Retinal breaks due to intravitreal ocriplasmin

Engineering of Ocriplasmin Variants by Bioinformatics Methods for the Reduction of Proteolytic and Autolytic Activities

BACKGROUND

Ocriplasmin has been developed for the induction of posterior vitreous detachment in patients with vitreomacular adhesion. At physiological pH, ocriplasmin is susceptible to autolytic and proteolytic degradation, limiting its activity duration. These undesirable properties of ocriplasmin can be reduced by site-directed mutagenesis, so that its enzymatic activities can be augmented. This study aimed to design ocriplasmin variants with improved biological/physicochemical characteristics via bioinformatics tools.

METHODS

This study was performed in Tabriz University of Medical Sciences, Tabriz, Iran, 2019. Through site-directed mutagenesis, three ocriplasmin variants were designed. Structural analysis was performed on the wild-type variant and the mutant variants using the Protein Interactions Calculator (PIC) server. The interactions between the S-2403 substrate and the ocriplasmin variants were studied by molecular docking simulations, and binding capability was evaluated by the calculation of free binding energy. The conformational features of protein-substrate complex systems for all the variants were evaluated using molecular dynamic simulations at 100 nanoseconds.

RESULTS

The structural analysis of ocriplasmin revealed that the substitution of threonine for alanine 59 significantly reduced proteolytic activity, while the substitution of glutamic acid for lysine 156 influenced autolytic function. The molecular docking simulation results indicated the appropriate binding of the substrate to the ocriplasmin variants with high-to-low affinities. The binding affinity of the wild-type variant for the substrate was higher than that between the mutant variants and the substrate. Simulation analyses, consisting of the root-mean-square deviation, the root-mean-square fluctuation, and the center-of-mass average distance showed a higher affinity of the substrate for the wild type than for the mutant variants.

CONCLUSION

The mutational analysis of ocriplasmin revealed that A59T and K156E mutagenesis could be used for the development of a new variant with higher therapeutic efficacy.

Clinical Features of Vitreomacular Traction Syndrome with Peripheral Vitreoretinal Adhesion

Purpose

To retrospectively review and analyze the clinical and imaging data of patients with vitreomacular traction syndrome (VMTS) with strong peripheral vitreoretinal adhesion.

Subjects and Methods

This retrospective case-series study involved 4 eyes of 4 VMTS patients with vitreoretinal adhesion in both the macular region and the periphery who underwent vitreous surgery. In all 4 cases, preoperative refraction, fundoscopic findings, optical coherence tomography (OCT) findings, and intraoperative findings were evaluated.

Results

The preoperative fundoscopy and OCT findings revealed fibrous membranes around the optic nerve head in 3 eyes. Thickened posterior vitreous membranes extending from the posterior pole to the periphery were observed in all eyes. Apparent VMTS or epimacular membrane was also found in the fellow eyes of 2 patients. The preoperative refractive errors ranged from +0.5 diopters (D) to +2.75 D (mean, +1.13 D). Intraoperatively, a thickened posterior vitreous membrane was found strongly adhered to the retina in the macula regions, optic nerve head, and periphery. In 2 eyes, when artificial posterior vitreous detachment (PVD) was created, an iatrogenic tear developed in the periphery.

Conclusion

The features of VMTS that cause strong peripheral vitreoretinal adhesion include the preoperative presence of a thickened posterior vitreous membrane over a wide area, hypermetropia, and a short axial length.

Pneumatic Vitreolysis for the Treatment of Vitreomacular Traction Syndrome

Objectives:

To evaluate the posterior vitreous release rates after a single injection of expansile gas in patients with vitreomacular traction (VMT) syndrome with or without associated full-thickness macular hole (FTMH).

Materials and Methods:

Thirteen eyes of 12 consecutive patients with VMT (11 eyes) or VMT+FTMH (2 eyes) were reviewed retrospectively. Intravitreal injection of 0.3 mL of pure sulfur hexafluoride (SF6) (9 eyes) or perfluoropropane (C3F8) (4 eyes) was performed. Bobbing the head forward and backward similar to ‘drinking bird’ head movements was instructed until VMT release. Full ophthalmic examination and optical coherence tomography was performed at each visit.

Results:

VMT was released in all patients (100%) and mean release time was 5.2 days (1-19 days). Macular hole closure was not achieved in either of the two eyes with FTMH. Mean central subfield thickness decreased significantly from 361 μm to 263 μm (p=0.007). The mean pretreatment visual acuity was 0.44 LogMAR, which significantly improved to 0.25 LogMAR at the last visit (p=0.003). One of 13 eyes had retinal tear after the procedure which was successfully treated with laser retinopexy. Gas migration to the anterior chamber occurred in one patient. No other complications were observed.

Conclusion:

Pneumatic vitreolysis with C3F8 and SF6 gases is a relatively safe, low-cost, and minimally invasive treatment modality for VMT. However, FTMH closure could not be achieved with pneumatic vitreolysis.

Pneumatic release of focal vitreomacular traction

PurposeTo study the efficacy of a single intravitreal injection of expansile gas as a valuable alternative to current treatment options (conservative, pharmacological, and surgical) in patients with symptomatic, focal vitreomacular traction (VMT).Patients and methodsThis study comprises a retrospective, interventional case series of patients. Twenty eyes in seventeen patients with symptomatic and persisting focal VMT were treated in an outpatient setting with an intravitreal gas injection of 0.2 ml. In 19 eyes, 100% hexafluoroethane (C₂F₆) was used. One eye received sulfur hexafluoride (SF₆). To all but three patients posturing advice was given. Patients were reviewed with a full-eye examination and ocular coherence tomography (OCT) after 14 days and later. The primary outcome measure was the release of VMT on OCT.ResultsIn 17 of the 20 (85.0%) treated eyes, a release of VMT was achieved as documented on OCT. The release of VMT was diagnosed during the first month after injection in 11 eyes of 11 patients and within 3 months in 16 eyes of 15 patients. In all but five of our patients, best corrected visual acuity (BCVA) remained stable or improved. In four patients, the progression or development of cataract was the probable cause of the decrease in BCVA. One patient developed a stage II macular hole after injection and needed vitrectomy. None of the treated patients developed retinal breaks.ConclusionIntravitreal expansile gas injection could offer a minimally invasive, low-cost alternative treatment in patients with symptomatic, persisting VMT. Additional studies on a larger number of patients are required.

Rhegmatogenous retinal detachment following intravitreal ocriplasmin

Purpose

To describe the characteristics and outcomes of patients presenting with rhegmatogenous retinal detachment (RRD) after ocriplasmin (OCP) injection.

Methods

Retrospective, multi-centre, observational case series with case note review.

Results

Eight patients with symptomatic vitreomacular traction (six with concomitant macular hole) were diagnosed with RRD after a median of 16 days (range 3–131 days) post-OCP injection. Presentation was within 3 weeks of the OCP injection in six of the cases. Five patients presented with symptoms post-OCP, and three were diagnosed asymptomatically on planned visits. Seven cases were phakic, one had high myopia (>8 dioptres), and two cases had lattice degeneration. Following RRD surgery, hole closure was achieved in 5/6 MH cases. The final median BCVA at 7 months was 20/80 (range 20/40–20/1200) similar to the baseline BCVA 20/80, with four patients gaining ≥1 line of vision compared to baseline but three losing ≥3 lines.

Conclusions

RRD is a non-negligible risk associated with intravitreal OCP, and it should be used with caution in eyes with high myopia and peripheral retinal pathology predisposing to RRD. Detailed peripheral retinal examination is recommended pre- and postoperatively at all visits. Patients should be advised to seek attention if symptoms recur after initial presentation.

Retinal Changes Induced by Epiretinal Tangential Forces

Two kinds of forces are active in vitreoretinal traction diseases: tangential and anterior-posterior forces. However, tangential forces are less characterized and classified in literature compared to the anterior-posterior ones. Tangential epiretinal forces are mainly due to anomalous posterior vitreous detachment (PVD), vitreoschisis, vitreopapillary adhesion (VPA), and epiretinal membranes (ERMs). Anomalous PVD plays a key role in the formation of the tangential vectorial forces on the retinal surface as consequence of gel liquefaction (synchysis) without sufficient and fast vitreous dehiscence at the vitreoretinal interface. The anomalous and persistent adherence of the posterior hyaloid to the retina can lead to vitreomacular/vitreopapillary adhesion or to a formation of avascular fibrocellular tissue (ERM) resulting from the proliferation and transdifferentiation of hyalocytes resident in the cortical vitreous remnants after vitreoschisis. The right interpretation of the forces involved in the epiretinal tangential tractions helps in a better definition of diagnosis, progression, prognosis, and surgical outcomes of vitreomacular interfaces.

Lamellar macular hole after intravitreal ocriplasmin injection

Intravitreal ocriplasmin was recently approved by the Food and Drug Administration to achieve medical vitreolysis in the setting of vitreomacular adhesion (VMA). We report a case of a 76-year-old woman who developed a lamellar macular hole following treatment with intravitreal ocriplasmin injection for VMA. A pathophysiological mechanism to explain this previously unreported complication of ocriplasmin injection is proposed.