Cigarette smoking, body mass index associated with the risks of age-related cataract in male patients in northeast China

Body mass index influences age-related cataracts: an updated meta-analysis and systemic review

PURPOSE

Visual impairment and blindness caused by cataracts are major public health problems. Several factors are associated with an increased risk of age-related cataracts, such as age, smoking, alcohol consumption, and ultraviolet radiation. This meta-analysis aimed to assess the association between body mass index and age-related cataracts.

METHODS

Studies on weight and age-related cataracts published from January 2011 to July 2020 were reviewed by searching PubMed, Medline, and Web of Science databases. The random-effects and fixed-effects models were used for the meta-analysis, and the results were reported as odd ratios.

RESULTS

A total of nine studies were included in the meta-analysis. No correlation was found between underweight and nuclear cataracts (OR=1.31, 95% CI [-0.50 to 3.12], p=0.156). The results of the random-effects model showed that overweight was significantly associated with age-related cataracts and reduced the risk of age-related cataracts (OR=0.91, 95% CI [0.80-1.02], p<0.0001; I2=62.3%, p<0.0001). Significant correlations were found between overweight and cortical, nuclear, and posterior subcapsular cataracts (OR=0.95, 95% CI [0.66-1.24], p<0.0001; OR=0.92, 95% CI (0.76-1.08), p<0.0001; OR=0.87, 95% CI [0.38-1.02], p<0.0001). Significant correlations were found between obesity and cortical, nuclear, and posterior subcapsular cataracts (OR=1.00, 95% CI [0.82-1.17], p<0.0001; OR=1.07, 95% CI [0.92-1.22], p<0.0001; OR=1.14, 95% CI [0.91-1.37], p<0.0001).

CONCLUSION

This finding suggested a significant correlation between body mass index and age-related cataracts, with overweight and obesity reducing or increasing the risk of age-related cataracts, respectively.

A Population-based Study of the Prevalence of Cataract and Its Relationship with Smoking in the Northwest of Iran: The Azar Cohort Eye Study

PURPOSE

The purpose of the to determine the prevalence of cataract and study the relationship of smoking and other potential risk factors with visually significant cataract.

METHODS

This is a cross-sectional study based on the Azar cohort databases including 11,208 participants aged 35-70 years of the general population. According to the questionnaire, participants were divided into five groups in terms of smoking. Eye examinations were performed in two steps. The first step was performed by an optometrist, and in the second step, participants with poor red reflex or visual acuity of <8/10 were examined by an ophthalmologist for diagnosing cataract.

RESULTS

Of the participants, 4992 (44.5%) were male and 6216 (55.5%) were female, with a mean age of 50.1 ± 9.27 years. The prevalence of visually significant cataract was 7.2%. The frequency of ex-smoking in the male and female population in the cataract group was significantly higher than that in the noncataract group (male: P = 0.008, female: P = 0.01), but after adjustment for age and education level, lost its significance (male odds ratio [OR] = 1.1 [0.8-1.5], P = 0.4; female OR = 1.5 [0.5-4], P = 0.3).

CONCLUSION

There is no association between cigarette smoking in different doses and the history of smoking with cataracts but other factors such as aging, education level, and underlying diseases including diabetes mellitus, hypertension, and myopia have statistically significant association with visually significant cataract.

Hyperglycemia and Hypo-HDL-cholesterolemia Are Primary Risk Factors for Age-related Cataract, and a Korean-style Balanced Diet has a Negative Association, based on the Korean Genome and Epidemiology Study

BACKGROUND

The prevalence of cataracts is steadily increasing among the middle-aged and elderly worldwide. We hypothesized that adults aged > 50 years with age-related cataracts (ARCs) have an association with metabolic syndrome (MS) and its components, and MS has interactions with different dietary patterns and lifestyles that affect ARC risk. We examined the hypothesis using the Korean Genome and Epidemiology Study (KoGES; a large-scale hospital-based cohort study), which collected data between 2004-2013.

METHODS

Participants ≥ 50 years old were classified as cases (1,972 ARC patients) and controls (38,290 healthy controls) based on a diagnosis of cataract by a physician. MS and its components were defined using WHO definitions for Asians. Dietary consumption was evaluated using a validated semi-quantitative food frequency questionnaire (SQFFQ), which contained 106 foods, and dietary patterns were analyzed by principal component analysis. After adjusting for potential covariates, logistic regression was used to investigate associations between MS and its components and between dietary patterns and a positive cataract history.

RESULTS

ARC had a positive association with MS after 1.32-fold adjusting for age, sex, residence area, body mass index, and energy intake. Plasma glucose and HbA1c concentrations exhibited an increased ARC risk in the participants with MS by 1.50- and 1.92-fold and without MS by 1.35 and 1.88-fold, respectively. Serum high-density lipoprotein (HDL) concentrations were negatively associated with ARC risk only in the MS patients, but not without MS. However, blood pressure, abdominal obesity, and serum triglyceride concentrations did not associate with ARC risk regardless of MS. High intake of a Korean-balanced diet (KBD) containing fermented food exhibited a negative association with ARC risk (OR = 0.81) only in the MS group. The fat and coffee intake had a negative association with ARC only in the non-MS group. Current- and former-smokers were positively associated with ARC risk.

CONCLUSION

Persons who have hyperglycemia and low-HDL-cholesterolemia had increased susceptibility of ARC prevalence. A KBD with a proper amount of fat (≥ 15%) is recommended, and smoking should be prohibited.

Biology of Inherited Cataracts and Opportunities for Treatment

Cataract, the clinical correlate of opacity or light scattering in the eye lens, is usually caused by the presence of high-molecular-weight (HMW) protein aggregates or disruption of the lens microarchitecture. In general, genes involved in inherited cataracts reflect important processes and pathways in the lens including lens crystallins, connexins, growth factors, membrane proteins, intermediate filament proteins, and chaperones. Usually, mutations causing severe damage to proteins cause congenital cataracts, while milder variants increasing susceptibility to environmental insults are associated with age-related cataracts. These may have different pathogenic mechanisms: Congenital cataracts induce the unfolded protein response and apoptosis. By contrast, denatured crystallins in age-related cataracts are bound by α-crystallin and form light-scattering HMW aggregates. New therapeutic approaches to age-related cataracts use chemical chaperones to solubilize HMW aggregates, while attempts are being made to regenerate lenses using endogenous stem cells to treat congenital cataracts.

Association of Single Nucleotide Polymorphisms in XRCC1 (194) and XPD (751) with Age-related cataract

PURPOSE

Age-related cataract (ARC) is a multifactorial disease and different risk factors, including genetic and environmental, are responsible for the development of its various types. The aim of this study was to find out a correlation, if any, between ARC and the single nucleotide polymorphisms (SNPs) in DNA repair genes XRCC1 (X-ray repair cross-complementary-1) [Arg194Trp (rs1799782)] and XPD (xerodermapigmentosa complementation group D) [Lys751Gln (rs13,181].

METHOD

The genotype at these two SNPs was analyzed in 260 subjects (125 control and 135 patients) from Southern Punjab population (Pakistan) by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) method. Genotype at both analyzed codons was correlated either individually or in various combinations with the studied epidemiological factors known to be associated with ARC.

RESULTS

Our results indicated that both SNPs Arg194Trp in XRCC1 (P = 0.967) and Lys751Gln in XPD (P = 0.995) were not associated with ARC whether they were analyzed individually or in combined form (P > 0.05). Analysis of epidemiological factors revealed that age (P < 0.001), cast of subjects (P = 0.001), diabetes (P < 0.001), hypertension (P = 0.001), smoking habit (P = 0.01), drug abuse (P < 0.05), steroid use (P = 0.001) and body weight (P < 0.001) can influence the incidence of ARC in enrolled subjects. After applying Binary logistic regression it was found that the weight (P < 0.01), family history (P = 0.05), drug abuse (P = 0.05), smoking (P < 0.05) and steroid use (P < 0.05) has a significant association with the phenotype of the subjects. All epidemiological factors were also studied in association with various genotypic combinations of both SNPS, diabetes was the only factor that had a significant association (P < 0.001) association with ARC. Hypertension (P = 0.01), body weight (P < 0.05) and cast (P < 0.001) were found associated with ARC when epidemiological factors were individually correlated with ARC. Result of the two proportion test indicated that gender had no influence on the incidence of disease.

CONCLUSION

It is concluded that studied SNPs in XRCC1 and XPD have no association with the incidence of age related cataract in the analyzed group of subjects.

Prevalence and risk factors of lens opacities in rural populations living at two different altitudes in China

AIM

To investigate the prevalence of and risk factors for lens opacities in populations living at two different altitudes in China.

METHODS

A total of 813 subjects aged ≥40y in Lhasa (Tibet Autonomous Region, China. Altitude: 3658 m) and Shaoxing (Zhejiang Province, China. Altitude: 15 m) were underwent eye examinations and interviewed in this cross-sectional study. Participants' lens opacities were graded according to the Lens Opacities Classification System II (LOCS II) and the types of opacities with LOCS II scores ≥2 were determined. Univariate and stepwise logistic regression were used to evaluate the associations of independent risk factors with lens opacities.

RESULTS

Lens opacities were significantly more prevalent in the high-altitude than in the low-altitude area (χ (2)=10.54, P<0.001). Lens opacities appear to develop earlier in people living at high than at low altitude. The main types of lens opacity in Lhasa and Shaoxing were mixed (23.81%) and cortical (17.87%), respectively. Independent risk factors associated with all lens opacities were age, ultraviolet (UV) radiation exposure, and educational level. Compared with participants aged 40-49y, the risk of lens opacities increased gradually from 2 to 85 times per 10y [odds ratio (OR)=2.168-84.731, P<0.05). The risk of lens opacities was about two times greater in participants with the highest UV exposure than in those with the lowest exposure (OR=2.606, P=0.001). Educational level was inversely associated with lens opacities; literacy deceased the risk by about 25% compared with illiteracy (OR=0.758, P=0.041).

CONCLUSION

Old age, higher UV exposure and lower educational level are important risk factors for the development of lens opacities. Lens opacities are more prevalent among high-altitude than low-altitude inhabitants.

Lens Biology and Biochemistry

The primary function of the lens resides in its transparency and ability to focus light on the retina. These require both that the lens cells contain high concentrations of densely packed lens crystallins to maintain a refractive index constant over distances approximating the wavelength of the light to be transmitted, and a specific arrangement of anterior epithelial cells and arcuate fiber cells lacking organelles in the nucleus to avoid blocking transmission of light. Because cells in the lens nucleus have shed their organelles, lens crystallins have to last for the lifetime of the organism, and are specifically adapted to this function. The lens crystallins comprise two major families: the βγ-crystallins are among the most stable proteins known and the α-crystallins, which have a chaperone-like function. Other proteins and metabolic activities of the lens are primarily organized to protect the crystallins from damage over time and to maintain homeostasis of the lens cells. Membrane protein channels maintain osmotic and ionic balance across the lens, while the lens cytoskeleton provides for the specific shape of the lens cells, especially the fiber cells of the nucleus. Perhaps most importantly, a large part of the metabolic activity in the lens is directed toward maintaining a reduced state, which shelters the lens crystallins and other cellular components from damage from UV light and oxidative stress. Finally, the energy requirements of the lens are met largely by glycolysis and the pentose phosphate pathway, perhaps in response to the avascular nature of the lens. Together, all these systems cooperate to maintain lens transparency over time.

Risk factors for cataracts in systemic lupus erythematosus (SLE)

Cataract is the most common ocular damage in systemic lupus erythematosus (SLE). We analyzed data from the Hopkins Lupus Cohort longitudinally to identify the factors that predict onset of cataract prior to 60 years of age. The Hopkins Lupus Cohort is a clinical cohort of patients with SLE seen quarterly. This analysis was based on the follow-up experience prior to age 60 of 2,109 SLE patients who had not had a cataract prior to cohort entry. Patients saw their ophthalmologist every 6 months. Cataract was defined by the SLICC/American College of Rheumatology Damage Index. The rate of incident cataract was calculated in subsets of the follow-up defined by patient characteristics and history. Multivariable logistic regression models were fit to identify predictors of cataract while controlling for potential confounding variables. The analysis was based on 11,887 persons-years of follow-up, with median follow-up time of 4.1 years per patient. The incidence of cataract was 13.2/1,000 persons-years. Adjusting for other predictors, a cumulative prednisone dose equivalent to 10 mg/day for 10 years was a strong predictor of cataract (RR = 2.9, P = 0.0010). Disease activity measured by SELENA-SLEDAI (P = 0.0004) and higher systolic blood pressure (P = 0.0003) were associated with cataract. Duration of SLE, diabetes mellitus, smoking, cholesterol, renal involvement, immunological profile and medication history other than prednisone were not associated with cataract. Cataract development in SLE patients is multifactorial with prednisone, systolic blood pressure and disease activity all playing a role.