Effects of Repeated Intravitreal Injections of Dexamethasone Implants on Intraocular Pressure: A 4-Year Study

Effect of twisting of intravitreal injections on ocular bio-mechanics: a novel insight to ocular surgery

Although intravitreal (IVT) injections provide several advantages in treating posterior segment eye diseases, several associated challenges remain. The current study uses the finite element method (FEM) to highlight the effect of IVT needle rotation along the insertion axis on the reaction forces and deformation inside the eye. A comparison of the reaction forces at the eye's key locations has been made with and without rotation. In addition, a sensitivity analysis of various parameters, such as the needle's angular speed, insertion location, angle, gauge, shape, and intraocular pressure (IOP), has been carried out to delineate the individual parameter's effect on reaction forces during rotation. Results demonstrate that twisting the needle significantly reduces the reaction forces at the penetration location and throughout the needle travel length, resulting in quicker penetration. Moreover, ocular biomechanics are influenced by needle insertion location, angle, shape, size, and IOP. The reaction forces incurred by the patient may be reduced by using a bevel needle of the higher gauge when inserted close to the normal of the local scleral surface toward the orra serrata within the Pars Plana region. Results obtained from the current study can deepen the understanding of the twisting needle's interaction with the ocular tissue.

Topical antibiotic prophylaxis before intravitreal injections: a pilot study

PURPOSE

To explore whether topical antibiotic prophylaxis in patients scheduled for intravitreal injections achieves surface sterility in a greater proportion of subjects as compared to povidone-iodine alone.

MATERIAL AND METHODS

A randomized, triple-blind clinical trial.

POPULATION

patients scheduled for intravitreal injections for maculopathy.

INCLUSION CRITERIA

any sex and race, age 18 years and above. Subjects were randomized into 4 groups: the first group applied chloramphenicol (CHLORAM), the second netilmicin (NETILM), the third a commercial ozonized antiseptic solution (OZONE), and the fourth applied no drops (CONTROL).

OUTCOME VARIABLE

percentage of non-sterile conjunctival swabs. Specimens were collected before and after the application of 5% povidone-iodine moments before the injection.

RESULTS

Ninety-eight subjects (33.7% females, 64.3% males), mean age: 70.2 ± 9.3 years (54-91). Before povidone-iodine, both the CHLORAM and NETILM group showed a lower percentage of non-sterile swabs (61.1% and 31.3% respectively), as compared to the OZONE (83.3%) and CONTROL (86.5%) groups (p < .04). However, this statistical difference was lost after the application of povidone-iodine for 3 min. Percentage of non-sterile swabs in each group after applying 5% povidone-iodine: CHLORAM 11.1%, NETILM 12.5%, CONTROL 15.4%, OZONE 25.0%. This was not statistically significant (p > .05).

CONCLUSIONS

Topical antibiotic prophylaxis with chloramphenicol or netilmicin drops decreases the bacterial load on the conjunctiva. However, after the application of povidone-iodine, all groups showed a significant reduction in the percentage of non-sterile swabs, and this value was comparable among all groups. For this reason, authors conclude that povidone-iodine alone is sufficient and prior topical antibiotic prophylaxis is not indicated.

Challenges and strategies for ocular posterior diseases therapy via non-invasive advanced drug delivery

Posterior segment diseases, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR) are vital factor that seriously threatens human vision health and quality of life, the treatment of which poses a great challenge to ophthalmologists and ophthalmic scientists. In particular, ocular posterior drug delivery in a non-invasive manner is highly desired but still faces many difficulties such as rapid drug clearance, limited permeability and low drug accumulation at the target site. At present, many novel non-invasive topical ocular drug delivery systems are under development aiming to improve drug delivery efficiency and biocompatibility for better therapy of posterior segment oculopathy. The purpose of this review is to present the challenges in the noninvasive treatment of posterior segment diseases, and to propose strategies to tackle these bottlenecks. First of all, barriers to ocular administration were introduced based on ocular physiological structure and behavior, including analysis and discussion on the influence of ocular structures on noninvasive posterior segment delivery. Thereafter, various routes of posterior drug delivery, both invasive and noninvasive, were illustrated, along with the respective anatomical obstacles that need to be overcome. The widespread and risky application of invasive drug delivery, and the need to develop non-invasive local drug delivery with alternative to injectable therapy were described. Absorption routes through topical administration and strategies to enhance ocular posterior drug delivery were then discussed. As a follow-up, an up-to-date research advances in non-invasive delivery systems for the therapy of ocular fundus lesions were presented, including different nanocarriers, contact lenses, and several other carriers. In conclusion, it seems feasible and promising to treat posterior oculopathy via non-invasive local preparations or in combination with appropriate devices.

Ultrasound-Mediated Ocular Drug Delivery: From Physics and Instrumentation to Future Directions

Drug delivery to the anterior and posterior segments of the eye is impeded by anatomical and physiological barriers. Increasingly, the bioeffects produced by ultrasound are being proven effective for mitigating the impact of these barriers on ocular drug delivery, though there does not appear to be a consensus on the most appropriate system configuration and operating parameters for this application. In this review, the fundamental aspects of ultrasound physics most pertinent to drug delivery are presented; the primary phenomena responsible for increased drug delivery efficacy under ultrasound sonication are discussed; an overview of common ocular drug administration routes and the associated ocular barriers is also given before reviewing the current state of the art of ultrasound-mediated ocular drug delivery and its potential future directions.

Optimization of an Injectable Hydrogel Depot System for the Controlled Release of Retinal-Targeted Hybrid Nanoparticles

A drawback in the development of treatments that can reach the retina is the presence of barriers in the eye that restrain compounds from reaching the target. Intravitreal injections hold promise for retinal delivery, but the natural defenses in the vitreous can rapidly degrade or eliminate therapeutic molecules. Injectable hydrogel implants, which act as a reservoir, can allow for long-term drug delivery with a single injection into the eye, but still suffer due to the fast clearance of the released drugs when traversing the vitreous and random diffusion that leads to lower pharmaceutic efficacy. A combination with HA-covered nanoparticles, which can be released from the gel and more readily pass through the vitreous to increase the delivery of therapeutic agents to the retina, represents an advanced and elegant way to overcome some of the limitations in eye drug delivery. In this article, we developed hybrid PLGA-Dotap NPs that, due to their hyaluronic acid coating, can improve in vivo distribution throughout the vitreous and delivery to retinal cells. Moreover, a hydrogel implant was developed to act as a depot for the hybrid NPs to better control and slow their release. These results are a first step to improve the treatment of retinal diseases by protecting and transporting the therapeutic treatment across the vitreous and to improve treatment options by creating a depot system for long-term treatments.

A narrative review on the association of high intraocular pressure and glaucoma in patients with retinal vein occlusion

BACKGROUND AND OBJECTIVE

Retinal vein occlusion (RVO) is a major cause of vision loss and elevated intraocular pressure (IOP), high ocular perfusion pressure, and glaucoma are known ophthalmic risk factors for RVO. The aim of this paper is to provide the update on the association and management of high IOP/glaucoma and RVO.

METHODS

A literature review was performed in PubMed and Medline until May 2022 utilizing specific keywords and cross-matched reference lists.

KEY CONTENT AND FINDINGS

The association of RVO with high IOP/glaucoma may be attributed to retinal ganglion cell loss due to retinal ischemia in high IOP and glaucoma. As new modalities showed, decreased optic disc perfusion, reduced density of blood vessels in the optic nerve head of glaucoma patients, changes in the peripapillary microvascular parameters, and decreased retinal nerve fiber layer (RNFL) thickness of the optic nerve head of eyes with RVO suggest a common pathway between RVO and glaucoma. Literature suggests the close follow up for glaucoma development among patients with non-arteriovenous (AV) crossing (optic cup or optic nerve sited) RVO in fellow eye and management of elevated IOP among RVO cases treated with anti-vascular endothelial growth factor (VEGF) antibodies/corticosteroids and those with preexisting primary open angle glaucoma (POAG).

CONCLUSIONS

Determining potential patient responses to treatment and considering therapeutic options are challenging among patients with RVO and glaucoma. However, IOP lowering managements in preventing IOP spikes in patients with preexisting glaucoma and early treatment of macular edema in eyes with RVO is recommended.

Intravitreal Corticosteroid Implantation in Diabetic Macular Edema: Updated European Consensus Guidance on Monitoring and Managing Intraocular Pressure

Intravitreal therapy for diabetic macular edema can, in susceptible patients, increase intraocular pressure (IOP). As uncontrolled IOP can potentially be sight threatening, monitoring is an essential component of patient management. It can be challenging for retina specialists to ensure that monitoring is rigorous enough to detect and resolve any potential problems at the earliest opportunity without it also being overburdensome for patients who have the lowest risk of developing an IOP rise. We have developed dynamic algorithms that: (1) tailor the frequency and extent of monitoring according to individual susceptibility and current IOP and (2) assist retina specialists in deciding when they should consider a referral to a glaucoma specialist. One algorithm is for patients with a relatively low susceptibility to developing an IOP rise (those whose baseline IOP is < 22 mmHg and who do not have a history of IOP events). Depending on their first post-implantation IOP check, the algorithm classifies them as: low risk if IOP remains < 22 mmHg; medium risk if IOP is 22-25 mmHg and any rise from baseline is < 10 mmHg; or high risk if IOP is > 25 mmHg or any rise from baseline is ≥ 10 mmHg. Thereafter, the algorithm guides on the frequency and extent of monitoring required in each of these groups and, if IOP rises or falls during treatment, patients may move up or down the risk groups accordingly. A different algorithm is provided for patients who are more susceptible to developing an IOP rise (those with a baseline IOP of ≥ 22 mmHg or a prior history of an IOP event). These patients need monitoring more closely so this algorithm has only medium- or high-risk classifications. These algorithms update the previous monitoring guidance by Goñi et al. (Goñi et al. in Ophthalmol Ther 5:47-61, 2016).

Predicting the safety zone for steroid-induced ocular hypertension induced by intravitreal dexamethasone implantation

BACKGROUND/AIMS

This study aimed to predict the possibility of steroid-induced ocular hypertension (OHT) after intravitreal dexamethasone (DEX) implantation and to identify a proper safety zone for such injections.

METHODS

A cross-sectional observational study was conducted and included 908 patient eyes that underwent DEX implant injection due to various retinal diseases. Intraocular pressure (IOP) was measured before injection, at 1 week, and at 1, 2, 3, 6 and 12 months thereafter. Eyes of enrolled patients were divided into the OHT and normal IOP groups. Univariable logistic regression analysis was used to assess significant associations between steroid-induced OHT and covariates; significant and previously reported significant variables were analysed with a multivariable model, and predictive nomograms were developed.

RESULTS

Age, sex, axial length, glaucomatous eye, neovascular glaucoma, secondary glaucoma, uveitis history, hypertension, depression, diabetes mellitus and a history of previous laser-assisted in-situ keratomileusis or laser-assisted subepithelial keratectomy were significantly related to steroid-induced OHT (p<0.05). The calibration plot revealed good prediction under a predicted value of 0.4. Cut-off values for 80%, 86%, 91%, 95% and 98% sensitivity and specificity were offered for the safety zone after intravitreal DEX implantation.

CONCLUSION

We developed two nomograms to predict a safety zone for intravitreal DEX implantation. These can be used to identify individuals who may be safely prescribed steroid treatments and for whom extra caution should be exercised.

Visual Acuity Gain Profiles and Anatomical Prognosis Factors in Patients with Drug-Naive Diabetic Macular Edema Treated with Dexamethasone Implant: The NAVEDEX Study

Brief Summary Statement

NAVEDEX (NAive diabetic macular Edema treated by DEXamethasone implant) study is a real-life multi-center study on drug-naive diabetic macular edema treated by Dexamethasone-implant. Two different visual acuity gain (VA) profiles were identified, based on baseline visual acuity (VA). Baseline disorganization of retinal inner layers or ellipsoid zone alterations (EZAs) negatively influence final VA but has no impact on VA gain.

Abstract

The purpose of this study is to evaluate the visual acuity (VA) gain profiles between patients with drug-naive diabetic macular edema (DME) treated by dexamethasone implant (DEX-implant) and assess the baseline anatomical and functional factors that could influence the response to the treatment in real-life conditions. A retrospective, multi-center observational study included 129 eyes with drug-naive DME treated by DEX-implant. The Median follow-up was 13 months. Two groups of VA gain trajectories were identified—Group A, with 71% (n = 96) of patients whose average VA gain was less than five letters and Group B, with 29% (n = 33) of patients with an average gain of 20 letters. The probability of belonging to Group B was significantly higher in patients with baseline VA < 37 letters (p = 0.001). Ellipsoid zone alterations (EZAs) or disorganization of retinal inner layers (DRILs) were associated with a lower final VA (53.0 letters versus 66.4, p = 0.002) but without a significant difference in VA gain (4.9 letters versus 6.8, p = 0.582). Despite a low baseline VA, this subgroup of patients tends to have greater visual gain, encouraging treatment with DEX-implant in such advanced-stage disease. However, some baseline anatomic parameters, such as the presence of EZAs or DRILs, negatively influenced final vision.