Cataractous Lenses Research Articles

Inverted meniscus IOLs reduce image shifts in the periphery compared to biconvex IOLs

Intraocular lenses (IOLs) are routinely used to replace cataractous crystalline lenses. Most current models have a biconvex design that reduces optical quality in the periphery since they are optimized only for central vision. Inverted meniscus IOLs are optimized to achieve similar optical performance to phakic eyes in the peripheral retina. Additionally, biconvex IOLs have been predicted to induce image shifts in the peripheral visual field. The aim of this study was to evaluate whether inverted meniscus IOLs produce a more consistent object-to-image mapping on the retina. For this purpose, retinal images before and after IOL implantation were recorded in subjects implanted with either standard biconvex or inverted meniscus IOLs, and the positions of landmarks were compared. The results showed that radial displacement of retinal landmarks increased with eccentricity in biconvex IOLs, as expected, but tended to have a flatter progression with smaller values in patients implanted with inverted meniscus lenses.

Measurement of absolute abundance of crystallins in human and αA N101D transgenic mouse lenses using 15N-labeled crystallin standards

Stable isotope labeled standards of all major human lens crystallins were created to measure the abundance of lens endogenous crystallins from birth to adulthood. All major human crystallins (αA, αB, βA2, βA3/A1, βA4, βB1, βB2, βB3, γA, γB, γC, γD, γS) were cloned with N-terminal 6 x His tagged SUMO for ease of purification and the ability to generate natural N-termini by SUMO protease cleavage when producing crystallins for structure/function studies. They were then expressed in 15N-enriched media, quantified by mass spectrometry, and mixed in proportions found in young human lens to act as an artificial lens standard. The absolute quantification method was tested using soluble protein from 5-day, 23-day, 18-month, and 18-year-old human lenses spiked with the 15N artificial lens standard. Proteins were trypsinized, relative ratios of light and heavy labeled peptides determined using high-resolution precursor and data independent MS2 scans, and data analysis performed using Skyline software. Crystallin abundances were measured in both human donor lenses and in transgenic mouse αA N101D cataract lenses. Technical replicates of human crystallin abundance measurements were performed with average coefficients of variation of approximately 2% across all 13 crystallins. αA crystallin comprised 27% of the soluble protein of 5-day-old lens and decreased to 16% by 18-years of age. Over this time period αB increased from 6% to 9% and the αA/αB ratio decreased from 4.5/1 to 2/1. γS-crystallin also increased nearly 2-fold from 7% to 12%, becoming the 3rd most abundant protein in adult lens, while βB1 increased from 14% to 20%, becoming the most abundant crystallin of adult lens. Minor crystallins βA2, βB3, and γA comprised only about 1% each of the newborn lens soluble protein, and their abundance dropped precipitously by adulthood. While 9 of the SUMO tagged crystallins were useful for purification of crystallins for structural studies, γA, γB, γC, and γD were resistant to cleavage by SUMO protease. The abundance of WT and N101D human αA in transgenic mouse lenses was approximately 40-fold lower than endogenous mouse αA, but the deamidation mimic human αA N101D was less soluble than human WT αA. The high content of αA and the transient abundance of βA2, βB3, and γA in young lens suggest these crystallins play a role in early lens development and growth. βB1 becoming the most abundant crystallin may result from its role in promoting higher order β-crystallin oligomerization in mature lens. The full set of human crystallin expression vectors in the Addgene repository should be a useful resource for future crystallin studies. 15N labeling of these crystallins will be useful to accurately quantify crystallins in lens anatomic regions, as well as measure the composition of insoluble light scattering crystallin aggregates. The standards will also be useful to measure the abundance of crystallins expressed in transgenic animal models.

A case of Atypical Keratitis by the rare fungus Pseudallescheria Boydii in a young male

We present a case of a 24-year-old male with fungal keratitis caused by a rare, atypical fungus Pseudallescheria boydii. Initially, aggressive medical therapy was given, but due to the virulent nature of fungus and its rapid spread, therapeutic keratoplasty had to be done to control the infection. Following healing and scarring after 4 months, Optical PK (penetrating keratoplasty) with cataractous lens exchange was done for visual rehabilitation.

Unveiling the Mysteries of the Chinese lens zonule balance tension: A statistical analysis

BackgroundThis study aims to provide an estimated dataset of lens zonule balance tension (LZBT) measurements in cataractous lenses among Chinese patients and to conduct a statistical analysis of anterior segment parameters. MethodsThis is a cross-sectional study. We included a total of 833 eyes from 833 Chinese participants aged 23–91 years who underwent cataract surgery. Anterior segment parameters were measured using swept-source anterior segment optical coherence tomography (SS-AS OCT) to calculate lens gravity (LG) and crystalline lens volume (VOL). Axial length (AL) was measured using IOL-Master 700. LZBT was calculated using force decomposition and synthesis methods. ResultsThe mean LZBT in the horizontal direction was 8.48E-05 ± 3.23E-05 N across all eyes. The LZBT in the subtemporal-supraspinal and supraspinal-temporal directions was 2 times greater than in the vertical direction. The balanced force on the suspensory ligament in the horizontal direction was twice as strong as in the vertical direction. Additionally, anterior segment parameters such as lens equivalent diameter (LE-dia), radius of the anterior lens surface curvature (RAL), radius of the posterior lens surface curvature (RPL), anterior chamber depth (ACD), iris area, iris volume, and iris thickness showed positive correlations with AL. ConclusionsAccounting for gravitational effects, we concluded that zonule force is asymmetrically distributed. Importantly, this study establishes the normal range of LZBT across different meridians using force synthesis and decomposition, offering new insights and feasibility for studying suspensory ligament biomechanics.

Phacoemulsification with Either Endocyclophotocoagulation or Ab-Interno Canaloplasty with or without Trabeculotomy in Uveitic Glaucoma

ABSTRACT Purpose Understanding the current role and efficacy of endocyclophotocoagulation (ECP) compared to ab-interno canaloplasty with or without trabeculotomy (OMNI), combined with cataract extraction and lens implantation (CEIOL), for the management of uveitic glaucoma (UG) is limited. Methods All UG patients ≥18 years old with ≥6 months of follow-up data (15.2 ± 5.9 months) after CEIOL combined with either ECP or OMNI from August 2019 to May 2022 at a single academic center were retrospectively reviewed [22 eyes of 15 patients (8 ECP, 14 OMNI)]. Surgical success was considered intraocular pressure (IOP) ≤21 mmHg and a reduction of baseline by ≥20% for two consecutive final visits without hypotony, additional surgery, or loss of light perception. Uveitic control was considered a <2-step increase in anterior chamber (AC) cell grade, <3+ AC cell grade, and no increase in steroid drop use at 3 months postoperatively. Secondary outcome measurements included postoperative change in IOP, glaucoma medications, best corrected visual acuity (VA), AC cell grade, and steroid drop frequency. Results Baseline ocular and preoperative characteristics of eyes (age, sex, laterality, uveitic location, systemic immunomodulating therapy, visual acuity, IOP, number of glaucoma medications, AC cell grade, and steroid drop frequency) did not significantly differ except for greater racial diversity in the ECP group. 62.5% eyes were surgically successful in the ECP group and 85.71% in the OMNI. Between-group analysis showed greater IOP reduction in the OMNI group (p < .05), but no difference in reduction of glaucoma medications (p = .33). No eyes displayed a two-step increase in or >3+ AC cell grade, however, 50% and 64.29%, respectively, increased steroid drop use. Between groups, no difference in the change of AC cell grade (p = .98) or steroid drop use (p = .84) was seen. Conclusions Both interventions improved visual acuity, IOP, and glaucoma medication use, however, OMNI was more successful at reducing IOP long term. An increase in steroid drop frequency may be the cost of a prolonged post-surgical inflammatory course related to underlying uveitis regardless of surgical approach.

Prospective Cytokine Profiling in Aqueous Humor Reveals a Proinflammatory Microenvironment in Highly Dense Nuclear Cataracts.

To investigate if the cytokine profile in the aqueous humor (AH) of cataract patients varies according to cataract type and severity. This prospective study included 397 eyes of 397 patients (median age, 76 years; range, 30-94 years) who underwent standard small-incision phacoemulsification surgery. Cataracts were graded using the LOCS III system: mild (≤3), moderate (3.5-5), and severe (≥5). Biometric measurements from the IOL master 700 (Zeiss, Oberkochen, Germany) were used to differentiate between thick (>4.5 mm) and thin lenses. Information about age, gender, and self-reported diseases was obtained from patient records. Eleven different proteins were measured in AH using a multiplex cytokine assay (AYOXXA Biosystems, Cologne, Germany), including IL- 6, IL-8, angiopoietin 2, C-reactive protein (CRP), vascular endothelial growth factor A (VEGF-A), platelet-derived growth factor BB, placental growth factor, CXCL12, CXCL13, and CXCL10. Statistical analysis was performed using R and included nonparametrical testing, linear regression, and k-means clustering. Higher nuclear LOCS grades correlated with increased levels of CCL2 (360 vs. 387 vs. 517 pg/mL, P < 0.001), VEGF-A (270 vs. 292 vs. 390 pg/mL, P = 0.012), IL-8 (3.1 vs. 4.2 vs. 5.7 pg/mL, P = 0.018), and CXCL10 (52 vs. 61 vs. 90 pg/mL, P = 0.003). No associations were observed for cortical and subcapsular cataracts. Thicker lenses were associated with significantly increased levels of CRP, CXCL10, CXCL12, IL-6, IL-8, and VEGF-A. The cytokine profile of AH varies based on cataract grading and lens thickness. In highly dense nuclear cataracts, CCL2, VEGF-A, IL-8, and CXCL10 were elevated.

A survey of intraocular lens preferences of UK refractive surgeons for cataract surgery and refractive lens exchange

BackgroundTo explore intraocular lens (IOL) preferences of United Kingdom-based (UK) refractive surgeons in cataract and refractive lens exchange (RLE) surgery.MethodsAn online survey on IOL preferences (and reasons for their choice) in cataract and RLE surgery was distributed. It also enquired about implementing mini-monovision with extended depth of field (EDoF) IOLs, about utilising IOL mix-and-match (different IOL types in each eye), and at what level of corneal astigmatism they prefer toric lenses.ResultsFollowing an 81.6% response rate, thirty responses were analysed; median years of refractive surgery experience was 12.5. The most popular IOL choices for cataract surgery were EDoF lenses (30%), monofocals (20%), and trifocals (20%). The most cited reason for each was better overall visual outcomes (88.9%), fewer unwanted symptoms (66.7%) and best spectacle independence (66.7%), respectively.For RLE, EDoF remained most popular (36.7%), followed by trifocals (30%), and multifocals (16.7%) with the same reasons for choice cited above.Mini-monovision with EDoF lenses was well-regarded (83% recommend for most/select patients), unlike utilising IOL mix-and-match (60% did not recommend). 40% prefer toric IOLs for astigmatism of 1 dioptre (D) or higher, whilst 30% opt for them at < 1D.ConclusionsExperienced UK refractive surgeons prefer newer IOLs with enhanced optics; ≥50% of respondents favoured either EDoF or trifocals for a ‘typical’ cataract or RLE patient. Notably, respondents have a low corneal astigmatism threshold for toric lenses. Mini-monovision with EDoF IOLs was well-regarded, whilst mix-and-match of different IOL types was less recommended.

Outcome of Phacoemulsification Cataract Surgery in Complicated Cataract Due to Uveitis

Background: Surgical removal of cataractous lens is the only of treatment of cataract irrespective of etiology. Phacoemulsification is a modern cataract surgery in which the eyes internal lens is emulsified with an ultrasonic hand-piece and aspirated from the eye. Complicated cataract due to anterior uveitis has difference in morphology and outcome from that of age-related cataract variety. Aim of the study: The purpose of this study was to evaluate the outcome of phacoemulsification in complicated cataract due to uveitis. Methods: This prospective observational cross-sectional study conducted in cataract clinic of National Institute of Ophthalmology &amp; Hospital, Dhaka, Bangladesh, from September 2018 to March 2019. Sample was selected by purposive sampling technique. Total 50 patients suffering from complicated cataract due to uveitis were included according to selection criteria. Data were gathered from the informant and recorded in a structured case report format. Clinical examination and relevant investigation were done meticulously. All acquired data was entered into a Microsoft Excel Work Sheet and analyzed using descriptive statistics in SPSS 24.0. Results: In this study, the maximum number of patients 18(36.0%) were 51-60 years age group, mean age of the patient was 52.7±6.37 years. Male to female ratio was 1:1.17. Postoperative best corrected visual acuity (BCVA) was better progressively and reached significance difference (P&lt;0.05). Astigmatism was measured in different follow up time. There was significant difference (p&lt; 0.05) present in all post-operative days. In time wise comparison revealed, there was also significant difference in between 1st postoperative day and 30th postoperative day but no significance was present between 30th postoperative day and 180th postoperative day (P= 0.161). In this study postoperative complications included posterior capsule opacification (55.5%), posterior synechiae (11.1%), cystoid macular edema (22.2%) &amp; glaucoma (11.1%). Conclusion: Present study concluded that phacoemulsification is safer for the uveitic cataract as less inflammation is induced than that by a manual extracapsular cataract extraction. In order to optimize the postoperative outcome of uveitic cataract surgery, it is necessary to be meticulous and thorough.

Lens Fragmentation with Picosecond Laser Pulses After Artificial Cataract Induction with Microwaves.

Objectives: In this work we demonstrate the first laboratory study results of lens fragmentation with low-energy picosecond ultrashort laser pulses after artificial induction of cataract with microwave radiation on an ex vivo animal model. Background: This method will be evaluated with regard to the further development of lens fragmentation with novel ultrashort picosecond laser systems instead of ultrasonic phacoemulsification or the significantly more complex femtosecond laser fragmentation. Methods: As samples we used postmortem porcine eyes. The lenses were dissected and then irradiated in a microwave oven for artificial cataract induction. Subsequent computer-driven lens fragmentation was performed with a 12 ps, 1064 nm pulsed laser source with 100 µJ pulse energy, and 10 kHz pulse repetition rate. Results: Both the artificial cataract induction and the lens fragmentation were demonstrated. When inducing cataract, different degrees/stages of opaqueness and hardness could be achieved with different irradiation times and methods. The fragmentation with 12 ps pulses led to good results with regard to ablation depth and rate, especially for the softer lenses. Conclusions: As could be shown, low-energy picosecond ultrashort laser pulses are feasible for cataractous lens fragmentation on an ex vivo animal model with artificial cataract induction. Thus, this technique may influence future cataract surgeries by possibly being an alternative or extension to state-of-the-art methods. This will be evaluated with further tests and studies.

The outcomes of paediatric cataract surgery with intraocular lens insertion in sub-Saharan Africa: a systematic review

ImportanceCataract is one of the leading causes of childhood blindness in Africa. The management of this condition requires timely surgical extraction of the cataractous lens with immediate optical correction and long-term follow-up to monitor visual improvement and manage complications that may arise. This review provides an opportunity to benchmark outcomes and to shed light on the reasons for those outcomes.ObjectivesTo review the published literature and report on the outcomes of paediatric cataract surgery with intraocular lens insertion in sub-Saharan Africa.Data sourceThe EMBASE, PubMed, Scopus, and Web of Science were searched for relevant articles.Study selectionWe included all published primary studies from sub-Saharan Africa on cataract surgery outcomes in children aged 0–16 years with primary intraocular lens implantation conducted between 1990 and 2020. Eligible studies were those published in English or for which an English translation was available. In addition, reviewers screened the reference lists of all studies included in the full-text review for eligible studies. During the review, studies fitting the inclusion criteria above except for having been conducted in middle and high-income countries were tagged and placed in a comparison arm.Data extraction and synthesisStudy eligibility was determined by two independent reviewers, and data extraction was conducted by one reviewer with entries checked for accuracy by another reviewer. Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines for data synthesis were followed. The Joanna Briggs Institute (JBI) critical appraisal checklist was used for quality appraisal of the studies. The statistical software R was used in the analysis, and data were pooled using a random-effects model. Forest plots were generated using the R package ‘metafor’.Main outcomes and measuresThe primary outcome was visual acuity (VA) after cataract surgery and the proportions of eyes that achieved good, borderline, or poor visual outcome according to the World Health Organisation (WHO) categorisation of post-operative visual acuity. The secondary outcome measures reported included lag time to surgery, rates of follow-up, and rate of complications.ResultsEight out of 4763 studies were eligible for inclusion in this review, and seven were included in the quantitative analysis. There was a male preponderance in the study population, and the mean age at the time of cataract surgery ranged from 3.4 to 8.4 years. Visual outcomes were available for short-term visual outcomes (1 to 6 months) as the studies had a significant loss to follow-up. The pooled proportion of eyes that achieved a good visual acuity (i.e. equal to or greater than 6/18) in the short-term period was 31% (CI, 20–42). The comparative studies from middle and high-income countries reported proportions ranging from 41 to 91%, with higher thresholds for good visual acuity of 6/12 and 6/15.Conclusion and relevanceThis review reports that there is a lower proportion of eyes with good outcomes after undergoing paediatric cataract surgery in sub-Saharan Africa than in middle- and high-income countries. Furthermore, this review states that there is a high proportion of patients lost to follow-up and suboptimal refractive correction and amblyopia treatment after paediatric cataract surgery.

Comparison of intraocular lens power prediction by American Society of Cataract and Refractive Surgery formulas and Barrett True-K TK in eyes with prior laser refractive surgery.

To evaluate the prediction accuracy of various intraocular lens (IOL) power calculation formulas on American Society of Cataract and Refractive Surgery (ASCRS) calculator and Barrett True-K total keratometry (TK) in eyes with previous laser refractive surgery for myopia. This retrospective study included eyes with history of myopic laser refractive surgery, which have undergone clear or cataractous lens extraction by phacoemulsification followed by IOL implantation. Those who underwent uneventful crystalline lens extraction were included. Eyes with any complication of refractive surgery or those with eventful lens extraction procedure and those who were lost to follow-up were excluded. Formulas compared were Wang-Koch-Maloney, Shammas, Haigis-L, Barrett True-K no-history formula, ASCRS average power, ASCRS maximum power on the ASCRS post-refractive calculator and the IOLMaster 700 Barrett True-K TK. Prediction error was calculated as the difference between the implanted IOL power and the predicted power by various formulae available on ASCRS online calculator. Forty post-myopic laser-refractive surgery eyes of 26 patients were included. Friedman's test revealed that Shammas formula, Barrett True-K, and ASCRS maximum power were significantly different from all other formulas (P < 0.00001 for each). Median absolute error (MedAE) was the least for Shammas and Barrett True-K TK formulas (0.28 [0.14, 0.36] and 0.28 [0.21, 0.39], respectively) and the highest for Wang-Koch-Maloney (1.29 [0.97, 1.61]). Shammas formula had the least variance (0.14), while Wang-Koch-Maloney formula had the maximum variance (2.66). In post-myopic laser refractive surgery eyes, Shammas formula and Barrett True-K TK no-history formula on ASCRS calculator are more accurate in predicting IOL powers.

Quercetin-Loaded Nanocarriers as Effective Inhibitors for Copper Metal Ion-Induced γD-Crystallin Aggregation.

Cataract is one of the leading causes of blindness worldwide. Till date, the only solution for cataracts is surgery, which is a resource-intensive solution. A much simpler solution is to find a potential drug that could inhibit aggregation. It is well established that nonamyloid aggregates of eye lens protein result in cataract. γD-Crystallin, a thermodynamically stable protein, is one of the most abundant proteins in the core of the eye lens and is found to aggregate under stress conditions, leading to the cataract. It has also been found that in cataractous lens, the concentration of metals like copper is elevated significantly as compared to healthy eye lens, suggesting their role in inducing aggregation. In our present study, aggregation of γD-Crystallin was carried out in the presence of Cu (II). Using techniques like turbidity assay, CD spectroscopy, ANS binding assay, and microscopic studies like TEM, it could be confirmed that protein aggregates in the presence of Cu (II) and the nature of aggregates is amorphous. Various polyphenols were tested to suppress aggregation of the protein. Quercetin was observed to be the most efficient. To overcome the problems associated with the delivery of polyphenols, such as solubility and bioavailability, quercetin was encapsulated in two types of nanocarriers. Their characterization was done using TEM, DLS, and other techniques. The potency of quercetin-loaded CS-TPP/CS-PLGA NPs as inhibitors of γD-Crystallin aggregation was confirmed by various experiments.

Safety of Phacoemulsification with Gradual Hydro Dissection on Posterior Polar Cataract

Introduction: Phacoemulsification has been a procedure of choice for treating cataractous lenses and restoring visual function. Posterior polar cataract have been one of many cases in which phaco surgeons should be careful and aware for more to perform phacoemulsification. One hydrodissection procedure is safe to perform as an alternative to hydrodileniation during phacoemulsification for posterior cataract. It is called gradual hydrodissection. Methods: This study performed a quasi-experimental pre-post study that tested the safety of gradual hydrodissection in phacoemulsification in 50 eyes of 50 patients. The safety parameter used in this study includes the incidence of posterior capsule rupture and nucleus drop during phacoemulsification until surgery is finished. Descriptive statistics were used to summarize the characteristics of the study participants, such as age, sex, race, eye laterality, and previous intraocular surgery. A paired student’s t-test was conducted to compare preoperative and postoperative values for visual acuity and intraocular pressure. The P &lt;0.05 was considered the level of statistical significance. Results: There was no complication of the posterior capsule during the hydrodissection procedure. There was a statistically significant difference in visual acuity and intraocular pressure before and after surgery by P value &lt;0.001. All of the phacoemulsification studies were considered uneventful and successful. Conclusions: Gradual hydrodissection may be safe to be performed in phacoemulsification for posterior polar cataract.

Ascorbic acid export from human donor lenses: Is the lens a source of ascorbic acid in the ocular humors?

In previous work, we have shown that the lens acts a reservoir of the antioxidant glutathione (GSH), capable of exporting this antioxidant into the ocular humors and potentially protecting the tissues of the eye that interface with these humors from oxidative stress. In this study, we have extended this work by examining whether the lens acts as a source of ascorbic acid (AsA) to maintain the high levels of AsA known to be present in the ocular humors either by the direct export of AsA into the humors and/or by functioning as a recycling site for AsA, via the direct uptake of oxidised ascorbate (DHA) from the humors, its regeneration to AsA in the lens and then its subsequent export back into the humors. To test this, human lenses of varying ages were cultured for 1 h under hypoxic conditions and AsA/DHA levels measured in the media and in the lens. Human lenses were also cultured in compartmentalised chambers to determine whether efflux of AsA/DHA occurs at the anterior or posterior surface. Immunohistochemistry was performed on human donor lenses and sections labelled with antibodies against GLUT1, a putative DHA uptake transporter. Vitreous humor was collected from patients undergoing vitrectomy who either had a natural clear lens, an artificial intraocular implant (IOL) or a cataractous lens, and AsA/DHA and GSH and oxidised GSH (GSSG) measured. We found that cultured human donor lenses released both AsA and DHA into the media. Culturing of lenses in a compartmentalised chamber revealed that AsA and DHA efflux occurs at both surfaces, with relatively equal amounts of AsA and DHA released from each surface. The posterior surface of the lens was shown to express the GLUT1 transporter. Analysis of vitreous samples from patients undergoing vitrectomy revealed that vitreous GSH and AsA levels were similar between the natural lens group, IOL and cataractous lens group. Taken together, while human donor lenses were shown to export AsA and DHA into the surrounding media, the amount of AsA and DHA released from donor lenses was low and not sufficient to sustain the high levels of total AsA normally present in the humors. This suggests that although the lens is not the main source for maintaining high levels of AsA in the ocular humors, the lens may help to support local AsA levels close to the lens.

Neuro-ophthalmic Tests for Assessment of Vision Before and After Phacoemulsification in Cataractous Dogs

Background: The aim of current study was to assess pre and post-operative vision status through neuro-ophthalmic examination of 24 canine eyes after phacoemulsification with implantation of different acrylic intra ocular lenses. Methods: The study was conducted on 24 canine eyes. Preoperatively, detailed neuro-ophthalmic tests viz. Menace response, Pupillary light reflex (PLR), Obstacle Course and Moving object (cotton ball) were conducted for assessment of vision due to cataract and to exclude other ocular pathologies. Dogs were divided in four groups with 6 eyes in each group and subjected to phacoemulsification procedure for removal of cataractous lens and implanted with square edge or round edge, hydrophilic or hydrophobic intra ocular lenses (IOL). Post operatively, aforementioned neuro-ophthalmic tests were conducted on 3, 7 and 15 days and scores were given and comparatively analysed for vision acuity. Result: Preoperatively, neuro-opthalmic tests indicated poor and absent vision in eyes affected with various stages of cataract. Post operatively, the visual outcome in dogs of all treatment groups were assessed from the scores obtained in various neuro-ophthalmic tests. Neuro-ophthalmic evaluation revealed restoration of vision in 50% dogs in group I, II, IV and in 66.66% dogs of group III on day 15 after phacoemulsification and intraocular lens (IOL) implantation. It was concluded that neuro-ophthalmic tests are useful and mandatory protocols for pre and post-operative vision assessment in dogs with cataract.

Animal model for in-vivo Nuclear Cataract. Lens hardness and elasticity assessment.

Age-related cataract is the most frequent cause of blindness in the world being responsible for 48% of blindness and affecting more than 10% of the working population. Currently there is no objective data of the lens biomechanical properties so the process by which the cataract affects the lens's properties (e.g. hardness and elasticity) is still unclear.A modified animal model was produced to create different severities of nuclear cataract. Different doses of sodium selenite were injected in two different moments of the rat’ eyes maturation resulting in 12, 13 and 11 rats with incipient, moderate and severe cataract, respectively. The nucleus and cortex's hardness and the stiffness were measured using NanoTest™.Statistically significant differences were found between healthy and cataractous lenses. Statistically significant differences were also found between the different nuclear cataract degrees (p = 0.016), showing that the lens’ hardness increases with cataract formation. The nucleus shows a higher hardness increase with cataract formation (p = 0.049).The animal model used in this study allowed for the first time the characterization of the lens's hardness and elasticity in two regions of the lens, in healthy and cataractous lenses.

Loss of αBa-crystallin, but not αA-crystallin, increases age-related cataract in the zebrafish lens

The vertebrate eye lens is an unusual organ in that most of its cells lack nuclei and the ability to replace aging protein. The small heat shock protein α-crystallins evolved to become key components of this lens, possibly because of their ability to prevent aggregation of aging protein that would otherwise lead to lens opacity. Most vertebrates express two α-crystallins, αA- and αB-crystallin, and mutations in each are linked to human cataract. In a mouse knockout model only the loss of αA-crystallin led to early-stage lens cataract. We have used the zebrafish as a model system to investigate the role of α-crystallins during lens development. Interestingly, while zebrafish express one lens-specific αA-crystallin gene (cryaa), they express two αB-crystallin genes, with one evolving lens specificity (cryaba) and the other retaining the broad expression of its mammalian ortholog (cryabb). In this study we used individual mutant zebrafish lines for all three α-crystallin genes to determine the impact of their loss on age-related cataract. Surprisingly, unlike mouse knockout models, we found that the loss of the αBa-crystallin gene cryaba led to an increase in lens opacity compared to cryaa null fish at 24 months of age. Loss of αA-crystallin did not increase the prevalence of cataract. We also used single cell RNA-Seq and RT-qPCR data to show a shift in the lens expression of zebrafish α-crystallins between 5 and 10 days post fertilization (dpf), with 5 and 6 dpf lenses expressing cryaa almost exclusively, and expression of cryaba and cryabb becoming more prominent after 10 dpf. These data show that cryaa is the primary α-crystallin during early lens development, while the protective role for cryaba becomes more important during lens aging. This study is the first to quantify cataract prevalence in wild-type aging zebrafish, showing that lens opacities develop in approximately 25% of fish by 18 months of age. None of the three α-crystallin mutants showed a compensatory increase in the expression of the remaining two crystallins, or in the abundant βB1-crystallin. Overall, these findings indicate an ontogenetic shift in the functional importance of individual α-crystallins during zebrafish lens development. Our finding that the lens-specific zebrafish αBa-crystallin plays the leading role in preventing age-related cataract adds a new twist to our understanding of vertebrate lens evolution.

Couching of cataractous lens in microphthalmic eyes with irido-fundal coloboma: revisiting the historical technique.

Cataract surgery in microphthalmic eyes is challenging due to anatomical restraints, hard bulky nucleus. This series aims to evaluate the safety and efficacy of couching of intraocular lens in irido-fundal coloboma with microphthalmos. Tertiary care centre in South India. Retrospective non-comparative study in eyes with irido-fundal coloboma, corneal diameter < 7mm and brown cataract. Visual acuity less than 6/60 in other eye. Anterior chamber entry made, zonules broken and lens dislocated into the vitreous cavity in a controlled manner. Baseline Clinico-demographic details, corrected distance visual acuity (CDVA), Intra-ocular pressure (IOP), corneal diameter, axial length, lens status and post-surgery CDVA, IOP and complications recorded and followed up for atleast 6months. Fifteen eyes of 15 subjects were evaluated with a mean age 49.4 ± 10.9years. At baseline, mean IOP 14.5 ± 3.8mmHg, mean axial length 19.3 ± 0.5mm, mean corneal diameter was 6.5 ± 0.34mm and CDVA 2 logMAR which improved to 1.5 logMAR at 3months (p value 0.002). Transient spike in IOP in 33.3% subjects was medically managed with no significant difference in IOP (p > 0.05) at baseline (14.5 ± 3.8mmHg), 3months post-surgery (16 ± 2.8mmHg) and 6months post-surgery (14.9 ± 2.5mmHg). One patient underwent re-couching. No other major complications were noted. Couching of cataractous lens is an effective and safe method in microphthalmic eyes with irido-fundal coloboma as last resort procedure, where no other surgical procedure may work. It provides an ambulatory gain of visual acuity in previously non-ambulatory subjects. Corneal measurements help in determining the subset of patients where couching offers viable option.

Analysis of long-range chromatin contacts, compartments and looping between mouse embryonic stem cells, lens epithelium and lens fibers

BackgroundNuclear organization of interphase chromosomes involves individual chromosome territories, “open” and “closed” chromatin compartments, topologically associated domains (TADs) and chromatin loops. The DNA- and RNA-binding transcription factor CTCF together with the cohesin complex serve as major organizers of chromatin architecture. Cellular differentiation is driven by temporally and spatially coordinated gene expression that requires chromatin changes of individual loci of various complexities. Lens differentiation represents an advantageous system to probe transcriptional mechanisms underlying tissue-specific gene expression including high transcriptional outputs of individual crystallin genes until the mature lens fiber cells degrade their nuclei.ResultsChromatin organization between mouse embryonic stem (ES) cells, newborn (P0.5) lens epithelium and fiber cells were analyzed using Hi-C. Localization of CTCF in both lens chromatins was determined by ChIP-seq and compared with ES cells. Quantitative analyses show major differences between number and size of TADs and chromatin loop size between these three cell types. In depth analyses show similarities between lens samples exemplified by overlaps between compartments A and B. Lens epithelium-specific CTCF peaks are found in mostly methylated genomic regions while lens fiber-specific and shared peaks occur mostly within unmethylated DNA regions. Major differences in TADs and loops are illustrated at the ~ 500 kb Pax6 locus, encoding the critical lens regulatory transcription factor and within a larger ~ 15 Mb WAGR locus, containing Pax6 and other loci linked to human congenital diseases. Lens and ES cell Hi-C data (TADs and loops) together with ATAC-seq, CTCF, H3K27ac, H3K27me3 and ENCODE cis-regulatory sites are shown in detail for the Pax6, Sox1 and Hif1a loci, multiple crystallin genes and other important loci required for lens morphogenesis. The majority of crystallin loci are marked by unexpectedly high CTCF-binding across their transcribed regions.ConclusionsOur study has generated the first data on 3-dimensional (3D) nuclear organization in lens epithelium and lens fibers and directly compared these data with ES cells. These findings generate novel insights into lens-specific transcriptional gene control, open new research avenues to study transcriptional condensates in lens fiber cells, and enable studies of non-coding genetic variants linked to cataract and other lens and ocular abnormalities.

DIFFERENT APPROACHES IN MANAGING LENS-INDUCED ANGLE CLOSURE GLAUCOMA: A SERIAL CASE

Introduction : Lens-induced angle-closure glaucoma can be caused by phacomorphic lens and ectopia lentis. Several factors affect the disease progression. Early diagnosis and appropriate management are important.&#x0D; Case Illustration : Case 1. A 67-year-old woman presented with acute redness and blurred vision in her left eye with visual acuity (VA) of 1/300 and intraocular pressure (IOP) of 60 mmHg. Axial length showed 23.66 mm and anterior chamber depth (ACD) was 1.61mm (Figure1). She was diagnosed with phacomorphic glaucoma. Phacoemulsification combined with trabeculectomy was performed (Figure2&amp;3). Her VA was improved to 0.08 and her IOP was reduced to 19mmHg after surgery. Case2. A 67-year-old man came with painful blurred vision in his right eye. His VA was a perception of light with an IOP of 40 mmHg. He had axial length of 22.7 mm and ACD of 2.07 mm (Figure4). The lens was anteriorly subluxated and showed zonular laxity. Intracapsular cataract extraction combined with trabeculectomy was performed (Figure5&amp;6). His VA was unchanged while his IOP was reduced to 18 mmHg after surgery.&#x0D; Discussion : Age older than 60 years old, female gender, short axial length (&lt;23.7 mm), shallow ACD, and zonular laxity are factors for progressivity of lens-induced glaucoma. Cataract removal was a definitive treatment along with IOP-lowering medications. The choice of lens extraction technique varies among individuals.&#x0D; Conclusion : Removal of cataractous lens is a definitive treatment in conjunction with intraocular pressure and inflammatory regulations for managing lens-induced angle-closure glaucoma. Comprehensive clinical assessments in patients are necessary for managing the symptoms and preventing complications.