Search Results (33)

Glaucoma is a complex condition with an unknown exact cause, but it involves progressive damage to the optic nerve. This damage is primarily driven by high eye pressure, poor blood flow, and oxidative stress, a process linked to cell ageing and inflammation that harms the retina. Recent research highlights that these issues stem from structural changes in the eye’s drainage system and visual pathways, which can be analysed through the lens of engineering thermodynamics. This study proposes a thermal explanation for the physiological processes linking ocular behaviour to inflammatory ion flux alterations. We develop a thermal model demonstrating that temperature increases are tied to the mechanical work necessary for maintaining water flux in the anterior ocular chamber. We show that these changes alter the membrane potential and tissue pH, resulting in elevated intraocular pressure. By clarifying the temperature–pressure effect, this research establishes a theoretical framework to study the developments of future glaucoma therapies. Full article

The ultra-precision machining of micro-optics from low glass transition temperature (T_g) hydrophobic polymers is frequently compromised by thermal instability and kinematic constraints imposed by on-axis turning. To address these challenges, this study presents a novel clamping–cooling system engineered for the off-axis diamond turning of low-T_g polymers. The design integrates vacuum clamping for workpiece stabilization with an embedded microchannel network for efficient thermal management. Strategic material selection effectively balances thermal insulation with mechanical stability. Performance evaluations demonstrated robust thermal regulation: lens blank surface temperatures stabilized at 6 °C during stationary testing, and the system was able to drop below 0 °C under maximum cooling targets. This strict thermal control enabled achieving nanometer surface roughness. Ultimately, this modular system facilitates the scalable, simultaneous production of high-quality, polishing-free intraocular lenses (IOLs), advancing manufacturing capabilities for complex precision optics. Full article

Elevated temperatures are frequently encountered in numerous occupational settings such as iron and steel foundries, non-ferrous metal foundries, brick and ceramic manufacturing plants, glass production facilities, rubber factories, electrical power plants, bakeries, laundries, chemical processing sites, mining operations, smelting plants, and steam tunnels. Employees working in these environments are at risk of developing various health issues and injuries, including ocular complications, due to prolonged exposure to heat and the physical demands of handling heavy materials. This study focuses on examining the pressure within the eye’s anterior chamber, referred to as Intraocular Pressure (IOP), and its association with the cornea’s biomechanical characteristics, with particular attention to corneal temperature. Our methodology is grounded in the principles of the first law of thermodynamics. The findings reveal a link between the temperature of the eye’s anterior chamber and the biomechanical behaviour of the cornea. Specifically, IOP serves as an indicator of the cornea’s elasticity and its optical properties as influenced by temperature variations. We investigated how the cornea’s elastic energy, or the work it performs, varies with temperature changes. The results show that an increase in temperature corresponds to a reduction in the work exerted by the cornea. The corneal temperature is affected by both the ambient environment and the temperature of the aqueous humour within the anterior chamber. This indicates a relationship between the mechanical work done by the cornea and the pressure exerted by the fluid in the eye’s front segment. Furthermore, our study identified a correlation between corneal thickness and IOP, which our modelling approach successfully quantifies. Utilizing the first law of thermodynamics, we calculated the work performed by the anterior chamber against the cornea’s internal surface. Temperature fluctuations influence the secretion, drainage, and flow characteristics of the aqueous humour, thereby impacting IOP and associated ocular conditions. These insights are valuable for devising strategies aimed at preventing eye injuries among workers exposed to high-temperature environments. Full article

Ocular disorders such as keratitis, glaucoma, age-related macular degeneration (AMD), diabetic retinopathy (DR), and dry eye disease (DED) are highly prevalent worldwide and remain major causes of visual impairment and blindness. Conventional therapeutic approaches for ocular diseases, such as eye drops, surgery, and laser therapy, are frequently hampered by limited drug bioavailability, rapid clearance, and treatment-related complications, primarily due to the eye’s unique anatomical and physiological barriers. Hydrogels, characterized by their three-dimensional network structure, high water content, excellent biocompatibility, and tunable physicochemical properties, have emerged as promising platforms for ophthalmic drug delivery. This review summarizes the classification, fabrication strategies, and essential properties of hydrogels, and highlights recent advances in their application to ocular diseases, including keratitis management, corneal wound repair, intraocular pressure regulation and neuroprotection in glaucoma, sustained drug delivery for AMD and DR, vitreous substitutes for retinal detachment, and therapies for DED. In particular, we highlight recent advances in stimuli-responsive hydrogels that enable spatiotemporally controlled drug release in response to ocular cues such as temperature, pH, redox state, and enzyme activity, thereby enhancing therapeutic precision and efficacy. Furthermore, this review critically evaluates translational aspects, including long-term ocular safety, clinical feasibility, manufacturing scalability, and regulatory challenges, which are often underrepresented in existing reviews. By integrating material science, ocular pathology, and translational considerations, this review aims to provide a comprehensive framework for the rational design of next-generation hydrogel systems and to facilitate their clinical translation in ophthalmic therapy. Full article

Introduction: Odontogenic infections may influence distant structures, including the eye. Their extension into the paranasal sinuses and orbital region can contribute to inflammatory and glaucomatous conditions. Case Report: A 46-year-old man was examined for a possible odontogenic source of chronic eye disease. The patient had an 18-year history of progressive vision loss in his left eye associated with Posner–Schlossmann syndrome, chronic uveitis, and episodic elevation of intraocular pressure (IOP). Imaging studies revealed the presence of a foreign body in the alveolar recess of the left maxillary sinus, as detected on panoramic radiography, cone-beam computed tomography (CBCT), and infrared thermography (IRT). Preliminary IRT examination showed marked thermal asymmetry (ΔT = 1.1 °C) between the left and right sides of the maxilla. Worsening of ocular symptoms and increased IOP despite steroid treatment prompted surgical treatment. The foreign body, identified as a root canal filling, was removed, and the chronically inflamed sinus mucosa was excised. During a follow-up visit two weeks later, the IRT examination showed a reduction in temperature difference (ΔT = 0.2 °C) and routine postoperative healing. After two months, no thermal asymmetry was found (ΔT = 0 °C), and an ophthalmological examination showed no active inflammation. Six months after the procedure, the patient remained asymptomatic, and the IRT examination revealed only minimal residual variability within the measurement tolerance (ΔT = 0.1 °C), consistent with the resolution of the sinus inflammation. Conclusions: This case highlights the value of interdisciplinary diagnostics in identifying odontogenic contributors to chronic ocular disease. Infrared thermography proved to be a helpful non-invasive adjunct for detecting and monitoring subclinical maxillary sinus inflammation. Full article

Background/Objectives: Cataract surgery often reveals preexisting corneal astigmatism, which can be corrected using a toric intraocular lens (T-IOL). However, postoperative T-IOL rotation may compromise correction. We investigated T-IOL rotation, focusing on deployment time and proximity to the posterior capsule (PC), using intraoperative optical coherence tomography (iOCT). Methods: Six different T-IOL models were inserted into acrylic simulated lens capsule models under different tacking durations (5 s, 30 s, and 60 s) and temperature conditions (23 °C, 28 °C, and 32 °C). The selection criteria for porcine lenses for examination required that they match human lens dimensions, typical of those used to train cataract surgeons. T-IOL misalignment due to vibration was assessed. Additionally, the impact of temporary intraocular pressure (IOP) reduction on T-IOL proximity to the PC was measured using iOCT in porcine eyes. Results: Tacking time and temperature independently affected T-IOL deployment, with shorter tacking durations and higher temperatures leading to faster deployment. Among lenses tested under identical tacking time and temperature conditions, iSert Micro Toric Aspheric 1-Piece IOL (355T3) had the slowest expansion time, while Avansee™ Preload 1-Piece Toric (YP-T3) had the fastest. Porcine eyes with a corneal white-to-white major axis < 16.0 mm fell within the 95% confidence interval for matching human lens size. Temporarily reducing IOP during surgery improved T-IOL adhesion to the PC, reducing both the occurrence and degree (from 14.0° to nearly 0°) of postoperative rotation. Conclusions: Optimal T-IOL deployment, temporary IOP reduction during surgery, and enhanced adhesion to the PC can reduce the risk and degree of T-IOL rotation. Intraoperative iOCT aids in monitoring T-IOL positioning, which is essential to prevent rotation. Accumulated fluid between the T-IOL and PC may contribute to rotation, which requires further investigation. These findings provide practical strategies for enhancing T-IOL stability and improving the effectiveness of astigmatism correction in cataract surgery. Full article

Complex anatomical and physiological barriers make the eye a challenging organ to treat from a drug delivery perspective. Currently available treatment methods (topical eyedrops) for anterior segment diseases pose several limitations in terms of bioavailability and patient compliance. Conventional drug delivery methods to treat posterior segment ocular diseases are primarily intravitreal injection (IVT) of solutions. IVT is highly invasive and leads to retinal toxicity, endophthalmitis, and intraocular inflammation, frequently requiring professional administration and frequent clinical visits. Advanced drug delivery treatment strategies could improve patient compliance and convenience. Long-acting drug delivery platforms (biodegradable or nonbiodegradable) provide sustained/controlled release of drugs for at least four to six months. Smart drug delivery alternatives, for instance, in situ forming implants, are injectable formulations that form semisolid-to-solid implants in response to the various stimuli of pH, light, osmolarity, and temperature. Additionally, nanoparticulate drug delivery systems, contact lenses, electrospun patches, and microneedle-based drug delivery systems provide minimally invasive treatment options for ocular disorders. This comprehensive review focuses on advanced drug delivery options for the management of ocular disorders. Full article

Background/Objectives: Latanoprost is a leading active pharmaceutical ingredient belonging to the synthetic prostaglandin F2α analogs, widely used as a first-line treatment for open-angle glaucoma and increased intraocular pressure. This study addresses the critical need for an accurate and precise chromatographic method that is capable of simultaneously quantifying latanoprost and six latanoprost-related substances in antiglaucoma eye drops. This will be crucial for patient safety and treatment efficacy. This method enables the separation of latanoprost isomers, (15S)-latanoprost, latanoprost enantiomer, and 5,6-trans latanoprost from latanoprost signal. Furthermore, it is specific for the well-known latanoprost degradants—the major latanoprost acid and the minor 15-ketolatanoprost—as well as synthetic derivatives, such as triphenylphosphine oxide (TPPO) and propan-2-yl 5-(diphenylphosphoryl)pentanoate (IDPP). Using forced degradation studies using high temperatures, UV light, alkalis, acids, and oxidizing agents, the degradation profiles of the drugs were characterized and the method’s stability-indicating power was confirmed. Methods: Separation was achieved on a stationary combined system comprising chiral and cyano columns. Reverse-phase gradient elution and UV 210 nm detection were employed. The novel method was validated according to the European Medicines Agency International Council for Harmonisation Q2 Validation of analytical procedures—Scientific guideline. Results: The method was shown to be linear in the range of 40–60 µg/mL for latanoprost and 0.05–2.77 µg/mL for related substances, confirmed by a correlation coefficient of r = 0.999. Recoveries for latanoprost were obtained within the range of 98.0–102.0% for assays and 90.0–110.0% for impurities. The detection and quantification limits for latanoprost were 0.025 µg/mL and 0.35 µg/mL, respectively. Conclusions: The analytical procedure developed is adequately sensitive, precise, and accurate compared to existing methods. The method can be reliably used to control the critical quality attributes of low-dose latanoprost products, ensuring their required high pharmaceutical quality, which translates into improvements in patient care. This advancement holds significant implications for enhancing the therapeutic management of glaucoma, ensuring drug safety and efficacy. Full article

Perioperative monitoring of the ocular heat transfer is important for increasing the safety of long-term vitreoretinal surgery. The study is aimed at studying new thermoelectric measuring devices for comprehensive perioperative monitoring of ocular temperature and heat fluxes in vitreoretinal surgery. This pilot, open-label, prospective study included 23 patients (23 eyes) with proliferative diabetic retinopathy (PDR) in both eyes. The thermoelectric devices were developed for measuring intraocular temperature in vitreoretinal surgery and for determining the ocular surface temperature (OST) and heat flux (HF) density. In all cases, OST and HF density of both eyes were recorded (before and after surgery). Intraocular temperature and temperature of the irrigation fluid were measured intraoperatively. No complications associated with the perioperative use of thermoelectric temperature and HF sensors were identified during the study. The successful application of thermoelectric temperature and HF sensors, developed specifically for ophthalmological applications, in comprehensive perioperative monitoring of ocular heat transfer in patients with PDR in vitreoretinal surgery was demonstrated for the first time. Further research is needed to confirm the benefits of perioperative temperature monitoring in vitreoretinal surgery, as well as to develop equipment for active management of temperature in surgical practice. Full article

Emulsification is a feared and common complication of the use of silicone oil (SO) as tamponade fluid after vitrectomy as it potentially associated with significant risks to ocular health, including elevated intraocular pressure (IOP), glaucoma, corneal and retinal changes. The aim of this study was to investigate the role and interplay of physical factors on the formation of SO emulsion. Experiments were performed in a model of the vitreous chamber with a realistic shape, filled with SO and an aqueous solution containing different concentrations of albumin, an endogenous protein known to modify the interfacial properties between SO and aqueous solutions. The model was subjected to harmonic and saccadic rotations and kept at body temperature. Results indicated that no emulsions were detected in the absence of albumin in the aqueous solution, while the presence of the protein facilitated emulsion formation, acting as a surfactant. Mechanical energy from eye movements was also found to be a key mechanism to produce emulsification, with higher mechanical energy provided to the system leading to smaller droplet sizes. The emulsions formed were stable over extended times. This study highlights the complex interplay of factors influencing SO emulsification in the vitreous chamber. A better understanding of the mechanisms underlying SO emulsification is crucial for developing strategies to mitigate SO emulsion and the related complications. Full article

The widespread use of hydrophilic intraocular lenses (IOLs) in eye surgery, fabricated by poly-2-(hydroxyethyl methacrylate) (PHEMA), has highlighted their calcification as a serious problem, implying that their surgical explantation is a rather risky process. The field of biomaterials has been developing rapidly in recent years, with research interest turning to the development of novel materials which involve either copolymers of PHEMA or protective functional coatings. Graphene coatings are particularly attractive because of their respective unique properties. In the present work, we present the results of the investigation of the development of graphene coatings on hydrophilic IOLs and their subsequent performance with respect to calcification opacification. Hydrophilic IOLs with a water content of 18% by weight were coated with graphene oxide (GO) by equilibration with GO suspensions in water. The concentrations of the suspensions ranged from 1 × 10⁻⁴ to 20 × 10⁻⁴% w/v. The GO suspensions were equilibrated with the IOLs for 5 days at a constant temperature, 37 °C, and rotated in 30 mL tubes end over end. This treatment resulted in the formation of a uniform coating of GO on the IOLs verified by scanning electron microscopy (SEM) and other physicochemical methods. The contact angle of the GO-coated IOLs decreased significantly in comparison with the uncoated IOLs. The GO-coated IOLs exhibited a higher tendency to calcify in supersaturated solutions simulating aqueous humor (SAH). The growth rate of hydroxyapatite (Ca₅(PO₄)₃OH, HAP) on GO-coated IOLs was higher in comparison with the respective untreated IOLs. The conversion of the GO coating via a reduction with phenyl hydrazine resulted in the formation of a reduced-graphene (rGO) surface film, as identified by Raman and XPS spectroscopy. The rGO film was hydrophobic (contact angle 100°) and did not calcify in supersaturated calcium phosphate solutions. Full article

The objective of the current study was to fabricate a thermosensitive in situ gelling system for the ocular delivery of carvedilol-loaded spanlastics (CRV-SPLs). In situ gel formulations were prepared using poloxamer analogs by a cold method and was further laden with carvedilol-loaded spanlastics to boost the precorneal retention of the drug. The gelation capacity, rheological characteristics, muco-adhesion force and in vitro release of various in situ gel formulations (CS-ISGs) were studied. The optimized formula (F2) obtained at 22% w/v poloxamer 407 and 5% w/v poloxamer 188 was found to have good gelation capacity at body temperature with acceptable muco-adhesion properties, appropriate viscosity at 25 °C that would ease its ocular application, and relatively higher viscosity at 37 °C that promoted prolonged ocular residence of the formulation post eye instillation and displayed a sustained in vitro drug release pattern. Ex vivo transcorneal penetration studies through excised rabbit cornea revealed that F2 elicited a remarkable (p ˂ 0.05) improvement in CRV apparent permeation coefficient (P_app = 6.39 × 10⁻⁶ cm/s) compared to plain carvedilol-loaded in situ gel (CRV-ISG; P_app = 2.67 × 10⁻⁶ cm/s). Most importantly, in normal rabbits, the optimized formula (F2) resulted in a sustained intraocular pressure reduction and a significant enhancement in the ocular bioavailability of carvedilol, as manifested by a 2-fold increase in the AUC_0–6h of CRV in the aqueous humor, compared to plain CRV-ISG formulation. To sum up, the developed thermosensitive in situ gelling system might represent a plausible carrier for ophthalmic drug delivery for better management of glaucoma. Full article

This study aimed at formulating the antiglaucoma agent, Bimatoprost (BMT), into niosomal in situ gel (BMT-ISG) for ocular delivery. Niosomes containing cholesterol/span 60 entrapping BMT were fabricated using a thin-film hydration method. The fabricated niosomes were optimized and characterized for entrapment efficiency (%EE) and size. The optimized BMT-loaded niosomal formulation prepared at a cholesterol/span 60 ratio of 1:2 exhibited the highest entrapment (81.2 ± 1.2%) and a small particle size (167.3 ± 9.1 nm), and they were selected for incorporation into in situ gelling systems (BMT-ISGs) based on Pluronic F127/Pluronic F68. Finally, the in vivo efficiency of the BMT-ISG formulation, in terms of lowering the intraocular pressure (IOP) in normotensive male albino rabbits following ocular administration, was assessed and compared to that of BMT ophthalmic solution. All the formulated BMT-ISGs showed sol–gel transition temperatures ranging from 28.1 °C to 40.5 ± 1.6 °C. In addition, the BMT-ISG formulation sustained in vitro BMT release for up to 24 h. Interestingly, in vivo experiments depicted that topical ocular administration of optimized BMT-ISG formulation elicited a significant decline in IOP, with maximum mean decreases in IOP of 9.7 ± 0.6 mm Hg, compared to BMT aqueous solution (5.8 ± 0.6 mm Hg). Most importantly, no signs of irritation to the rabbit’s eye were observed following topical ocular administration of the optimized BMT-ISG formulation. Collectively, our results suggested that niosomal in situ gels might be a feasible delivery vehicle for topical ocular administration of anti-glaucoma agents, particularly those with poor ocular bioavailability. Full article

Bacterial conjunctivitis (BC) entails inflammation of the ocular mucous membrane. Early effective treatment of BC can prevent the spread of the infection to the intraocular tissues, which could lead to bacterial endophthalmitis or serious visual disability. In 2003, gatifloxacin (GTX) eyedrops were introduced as a new broad-spectrum fluoroquinolone to treat BC. Subsequently, GTX use was extended to other ocular bacterial infections. However, due to precorneal loss and poor ocular bioavailability, frequent administration of the commercial eyedrops is necessary, leading to poor patient compliance. Thus, the goal of the current investigation was to formulate GTX in a lipid-based drug delivery system to overcome the challenges with the existing marketed eyedrops and, thus, improve the management of bacterial conjunctivitis. GTX-NLCs and SLNs were formulated with a hot homogenization–probe sonication method. The lead GTX-NLC formulation was characterized and assessed for in vitro drug release, antimicrobial efficacy (against methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa), and ex vivo permeation. The lead formulation exhibited desired physicochemical characteristics, an extended release of GTX over a 12 h period, and was stable over three months at the three storage conditions (refrigerated, room temperature, and accelerated). The transcorneal flux and permeability of GTX from the GTX-NLC formulation were 5.5- and 6.0-fold higher in comparison to the commercial eyedrops and exhibited a similar in vitro antibacterial activity. Therefore, GTX-NLCs could serve as an alternative drug delivery platform to improve treatment outcomes in BC. Full article

The primary objective of this study was to objectively compare the visual performance of patients following premium pseudophakic presbyopia corrections in different light combinations for near- and intermediate-vision activities of daily living (ADLs). This is a prospective, comparative study. A total of 75 patients populated three study groups: G1-patients with bilateral trifocal implantation, G2-patients with bilateral bifocal implantation, and G3-patients with bilateral monofocal implantation. All participants addressed 10 ADLs in nine combinations of light temperature (3000 K, 4000 K, and 6000 K) and light intensity (25 fc, 50 fc, and 75 fc) and declared their subjectively optimal light combination while reading. G2 and G3 had the best total ADL scores in 6000 K/75 fc, while G1 had the best total ADL score in 4000 K/75 fc. Total ADL, easy ADL, and moderate difficulty ADL scores were significantly better in G2, while difficult ADL score was significantly better in G1. The majority of all groups selected 6000 K/75 fc as the most comfortable light combination, and no group selected 3000 K and 25 fc. In conclusion, trifocal patients benefit from intense daylight, while bifocal and monofocal patients benefit from intense, cold lighting. Trifocal patients present superior near-vision capacity in difficult near-vision daily tasks, while bifocal patients present superiority in easy and moderate-difficulty ADLs. Full article