Risk factors for age-related cataract

The Influence of Inflammation in Posterior Capsule Opacification Development

Cataract represents the reduction of the transparency of the crystalline lens. Cataract surgery is the most commonly performed surgical procedure worldwide. One of the most common postoperative complication of successfully performed cataract surgery is a development of posterior capsule opacification (PCO). In the postoperative period, lens epithelial cells (LECs) undergo proliferation, migration and differentiation, which is clinically manifested by the development of PCO. Inflammation has a central role in these processes. Cytokines, such as transforming growth factor β, fibroblast growth factor, interleukin 1, interleukin 6, matrix metalloproteinases have a huge effect on the activity of LECs. Understanding these processes can find a great usage in clinical practice. By prescribing anti-inflammatory therapy in the early postoperative period, the incidence of PCO can be significantly reduced.

Prevalence of cataract and cataract surgery in urban and rural Chinese populations over 50 years old: a systematic review and Meta-analysis

AIM

To summarize the data of epidemiological studies on cataract prevalence over 50 years old in urban and rural areas of China from 2000 to 2020, and to analyze the prevalence of cataract and operation rate in China.

METHODS

By searching PubMed, EMBASE, Web of Science, Wanfang Data and CNKI, Chinese and English literatures on the prevalence of cataract in China were retrieved, and the relevant characteristic data were extracted. Then, Stata v15SE software was used for Meta-analysis and heterogeneity test. According to the results of heterogeneity, the corresponding effect models were selected to combine the extracted data.

RESULTS

A total of 20 studies were included in this study, with a total of 111 434 cases. Meta-analysis showed heterogeneity. According to the random effect model, the overall prevalence of cataract in Chinese people over 50 years old was 27.45%, that in rural was 28.79%, and that in urban was 26.66%. The overall coverage rate of cataract surgery was 9.19%.

CONCLUSION

The prevalence of cataract is high in China, and there is still room for improvement in surgical coverage, so it is very important to promote cataract screening and prevention.

Knockdown of lncRNA TUG1 protects lens epithelial cells from oxidative stress-induced injury by regulating miR-196a-5p expression in age-related cataracts

Oxidative stress plays an important role in the pathogenesis of cataracts. Under oxidative stress, apoptosis of lens epithelial cells (LECs) is activated, which may cause lens opacity and accelerate the development of cataracts. Long non-coding RNA (lncRNA) and microRNA (miRNA/miR) are involved in cataracts. Previous studies have demonstrated that lncRNA taurine upregulated 1 (TUG1) promotes cell apoptosis induced by ultraviolet radiation by downregulating the expression of miR-421. However, the mechanism underlying TUG1 in age-related cataract remains to be elucidated. The present study aimed to investigate the effect of TUG1 in age-related cataracts and to determine the related underlying molecular mechanism. In the present study, the association between TUG1 and microRNA (miR)-196a-5p was predicted using StarBase and verified using a dual luciferase reporter assay in 293 cells. The LEC line SRA01/04 was exposed to 200 µM hydrogen peroxide (H₂O₂) for 24 h to establish an in vitro oxidative stress model. The mRNA expression levels of TUG1 and miR-196a-5p were analyzed using reverse transcription-quantitative PCR, whilst cell viability and apoptosis were determined using MTT and flow cytometry assays, respectively. The protein expression levels of cleaved caspase-3 and caspase-3 in SRA01/04 cells were determined using western blotting. The results of the present study revealed that TUG1 directly targeted miR-196a-5p expression. In addition, the expression levels of miR-196a-5p were downregulated in SRA01/04 cells following oxidative stress, whilst TUG1 expression was upregulated. Cell transfection with TUG1-small interfering RNA (siRNA) upregulated miR-196a-5p expression levels in SRA01/04 cells, which was reversed following co-transfection with the miR-196a-5p inhibitor. Transfection with TUG1-siRNA also reduced the levels of H₂O₂-induced oxidative damage in SRA01/04 cells, which was demonstrated by increased cell viability, reduced levels of apoptosis and downregulated cleaved caspase-3 levels. Conversely, transfection with the miR-196a-5p inhibitor reversed these effects aforementioned. Overexpression of miR-196a-5p reduced H₂O₂-induced oxidative damage in SRA01/04 cells. In conclusion, findings from the present study suggested that knocking down TUG1 expression may protect LECs from oxidative stress-induced apoptosis by upregulating the expression of miR-196a-5p.

miR-23a-3p regulates the proliferation and apoptosis of human lens epithelial cells by targeting Bcl-2 in an in vitro model of cataracts

Cataracts account for ~50% of the cases of blindness in individuals worldwide. The apoptosis of lens epithelial cells (LECs) occurs during the formation of cataracts, which is a non-congenital condition. Numerous microRNAs (miRs) have been reported to regulate apoptosis in LECs. For instance, miR-23a expression levels were shown to be upregulated in cataractous lenses; however, the function of miR-23a in cataracts remains undetermined. To establish an in vitro model of cataracts, human LECs, HLE-B3 cells, were induced with 200 µmol/l H₂O₂ for 24 h. HLE-B3 cells were transfected with the miR-negative control (NC) mimic, miR-23a-3p mimic, miR-NC inhibitor, miR-23a-3p inhibitor, small interfering RNA (siRNA) targeting BCL2 (siRNA-BCL2) and siRNA-NC. The expression levels of miR-23a-3p were detected using reverse transcription-quantitative PCR. The interaction between miR-23a-3p and the 3'-untranslated region (UTR) of the target mRNA BCL2 was predicted by TargetScan 7.1, and further validated using a dual luciferase reporter assay. The BCL2 protein expression levels were analyzed using western blotting, cell proliferation was determined using a CCK-8 assay and the levels of cell apoptosis were analyzed using flow cytometric analysis. The results of the present study revealed that the expression levels of miR-23a-3p were significantly upregulated, while the expression levels of BCL2 were significantly downregulated in H₂O₂-induced HLE-B3 cells compared to untreated control cells. BCL2 was shown to be a target of miR-23a-3p. The miR-23a-3p inhibitor subsequently attenuated H₂O₂-induced apoptosis and increased the proliferation of HLE-B3 cells, which was partially reversed by siRNA-BCL2. In conclusion, the findings of the current study suggested that the inhibition of miR-23a-3p may attenuate H₂O₂-induced cataract formation by targeting BCL2, thus providing a novel therapeutic target for the treatment of patients with cataracts in the clinic.

Comparison of physical activity levels in Spanish people with diabetes with and without cataracts

Background

The objective was to compare levels of physical activity (PA) in a large sample of Spanish people with diabetes with and without cataracts. To our knowledge, this is the first study comparing PA levels in people with diabetes with and without cataracts in a large representative sample.

Methods

Cross-sectional data from the Spanish National Health Survey 2017 were analyzed (n = 1014 people with diabetes; 43.1% females; age range 15–69 years; mean age 58.4 ± 9.2 years). International Physical Activity Questionnaire (IPAQ) short form was used to measure PA. Total MET-min week−1 of PA were calculated and participants were divided into two categories according to American Diabetes Association PA guidelines: (i) <600 MET-min week−1. (ii) At least 600 MET-min week−1. Diabetes and cataracts were self-reported in response to the questions ‘Have you ever been diagnosed with diabetes/cataracts?’ Participants also reported other variables including age, gender, marital status, living as a couple, education, smoking, alcohol consumption and obesity. Statistical analysis was performed with SPSS 23.0.

Results

The overall prevalence of cataract was 14.0% and the overall prevalence of people doing <600 MET-min week−1 of PA was 35.4%. The prevalence of cataract was significantly lower in those doing more PA (12.1% vs. 17.5%; P = 0.016). Those without cataracts were significantly more active than those with cataracts (1846.8 vs. 1289.4 MET-min week−1; P = 0.001). The adherence to American Diabetes Association PA guidelines was significantly higher in those without cataracts (66.1% vs. 55.6%; P = 0.016).

Conclusions

Interventions to promote PA targeting people with both diabetes and cataracts are warranted.

The Association between Difficulty Seeing and Physical Activity among 17,777 Adults Residing in Spain

This is the first representative population-based study exploring the association between difficulty seeing (i.e., low vision) and physical activity in Spain. Cross-sectional data from the Spanish National Health Survey 2017 were analysed (n = 17,777, ≥15 years; 52% females). Difficulty seeing was self-reported in response to the question ‘‘Do you have difficulty seeing?” The international physical activity questionnaire (IPAQ) short form was used to measure level of physical activity. Multivariable logistic regression was used to assess associations overall and by age group (15–49, 50–64, ≥65 years). Covariates included in the analysis were sex, age, education, marital status, use of glasses or contact lenses, cataracts, diabetes, obesity, hypertension, smoking and alcohol consumption. The overall prevalence of difficulty seeing was 11%, and the overall prevalence of participating in less than 600 metabolic equivalent (MET)-min/week of physical activity was 30.2%. After adjustment for covariates, difficulty seeing was associated with significantly higher odds of performing less than 600 MET-min/week of physical activity with the odds ratio (OR) = 1.222 (95% confidence interval = 1.099–1.357). Considering the impact on health and quality of life due to reduced physical activity in people with difficulty seeing, at least 600 MET-min/week of physical activity should be promoted to this population.

Correlation between serum homocysteine, folate, vitamin B6 and age-related cataract

Age-related cataracts (ARC) are the leading cause of visual impairment and blindness, affecting 16 million subjects globally. This work aimed to investigate the correlation of serum homocysteine (Hcy), folate, vitamin B6 (VitB6) and ARC. We prospectively enrolled 60 ARC, and 58 age-matched healthy controls in this study. The serum concentrations of Hcy were determined using a fully automatic biochemical analyzer and folate/VitB6 by enzyme-linked immunosorbent assay (ELISA). The diagnostic performance of serum Hcy, folate and VitB6 for ARC were evaluated by receiver operating characteristics (ROC). The mean serum levels of Hcy, folate and VitB6 from the control group were 9.8 ± 2.1 μmol/L, 17.4 ± 2.3 nmol/L, 42.3 ± 5.7 pmol/L, respectively. In comparison, the mean serum levels of Hcy, folate and VitB6 from the ARC group were 12.2 ± 2.5 μmol/L, 15.3 ± 2.6 nmol/L, 40.3 ± 5.1 pmol/L, respectively. Significant statistical difference (p<0.05) were found between the control and ARC groups. The diagnostic sensitivity, specificity and AUC of serum Hcy as a biomarker for ARC were 53.1%, 76.3% and 0.66 (95% CI:0.61-0.76), respectively, which were superior to that of serum folate and VitB6. Serum Hcy was significantly elevated in ARC patients and correlated with ARC development, thus may be used as a serological marker for ARC diagnosis.