Surgical Tamponade in the Treatment of Retinal Detachment

A review of current agents and techniques

KAMYAR VAZIRI, MD • STEPHEN G. SCHWARTZ, MD, MBA • CHRISTOPHER T. LEFFLER, MD, MPH • HARRY W. FLYNN, JR., MD

Despite continuing advances in vitreoretinal care, retinal detachment remains a major cause of worldwide visual loss. The incidence of RD varies from country to country, ranging from 6.3 to 17.9 per 100,000 population members, with a rate of approximately 12 per 100,000 in the United States.¹

The most commonly utilized management options for the treatment of RD are scleral buckling, pars plana vitrectomy, pneumatic retinopexy, and combination techniques.² Overall, these treatment options have been reported to yield a single operation success rate of greater than 90%.³

In recent years, there has been a trend toward PPV as the preferred method of treatment for RD. In the American Society of Retina Specialists (ASRS) 2014 Global Trends in Retina survey, 78% of US respondents would use PPV, while only 13% would use scleral buckling to treat pseudophakic RD without proliferative vitreoretinopathy.⁴ These numbers were 48% and 23%, respectively, for phakic RD without PVR.

When PPV is chosen for the treatment of RD, it is typically accompanied by the use of a postoperative intraocular tamponade agent.

INTRAOCULAR TAMPONADE FOR RETINAL DETACHMENT

Purpose of Intraocular Tamponade

“Tamponade” is defined as the use of a tampon, which itself is defined as “a plug or tent inserted tightly into a wound, orifice, etc., to arrest hemorrhage.”⁵ In the context of RD surgery, tamponade agents are used to provide temporary or permanent surface tension across retinal breaks, during which time previously placed retinopexy (photocoagulation or cryopexy) provides a seal.⁶

The purpose of the tamponade agent is to physically prevent fluid flow through the retinal break into the subretinal space, rather than “pushing the retina back into position,” which is how it is sometimes explained to patients. Commonly used tamponade agents include various gases and silicone oils.

Tamponade was described as early as 1970 by Cockerham and colleagues in eyes with complex RD treated with scleral buckling but no PPV: “Silicone injection has two purposes: to free adhesions between vitreous membranes and the retina and to forcibly tamponade the retina against the choroid.”⁷

In 1971, Dunn and colleagues described the use of a collagen gel intravitreal implant in animal eyes: “[Remaining in gel form] is essential if the implant is to act as a tamponade and not flow through retinal holes.”⁸

In the past, the inert expansile gas sulfur hexafluoride (SF₆) had been used in the management of pulmonary tuberculosis and pneumothorax because it lasted longer than air. In the early 1970s, Edward W.D. Norton, MD, following the suggestion of Paul Sullivan, MD, investigated the use of SF₆ as a vitreous substitute.⁹

In 1973, Dr. Norton presented his findings and proposed the use of SF₆ in the management of complex RD: “I have not intended to present SF₆ as a panacea for retinal detachment, but only as an extremely useful adjunct because it enables the retinal surgeon not only to push the coats of the eye inward against the retinal breaks with a buckle but also to push the retinal breaks outward against the irritated pigment epithelium and tamponade the hole with the gas.”⁹

Properties and Characteristics of Commonly Used Agents

The most common gas tamponades used in the US are air, SF₆, and perfluoropropane (C₃F₈) (Figure).¹⁰ In some centers, perfluoroethane (C₂F₆) is used. Air is nonexpansile, while 100% SF₆ expands approximately two times over 1-2 days, 100% C₂F₆ expands approximately three times over 1-2 days, and 100% C₃F₈ expands approximately four times over 3-4 days.¹¹

Figure. Fundus photograph, left eye, demonstrating partial gas fill in an eye following pars plana vitrectomy and gas-fluid exchange.

Typically, however, lower isoexpansile concentrations are used following PPV: these concentrations are 20% for SF₆, 16% for C₂F₆, and 14% for C₃F₈.¹² Following a complete fluid-gas exchange, gas tamponade agents resorb spontaneously from the vitreous cavity, over a period of 5-7 days for air, approximately two weeks for 20% SF₆, approximately 4-5 weeks for 16% C₂F₆, and approximately eight weeks for 14% C₃F₈.

Unlike gases, silicone oil is permanent.¹² Gases have both higher surface tension and higher buoyancy than silicone oil,¹³ so the reported tension exerted by a gas bubble is approximately 30 times greater than that of silicone oil.¹⁴

In the US, commonly used viscosities of silicone oils include 1,000 and 5,000 centistokes (cSt).¹⁵ Silicone oils have a lower specific gravity (0.97 g/mL) than vitreous (1.005-1.008 g/mL),¹⁶ and as a result, they float in the vitreous cavity.

Therefore, silicone oils provide less effective tamponade for cases with inferior retinal breaks, which has led to the investigation of heavier-than-water tamponades, including heavy silicone oils and perfluorocarbon liquids (Table).¹¹

Advantages and Disadvantages

Both gas and silicone oil have advantages and disadvantages, primarily related to the temporary nature of gas and the permanent nature of silicone oil. In addition, patients with gas tamponade are unable to travel by air until the gas is resorbed, and long-term use of silicone oil is associated with specific complications, including microemulsification, band keratopathy, and increased intraocular pressure.^{10,12,13,17-19}

EFFECTIVENESS OF VARIOUS INTRAOCULAR TAMPONADES

Silicone Oil vs Gas Tamponade

The Silicone Study^20,21 was a randomized clinical trial comparing 1,000-cSt silicone oil to 20% SF₆ or 14% C₃F₈ in patients with RD associated with PVR.²¹ The Silicone Study reported significantly better anatomic and visual outcomes with silicone oil vs SF₆ at one year, but no significant differences in anatomic or visual outcomes between silicone oil and C₃F₈.²²

A long-term follow-up report on this study found that, among the original participants who still had attached maculas at 36 months, there were no significant anatomical and visual outcome differences among silicone oil, SF₆, and C₃F₈ groups after follow-up of up to six years.^23,24

The European Vitreo-Retinal Society (EVRS) Retinal Detachment Study was a retrospective study comparing the treatment outcomes of complex RD associated with PVR, giant retinal tear, choroidal detachment, or macular hole. A subanalysis of its first report compared the PPV level 1 failure rates, defined as failed reattachment deemed inoperable by the end of the study, between gas and silicone oil tamponade among patients with PVR, and it reported no significant differences.²⁵

Other smaller studies, however, demonstrated a benefit of silicone oil over gas or vice versa for certain groups of patients. In a retrospective study comparing silicone oil vs C₃F₈ gas in the treatment of RD among 30 highly myopic eyes (mean refractive error of -15.40 D) with posterior staphyloma, it was reported that C₃F₈ was associated with significantly better initial success rates and significantly better visual outcomes.²⁶

In a retrospective series of 56 eyes with recurrent RD associated with PVR and treated with PPV and retinectomy, silicone oil tamponade yielded significantly higher success rates than gas.²⁷ (In this study, 88% of eyes underwent scleral buckle placement or revision during retinectomy, but scleral buckling did not have a significant impact on anatomic success rates.)

Air vs Other Gas Tamponades

Two recent studies have evaluated the efficacy of air vs longer-acting gas with conflicting results. In a retrospective study of 524 eyes with primary rhegmatogenous RD,²⁸ it was reported that there were no significant differences overall in the success rates of PPV with air or 20% SF₆ tamponade. In a subanalysis, however, among eyes with inferior RDs, air was associated with a lower primary success rate than gas.

In a prospective, randomized, comparative study of 64 eyes with RD associated with inferior retinal breaks, there were no significant differences between air or C₃F₈ tamponade in terms of primary or overall anatomic success rates.²⁹

Conventional Silicone Oil: 1,000 cSt vs 5,000 cSt

In a retrospective series of 325 eyes with complex RD (defined as RD associated with Cytomegalovirus retinitis, giant retinal tear, proliferative diabetic retinopathy, PVR, or trauma), there were no significant differences in anatomic success rates or visual outcomes between 1,000-cSt or 5,000-cSt silicone oil.³⁰

In another retrospective series of 82 eyes with complex RDs, however, the use of 5,000-cSt silicone oil was associated with a significantly higher rate of recurrent RD following silicone oil removal.³¹

HEAVY SILICONE OIL VS CONVENTIONAL SILICONE OIL TAMPONADE

Due to its low density and high flotation force, conventional silicone oil is relatively less effective in the treatment of inferior RD. Heavy silicone oils (HSOs) with higher specific gravities are being investigated.

Two HSOs that are currently available for clinical use in Europe, but not approved for use in the US, are Densiron 68 (a mixture of silicone oil and perfluorohexyloctane; Fluoron, Neu-Ulm, Germany) and Oxane HD (a mixture of silicone oil and partially fluorinated olefin, RMN-3; Bausch + Lomb, Toulouse, France).

The Heavy Silicone Oil Study³² was an RCT comparing Densiron 68 with conventional silicone oil (either 1,000 or 5,000 cSt per surgeon preference) among patients with inferior RD associated with PVR. The interim analysis of this study reported that, at 12 months, there were no significant differences in the anatomic success rates or visual outcomes between HSO tamponade and conventional silicone oil tamponade. (At this time, final Heavy Silicone Oil Study results have not been published.)

Another randomized, prospective, comparative study compared PPV with Densiron 68 to 1,000-cSt conventional silicone oil among 61 consecutive eyes with primary RD due to inferior breaks; no significant anatomic or functional differences between the two groups were reported.³³

To date, there have been no large RCTs evaluating the efficacy of Oxane HD. In a prospective, comparative study, PPV with Oxane HD tamponade was compared to conventional silicone oil among patients with complex inferior RDs. The results reported no significant differences in anatomic or visual outcomes.³⁴

In a small, prospective RCT involving 20 consecutive patients, PPV with conventional 1,300-cSt silicone oil combined with scleral buckling was compared to PPV with Oxane HD alone in patients with inferior RD associated with PVR. Following silicone oil removal, there were no significant differences in outcomes.³⁵

Perfluorocarbon Liquids

Perfluorocarbon liquids are a group of heavier-than-water liquids that are used intraoperatively to manipulate or flatten the retina, and they are typically removed by the end of the PPV.³⁶ Despite toxicity concerns, some studies have reported beneficial results using perfluorocarbon liquids as short- to medium-term tamponade agents in patients with inferior or complex RD.

In a retrospective series of 62 eyes with giant retinal tears, temporary use of perfluorocarbon liquids (mean of 7.5 days, then exchanged for gas or silicone oil) resulted in a final success rate of 93.5% with no serious complications associated.³⁷

In another retrospective study of 39 eyes with RD with giant retinal tears or multiple breaks in more than one retinal quadrant, perfluorocarbon liquids were retained for a median of 11 days and exchanged for gas or silicone oil.³⁸ The authors reported a 100% reattachment rate.

COMPLICATIONS OF SILICONE OIL OR GAS TAMPONADE

Silicone oil and gas tamponade use are associated with several complications. The Silicone Study reported that chronic postoperative elevated IOP and hypotony occurred in both the C₃F₈ gas and silicone oil groups, with elevated IOP significantly more common with silicone oil and hypotony significantly more common with gas.³⁹

Another Silicone Study report evaluated the corneal complications of silicone oil and gas tamponade. At 24 months, the overall proportion of corneal abnormalities was not significantly different between the silicone oil and gas tamponade groups.⁴⁰

Cataract formation is another common complication of both gas and silicone oil tamponade, with reported rates of up to 100%.⁴¹ Complications unique to silicone oil tamponade include RD associated with silicone oil removal, silicone oil microemulsification, and subconjuctival silicone oil.^11,12,42,43

CONCLUSION

The bulk of the literature suggests that the use of either gas or silicone oil tamponade contributes to favorable outcomes for the majority of patients with RD. The Silicone Study reported better outcomes with either C₃F₈ or silicone oil compared to SF₆ in patients with RD associated with PVR.

Heavy silicone oils have been investigated in Europe but are not available for routine clinical use in the US. The use of short- to medium-term tamponade with perfluorocarbon liquid can be utilized in certain patients with inferior or complex pathology.

Ultimately, the choice of tamponade agent should be individualized based on the specific configuration of the RD, the expected ability of the patient to comply with postoperative positioning requirements, and other perioperative factors. RP

REFERENCES