Single injection of triamcinolone versus three repeated injections of bevacizumab for treatment of diabetic macular edema

Chitosan as a promising materials for the construction of nanocarriers for diabetic retinopathy: an updated review

Diabetic retinopathy (DR) is a condition that causes swelling of the blood vessels of the retina and leaks blood and fluids. It is the most severe form of diabetic eye disease. It causes vision loss in its advanced stage. Diabetic retinopathy is responsible for causing 26% of blindness. Very insufficient therapies are accessible for the treatment of DR. As compared to the conventional therapies, there should be enhanced research on the controlled release, shorter duration, and cost-effective therapy of diabetic retinopathy. The expansion of advanced nanocarriers-based drug delivery systems has been now employed to exploit as well as regulate the transport of many therapeutic agents to target sites via the increase in penetration or the extension of the duration of contact employing production by enclosing as well as distributing tiny molecules in nanostructured formulation. Various polymers have been utilized for the manufacturing of these nanostructured formulations. Chitosan possesses incredible biological and chemical properties, that have led to its extensive use in pharmaceutical and biomedical applications. Chitosan has been used in many studies because of its enhanced mucoadhesiveness and non-toxicity. Multiple studies have used chitosan as the best candidate for manufacturing nanocarriers and treating diabetic retinopathy. Numerous nanocarriers have been formulated by using chitosan such as nanostructured lipid carriers, solid lipid nanoparticles, liposomes, and dendrimers for treating diabetic retinopathy. This current review elaborates on the recent advancements of chitosan as a promising approach for the manufacturing of nanocarriers that can be used for treating diabetic retinopathy.

The effects of intravitreal injections on intraocular pressure and retinal nerve fiber layer: a systematic review and meta-analysis

The number of eye diseases treated with intravitreal injections is increasing. Obviously, an injection of fluid into the eye results in an increase of intraocular pressure (IOP), the main risk factor for glaucoma. However, the effect of these repeated IOP increases on the eye is unclear. Therefore, we performed a systematic review with meta-analyses. PubMed, Embase and Clinical Trials Registries were searched for articles investigating the relationship between intravitreal injections (anti-vascular endothelial growth factor [anti-VEGF] or steroids) and either IOP, retinal nerve fiber layer (RNFL)-thickness and glaucoma. Multiple meta-analyses were performed, combining data on intravitreal injection of anti-VEGF medication and dexamethasone implants. A total of 74 articles were eligible for meta-analyses. The short-term effect of an intravitreal injection of anti-VEGF showed a statistically significant increase in IOP. One day after injection of anti-VEGF, however, IOP was significantly lower than baseline. The long-term time-intervals showed no significant difference in IOP. After intravitreal injection of a dexamethasone implant, IOP was significantly higher than baseline 1 month post-injection. RNFL-thickness was significantly reduced 6 and 12 months post-injection of anti-VEGF, as well as at end of follow up. Caution is advised when using intravitreal medication, especially when treating patients with advanced glaucoma; in these cases, prophylactic IOP-lowering medication may be considered.

Corticosteroids for Diabetic Macular Edema

Diabetic macular edema (DME) is a chronic condition with a multifactorial pathogenesis. Vascular endothelial growth factor (VEGF) and several inflammatory mediators are upregulated in eyes with DME. VEGF inhibitors and corticosteroids have all been used successfully in the management of DME. Currently available corticosteroids include triamcinolone acetonide (TA), the dexamethasone (DEX) intravitreal implant, and the fluocinolone acetonide (FA) intravitreal implant. The response to treatment can vary substantially with each treatment modality. Some cases of DME are VEGF driven, and in others, inflammation plays a key role. Chronicity appears to favor corticosteroid treatment. There are no clear guidelines to guide switching from an anti-VEGF to a corticosteroid. Combination therapy of an anti-VEGF drug and a corticosteroid does not appear to provide additional benefit over monotherapy with either drug. The main advantage of corticosteroids over VEGF inhibitors is their longer duration of action. Vitrectomy does not affect the pharmacokinetics of the corticosteroid implants. Common adverse events of corticosteroids include cataract formation, cataract progression, and ocular hypertension. TA may cause a sterile endophthalmitis and pseudoendophthalmitis. Migration of the intravitreal DEX and FA implants into the anterior chamber can be problematic. Because of their less favorable safety profile, corticosteroids are generally used as a second-line treatment for DME. Advantages of using an intravitreal corticosteroid implant include the reduction of treatment burden and predictable pharmacokinetics even in vitrectomized eyes. Pseudophakic eyes, previously vitrectomized eyes and eyes with long-standing DME, particularly of patients who have difficulty in maintaining a monthly appointment, may benefit from primary treatment with a corticosteroid intravitreal implant.

Efficacy of the Intravitreal Sustained-Release Dexamethasone Implant for Diabetic Macular Edema Refractory to Anti-Vascular Endothelial Growth Factor Therapy: Meta-Analysis and Clinical Implications

BACKGROUND AND OBJECTIVE

To assess the effect on best-corrected visual acuity (BCVA) and efficacy of the intravitreal sustained-release 0.7 mg dexamethasone implant (Ozurdex; Allergan, Irvine, CA) in patients with recalcitrant diabetic macular edema (DME).

PATIENTS AND METHODS

Meta-analysis utilizing the MOOSE framework and a random effects model. Studies included adults undergoing treatment with Ozurdex for DME. The methodologic quality of each study was assessed using the MINORS and the Cochrane Collaboration Risk of Bias for randomized studies.

RESULTS

A total of 3,859 patients among 15 studies were included in the final analysis. The mean difference in BCVA was a gain of four lines or 20 Early Treatment of Diabetic Retinopathy Study letters with Ozurdex at a mean follow-up period of 6 months.

CONCLUSIONS

Treatment with Ozurdex is associated with significant mean improvement in visual acuity. Clinicians should have a multimodality approach to treating DME and be aware of this treatment option in those who have a suboptimal response to anti-VEGF therapy. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:160-166.].

A 12-MONTH, SINGLE-MASKED, RANDOMIZED CONTROLLED STUDY OF EYES WITH PERSISTENT DIABETIC MACULAR EDEMA AFTER MULTIPLE ANTI-VEGF INJECTIONS TO ASSESS THE EFFICACY OF THE DEXAMETHASONE-DELAYED DELIVERY SYSTEM AS AN ADJUNCT TO BEVACIZUMAB COMPARED WITH CONTINUED BEVACIZUMAB MONOTHERAPY

PURPOSE

To determine whether a dexamethasone intravitreal implant 0.7 mg (dexamethasone delivery system [DDS], Ozurdex) combined with bevacizumab 1.25 mg (Avastin) provides greater benefit than bevacizumab monotherapy in eyes with diabetic macular edema with incomplete response to multiple antivascular endothelial growth factor injections.

METHODS

Eyes with diabetic macular edema were randomly assigned to receive combination therapy (bevacizumab plus DDS) or bevacizumab monotherapy. Combination therapy eyes received intravitreal bevacizumab at baseline, DDS at Month 1, and subsequent DDS (at Months 5 and 9), whereas monotherapy eyes received bevacizumab (monthly) if indicated. Eyes were eligible for retreatment if the central subfield thickness measured >250 μm, and Early Treatment of Diabetic Retinopathy Study visual acuity was <80 letters (20/25).

RESULTS

Forty eyes of 30 patients were enrolled. The mean visual acuity changes from baseline to 12 months were similar in the 2 groups (combined: +5.4 letters; bevacizumab: +4.9 letters; difference = 0.2 letters, 95% confidence interval = -5.9 to 6.3; P = 0.75). The mean reduction in central subfield thickness was greater in the combination group (-45 μm vs. -30 μm, difference = 69 μm, 95% confidence interval = 9-129; P = 0.03) and more patients in the combination group had central subfield thickness <250 μm. The combined treatment group received three fewer supplemental injections of bevacizumab, but this was counterbalanced by the need for an average of 2.1 DDS injections.

CONCLUSIONS

The dexamethasone implant combined with bevacizumab significantly improves visual acuity and significantly improves macular morphology in eyes with refractory diabetic macular edema, although visual acuity changes are not superior to continued bevacizumab monotherapy.

Short term apoptotic activity of intravitreal bevacizumab on rabbit retina

AIM

To evaluate the safety and the short term apoptotic activity of intravitreal bevacizumab in rabbit eyes by histopathological analysis.

METHODS

Twenty-eight eyes of 14 rabbits were divided into three groups: 8 rabbits in group 1 and 3 rabbits in each of group 2 and group 3. Intravitreal bevacizumab (1.25mg/0.05mL) was applied to the right eyes of each subject in group 1 and group 2 (11 eyes) and the same volume of saline was applied to the left eyes of each subject in group 1 and group 3 (11 eyes). The left eyes in group 2 and the right eyes in group 3 were left untreated and used as control. Enucleated eyes were used for histopathologic analyses.

RESULTS

After immunohistochemical staining with caspase-3 and p53, there was no histological evidence of toxicity to the retina and the optic nerve in any of the sections that were analyzed in all three groups. In addition, vascular endothelial cells located at the retina and the optic nerve tissues in all groups showed a similar staining pattern with caspase-3 and p53.

CONCLUSION

Our study showed that intravitreal bevacizumab with the dose of 1.25mg/0.05mL caused no histological signs of toxicity or apoptotic activity on the rabbit retina.