Use of Heavy Silicon Oil as Intraocular Tamponade for Inferior Retinal Detachment Complicated by Proliferative Vitreoretinopathy: A Multicentric Experience

INTRODUCTION

This is a multicentric study on the use of heavy silicon oil (HSO) as an intraocular tamponade for inferior retinal detachment (RD) complicated by proliferative vitreoretinopathy (PVR).

METHODS

139 eyes treated for RD with PVR were included in the study. 10 (7.2%) were affected by primary RD with inferior PVR, while 129 (92.8%) were affected by recurrent RD with inferior PVR. 102 eyes (73.9%) had received a silicon oil (SO) tamponade in a previous intervention prior to receiving HSO. Mean follow-up was 36.5 (standard deviation = 32.3) months.

RESULTS

The median interval between HSO injection and removal was 4 months (interquartile range: 3). At the time of HSO removal, the retina was attached in 120 eyes (87.6%), whereas in 17 eyes (12.4%), it had re-detached while the HSO was in situ. 32 eyes (23.2%) showed recurrent RD. A subsequent RD relapse was observed in 14.2% of cases with no RD at the time of HSO removal, and in 88.2% if an RD was present at the time of HSO removal. Advancing age showed a positive association with retinal attachment at the end of follow-up, while the risk of RD relapse at the end of the follow-up showed a significant negative association with HSO tamponade duration and with the use of SO rather than air or gas as post-HSO tamponade materials. Mean best corrected visual acuity was 1.1 logarithm of minimum angle of resolution at all follow-up time points. 56 cases (40.3%) needed treatment for elevated intraocular pressure (IOP), with which no clinically relevant variables were associated during follow-up.

CONCLUSION

HSO represents a safe and effective tamponade in cases of inferior RD with PVR. The presence of RD at the time of HSO removal is a negative prognostic factor for the development of a subsequent RD relapse. According to our findings, in cases of RD at the time of HSO removal, a short-term tamponade should definitely be avoided, in favor of SO. Special attention must be paid to the risk of IOP elevation, and patients should be closely monitored.

Retinoic acid-loaded alginate microspheres as a slow release drug delivery carrier for intravitreal treatment

Pharmacotherapy were the mainstream methods for the treatment of proliferative vitreoretinopathy (PVR), one of the leading causes of blindness. Due to the negligible side-effects, retinoic acid (RA) was considered to be a promising candidate drug. However, it was still a challenge to deliver drugs into vitreous with both long-term efficiency and biosafety. Sodium alginate was considered to be an excellent drug carrier owing to its controlled size, good biocompatibility and degradability. Based on a one-time synthetic strategy of preparing RA-sodium alginate microspheres, the study was aimed to establish a non-toxic and effective RA slow release platform. The prepared microspheres were smoothly round and relatively homogenous with an average diameter of 95.7±9.6μm. RA release rate from RA-MS was assessed in vitro by UV spectrometry and in vivo by high performance liquid chromatography, achieving a steady, long-term and effective level of RA. The biocompatibility of RA-MS was further confirmed through histology using HE staining and fundus microscope, finding no inflammation and other toxic response. Collectively, it could be concluded that RA-MS possessed a great potential in retinal PVR treatment.

Towards an ideal biomaterial for vitreous replacement: Historical overview and future trends

Removal of the natural vitreous body from the eye and its substitution with a tamponade agent may be necessary in cases of complicated retinal detachment. Many materials have been variously proposed and tested over the years in an attempt to find an ideal vitreous substitute. This review highlights the evolution of research in the field of vitreous replacement and chronicles the main advances that have been made in such a context. The suitability and limitations of vitreous tamponade agents and substitutes in current clinical use are examined, and the future promise of experimentally tested biomaterials are described and discussed. Future trends in research are also considered and, specifically, the great potential of polymeric hydrogels is emphasized, as they seem to be very effective in closely mimicking the features of the natural vitreous and they could successfully act as long-term vitreous substitutes without inducing clinical complications in the patient's eye.

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.

Clinical Research. Further evidence for proinflammatory nature of perfluorohexyloctane in the eye

BACKGROUND

The authors present a clinicopathological report of their initial experience with perfluorohexyloctane (F6H8), a novel semifluorinated liquid fluorocarbon developed as a long-term vitreous substitute.

METHODS

A retrospective observational review was performed of five patients in whom F6H8 had been used for management of rhegmatogenous retinal detachment. Surgical specimens taken from two patients at the time of F6H8 removal were also submitted for histopathological, immunohistochemical and electron microscopic analysis.

RESULTS

Clinical and histological analysis of the present small case series confirmed the propensity of F6H8 to emulsify, and suggested a probable biological reaction to F6H8. Surrounding and engulfing the F6H8 were numerous cells morphologically in keeping with macrophages. Immuno-histochemistry confirmed macrophage phenotype but electron microscopic evaluation showed epithelial ultra-structural features. It is suggested that the finding of macrophagic phenotype in cells with epithelial ultra-structure provides further evidence for a continuum of phenotypic differentiation of the pigment epithelial cells as part of the repair and regeneration that is the proliferative vitreo-retinopathy (PVR) response.

CONCLUSIONS

The data do not indicate any benefit of F6H8 over other perfluorocarbons for use in short-term post-operative intraocular tamponade. Although early experience suggests that F6H8 use in primary vitrectomy with minimal PVR is acceptable and produces temporary inflammatory effects only, these cases can often be successfully managed by conventional scleral buckling techniques, or vitrectomy with standard tamponading agents, without the need for F6H8 and subsequent extra surgical procedures. Furthermore in eyes already predisposed to inflammation through prior surgery and/or presence of PVR, the inflammatory effects were not insignificant. The use of F6H8 is not recommended in the clinical setting, except as part of a controlled trial subject to the approval of an ethics committee and informed consent.

Perfluorinated blood substitutes and artificial oxygen carriers

Blood transfusion is a remarkably safe, routine clinical procedure. However, the need for sophisticated blood processing, storage and cross-matching, coupled with increasing concerns about the safety of blood products, has fuelled the search for safe and efficacious substitutes. Candidate materials based on modified haemoglobin (including recombinant molecules) or highly inert, respiratory gas-dissolving perfluorinated liquids (perfluorochemicals) have been developed. The latter are immiscible in aqueous systems and must, therefore, be injected as emulsions. Second-generation perfluorochemical emulsions are available and in clinical trials as temporary intravascular oxygen carriers during surgery, thereby reducing patient exposure to donor blood. One commercial product is currently under Phase III clinical evaluation, with regulatory approval expected within 1 2 years. Other biomedical applications for perfluorochemicals and their emulsions include their use as pump-priming fluids for cardiopulmonary bypass, lung ventilation fluids, anti-cancer agents, organ perfusates and cell culture media supplements, diagnostic imaging agents and ophthalmologic tools. Novel applications for perfluorochemicals as immunomodulating agents are also being explored.