Prevention and control of proliferative vitreoretinopathy: primary retinal detachment surgery using silicone oil as a planned two-stage procedure in high-risk cases

Gene Therapy Activates Retinal Pigment Epithelium Cell Proliferation for Age-related Macular Degeneration in a Mouse Model

OBJECTIVE

Age-related macular degeneration (AMD) is a degenerative retinal disease. The degeneration or death of retinal pigment epithelium (RPE) cells is implicated in the pathogenesis of AMD. This study aimed to activate the proliferation of RPE cells in vivo by using an adeno-associated virus (AAV) vector encoding β-catenin to treat AMD in a mouse model.

METHODS

Mice were intravitreally injected with AAV2/8-Y733F-VMD2-β-catenin for 2 or 4 weeks, and β-catenin expression was measured using immunofluorescence staining, real-time quantitative reverse transcription polymerase chain reaction (PCR), and Western blotting. The function of β-catenin was determined using retinal flat mounts and laser-induced damage models. Finally, the safety of AAV2/8-Y733F-VMD2-β-catenin was evaluated by multiple intravitreal injections.

RESULTS

AAV2/8-Y733F-VMD2-β-catenin induced the expression of β-catenin in RPE cells. It activated the proliferation of RPE cells and increased cyclin D1 expression. It was beneficial to the recovery of laser-induced damage by activating the proliferation of RPE cells. Furthermore, it could induce apoptosis of RPE cells by increasing the expression of Trp53, Bax and caspase3 while decreasing the expression of Bcl-2.

CONCLUSION

AAV2/8-Y733F-VMD2-β-catenin increased β-catenin expression in RPE cells, activated RPE cell proliferation, and helped mice heal from laser-induced eye injury. Furthermore, it could induce the apoptosis of RPE cells. Therefore, it may be a safe approach for AMD treatment.

Montgomery and informed consent during Covid-19: Pneumatic retinopexy versus pars plana vitrectomy or scleral buckling for retinal detachment repair

Recent reports suggest that the use of an outpatient-based procedure (pneumatic retinopexy, PR) for retinal detachment repair should be encouraged within the UK, especially in light of Covid-19 and possible restrictions/competing demands on access to operating theatres. It is therefore essential that patients receive comprehensive information about the risks and benefits of this approach compared with a formal surgical repair either by pars plana vitrectomy (PPV) and/or scleral buckling (SB). We report a retrospective case series of retinal detachments (RD) satisfying the strict selection criteria for PR but who were managed with formal surgery. Single-operation success rate for PPV/SB at six months follow-up was 93.8% in our study, higher than published primary success rates for PR (60-80%). When counselling patients for possible PR, the ease, speed and potentially reduced co-morbidity of an outpatient-based procedure needs to be balanced against its significantly higher failure rate in comparison with primary PPV/SB.

Scleral buckling-a brief historical overview and current indications

The key to successful management of rhegmatogenous retinal detachment (RRD) is to find and seal all of the retinal breaks, and the two main surgical techniques used to achieve this are scleral bucking (SB) or pars plana vitrectomy (PPV). Techniques for SB have remained mostly unchanged for the last 60 years, whilst PPV techniques and instruments have developed substantially over that time and have greatly contributed to increased success rate for types and configurations of retinal detachments unsuitable or difficult to manage with buckling alone. However, there is a growing dependency to rely on PPV as the sole and only approach for repair of all types of retinal detachment, such that some centres are no longer offering training in scleral buckling. There are also many studies comparing SB with PPV, but many of these lack information on the type, technique or rationale for deployment of the buckle. Many studies deploy the same scleral buckle technique without customising it to the type, position or number of tears being treated. Scleral buckling is not a one-size-fits-all technique. It requires careful patient selection and careful buckle selection and orientation tailored to the tear(s) to ensure success. When used appropriately, it is a simple and highly effective technique, particularly for retinal dialyses, round retinal hole detachments and selected cases of retinal detachment associated with horseshoe retinal tears. There is no doubt that for some more complex cases, such as multiple large breaks, giant retinal tears, bullous detachments and cases complicated by proliferative retinopathy, PPV offers a safer and more effective management. However, SB remains an important and relevant surgical technique, and for the right cases, the results can be superior to PPV with reduced comorbidity.

Retinal pigment epithelium transplantation: concepts, challenges, and future prospects

The retinal pigment epithelium (RPE) is a single layer of cells that supports the light-sensitive photoreceptor cells that are essential for retinal function. Age-related macular degeneration (AMD) is a leading cause of visual impairment, and the primary pathogenic mechanism is thought to arise in the RPE layer. RPE cell structure and function are well understood, the cells are readily sustainable in laboratory culture and, unlike other cell types within the retina, RPE cells do not require synaptic connections to perform their role. These factors, together with the relative ease of outer retinal imaging, make RPE cells an attractive target for cell transplantation compared with other cell types in the retina or central nervous system. Seminal experiments in rats with an inherited RPE dystrophy have demonstrated that RPE transplantation can prevent photoreceptor loss and maintain visual function. This review provides an update on the progress made so far on RPE transplantation in human eyes, outlines potential sources of donor cells, and describes the technical and surgical challenges faced by the transplanting surgeon. Recent advances in the understanding of pluripotent stem cells, combined with novel surgical instrumentation, hold considerable promise, and support the concept of RPE transplantation as a regenerative strategy in AMD.

Myofibroblast and extracellular matrix origins in proliferative vitreoretinopathy

BACKGROUND

To evaluate origins of the fibrocontractive cell populations and their relation to collagens I and II in proliferative vitreoretinopathy (PVR).

METHODS

Human PVR membranes were evaluated by indirect immunofluorescence for GFAP, cytokeratin-18 (CK-18), α-smooth muscle actin (αSMA), collagens I and II. Collagen expression by porcine Müller and retinal pigment epithelial cells (RPE) was evaluated using RT-PCR of RNA harvested from freshly isolated primary and proliferating cultures.

RESULTS

Collagen I was detected in all PVR samples and was widely distributed in the extracellular matrix. In contrast, collagen II was present in only two of the ten samples and was localized to thin, acellular bands near the border of the tissues. Using cell type-specific markers CK-18 and GFAP, RPE and glia were localized to the collagen I-rich matrices. Cells positive for GFAP and CK-18 can also co-express αSMA. Normal and proliferating RPE express collagen I, but Müller cells show no evidence of collagen I expression until they proliferate in culture. In contrast, normal RPE and Müller cells contain message for collagen II which is lost shortly after introduction into culture.

CONCLUSIONS

Collagen I appears to be the predominate fibrillar collagen in human PVR membranes and collagen II a comparatively minor component. Müller cells and RPE are physically associated with the collagen I matrix and are capable of expressing this protein suggesting that they are the origin. It also appears that the majority of myofibroblasts in PVR membranes are derived from either RPE or Müller cells suggesting that they play a major role in membrane development.

[Prospective study of 34 retinal detachments associated with giant retinal tear]

PURPOSE

To report the anatomical and functional outcomes of vitrectomy with silicone oil tamponade in the treatment of retinal detachment associated with giant retinal tears due to various factors.

METHODS

We prospectively followed 34 eyes of 33 patients with giant retinal tear. That underwent vitrectomy, injection of perfluorocarbon liquids and silicone oil tamponade. Scleral buckle was associated with vitrectomy in cases of inferior giant retinal tear; 26,5 % and 11,8 %, respectively, demonstrated pseudophakia and aphakia. Seven eyes (20,5 %) had a history of trauma (blunt injuries in four and a penetrating injury in three) and, 14 eyes (41,2 %) had severe myopia. One patient developed a bilateral giant retinal tear during the follow-up.

RESULTS

Retinal attachment was obtained in 33 (97 %) of 34 eyes, with a mean follow-up of 14,5+/-6 months. Retinal detachment reoccurred in four eyes (11,6 %) under silicone oil, in one eye (2,9 %) during the silicone removal, and in two eyes (5,8 %) after silicone removal and cataract surgery. Silicone oil was removed from all eyes (4,3+/-1 months). The most frequent postoperative complication was cataract in ten of 18 phakic eyes (55,5 %). Functional success with visual acuity 0,4 or better was obtained in 18 cases (52,96 %).

CONCLUSION

Pars plana vitrectomy with silicone oil tamponade proved to be highly effective in giant retinal tears in terms of the anatomical and functional results. The analysis of recurrent retinal detachment allowed us to refine the technique and to suggest scleral buckle in one case of inferior retinal tear with laser over 360 degrees .

Heavy tamponade 1: a review of indications, use, and complications

BACKGROUND

Heavier than water intraocular tamponades have several theoretical advantages over conventional tamponades, especially in the treatment of complicated retinal detachments and proliferative viteroretinopathy of the lower fundus periphery. However, initial clinical series of various heavy tamponades have reported significant complication rates. Therefore, heavy tamponades have not found widespread acceptance. Three recently developed heavy silicone oil tamponades, Oxane HD, Densiron 68, and HWS 46-3000, are much better tolerated and presently seem to enter routine clinical practice.

MATERIALS AND METHODS

Literature review of 21 publications on the clinical application of 9 different heavy tamponades (fluorosilicone, C10F18, F6H8, OL62HV, Oxane HD, O62, F6H8-silicone oil mixture, Densiron 68, and HWS 46-3000).

RESULTS

The first generation (fluorinated silicone and perfluorocarbon liquids) and second generation (partially fluorinated alkanes) of heavy tamponades were associated with relatively high complication rates, for example, tamponade emulsification, intraocular inflammation, and rise in intraocular pressure. The complication spectrum of the new generation of heavy silicone oils (Oxane HD, Densiron 68, and HWS 46-3000) seems to be comparable to conventional silicone oil tamponades while providing better support for the inferior retina and the posterior pole.

CONCLUSION

The recently developed heavy silicone oil tamponades are safe and effective tools for the use of complicated retinal detachments of the inferior fundus.