Development Of Lens Opacities Research Articles

Phenotypic and transcriptional changes in lens epithelial cells following acute and fractionated ionizing radiation exposure

Purpose Exposure to ionizing radiation is one of the known risk factors for the development of lens opacities. It is believed that radiation interactions with lens epithelial cells (LEC) are the underlying cause of cataract development, however, the exact mechanisms have yet to be identified. The aim of this study was to investigate how different radiation dose and fractionation impact normal LEC function. Materials and methods A human derived LEC cell line (HLE-B3) was exposed to a single acute x-ray dose (0.25 Gy) and 6 fractionated doses (total dose of 0.05, 0.1, 0.25, 0.5, 1, and 2 Gy divided over 5 equal fractions). LEC were examined for proliferation using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and migration using a Boyden chamber assay at various time points (0.25, 0.5, 1, 2, 4, 7, 9, 11, and 14 d) post-irradiation. Transcriptomic analysis through RNA sequencing was also performed to identify differentially expressed genes and regulatory networks in cells following 4 different acute exposures and 1 fractionated exposure. Results Exposure to an acute dose of 0.25 Gy significantly increased proliferation and migration rates, peaking at 7 d post irradiation (20% and 240% greater than controls, respectively), before returning to baseline levels by day 14. Fractionated exposures had minimal effects up to a dose of 0.5 Gy, but significantly reduced proliferation and migration after 1 and 2 Gy by up to 50%. The largest transcriptional response occurred 12 h after an acute 0.25 Gy dose, with 362 genes up-regulated and 288 genes down-regulated. A unique panel of differentially expressed genes was observed between moderate versus high dose exposures, suggesting a dose-dependent transcriptional response in LEC that is more pronounced at lower doses. Gene ontology and upstream regulator analysis identified multiple biological processes and molecular functions implicated in the radiation response, in particular differentiation, motility, receptor/ligand binding, cell signaling and epithelial-mesenchymal cell transition. Conclusions Overall, this research provides novel insights into the dose and fractionation effects on functional changes and transcriptional regulatory networks in LEC, furthering our understanding of the mechanisms behind radiation induced cataracts.

Biometry in Silicone Oil Filled Eyes. A Review

The “gold standard” of modern vitreoretinal surgery is silicone oil tamponade of the vitreous cavity. The lens opacity development is in the list of complications of prolonged silicone oil eye filling (from 2 weeks to 2 years). Polydimethylsiloxanes hydrophobicity, direct contact with the front of the silicone bladder, macrophage and toxic reaction, trophic disturbances are the causes leading to the cataract initiation. This makes the problem of cataract surgery and preliminary intraocular lens calculation in silicone oil filled eyes before its removing very relevant as well as cloudy retina visualization and the necessity of minimization of number of operations through their combination. Certainly, the main error in IOL power calculation is associated with axial length measurement inaccuracy, as the most significant term of an equation. Silicone oil filled eyes biometry errors, and, consequently, postoperative refraction biases remain unresolved problem until now. To date authors report only 58 % of cases in which target refraction was achieved after combined surgery. Some researchers figure out that average calculation error after phacoemulsification with IOL implantation in avitreal eyes was 0.8 D despite of the optical biometry usage. Today it is represented by several methods: partial coherent interferometry, optical low-coherence reflectometry and optical coherence tomography, which are implemented in devices such as IOLMaster 500, Lenstar LS 900 and IOLMaster 700, which have their own characteristics and measurement accuracy. Their advantages as well as creation an accurate IOL calculation method for silicone oil filled eyes could reduce postoperative refraction error that outline significant medical and social problem.

Incidence and Factors of Postoperative Lens Opacity after Lens-Sparing Vitrectomy for Retinopathy of Prematurity

To determine the incidence and factors associated with lens opacity after lens-sparing vitrectomy (LSV) for retinopathy of prematurity (ROP). Retrospective, comparative case series. Among the 141 eyes of 94 patients who underwent LSV for ROP between 2006 and 2019, 108 eyes of 71 patients with a minimum follow-up of 12 months after LSV were investigated. Data were collected from patients' charts, including gender, gestational age at birth, birth weight, stage of ROP, postmenstrual age (PMA) at LSV, surgical procedure, preoperative injection of anti-vascular endothelial growth factor (VEGF) agents, subsequent retinal surgeries, and lensectomy during follow-up. Lens status at last visit, incidence and timing of lensectomy, and risk factors for lens opacity requiring lensectomy. Stages of ROP at LSV were 4A, 4B, and 5 in 92 eyes, 13 eyes, and 3 eyes, respectively. The median PMA at LSV was 40.6 weeks. Thirty-two eyes received anti-VEGF therapy before LSV. Lens opacity was found in 17 eyes (15.7%), of which 10 eyes (9.3%) underwent lensectomy. The period between LSV and lensectomy ranged from 21 days to 131.9 months (median, 21.1 months). Eleven other eyes (10.2%) underwent lensectomy as part of a reoperation for worsening of ROP. A total of 80 eyes (74.1%) preserved clear lenses at the latest follow-up examination after surgery (median, 6.8 years; range, 1-14 years). The Kaplan-Meier estimate showed that the proportion of patients with phakia at 5 and 10 years was 92.4% and 89.0%, respectively. Multivariate Cox regression analysis revealed that eyes with the use of tamponade at LSV (P= 0.005; odds ratio [OR], 25.68; 95% confidence interval [CI], 4.187-157.5) and young PMA at LSV (P= 0.033; OR, 1.047; 95% CI, 1.012-1.099) were associated significantly with lens opacity requiring lensectomy. However, anti-VEGF therapy was not associated with lens opacity requiring lensectomy. Nearly 10% of eyes required lensectomy because of lens opacity after LSV for ROP. The development of lens opacity requiring lensectomy seems to be associated with the use of tamponade and young PMA at LSV.

Human cataractous lenses contain cross-links produced by crystallin-derived tryptophanyl and tyrosyl radicals

Protein insolubilization, cross-linking and aggregation are considered critical to the development of lens opacity in cataract. However, the information about the presence of cross-links other than disulfides in cataractous lenses is limited. A potential role for cross-links produced from tryptophanyl radicals in cataract development is suggested by the abundance of the UV light-sensitive Trp residues in crystallin proteins. Here we developed a LC-MS/MS approach to examine the presence of Trp−Trp, Trp−Tyr and Tyr−Tyr cross-links and of peptides containing Trp−2H (−2.0156 Da) in the lens of three patients diagnosed with advanced nuclear cataract. In the proteins of two of the lenses, we characterized intermolecular cross-links between βB2-Tyr153−Tyr104-βA3 and βB2-Trp150−Tyr139-βS. An additional intermolecular cross-link (βB2-Tyr61−Trp200-βB3) was present in the lens of the oldest patient. In the proteins of all three lenses, we characterized two intramolecular Trp−Trp cross-links (Trp123−Trp126 in βB1 and Trp81−Trp84 in βB2) and six peptides containing Trp −2H residues, which indicate the presence of additional Trp−Trp cross-links. Relevantly, we showed that similar cross-links and peptides with modified Trp−2H residues are produced in a time-dependent manner in bovine β-crystallin irradiated with a solar simulator. Therefore, different crystallin proteins cross-linked by crystalline-derived tryptophanyl and tyrosyl radicals are present in advanced nuclear cataract lenses and similar protein modifications can be promoted by solar irradiation even in the absence of photosensitizers. Overall, the results indicate that a role for Trp−Tyr and Trp−Trp cross-links in the development of human cataract is possible and deserves further investigation.

Acute lens opacity induced by different kinds of anesthetic drugs in mice.

To study whether specific anesthetic drugs or tear layer evaporation was primarily responsible for the acute cataract and what the change of lens structure is in anesthetized mice. Five groups were set up in the experiment: Group A (topicamide and phenylephrine mixed eye drop+ chloral hydrate), Group B (tropicamide and phenylephrine mixed eye drop+sevoflurane), Group C (tropicamide and phenylephrine mixed eye drop), Group D (topicamide and phenylephrine mixed eye drop+chloral hydrate, carbomer eye drop in the right eyes), and Group E (tropicamide and phenylephrine mixed eye drop+sevoflurane, carbomer eye drop in the right eyes). A simple classification system was used to assess the severity of lens opacity. And a numerical value from 0 to 3 to each grade was assigned for the cataract index calculation and data analysis. The gross appearance and time course of development of lens opacity were assessed. Hematoxylin and eosin staining was used to observe the lens structure changes in the reversible cataract. Tropicamide did not induce lens opacification in mice. Lens opacity caused by inhaled sevoflurane was similar to injected cholral hydrate. Both inhaled-anesthetic-induced lens opacity and injected-anesthetic-induced lens opacity could be prevented by carbomer eye drop. In the severe opacity lens, a wide range of lens fiber cell structure had disordered. The fiber cells became uneven thickness. The acute reversible lens opacity can unilaterally develop or be induced by a local cause. The structure of lens fiber cells changed in the lens opacity which may influence the permanent connection of the lens fiber cells. This study was not only of practical significance to help maintain lens transparency for eye research, but also of the deeper consideration about the reversible lens opacification phenomenon.

“Important Players” in the Development of Age-Related Cataracts (Literature Review)

Millions people around the world, especially in old age, lose sight because of cataracts. The age-related cataract affects approximately 37 million people in the world annually, and in 51 % of cases, it is the cause of poor vision. Relevant is the importance of identifying risk factors for the development of age-related cataracts. This literature review is devoted to studies examining the influence of various factors on the development of lens opacities. The paper presents data on the effect of age on the development of age-related cataracts, so the prevalence of cataracts at the age of 52–62 years is 5 %, at the age of 60–69 years — 30 %, at the age of 70 and older — 64 %. Its gender features are highlighted — the frequency of lens opacities in women increases significantly with age, and its appearance coincides with the appearance of estrogen deficiency in menopause. Reflected literature data on the dependence of cataract prevalence on race (revealed a higher prevalence in various Asian populations compared with the population of Western countries). This review also had showed the influence of lifestyle and bad habits on the occurrence of cataracts. It was found that smokers have an increased risk of occurrence of a nuclear cataract and, to a lesser extent, the development of its cortical type. It is noted that the development of lens opacification is also influenced by the amount of alcohol consumed, increasing the risk of cataracts, so when studying individual types of cataracts, it is shown that the consumption of strong drinks and wine is associated with an increased risk of nuclear cloudiness. Presents data from large cohort studies that compare (using odds ratios and confidence intervals) the association of cataracts with such somatic diseases as diabetes mellitus, hypertension, also with body mass index and some medications.

Radiation-associated lens changes in the cardiac catheterization laboratory: Results from the IC-CATARACT (CATaracts Attributed to RAdiation in the CaTh lab) study.

To examine the relationship between occupational exposure to ionizing radiation and the prevalence of lens changes in interventional cardiologists (ICs) and catheterization laboratory ("cath-lab") staff. Exposure to ionizing radiation is associated with the development of lens opacities. ICs and cath-lab staff can receive high doses of ionizing radiation without protection, and may thus be at risk for lens opacity formation. We conducted a cross-sectional study at an interventional cardiology conference. Study participants completed a questionnaire pertaining to occupational exposure to radiation and potential confounders for the development of cataracts, followed by slit-lamp examination and grading of lens findings. A total of 117 attendees participated in the study, including 99 (85%; 49 ± 11 years-old; 82% male) with occupational exposure to ionizing radiation and 18 (15%; 39 ± 12 years-old; 61% male) unexposed controls. The prevalence of overall cortical and posterior subcapsular lens changes (including subclinical findings) was higher in exposed participants compared with controls (47 vs. 17%, P = 0.015). Occupational exposure and age over 60 were independent predictors of lens changes (odds ratio [95% CI]: 6.07 [1.38-43.45] and 7.72 [1.60-43.34], respectively). The prevalence of frank opacities was low and similar between the two groups (14 vs. 6%, P = 0.461). Most lens findings consisted of subclinical changes in the periphery of the lens without impact on visual acuity. Compared with unexposed controls, ICs and cath-lab staff had a higher prevalence of lens changes that may be attributable to ionizing radiation exposure. While most of these changes were subclinical, they are important due to the potential to progress to clinical symptoms, highlighting the importance of minimizing staff radiation exposure.

Protective Effects of Acetylation on the Pathological Reactions of the Lens Crystallins with Homocysteine Thiolactone.

Various post-translational lens crystallins modifications result in structural and functional insults, contributing to the development of lens opacity and cataract disorders. Lens crystallins are potential targets of homocysteinylation, particularly under hyperhomocysteinemia which has been indicated in various eye diseases. Since both homocysteinylation and acetylation primarily occur on protein free amino groups, we applied different spectroscopic methods and gel mobility shift analysis to examine the possible preventive role of acetylation against homocysteinylation. Lens crystallins were extensively acetylated in the presence of acetic anhydride and then subjected to homocysteinylation in the presence of homocysteine thiolactone (HCTL). Extensive acetylation of the lens crystallins results in partial structural alteration and enhancement of their stability, as well as improvement of α-crystallin chaperone-like activity. In addition, acetylation partially prevents HCTL-induced structural alteration and aggregation of lens crystallins. Also, acetylation protects against HCTL-induced loss of α-crystallin chaperone activity. Additionally, subsequent acetylation and homocysteinylation cause significant proteolytic degradation of crystallins. Therefore, further experimentation is required in order to judge effectively the preventative role of acetylation on the structural and functional insults induced by homocysteinylation of lens crystallins.

Evidence for apoptosis in the lens after in vivo exposure to ultraviolet radiation

SummaryThe eye is exposed to ultraviolet radiation (UVR) in daylight. Epidemiological studies suggest a dose dependent association between UVR and cataract development. Experimental data confirm that UVR induces damage in the lens epithelium and trigger apoptosis. The time delay between exposure and onset of apoptosis in the lens varies depending on the dosage of UVR. The higher the in vivo UVR dose, the faster the onset of apoptosis and the development of lens opacification. Apoptotic events in the epithelium precede macroscopic cataractogenesis. Lens epithelium is a primary target for UVR exposure. Immunohistochemistry shows that the expression of apoptotic markers, caspase 3 and p53, increase in the lens epithelium after radiation. TUNEL‐labeling visualizes the transient increase of apoptosis products after UVR. After higher doses of UVR, apoptosis features are observed 1 h after radiation. Transmission electron microscopy shows the multi‐layered stack of epithelial cells, membrane infolds, nuclear fragmentation and chromatin condensation, phagosomes and apoptotic bodies, phagocytosis of apoptotic bodies and pyknosis. UVR causes apoptosis in the lens epithelial cells. The onset of apoptosis depends on the radiation dose.

The structural alteration and aggregation propensity of glycated lens crystallins in the presence of calcium: Importance of lens calcium homeostasis in development of diabetic cataracts

The imbalance of the calcium homeostasis in the lenticular tissues of diabetic patients is an important risk factor for development of cataract diseases. In the current study, the impact of elevated levels of calcium ions were investigated on structure and aggregation propensity of glycated lens crystallins using gel electrophoresis and spectroscopic assessments. The glycated proteins indicated significant resistance against calcium-induced structural insults and aggregation. While, glycated crystallins revealed an increased conformational stability; a slight instability was observed for these proteins upon interaction with calcium ions. Also, in the presence of calcium, the proteolytic pattern of native crystallins was altered and that of glycated protein counterparts remained almost unchanged. According to results of this study it is suggested that the structural alteration of lens crystallins upon glycation may significantly reduce their calcium buffering capacity in eye lenses. Therefore, under chronic hyperglycemia accumulation of this cataractogenic metal ion in the lenticular tissues may subsequently culminate in activation of different pathogenic pathways, leading to development of lens opacity and cataract diseases.

Clinical Outcomes and Cataract Formation Rates in Eyes 10 Years After Posterior Phakic Lens Implantation for Myopia.

Intraocular collamer lenses (ICLs) are posterior chamber phakic lenses that provide a refractive surgery option for those with high myopia or astigmatism. The short-term and midterm results indicate good refraction stability, efficacy, and safety. Cataract has been suggested to be an important long-term complication of ICL implantation. To report the rates of cataract development and refractive outcomes 10 years after ICL implantation. The study included 133 eyes of 78 patients undergoing consecutive V4 model ICL implantations, which took place from January 1, 1998, through December 31, 2004, at Jules-Gonin Eye Hospital, Lausanne, Switzerland. Data analysis was performed from January 1, 2014, to May 31, 2014. The lenses implanted were as follows: 53 V4 model ICLs of -15.5 D or greater, 73 V4 model ICLs of less than -15.5 diopter (D), and 7 V4 model toric ICLs for myopia. Rate of cataract surgery, lens opacity, ocular hypertension, refractive safety, predictability, and stability. A total of 133 eyes of 78 patients (34 men and 44 women, with a mean [SD] age of 38.8 [9.2] years at enrollment) met the inclusion criteria. The rate of lens opacity development was 40.9% (95% CI, 32.7%-48.8%) and 54.8% (95% CI, 44.7%-63.0%) at 5 and 10 years, respectively. Phacoemulsification was performed in 5 eyes (4.9%; 95% CI, 1.0%-8.7%) and 18 eyes (18.3%; 95% CI, 10.1%-25.8%) at 5 and 10 years after ICL implantation, respectively. The vault height (distance between the posterior ICL surface and anterior lens surface) measured a mean (SD) of 426 (344) μm immediately postoperatively, decreasing to 213 (169) μm at 10 years. A smaller vault height was associated with the development of lens opacity and phacoemulsification (P = .005 and .008, respectively). The intraocular pressure was 15 mm Hg postoperatively, and there was no significant increase in intraocular pressure observed until the 10-year follow-up (16 mm Hg, P = .02). At 10 years, 12 eyes (12.9%; 95% CI, 5.6%-19.6%) had developed ocular hypertension that required topical medication. At 10 years, the mean (SD) safety index was 1.25 (0.57), with a manifest spherical equivalent of -0.5 D at 1-year postoperatively vs -0.7 D at 10 years postoperatively in eyes aimed at emmetropia. This retrospective single center study indicates that ICL implantation provides good long-term safety and stability of refraction in patients with high myopia compared with similar short-term studies. However, the rates of cataract formation and ocular hypertension at 10 years have important clinical implications, and as such this information should be part of the available patient information before ICL implantation.

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

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

Analysis of the prevalence of polymorphisms in the glutathione S transferase gene (GST) in cataract patients from Goiânia

The aim of this study was to determine the prevalence of polymorphisms in the glutathione S-transferase genes GSTM1 and GSTT1 in patients with lens opacity (cataract). Peripheral blood samples were obtained from male and female patients (N = 23) with cataract. The GSTM1 and GSTT1 polymorphic regions were amplified by polymerase chain reaction, and the amplification products were electrophoresed on a 2% agarose gel. The obtained bands were by staining with ethidium bromide. The results were compared by a chi-square test using the BioEstat software (v.5.0). The frequencies of the GSTM1- and GSTT1-null genotypes were higher than those of the GSTM1- and GSTT1-present genotypes. The frequency of GSTT1-null genotypes was approximately 1.7 times higher than that of GSTM1, which was a statistically significant difference (P = 0.0019). Although a consensus remains to be reached on the correlation between genetic polymorphisms in GSTs and cataract susceptibility, the observations from most scientific studies are similar to those reported in this study. Thus, we conclude that the absence of these genes, particularly GSTT1, is correlated with the development of lens opacity.

Topical Use of NaCl Solution with Different Concentration Affects Lens Transparency in Anesthetized Mice

ABSTRACT Purpose: To study the influence of NaCl solution with different concentration on lens transparency in anesthetized mice. Methods: Four kinds of NaCl solution with different concentration were prepared as eye drops to imply graded osmolarity (100, 300, 500 and 1000 mOsmol/kg). Five groups of anesthetized mice were set-up to induce lens opacity, in which four groups were treated with NaCl solution and another group naturally exposed to air. The lens opacity was graded as no opacity, mild, medium and severe opacity at 0, 10, 20, 30, 45 and 60 min after the start of the experiment. A numerical value from 0 to 3 was assigned to each grade for the cataract index (CI) calculation and data analysis. The same procedure was repeated in all groups 48 h later. The reversion process of lens opacity was explored using a hypotonic NaCl solution (100 mOsmol/kg) in another pair of groups, a 500 mOsmol/kg NaCl solution group and natural exposure group. The gross appearance and time course of development and reversion of lens opacity were assessed. Results: Lens opacity primarily developed in a hypertonic NaCl solution-treated and naturally exposed eyes, and the gross anatomical appearance were similar. The speed of lens opacity development and CI changes were osmolarity-dependent, and the higher NaCl concentration solution used, the faster and more severe the formation of opacification. Both hypertonic NaCl-solution-induced lens opacity and natural exposure induced lens opacity could be resolved by hypotonic NaCl solution prior to anesthesia recovery. Conclusions: This study indicates a crucial effect of NaCl concentration on the development and reversion of lens opacity in the anesthetized mice, and support the osmolarity theory in the reversible lens opacification phenomenon. It is also of practical significance to mouse eye studies that require lens transparency.

The Association of Dietary Lutein plus Zeaxanthin and B Vitamins with Cataracts in the Age-Related Eye Disease Study: AREDS Report No. 37

To evaluate whether dietary intake of luteiin/zeaxanthin and B vitamins is associated with cataract prevalence and incidence.Clinic-based, baseline cross-sectional and prospective cohort study designs.Three thousand one hundred fifteen patients (6129 eyes) enrolled in the Age-Related Eye Disease Study 55 to 80 years of age followed up for mean of 9.6 years.Participants completed baseline food frequency questionnaires. Baseline and annual lens photographs were graded centrally. Multivariate models controlling for previously identified risk factors for cataracts tested for the association of cataracts with reported dietary intake, using the lowest quintile as reference.Cataract surgery, cataract status (type and severity) at baseline, and development of cataracts.At baseline, increased dietary riboflavin and B12 were associated inversely with nuclear and cortical lens opacities. In comparisons of persons with and without cataract, persons with the highest riboflavin intake versus those with the lowest intake had the following associations: mild nuclear cataract: odds ratio (OR), 0.78; 95% confidence interval (CI), 0.63-0.97; moderate nuclear cataract: OR, 0.62; 95% CI, 0.43-0.90; and mild cortical cataract: OR, 0.80; 95% CI, 0.65-0.99. For B12, the results were: mild nuclear cataract: OR, 0.78; 95% CI, 0.63-0.96; moderate nuclear cataract: OR, 0.62; 95% CI, 0.43-0.88; and mild cortical cataract: OR, 0.77; 95% CI, 0.63-0.95. Highest dietary B6 intake was associated with a decreased risk of moderate nuclear lens opacity developing compared with the lowest quintile (OR, 0.67; 95% CI, 0.45-0.99). Highest dietary intake levels of niacin and B12 were associated with a decreased risk of development of mild nuclear or mild cortical cataracts in participants not taking Centrum (Pfizer, New York, NY) multivitamins. For participants taking multivitamins during the study, the highest intake of dietary folate was associated with an increased risk of mild posterior subcapsular lens opacity development. No statistically significant associations were found between lutein plus zeaxanthin intake and presence at baseline or development of nuclear or cortical lens opacity outcomes.These findings are consistent with earlier studies suggesting that dietary intake of B vitamins may affect the occurrence of age-related lens opacities. Further investigations are warranted.

Molecular mechanism of formation of cortical opacity in CRYAAN101D transgenic mice.

The CRYAAN101D transgenic mouse model expressing deamidated αA-crystallin (deamidation at N101 position to D) develops cortical cataract at the age of 7 to 9 months. The present study was carried out to explore the molecular mechanism that leads to the development of cortical opacity in CRYAAN101D lenses. RNA sequence analysis was carried out on 2- and 4-month-old αA-N101D and wild type (WT) lenses. To understand the biologic relevance and function of significantly altered genes, Ingenuity Pathway Analysis (IPA) was done. To elucidate terminal differentiation defects, immunohistochemical, and Western blot analyses were carried out. RNA sequence and IPA data suggested that the genes belonging to gene expression, cellular assembly and organization, and cell cycle and apoptosis networks were altered in N101D lenses. In addition, the tight junction signaling and Rho A signaling were among the top three canonical pathways that were affected in N101D mutant. Immunohistochemical analysis identified a series of terminal differentiation defects in N101D lenses, specifically, increased proliferation and decreased differentiation of lens epithelial cells (LEC) and decreased denucleation of lens fiber cells (LFC). The expression of Rho A was reduced in different-aged N101D lenses, and, conversely, Cdc42 and Rac1 expressions were increased in the N101D mutants. Moreover, earlier in development, the expression of major membrane-bound molecular transporter Na,K-ATPase was drastically reduced in N101D lenses. The results suggest that the terminal differentiation defects, specifically, increased proliferation and decreased denucleation are responsible for the development of lens opacity in N101D lenses.

Risk Factors for Incident Cortical, Nuclear, Posterior Subcapsular, and Mixed Lens Opacities: The Los Angeles Latino Eye Study

Purpose: To identify sociodemographic and biological risk factors associated with the 4-year incidence of nuclear, cortical, posterior subcapsular (PSC), and mixed lens opacities. Design: Population-based, longitudinal study. Participants: We included 4658 Latinos 40 years from 6 census tracts in Los Angeles, California. Methods: Participants underwent an interview and detailed eye examination, including best-corrected visual acuity and slit-lamp assessment of lens opacities using the Lens Opacities Classification System II (LOCS II) at baseline and again 4 years later. Each opacity type was defined in persons with a LOCS II score of 2. Univariate and forward stepwise logistic regression analyses were used to identify independent baseline risk factors associated with 4-year incidence of nuclear only, cortical only, PSC only, and mixed (when 1 opacity type developed in a person) lens opacities. These comprised 4 mutually exclusive groups, and were based on person rather than eye. Main Outcome Measures: Odds ratios for independent risk factors associated with 4-year incidence of nuclear-only, cortical-only, PSC-only, and mixed lens opacities. Results: Of the 3471 participants with gradable lenses in the same eye at baseline and 4-year follow-up, 200 (5.8%) had incident nuclear-only opacities, 151 (4.1%) had incident cortical-only opacities, 16 (0.5%) had incident PSC-only lens opacities, and 88 (2.5%) had mixed lens opacities. Independent baseline risk factors for incident nuclear-only lens opacities included older age, current smoking, and presence of diabetes. Independent risk factors for incident cortical-only lens opacities included older age and having diabetes at baseline. Female gender was an independent risk factor for incident PSC-only lens opacities. Older age and presence of diabetes at baseline examination were independent risk factors for incident mixed lens opacities. Specifically, in diabetics, higher levels of hemoglobin A1c was associated with greater risk for 4-year incident nuclear-only, cortical-only and mixed lens opacities. Conclusions: Improved diabetic control and smoking prevention may reduce the risk of developing lens opacities. Understanding both modifiable and nonmodifiable risk factors provides insight into the development of lens opacification. Financial Disclosure(s): The authors have no proprietary or commercial interest in any of the materials discussed in this article. Ophthalmology 2012;119:2040–2047 © 2012 by the American Academy of Ophthalmology.

Enhanced age‐related cataract in copper‐zinc superoxide dismutase null mice

As the lens is constantly exposed to light and oxygen that generate harmful reactive oxygen species, the importance of the intracellular antioxidant enzyme copper-zinc superoxide dismutase for the protection against age-related cataract development was explored. The development of lens opacities and the lens oxidative status were studied in different age groups of mice lacking copper-zinc superoxide dismutase and in wild-type mice. The lens opacities were quantified from lens photographs using digital image analysis. Thereafter, the lenses were homogenized and analysed regarding their contents of reduced glutathione and protein carbonyls suggestive of protein oxidation. The 18-week-old mice of both genotypes had clear lenses. At 1 year of age, the copper-zinc superoxide dismutase null mice had developed cortical lens opacities, whereas the wild-type mice did not show equivalent changes until 2 years of age. The lens contents of glutathione decreased only in the 2-year-old wild-type mice, whereas the carbonyls increased over time without any differences between the two genotypes. This study indicates that the lack of copper-zinc superoxide dismutase may accelerate age-related lens opacity development and that intracellular superoxide-derived oxidative stress may be damaging to the lens during ageing. Participation of the anti-oxidant enzyme copper-zinc superoxide dismutase in the protection against age-related cataract was thus suggested.

Osmotic stress induced oxidative damage: Possible mechanism of cataract formation in diabetes

Chronic hyperglycemia causes increased level of reactive oxygen species which is thought to be involved in the pathogenesis of diabetes associated complications including cataract. In diabetic cataractous lens, over production of free radicals and decreased capacity of antioxidant defense system are the major contributors to oxidative damage by polyol pathway and advanced glycation end products. The current study focused on analysis of factors associated with osmotic imbalance and oxidative stress in aging and diabetic human cataractous lenses. We examined activities of polyol pathway enzymes, G6PD and glutathione system in lenses from subjects suffering from cataract due to aging and diabetes. We observed elevated activities of aldose reductase and sorbitol dehydrogenase while G6PD and glutathione system enzyme activities were found to be lower in cataractous subjects suffering from diabetes. The findings from the current study support the premise that osmotic imbalance, AGEs formation and oxidative stress contribute synergistically to the development of lens opacity in hyperglycemia.

Cysteamine Prevents the Development of Lens Opacity in a Rat Model of Selenite-Induced Cataract

The activation of transglutaminase 2 (TG2) by oxidative stress through TGFβ has been reported to play a crucial role in cataract formation. The authors investigated whether TG2 is involved in selenite-induced cataract formation in rats and whether cysteamine, a chemical inhibitor of TG2, can prevent cataract formation in this model. Intracellular TG2 activity was monitored in a human lens epithelial cell (HLE-B3) line and cultured rat lenses after treatment with selenite. Rat pups (13 days old) were injected subcutaneously with sodium selenite (Na(2)SeO(3); 20 μmol/kg) and intraperitoneally with cysteamine (30, 40, and 60 mg/kg) for 14 days. Lenses were evaluated photographically at days 7 and 14. The concentrations of malondialdehyde and glutathione in the lenses were determined. In HLE-B3 cells or rat lenses, selenite induced intracellular TG activity, which was inhibited by cysteamine. In selenite-treated rats, the rate of cataract formation was significantly reduced by cysteamine (P < 0.001). The mean cataract area in the lenses of cysteamine-treated rats was smaller than that of control rats (P < 0.01). The levels of total and reduced glutathione in the lenses of cysteamine-treated rats extracted at day 14 were higher than those of control rats. Cysteamine suppresses cataract formation induced by selenite in rats, suggesting that cysteamine can be used as a pharmaceutical intervention to prevent or delay cataract formation.