated based on the values of AL, CP, and SE.

Results

Central-type WC showed significant decrease in CDVA and CVA and increase in straylight compared with control. Total-type WC showed significant decreases in CDVA, CVA, and LP, and increase in straylight, compared with control and peripheral-type WC. Total- and central-type WCs had significantly higher ocular total HOA and total-type WC had significantly higher internal total HOA than control. HOA correlated positively with CDVA (P < 0.001) and straylight (P = 0.020), and CDVA negatively with straylight in eyes with WCs (P = 0.008).

Conclusions

Total-type WC was associated with decreased LP, causing hyperopia, decreased CDVA and higher straylight; thus, such lenticular change should be considered for surgery indication. Significant correlations between HOA and both CDVA and straylight suggested increased HOA may decrease visual function in eyes with WCs.

Clinical Aspects of Pterygium in the Presence of Cataract

Two of the most common UV-induced eye affections are pterygium and cataract. They are both defined as progressive diseases that impair patients’ vision and share some common elements in their evolution process. The purpose of this study was to determine whether the presence of cataract influences the clinical signs and symptoms of patients with pterygium. Therefore, we have analyzed 84 patients with pterygium, among which 23 also presented cataract, as an overall study lot, as well as divided by age decades. We have determined that almost all patients with both pterygium and cataract declared extensive UV exposure in antecedents and have also reported a blurred vision. We found no correlation between the presence of cataract and the size of pterygium lesions, or symptoms like foreign body sensation, tearing or symblepharon.

Correction: Association between ultraviolet radiation exposure dose and cataract in Han people living in China and Taiwan: A cross-sectional study

[This corrects the article DOI: 10.1371/journal.pone.0215338.].

Correction: Association between ultraviolet radiation exposure dose and cataract in Han people living in China and Taiwan: A cross-sectional study

[This corrects the article DOI: 10.1371/journal.pone.0215338.].