Results of silicone oil injection into the vitreous

Electroretinograms recorded with skin electrodes in silicone oil-filled eyes

Purpose

To assess the physiology of the retina by electroretinography (ERG) with skin electrodes in eyes that had undergone vitrectomy with silicone oil (SO) tamponade.

Design

Retrospective case series.

Method

ERGs were recorded from eleven eyes with complex vitreoretinal disorders and from the normal fellow eyes. The affected eyes underwent pars plana vitrectomy (PPV) with SO tamponade. ERGs were recorded before and after the SO was removed. The amplitudes and implicit times of the a- and b-waves of the affected eyes were compared to those of the normal fellow eyes. In addition, the ratios of the amplitudes of the b-waves of the affected eyes to those of the fellow eyes were compared before and after the SO was removed.

Results

ERGs were recordable from 7 eyes (63.6%) before the SO was removed and 11 eyes (100%) after the SO was removed. The a- and b-wave amplitudes were significantly smaller in the affected eyes than those of the fellow eyes at the baseline. The b-wave amplitude before the removal of the SO was significantly and positively correlated with that after the SO removal. The ratios of the b-waves of the affected/normal fellow eye significantly increased after the SO was removed.

Conclusion

The results indicate that ERGs picked up by skin electrode can be used to assess the physiology of the retina in eyes with a SO tamponade. The amplitude of the b-waves of the ERGs in silicone-filled eyes can be used to predict the amplitude after the silicone is removed.

Glaucoma management after vitreoretinal surgeries

PURPOSE OF REVIEW

The surgical management of retinal disorders, including scleral buckling procedures, pars plana vitrectomy, and intravitreal injections of gas or silicone oil, can lead to short-term elevations in intraocular pressure (IOP) and ultimately long-term glaucomatous damage if not treated in a timely manner. Glaucoma in these cases is commonly refractory to conventional therapies. This review highlights the treatment strategies for glaucoma in eyes that have previously undergone vitreoretinal surgery.

RECENT FINDINGS

Although medical therapy is often used initially to control a temporary rise in IOP, laser and surgical therapy may be required to treat sustained IOP elevation and subsequent glaucomatous damage in eyes that have undergone intraocular surgery for retinal disorders. Glaucoma drainage devices are an important treatment modality, particularly when there is high risk of failure with filtering surgery.

SUMMARY

Previous vitreoretinal surgery is a known risk factor for the development of glaucoma. Treatment is usually initiated with medical therapy, however, surgical intervention is frequently required to control IOP and prevent progressive glaucomatous damage in patients with refractory glaucoma.

Vitreous Substitutes

Modern vitreoretinal surgery is a young science. While tremendous developments have occurred in instrument design and technique since Machemer first described vitrectomy surgery in 1973[1], the application of advanced materials concepts to the development of intra-ocular compounds is a particularly exciting area of research. To date, the development of vitreous substitutes has played a significant role in enabling the dramatic and progressive improvement in surgical outcome, but perhaps no other area of research has the potential to further improve the treatment of retinal detachment and other retinal disorders. While prior research has focused solely upon the ability of a compound to re-attach the retina, future research should seek to enable the surgeon to inhibit the development of proliferative vitreoretinopathy and re-detachment, the integration of stem-cell therapies with surgical retina, long-term delivery of medications to the posterior segment, and the promotion of more rapid and complete visual rehabilitation.

Management of glaucoma after retinal detachment surgery

Secondary glaucoma may complicate retinal detachment surgery. Intraocular pressure (IOP) elevation has been described after scleral buckling procedures and vitrectomy with intravitreal injection of gas or silicone oil. Angle-closure glaucoma after scleral buckling develops because of congestion and anterior rotation of the ciliary body. Medical therapy and laser iridoplasty are usually successful in controlling IOP, but the presence of conjunctival scarring and recession and retinal hardware after scleral buckling procedures can make surgical management challenging. Intravitreal injection of expansile gases like sulfur hexafluoride (SF6) and perfluoropropene (C3F8) may produce secondary angle-closure glaucoma with or without pupillary block. Aspiration of a portion of the intraocular gas may be needed, especially if IOP is elevated to a level that may compromise ocular perfusion. Glaucoma also can develop after intravitreal injection of silicone oil secondary to pupillary block, inflammation, synechial angle closure, rubeosis iridis, or migration of emulsified or nonemulsified silicone oil into the anterior chamber. A prophylactic inferior iridectomy at the time of surgery serves to prevent pupillary block. Patients with medically uncontrolled glaucoma after silicone oil injection may require oil removal with or without concurrent glaucoma surgery.

Incidence and management of glaucoma after intravitreal silicone oil injection for complicated retinal detachments

BACKGROUND

Intravitreal silicone oil injection used for managing complicated retinal detachments can be associated with elevated intraocular pressure (IOP). This study was undertaken to determine the incidence of glaucoma in patients who underwent silicone oil injection, as well as to evaluate the effectiveness of medical and surgical therapy in patients in whom glaucoma developed.

METHODS

The postoperative courses of 50 eyes of 47 consecutive patients who underwent pars plana vitrectomy and silicone oil injection for the management of complicated retinal detachments were reviewed retrospectively. The outcomes of patients who underwent silicone oil removal and/or glaucoma surgery also were evaluated.

RESULTS

The mean overall postoperative IOP before any glaucoma surgery was 16.7 +/- 9.3 mmHg (range, 0 to 45 mmHg), with a mean follow-up of 16.6 +/- 12.1 months (range, 2 to 51 months). Twenty-four (48%) eyes had postoperative IOPs of at least 25 mmHg and IOP elevations of at least 10 mmHg above the preoperative levels. Twenty-one (42%) eyes underwent complete removal of silicone oil and/or glaucoma surgery to effect IOP control. The IOPs were controlled to 21 mmHg or less (but > 5 mmHg) in 8 of 14 eyes that underwent removal of silicone oil alone, in 3 of 5 eyes that underwent Molteno implantation, and in 1 eye that underwent Nd:YAG transscleral cyclophotocoagulation, but not in 1 eye that underwent a modified Schocket procedure (mean follow-up, 13.5 +/- 11.0 months; range, 0.2 to 33 months).

CONCLUSION

Intraocular pressure elevation is a common occurrence after intravitreal silicone oil injection. The underlying mechanism may often be multifactorial in nature. Patients in whom uncontrolled IOP develops may benefit from aggressive medical and/or surgical treatment with silicone oil removal, glaucoma implants, or cyclodestructive procedures.

Silicone oil in the aphakic eye: the influence of a six o'clock peripheral iridectomy

Complications after six months, in a series of 44 aphakic eyes treated by vitrectomy and fluid/silicone-oil exchange with six o'clock (Ando) peripheral iridectomy, are reported. Comparisons are made with the complications after six months in a similar series treated prior to the introduction of the six o'clock iridectomy. It is concluded that a patent six o'clock iridectomy is effective in reducing the complications of intraocular silicone oil in the aphakic eye.

The question of ocular tolerance to intravitreal liquid silicone. A long-term analysis

The authors report a retrospective review of 407 eyes that received intravitreal liquid silicone between 1961 and 1984. Initial anatomical success was noted in 270 eyes (66.3%), while initial functional success was achieved in 103 eyes (25.3%). Ten years postoperatively, approximately half of the eyes with initial functional success still had functional vision (49.2%). These eyes had less advanced proliferative vitreoretinopathy and fewer inferior breaks than others. Recurrent retinal detachment rather than late complications was the predominant cause of functional failure in those eyes losing functional vision in less than ten years postoperatively. Late complications were common and frequently required therapeutic intervention. Intravitreal liquid silicone was of great benefit to many monocular patients, but of little benefit to the binocular patients in our series.

One-step extracapsular cataract extraction and silicone oil-injection in the management of proliferative vitreoretinopathy

A combined technique of extracapsular cataract extraction and silicone oil injection is described. The anterior capsule is preserved to prevent movement of the silicone oil from the vitreous cavity to the anterior chamber. An anterior chamber tap ensures that the vitreous cavity is completely filled with silicone oil, while a peripheral iridectomy prevents postoperative pupillary block glaucoma.

Silicone oil and its influence on electrophysiologic findings

Twenty patients with complicated retinal detachments who were treated with scleral buckling procedures, vitrectomy, and temporary silicone oil filling underwent electrophysiologic tests before and after silicone oil removal. Electroretinographic responses were markedly low or even absent as long as the silicone oil was in the eye but a few days after silicone oil removal the electroretinographic amplitudes had increased in all 20 patients and did not change significantly thereafter. In 12 patients the basic level of the electrooculogram was low as long as the oil was in the eye but was at least twice the previous value in seven patients after oil removal. A light peak of more than 150% occurred in two patients before oil removal and in six after oil removal.