Surgical Management of Complications after Dexamethasone Implant

Effect of intralenticular dexamethasone implant: A case report

INTRODUCTION

Intravitreal dexamethasone (DEX) implant is indicated for the treatment of macular oedema due to diabetic retinopathy, retinal vein occlusion and uveitis. The most common complications are cataract and elevated intraocular pressure (IOP). Accidental injection of DEX implant into the lens is a rare complication and only few papers presented it.

CASE PRESENTATION

A 40-year-old man was treated with DEX implant for diabetic macular oedema in both eyes. At 1 week follow-up visit, slit lamp examination showed the DEX implant was located in the crystalline lens of the right eye (RE) without any sign of inflammation, cataract or elevated IOP, so we decided to plan a normal follow-up schedule. Macular oedema relapsed 5 months after the injection in the left eye (LE), whereas the RE did not show any sing of intraretinal or subretinal fluid. Six months after DEX implantation an uneventful phacoemulsification and intraocular lens placement were performed in the RE because of IOP elevation.

CONCLUSIONS

The therapeutic effect of DEX implant can be maintained for a longer period of time than intravitreal implant, determining complete reabsorption of macular oedema. Intralenticular implant can be maintained inside the lens until either IOP increases, cataract progresses, or other complications occur.

Review of Risk Factors and Complications of Anterior Migration of Ozurdex Implant: Lessons Learnt from the Previous Reports

Purpose: Ozurdex had shown promising anatomical and functional outcomes in managing refractory Irvine-Gass syndrome over the years. Burgeoning usage of Ozurdex has prompted the study of its related complications, particularly the anterior chamber migration of the implant. Methods: Literature reviews on the anterior chamber migration of the Ozurdex via PubMed, EBSCO, and TRIP databases were searched from 2012 to 2020. The predisposing factors, outcomes, and management of such cases were evaluated. Results: A total of 54 articles consisting of 105 cases of anterior migration of Ozurdex were included in this analysis. The vitrectomized eye and compromised posterior capsule were highly associated with this complication. About 81.9% of the cases had cornea edema upon presentation, with 31.4% of them ending up with cornea decompensation despite intervention. Although there was high intraocular pressure reported initially in 22 cases, only 2 cases required glaucoma filtration surgeries in which they had preexisting glaucoma. Numerous techniques of repositioning or surgical removal of the implant were described but they were challenging and the outcomes varied. Conclusions: A noninvasive method of manipulating the Ozurdex into the vitreous cavity via the "Trendelenburg position, external pressure with head positioning" maneuvers is safe yet achieves a favorable outcome. Precaution must be taken whenever offering Ozurdex to the high-risk eyes. Prompt repositioning or removal of the implant is crucial to deter cornea decompensation. Clinical Trial Registration number: NMRR-22-02092-S9X (from the Medical Research and Ethics Committee (MREC), Ministry of Health, Malaysia).

Mid-term safety and effectiveness of intravitreal dexamethasone implant to treat persistent cystoid macular edema in vitrectomized eyes for bacterial endophthalmitis

PURPOSE

To evaluate the mid-term safety and effectiveness of intravitreal dexamethasone implant (DEX-i) for treating unresponsive to medical therapy cystoid macular edema (CME) in vitrectomized eyes for endophthalmitis.

METHODS

Retrospective and interventional case series study conducted on vitrectomized eyes for endophthalmitis that developed a CME that did not adequately respond to medical therapy, who underwent 0.7-mg DEX-i. Main outcome measures were changes in central retinal thickness (CRT) and best corrected visual acuity (BCVA).

RESULTS

Eleven eyes were included in the study. Microbiological findings of vitreous biopsies were 7 (63.6%) staphylococcus epidermidis; 3 (27.3%) Pseudomonas aeruginosa; and 1 (9.1%) Propionibacterium acnes. Median (interquartile range, IqR) duration of CME was 4.0 (3.0-4.0) months. Median (IqR) time between vitrectomy and DEX-i was 9.0 (9.0-11.0) months. Median CRT was significantly decreased from 548.0 (412.8-572.5) µm at baseline to 308.0 (281.3-365.5) µm at month 6 (p = 0.0009, Friedman test). Median BCVA significantly improved from 38.0 (30.5-44.8) letters at baseline to 50.0 (46.8-53.0) letters at month 6 (p < 0.0001, Friedman), with 9 (81.8%) eyes gaining ≥ 10 letters. Elevation of intraocular pressure was observed in one (9.1%) eye, which was successfully controlled with medical therapy. No recurrence of endophthalmitis or other complications was observed. Eight (72.7%) eyes required an additional DEX-i, while 3 (27.3%) were successfully controlled with only one DEX-i. CME recurrence occurred in 5 (62.5%) Gram-positive and 3 (100.0%) Gram-negative bacteria (p = 0.2357).

CONCLUSION

In vitrectomized eyes for endophthalmitis affected by CME unresponsive to medical therapy, DEX-i had an acceptable safety profile and achieved favorable outcomes. The possibility of suppressing mechanisms for infection control should be taken into account, although correct management of endophthalmitis and long time without reactivation before DEX-i reduce the risk.

Pharmacokinetics of Pullulan-Dexamethasone Conjugates in Retinal Drug Delivery

The treatment of retinal diseases by intravitreal injections requires frequent administration unless drug delivery systems with long retention and controlled release are used. In this work, we focused on pullulan (≈67 kDa) conjugates of dexamethasone as therapeutic systems for intravitreal administration. The pullulan-dexamethasone conjugates self-assemble into negatively charged nanoparticles (average size 326 ± 29 nm). Intravitreal injections of pullulan and pullulan-dexamethasone were safe in mouse, rat and rabbit eyes. Fluorescently labeled pullulan particles showed prolonged retention in the vitreous and they were almost completely eliminated via aqueous humor outflow. Pullulan conjugates also distributed to the retina via Müller glial cells when tested in ex vivo retina explants and in vivo. Pharmacokinetic simulations showed that pullulan-dexamethasone conjugates may release free and active dexamethasone in the vitreous humor for over 16 days, even though a large fraction of dexamethasone may be eliminated from the eye as bound pullulan-dexamethasone. We conclude that pullulan based drug conjugates are promising intravitreal drug delivery systems as they may reduce injection frequency and deliver drugs into the retinal cells.