Stages Of Cataract Development Research Articles

"Stamp the tunnel"- Innovative tool - for perfection in manual small incision cataract surgery.

Manual small incision cataract surgery (SICS) is a cost-effective and safe procedure offering comparable outcomes to phacoemulsification. It holds significance for outreach and economically disadvantaged patients in developing countries, while also being important for complex cataracts in developed nations. The SICS technique revolves around a three planar self-sealing sclero corneal tunnel (SCT), a critical element for rapid and suture-less healing. The tunnel's components include the incision, side pocket, internal entry, and depth each affecting astigmatism and successful nucleus delivery.[1-3] Various incision types are explored, with the frown incision yielding minimal astigmatism but posing challenges.[2,4] Inappropriate SCT leads on to high induced astigmatism, post op hypotony, and chances of infection. This video introduces "Tunnel stamp" which is a novel device designed to guide the incision length, internal entry line, and side pocket accuracy thus making a perfect SCT particularly for novice surgeons, who often encounter intraoperative and postoperative complications due to inappropriate SCT. The device is produced through 3D printing with thermoplastic polyurethane (TPU), an easily available and economically feasible material. The prototype's practicality is demonstrated through successful wet lab trials on goat eyes and subsequently on human eyes. The device is aligned using a limbus-matching step and a sterilized marker pen. This device has unique advantage to take care of the three aspects of SCT, that is, incision, side pocket, and internal entry. One can have custom-made guarded knife to perform scleral groove in optimum depth, which is another important dimension of SCT. Future developments involve creating the tunnel stamp in transparent flexible silicon to enhance alignment accuracy. Given the diversity of cataract types, multiple sizes of the device are envisioned to accommodate nucleus size variability and different stages of cataract development. To aid novice surgeons, two variations of incision guides (straight and frown) are proposed for immature and harder cataracts reducing induced astigmatism. Overall, this innovative tunnel stamp aims to enhance SICS outcomes, enabling more precise and consistent SCT creation while addressing challenges posed by various cataract types and surgeon experience levels. https://youtu.be/yzV-UC4jwPg.

Progression and complications of canine cataracts for different stages of development and aetiologies.

To evaluate progression and complications of various cataract aetiologies and stages of development. In all, 447 eyes of 250 dogs with cataracts were monitored between 2012 and 2015. Breed, gender, age, vision, types of cataract, stage of cataract development (incipient, immature, mature and hypermature), complications of cataracts, ocular ultrasonography and electroretinography findings were recorded. Re-examinations were performed after a minimum of 1, 6 and 12 months. A relative rate of progression within 1 month was determined and progression was categorised as stationary, slow, moderate or rapid. Overall, 44∙7% cataracts progressed and 55∙3% remained stationary. Incipient, immature, mature and hypermature cataracts progressed in 34∙1, 72∙7, 66∙7 and 44∙6% of cases, respectively. Hereditary, congenital, diabetic, contusive trauma-related, perforating trauma-related, radiation-related, senile cataracts and cataracts secondary to concurrent ocular diseases progressed in 47∙1, 66∙7, 66∙7, 50, 44∙4, 0, 29∙9 and 48∙9% of cases, respectively. Rapid progression was identified in 13∙3% of diabetic and 4∙3% of hereditary cataracts. Complications were diagnosed in 43∙5% and occurred at any stage but more frequently the further the cataract had developed. Lens-induced uveitis was the most common complication. Diabetic, traumatic, secondary and hereditary cataracts were associated with more complications than senile cataracts. Stage of development and cataract aetiology are associated with different rates of progression and complications.

All Stages of Cataract Development in Diabetic Rats and the Preventive Effect of Resveratrol on the Progression of Diabetic Cataracts

All Stages of Cataract Development in Diabetic Rats and the Preventive Effect of Resveratrol on the Progression of Diabetic Cataracts

Fluorescence diagnosis of the status of the human lens in vivo

We have studied fluorescence spectra of the human lens in vivo for healthy eyes and in different stages of senile cataract development. We propose a spectral criterion, the lens opacity index, allowing us to differentiate between stages of cataract development. We show a high correlation between the stage of cataract development and the opacity index. We propose an empirical expression for determining the stage of senile cataract development from the value of the lens opacity index. The technique has been clinically tested.

Clinical manifestations of cataracts in small breed dogs

To determine the incidence, etiology, and concurrent ophthalmic findings in small breed dogs that presented with cataracts. Five hundred and sixty-one small breed dogs (942 eyes) were presented to the Veterinary Medical Teaching Hospital of Seoul National University between July 2002 and December 2007 with cataract. The medical records of small breed dogs with cataract were reviewed. The reason for presentation, cataract duration, bilaterality, breed, gender, age, vision, etiology, stage of cataract development, concurrent ophthalmic findings, IOP, ocular ultrasonography findings, and scotopic electroretinography (ERG) findings were investigated. The most frequently presented breeds were the Miniature/Toy Poodle (n = 112, 20.0%), Yorkshire Terrier (n = 110, 19.6%), and Shih Tzu (n = 95, 16.9%). The Miniature/Toy Poodle showed a significantly higher odds ratio for cataract formation (2.6). The proportion of female cataract patients was significantly higher than that of male cataract patients in the overall population (P < 0.05). The Miniature/Toy Poodles had significantly higher numbers of females affected with cataract (P < 0.01). The mean age for cataract formation was 8.3 +/- 3.9 years. The mean age at onset in the Miniature/Toy Poodle and Yorkshire Terrier was significantly higher, whereas that in the Miniature Schnauzer group was significantly lower (P < 0.0001). Clinical signs related to lens induced uveitis had a tendency to increase with cataract progression (P < 0.05). There were no significant differences in the b-wave amplitude for mixed rod cone response by stage (P = 0.137). Small breed dogs with cataracts had characteristics with regard to age of onset and gender distribution, depending on the breed.

Congenital cataract extraction with primary aphakia and secondary intraocular lens implantation in the ciliary sulcus

To evaluate the results of cataract extraction without primary intraocular lens (IOL) implantation in children. Ophthalmology Unit, University Hospital, Strasbourg, France. This retrospective study comprised 157 congenital cataract cases (55 bilateral and 47 unilateral) treated between 1985 and 2001. Evaluated were the functional results (visual acuity, binocular vision) and factors influencing the prognosis (age at surgery, stage of cataract development, associated pathology, postoperative complications). In all patients, cataract extraction was via the pars plana and anterior vitrectomy was performed, leaving a peripheral capsular collarette in place. Postoperatively, all the patients were fitted with glasses or contact lenses, after which they had secondary implantation of an IOL in the ciliary sulcus. The functional results were similar to those in the literature for eyes with or without an IOL. Nevertheless, the literature reports a 25% risk for reoperation in the first 2 years after implantation and secondary vitrectomy for reopacification of the visual axis in 20% of bilateral cases and 38% of unilateral cases. Our functional results indicate that in cases of bilateral congenital cataracts, initial rehabilitation with aphakic correction and secondary IOL implantation leads to a predictable postoperative refraction and fewer complications. Visual rehabilitation in unilateral aphakia was more difficult because of poor compliance with contact lenses, generally leading to a preference for early IOL implantation.

Analysis of Lipid Peroxidation and??Electron Microscopic Survey of??Maturation Stages during Human Cataractogenesis

Morphological and biophysical techniques described in this study have shown that membrane derangement occurs in human cataractous lenses. The data suggest that these disruptions were globules, vacuoles, multilamellar membranes and clusters of highly undulating membranes. Deleterious structural damage of the lens fibre cell plasma membranes serve as the primary light-scattering centres that cause the observed lens opacity. Nuclear cataract, a major cause of loss of lens transparency in the aging human, has been thought to be associated with oxidative damage, particularly at the site of the nuclear plasma membrane. Phospholipid molecules modified by oxygen accumulate in the lipid bilayer, change its geometry and impair lipid-lipid and protein-lipid interactions in lenticular fibre membranes. Lipid peroxidation (LPO) is a causative and pathogenic factor in cataract. Increased concentrations of primary molecular LPO products (diene conjugates, lipid hydroperoxides, oxy-derivatives of phospholipid fatty acids) and end-fluorescent LPO products have been detected in the lipid moieties of aqueous humour samples and human lenses obtained from patients with senile and complicated cataracts as compared with normal donors. In the present study, a rapid and simple high-performance liquid chromatographic (HPLC) assay for determination of imidazole-containing dipeptides in the aqueous humour of the eye was developed. The method was applied to determine the pharmacokinetic parameters and the time-course of N-acetylcarnosine and L-carnosine-related product in the eye, following a single dosage of topical ocular administration of peptide. Utilising data from pharmacokinetic studies and the specific purity of the N-acetylcarnosine (NAC) ingredient as a source of the pharmacological principle L-carnosine, we have created an ophthalmic time-release prodrug form including the US FDA-approved carboxymethylcellulose lubricant and other essential ingredients (Can-C, private label Nu-Eyes). This formulation increases the intraocular absorption of L-carnosine in the aqueous humour and optimises its specific antioxidant activity in vivo while reducing the toxic effects of lipid peroxides on the crystalline lens. L-carnosine that enters the aqueous humour can accumulate in the lens tissue for a reasonable period of time. The presence of L-carnosine in transparent crystalline lenses during normal aging was detected and its concentration in this case was about 25 microM. At different stages of cataract development, the level of L-carnosine drastically decreased, reaching about 5 microM in ripe human cataracts. However, administration of pure L-carnosine (1% solution) to the rabbit eye (instillation or subconjunctival injection) does not lead to accumulation of this natural compound in the aqueous humour at the time level over 30 minutes at a concentration exceeding that in placebo-treated matched eyes, and its effective concentration is exhausted more rapidly. Use of NAC prodrug eye drops optimises the clinical effects of L-carnosine in the treatment of ophthalmic disorders (such as prevention and reversal of cataracts in human and animal [canine] eyes). The data provided predict a clinical effect with NAC ophthalmic prodrug, and show that the magnitude and duration of this effect are directly related to the bioavailability of L-carnosine released from NAC in the aqueous humour of the anterior eye segment. The ophthalmic NAC drug shows promise in the treatment of a range of ophthalmic disorders that have a component of oxidative stress in their pathogenesis (including cataract, glaucoma, dry eye, vitreous floaters, inflammatory disorders, and corneal, retinal and systemic diseases [such as diabetes mellitus and its ophthalmic complications]). There is a need for further and better collaboration between Innovative Vision Products' cataract control and ophthalmic services, improved education of people affected by cataract, a commitment that N-acetylcarnosine eye drops will be the preferred treatment before orthodox cataract surgery is attempted, and consideration of outcomes and a possible role of the NAC drug cataract treatment as source of referral for orthodox surgical, ophthalmic and optometric services.

Alterations in lens protein tyrosine phosphorylation and phosphatidylinositol 3-kinase signaling during selenite cataract formation

Purpose. Protein tyrosine phosphorylation is an important event in the cell signal transduction process. Phosphatidylinositol-3kinase (PI-3K) is an intracellular signal mediator and plays a key role in many cellular functions. In this study we have examined the changes in lens protein tyrosine phosphorylation and its impact on phosphatidylinositol 3-kinase (PI-3K) signaling during selenite cataract development. Methods. Cataract was induced in 10 days old rat pups by a single sub-cutaneous injection of sodium selenite (30µM/Kg body weight) and lenses were collected at different stages of cataract development. Immunoprecipitation and Western immunoblotting were employed to determine protein tyrosine phosphorylation, PI-3K activity and protein in lens cell extracts. Tyrosine kinase activity in lens membrane preparations was assayed in the presence of a synthetic substrate peptide and [ 32 P]ATP. Results. Protein tyrosine phosphorylation in the lens was disrupted before the onset of cataract. A decrease in tyrosine phosphorylation of lens proteins was observed within 2–3 days of selenite injection (pre-cataract stage). The effect was much more prominent with the progression of cataract. The decrease in protein tyrosine phosphorylation correlated with the decrease in tyrosine kinase activity associated with the lens membrane fraction. Stimulation of normal rat lenses in organ culture with insulin and IGF-1 caused an increase in the phosphorylation of proteins, whose tyrosine phosphorylation status appeared to be diminished during cataract development. Insulin and IGF-1 also stimulated rat lens PI-3K activity. While there was no change in total PI-3K activity during the onset of cataract, the activity of PI-3K associated with tyrosine phosphorylated proteins decreased markedly in pre-cataract lenses. Further, the ability of IGF-1 to stimulate PI-3K activity was significantly reduced in lens epithelial cells treated with selenium. Conclusions. These studies show that signaling events involving the protein tyrosine phosphorylation process and activation of PI-3K are altered during selenite cataract formation and implicate defects in signal transduction mechanisms as contributing factors in the development of cataract.

Development of glaucoma after cataract surgery in dogs: 220 cases (1987-1998).

To examine postoperative ocular hypertension (POH) and other variables as predictors of the risk of developing glaucoma after cataract surgery in dogs. Retrospective study. 220 dogs that had cataract surgery. Medical records of 220 dogs (346 eyes) that had extracapsular cataract removal or phacoemulsification of cataracts were reviewed. With respect to glaucoma development, 8 variables were analyzed, which included development of POH, breed, sex, age at time of surgery, eye (right vs left), phacoemulsification time, intraocular lens (IOL) placement (yes or no), and stage of cataract development. Eyes developed glaucoma within 6 or 12 months of surgery or did not have signs of glaucoma at least 6 or 12 months after cataract surgery. Of 346 eyes, 58 (16.8%) developed glaucoma after surgery. At 6 months, 32 of 206 (15.5%) eyes examined had glaucoma; at 12 months, 44 of 153 (28.8%) eyes examined had glaucoma. Median follow-up time was 5.8 months (range, 0.1 to 48 months). Mixed-breed dogs were at a significantly lower risk for glaucoma, compared with other breeds. Eyes with IOL placement were at a significantly lower risk for glaucoma, compared with eyes without IOL placement. Eyes with hypermature cataracts were at a significantly higher risk for glaucoma, compared with eyes with mature or immature cataracts. Multiple factors appear to contribute to the onset of glaucoma in dogs after cataract surgery. Complications prohibiting IOL placement during cataract surgery may lead to a high risk of glaucoma development.

Prevention of selenite-induced opacification and biochemical changes in the rat pup lens through amiloride pretreatment

To determine the effects of amiloride on selenite-induced cataracts, to identify this agent's role as an anti-oxidant, and to study related effects on ion levels in the rat lens. Wistar albino rat pups were assigned to one of three groups, one control and two experimental. The first experimental group (Group 1; n = 22) received a subcutaneous injection of sodium selenite (30 nmol/g body weight) on postpartum day 10. The second experimental group (Group 2; n = 21) received a subcutaneous injection of amiloride (1 nmol/g body weight) 15 minutes before the sodium selenite injection. The control group (n = 22) received no injection. The pups in each group were observed during three weeks after the injection date. At the end of this period, the stage of cataract development was identified by comparison with slit lamp photographs and then the pups were sacrificed and their lenses were removed intracapsularly using a posterior approach. Cation analysis was carried out and glutathione and malondialdehyde levels were measured for each group. Cataract stage in Group 1 was significantly higher than Group 2. Mean cataract stages in Groups 1 and 2 were 3.8+/-0.12 and 1.6+/-0.25 respectively. None of the control animals developed cataracts. Amiloride-pretreated group contained significantly higher glutathione levels than Group 1. The level of malondialdehyde in Group 1 lenses was approximately twice that in the lenses of the Group 2 amiloride+selenite-treated animals. The Ca(2+) level was significantly higher in Group 1 lenses compared to the amiloride-pretreated rats, but there was no significant difference between Groups 1 and 2 with regard to Na(+) and K(+) levels. Amiloride was very effective in preventing cataract formation in the selenite-induced cataract model. This protective effect of amiloride was accompanied by higher glutathione levels and lower malondialdehyde levels in the rat pups' lenses compared to levels in animals that received selenite alone. These results suggest an anti-oxidant role for this agent, in addition to its effects on lens ion homeostasis.

Histologic and immunohistochemical characterization of lens capsular plaques in dogs with cataracts.

To determine histologic and immunohistochemical characteristics of the multifocal adherent plaques that commonly develop on the internal surfaces of the anterior and posterior lens capsules in dogs with cataracts. 31 anterior and 4 posterior capsular specimens collected during lens extraction surgery in dogs with cataracts. Specimens were evaluated, using light and transmission electron microscopy. Immunohistochemical techniques were used to localize cytokeratin, vimentin, alpha-smooth muscle-specific actin, fibronectin, tenascin, and transforming growth factor-beta (TGF-beta) within plaques. Histologically, plaques comprised elongated spindle-shaped cells that formed a placoid mass. Cells were embedded in an extracellular matrix containing collagen fibrils, often with duplicated or split basement membranes. Immunohistochemically, normal lens epithelial cells and cells within plaques stained for vimentin. Most cells and some areas of the extracellular matrix within plaques stained for TGF-beta and alpha-smooth muscle-specific actin. Fibronectin and tenascin were also detected in the extracellular matrix. Canine lens capsular plaques are histologically and immunohistochemically similar to posterior capsule opacification and subcapsular cataracts in humans, which suggests that the canine condition, like the human conditions, is associated with fibrous metaplasia of lens epithelial cells. Transforming growth factor-beta may play a role in the genesis of capsular plaques. Because severity of plaques was correlated with stage of cataract development, earlier surgical removal of cataracts may be useful to avoid complications associated with plaque formation.

Disulfonic stilbene prevents selenite-induced cataract in rat pup lens.

It is known that the subcutaneous injection of a single dose of sodium selenite into suckling rats results in the development of large nuclear opacities. The intracellular transport of selenite in various cells, except lens cells, occurs via the Cl/HCO3 exchanger. The aim of the present study is to investigate the possible role of the anion-exchange inhibitor, disulfonic stilbene (SITS), in the selenite-induced catarogenesis in the rat pups. Wistar albino rats (8-10 d old) were separated into three groups: one control and two experimental. The first experimental group was injected subcutaneously with a single dose of 30 nmol sodium selenite/g body weight. The second experimental group was injected with a single dose of 10 nmol SITS/g body weight 15 min before the same dose selenite injection. The control group did not have any injections. The stage of cataract development was examined on d 7 postinjection with slit-lamp photographs. In SITS pretreated group, all eyes remained transparent (considered as stage 0), whereas in the selenite-injected group, the animals did have different stage of nuclear cataract; 8 animals have stage 5, 10 animals have stage 4, and 4 animals have stage 3. A pretreatment of SITS completely prevented cataract formation of the selenite-induced cataract model in rat pups.

Prevention of selenite-induced opacification and biochemical changes in the rat pup lens through amiloride pretreatment

Purpose. To determine the effects of amiloride on selenite-induced cataracts, to identify this agent’s role as an anti-oxidant, and to study related effects on ion levels in the rat lens. Methods. Wistar albino rat pups were assigned to one of three groups, one control and two experimental. The first experimental group (Group 1; n = 22) received a subcutaneous injection of sodium selenite (30 nmol/g body weight) on postpartum day 10. The second experimental group (Group 2; n = 21) received a subcutaneous injection of amiloride (1 nmol/g body weight) 15 minutes before the sodium selenite injection. The control group (n = 22) received no injection. The pups in each group were observed during three weeks after the injection date. At the end of this period, the stage of cataract development was identified by comparison with slit lamp photographs and then the pups were sacrificed and their lenses were removed intracapsularly using a posterior approach. Cation analysis was carried out and glutathione and malondialdehyde levels were measured for each group. Results. Cataract stage in Group 1 was significantly higher than Group 2. Mean cataract stages in Groups 1 and 2 were 3.8 ± 0.12 and 1.6 ± 0.25 respectively. None of the control animals developed cataracts. Amiloride-pretreated group contained significantly higher glutathione levels than Group 1. The level of malondialdehyde in Group 1 lenses was approximately twice that in the lenses of the Group 2 amiloride+selenite-treated animals. The Ca 2+ level was significantly higher in Group 1 lenses compared to the amiloride-pretreated rats, but there was no significant difference between Groups 1 and 2 with regard to Na + and K + levels. Conclusion. Amiloride was very effective in preventing cataract formation in the selenite-induced cataract model. This protective effect of amiloride was accompanied by higher glutathione levels and lower malondialdehyde levels in the rat pups’ lenses compared to levels in animals that received selenite alone. These results suggest an anti-oxidant role for this agent, in addition to its effects on lens ion homeostasis.

Cataractous lens and its environment

Abstract

Differential glycation of rat α-, β- and γ-crystallins

Crystallin glycation seems to play an important role in the development of diabetic cataract. In order to understand the role of glycation in cataractogenesis, levels of glycation of different crystallins were determined by in vitro glycation of rat lens soluble fraction with 50 m m glucose or glucose-6-phosphate (G6P) for up to 5 days and in streptozotocin-diabetic rats during various stages of cataract development. All samples were reduced with [ 3H]NaBH 4 and the tritium incorporation was taken as a measure of glycation. Proteins were routinely separated by molecular sieve HPLC. In vitro studies with glucose showed that γ-crystallin was readily glycated and reached a plateau by 3 days, while α- and β-crystallins were glycated slowly initially up to 3 days followed by a steep increase as seen on the fifth day. Incubation with 50 m m G6P resulted in an approximately two fold increase in glycation compared to glucose of all crystallins. In the diabetic animals also γ-crystallin glycation increased approximately twofold within 15 days after the onset of diabetes and an additional threefold within the next 45 days followed by a slight decrease during the following 90–120 days. Increase in glycation, on the contrary, was very slow up to 30 days for α-crystallin and up to 60 days for β-crystallin, followed by a steep increase during the remainder of the experimental period. The high molecular weight (HMW) aggregates had higher levels of glycation than other proteins; the insoluble HMW aggregates contained higher levels of glycation than the soluble HMW aggregates. Protein conformational changes may be involved in facilitating the glycation of polymeric α-and β-crystallins with increasing duration of glycation, while the monomeric γ-crystallin is readily glycated even from the beginning.

Accumulation of lipid peroxidation products in human cataracts.

The role of free-radical-induced lipid peroxidation (LPO) in the development of human lens opacity was investigated. 130 human crystalline lenses impaired with cataract of various etiology (senile, traumatic, complicated cataracts) at different stages of cataract development as well as 18 transparent human lenses were studied. Primary products of LPO (diene conjugates), secondary products (ketodienes) and the end products (Schiff bases) were distinctly accumulated in cataractous lenses. Initial stages of cataract were characterized by the accumulation of primary LPO products, while in the latest stages there was a prevalence of fluorescent end products of LPO. It was concluded that the accumulation of polar hydroxy groups in the lipid bilayer of plasma membranes of lenticular fibers is one of the possible causes of their injury in cataracts.