Management of Large Subretinal Gas Bubble After Pneumatic Retinopexy With Head-Positioning Maneuver

Abstract

Purpose:

This work reports on the management of a large subretinal gas bubble after pneumatic retinopexy.

Methods:

A case report is discussed.

Results:

We report a case of subretinal gas after pneumatic retinopexy for rhegmatogenous retinal detachment that was managed with a series of head-positioning maneuvers to allow the subretinal gas to migrate into the vitreous cavity through the retinal break. Despite the subretinal bubbles being larger than the retinal break, this approach eliminated the subretinal gas and averted surgical intervention.

Conclusions:

Subretinal gas after pneumatic retinopexy can be successfully managed by head-positioning maneuvers in some cases, even if the subretinal gas bubble is larger than the retinal break.

Introduction

Subretinal gas is a known complication of pneumatic retinopexy to repair rhegmatogenous retinal detachment (RRD). Risk factors for this complication include a larger retinal break and the presence of multiple “fish-egg” bubbles. ^{1 -3} Subretinal gas can be managed with vitrectomy, scleral buckle, or head positioning with or without scleral depression. We present a case with fundus photographic documentation of subretinal gas management by head-positioning maneuvers that allowed the large subretinal gas bubbles to pass through the smaller retinal break and into the vitreous cavity.

Methods

Case Report

A 57-year-old man was referred for subretinal gas after undergoing pneumatic retinopexy to repair a macula-on RRD with a superior retinal tear and 2 smaller adjacent tears in his left eye (Figure 1). During the pneumatic retinopexy, a total of 0.5 mL of pure perfluoropropane (C₃F₈) gas had been injected into the vitreous cavity in the following fashion. A paracentesis had been made and 0.3 mL of aqueous had been removed. The patient had been put in the Trendelenburg position and pure C₃F₈ gas (0.35 mL) had been injected through the pars plana at the 6 o’clock position. Another 0.2 mL of aqueous had been removed. Additional pure C₃F₈ gas (0.15 mL) had been injected in the same manner. Examination immediately after the gas injection had shown 1 large bubble with several fish-egg bubbles, and the patient had been instructed to position face down overnight. The next day, laser retinopexy to the superior tears had been performed; mild, fresh vitreous hemorrhage and subretinal gas had been noted; and the patient was immediately referred to Massachusetts Eye and Ear.

Figure 1.

(A) Wide-field preprocedural fundus photograph of the left eye shows a superior macula-on rhegmatogenous retinal detachment with a large superior retinal break. Smaller adjacent breaks are outlined with faint, gray dotted lines. (B) Widefield preprocedural fundus autofluorescence shows hypoautofluorescence in the area of retinal detachment with the large retinal break more clearly highlighted.

Best-corrected visual acuity in the affected eye on presentation that same day was counting fingers, and intraocular pressure was 17 mm Hg. The eye was phakic and fundus examination showed moderately dense vitreous hemorrhage, as well as superior breaks that were surrounded by laser and covered by a large superior preretinal gas bubble with a small adjacent preretinal gas bubble located superotemporally. In addition, a large subretinal gas bubble temporal to the superior break and a smaller subretinal gas bubble more posteriorly were present. Subretinal fluid extended from 8:00 to 10:30 and from 1:00 to 4:30 clock positions and posteriorly to the temporal edge of the macula (Figures 2A and 3A). The diameter of the larger subretinal gas bubble was slightly more than twice the largest dimension of the main retinal break based on measurements from fundus imaging.

Figure 2.

(A) Widefield fundus photograph of the left eye at presentation (after pneumatic retinopexy) shows laser surrounding the main retinal break (the break is outlined with a faint dotted ellipse), 2 preretinal gas bubbles, and 2 subretinal gas bubbles (outlined with faint dotted circles). (B) Widefield fundus photograph after head-positioning maneuvers demonstrates a total of 5 preretinal gas bubbles and no subretinal gas. (C) Widefield fundus photograph 2 days after head-positioning maneuvers shows 1 large coalesced preretinal gas bubble with attached retina. (D) Widefield fundus photograph 6 weeks after head-positioning maneuvers demonstrates attached retina with the gas almost completely dissipated.

Figure 3.

Schematic showing the sequence of head-positioning maneuvers. (A) When the patient is upright, a corresponding fundus diagram shows 2 preretinal gas bubbles and 2 subretinal gas bubbles. (B) The patient’s head is tilted to the left, and the fundus diagram shows the larger subretinal gas bubble moving toward the retinal break and forming 2 bubbles, the smaller of which is at the break. (C) The patient’s head is tilted more to the left, and the fundus diagram shows an additional preretinal gas bubble. The remaining larger subretinal gas bubble is now at the break. (D) The fundus diagram in (C) showing the anterior-posterior cross section. (E) The patient’s head is tilted back, and a 3-dimensional diagram of the cross section in (D) shows the migration of a subretinal gas bubble into the vitreous cavity. (F) The patient is once again upright at the conclusion of the maneuver, and the fundus diagram shows 5 preretinal gas bubbles and no remaining subretinal gas.

The vitreous hemorrhage precluded a clear view of the fovea and optical coherence tomography could not be obtained because of the media opacity. Owing to concern that apposition of the edge of the retinal break to the underlying retinal pigment epithelium would be prevented by the still-expanding subretinal gas bubbles, the decision was made to attempt the following head-positioning maneuvers.

The patient’s head was tilted slowly to the left to allow the superior preretinal gas bubble to move nasally and the superotemporal subretinal gas to move superiorly toward the retinal break. Fundus examination in this position showed that the larger subretinal bubble had pinched off into 2 smaller bubbles, one of which was at the break and the other at the temporal edge of the break (Figure 3B). The patient’s head was then tilted even more to the left. Another fundus examination showed an additional small preretinal bubble and the remaining subretinal gas bubble at the retinal break (Figure 3, C and D). At this point, the patient’s head was slowly tilted back to allow the subretinal bubble to migrate into the vitreous cavity (Figure 3E). Another fundus examination with the patient upright showed a total of 5 preretinal gas bubbles and no subretinal gas bubbles (Figures 2B and 3F). The patient was instructed to remain upright. Two days later, the retina was attached and 1 large preretinal gas bubble was noted with no subretinal gas bubbles (Figure 2C).

Supplemental laser retinopexy was performed to reinforce the edges of the breaks 1 week later. Six weeks after the head-positioning maneuver, the retina remained fully attached with the vitreous hemorrhage resolved, a tiny remaining preretinal bubble, and best-corrected visual acuity of 20/20-2 (Figure 2D). The retina remained attached at most recent follow-up, 6 months after the procedure.

Results

We have presented a case with fundus photographic documentation of subretinal gas after pneumatic retinopexy for RRD that was managed successfully with a series of head-positioning maneuvers. Subretinal gas may lead to failure of the procedure if the bubble prevents apposition of the edges of the retinal break to the underlying retinal pigment epithelium.

In 1987, McDonald et al reported a case series of eyes with subretinal gas after attempted pneumatic retinopexy for RRD. ³ In all cases, multiple gas bubbles were visualized in the vitreous cavity immediately after gas injection, similar to the present case. Of the 6 cases in that study, 3 underwent vitrectomy with or without scleral buckle, and the subretinal gas was successfully removed during fluid-air exchange. The other 3 underwent head-positioning maneuvers, which were initially successful. One subsequently underwent scleral buckle, but the retina ultimately redetached because of proliferative vitreoretinopathy; later attempts to reattach the retina failed. Another underwent a second pneumatic retinopexy with cryotherapy for redetachment that also ultimately failed, and the patient refused further treatment. Only 1 case was reported to be successful, but the duration of follow-up was not mentioned. In our case, modern widefield fundus imaging technology allowed for photographic documentation immediately before and after the maneuver.

Our patient presented 1 day after pneumatic retinopexy when the subretinal gas bubble was still in the expansion phase. Even though the larger subretinal gas bubble was larger than the largest retinal break, the bubble pinched off to form 2 smaller bubbles during the maneuver, which allowed the gas to pass through the retinal break and enter the vitreous cavity. Scleral depression can also be performed to “milk” the subretinal gas bubble through the retinal break, whether the break is positioned superiorly ¹ or inferiorly, ² but it was not necessary to perform scleral depression in this case. It is unknown how much larger the subretinal gas bubble can be relative to the retinal break and still pass through, but if the subretinal bubble is too large to pass through with attempted head positioning, then vitrectomy would be needed.

Conclusions

One of the strategies to prevent the occurrence of subretinal gas after pneumatic retinopexy includes brisk, steady injection of gas at the highest point of the globe, injecting perpendicularly toward the floor into the growing gas bubble with the tip of the needle protruding just slightly into the vitreous cavity. ⁴ If the needle tip is too deep or the injection is given too slowly, formation of multiple fish-egg bubbles is more likely. Softening the globe prior to gas injection with scleral depression and/or anterior chamber paracentesis can be performed to avoid fish-egg bubble formation. Furthermore, it is important to exercise caution when large retinal breaks are present, although subretinal gas can still occur even if retinal breaks are small. In fact, in one of the cases by McDonald the length of the retinal break was only one-quarter clock hour. ³ Even if the aforementioned steps are followed, multiple fish-egg bubbles may still form. In that scenario, flicking the globe with a cotton-tipped applicator to coalesce the bubbles can be attempted. ² Positioning the retinal break away from the gas for the first 24 hours while the bubbles coalesce is also recommended. ^2,3

This case highlights the concept and sequence of head-positioning maneuvers for subretinal gas management after pneumatic retinopexy, even when the subretinal gas is larger than the retinal break. When the maneuver is successful, surgery can be avoided.