The Management of Subretinal Gas Following Attempted Pneumatic Retinal Reattachment H. RICHARD McDONALD, MD,* GARY W. ABRAMS, MD,t ALEXANDER R. IRVINE, MD,* JACK 0. SIPPERLEY, MD, BLAINE S. BOYDEN, MD,* JOHN V. FIORE, Jr., MD, HERNANDO ZEGARRA, MD~

Abstract: Pneumatic retinopexy is a recently described procedure for treating retinal detachments with cryotherapy and intraocular gas injection, rather than scleral buckling. Prospective studies are underway to assess its safety and efficacy. One potential complication of this technique is persistent detachment due to subretinal gas. We report seven cases of subretinal gas following at­tempted pneumatic retinal reattachment. In all cases, multiple fish-egg gas bub­bles were present following injection; some of these bubbles gained access to the subretinal space during the early postoperative period. The subretinal gas gave the detached retina a pearly, dome-shaped, refractive sheen. Three cases were managed by positioning the patients' heads to allow the subretinal gas to pass through the retinal break back into the vitreous cavity. One case un­derwent successful scleral buckling that closed the retinal break despite the presence of a small subretinal gas bubble. Three cases required vitrectomy, air-fluid exchange, and cryotherapy or endolaser treatment. In five of the seven eyes the retina was eventually reattached successfully. [Key words: intraocular gas injection, intravitreal gas, pneumatic retinal reattachment, pneumatic retin­opexy, retinal detachment, scleral buckle, subretinal gas, vitrectomy.] Oph­thalmology 94:319-326, 1987

Over the last 15 years, Lincoff, Norton, and others have shown the value of expansile, intravitreal gases in the treatment of retinal detachment. 1-

10 In 1986, Hilton and Grizzard presented a prospective study of 20 patients with retinal detachment who were treated with intravitreal gas injection and cryotherapy. 11 They injected 0.3 cc of per­fluoropropane (C3F8) gas or 0.6 cc of sulfur hexafluoride

From the Departments of Ophthalmology, University of California,* San Francisco, and Medical College of Wisconsin, t Milwaukee, and the Cleve­land Clinic Foundation,:j: Cleveland.

Presented at the Ninety-first Annual Meeting of the American Academy of Ophthalmology, New Orleans, Louisiana, November 9-13, 1986.

Reprint requests to H. Richard McDonald, MD, 390 Laurel Street, San Francisco, CA 94118.

(SF6) gas. This technique resulted in an initial reattach­ment in 100% of their cases. Two eyes subsequently re­detached: one redetachment was caused by a new retinal break, and the other by proliferative vitreoretinopathy. This study noted no complications, though it mentioned the possibility that patients might develop cataract, glau­coma, vitreous inflammation, or endophthalmitis. A sim­ilar pneumatic retinal reattachment procedure, described by Dominquez, has also had impressive results, without significant complications. 12

In an addendum to their study, Hilton and Grizzard noted reports of subretinal gas following attempted pneu­matic retinal reattachment. 13 This report on the manage­ment of subretinal gas comprises those reports and other cases of subretinal gas arising as a complication of the pneumatic retinopexy technique.

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CASE REPORTS

Case 1. This 37-year-old phakic myope presented with a mac­ula-off retinal detachment extending from 10 to 5 o'clock in the left eye. There was a 1h-clock-hour horseshoe tear just pos­terior to the equator in the I o'clock meridian.

The patient received 0.3 cc of 100%C3F8 gas through the pars plana at the 2 o'clock meridian. The 30-gauge needle was inserted into the mid vitreous, then retracted so that the needle was barely passing through the pars plana. The injection was rapid and resulted in two large and three small intravitreal gas bubbles.

Reexamination of the patient 36 hours after injection revealed that he had a persistent retinal detachment. The retina appeared drawn toward the lens and had a glistening, pearly, refractile sheen, indicative ofsubretinal gas. The retina was dragged toward the subretinal gas, which could be moved by changing the pa­tient's head position. The number ofsubretinal gas bubbles could not be determined, but a computed tomography (CT) scan re­vealed three bubbles. Two large gas bubbles were still present in the vitreous.

The patient underwent posterior vitrectomy, scleral buckle, air-fluid exchange, and endophotocoagulation. During the air­fluid exchange, the tapered extrusion needle was placed through the retinal tear, and most of the subretinal gas was removed. After a complete exchange was accomplished, examination of the eye revealed a small persistent, subretinal bubble. With a cotton swab this bubble was manipulated to the retinal tear, where further mechanical extrusion was used to remove the sub­retinal gas bubble.

Postoperatively the patient has had a flat retina, and five months following surgery, the vision was 20/70.

Case 2. This 33-year-old phakic myope presented with a mac­ula-off retinal detachment extending from II to 3 o'clock in the left eye. A one-clock-hour tear extended from 12:30 o'clock to 1:30 o'clock, posterior to the equator.

The patient received a 0.6 cc injection of 100% SF6 gas through the clock-hour meridian pars plana. The needle tip was passed just through the pars plana epithelium. The injection was given in a deliberate steady push. At the end of the injection there were multiple bubbles in the vitreous but none under the retina.

Three hours later the patient was diagnosed as having sub­retinal gas with a profound dragging at the retina anteriorly to­ward the lens. The patient was taken to the operating room the following morning for vitrectomy, air-fluid exchange, and cryo­therapy. During air-fluid exchange the tapered 24-gauge extru­sion needle was passed through the retinal break, and the ma­jority of the subretinal gas was removed. Scleral depression was used to nudge the residual subretinal gas bubbles to the edge of the break, where they were mechanically extruded. Following this procedure a small subretinal bubble that did not interfere with the retinal break was remaining, and it was left beneath the retina. Cryotherapy was placed around the hole and a gas bubble left in the vitreous cavity; no scleral buckle was placed.

The retina remained flat postoperatively, and the visual acuity improved to 20/20 3 months following surgery.

Case 3. This 66-year-old phakic emmetrope presented with a macula-off retinal detachment extending from 8 to 12 o'clock in the right eye. There was a 112-clock-hour horseshoe tear just anterior to the equator in the 10 o'clock meridian.

The patient received a 0.4 cc injection of 100% C3F8 gas through the pars plana in the 8 o'clock position. The tip of the needle was viewed with indirect ophthalmoscopy and the injec­tion was given rapidly. At the end of the injection there were many small bubbles in the vitreous, but none under the retina.

Reexamination of the patient 24 hours later showed that she had a persistent retinal detachment. The intravitreal bubble seemed of adequate size and covered the retinal break, but the subretinal fluid persisted. No subretinal gas was recognized at this time. The patient underwent a scleral buckling procedure five days after the original injection. The hole was closed with a segmental sponge. At the time of surgery the intravitreal air bubble was aspirated with a 27-gauge needle. It was only at that time that the subretinal gas was detected. A small bubble at the inferior edge ofthe tear seemed to hold the edge ofthe tear open. The sponge closed the tear and the gas was pushed away from its edge. The treating physician decided to leave the sub­retinal gas.

Postoperatively, the retina flattened without complication, and the subretinal gas resorbed in one week. Three months post­operatively, the retina was flat and the vision was 20/50.

Case 4. This 60-year-old phakic emmetrope was seen with a macula-off retinal detachment extending from 3 to 9 o'clock in the right eye. There was a one-clock-hour, post equatorial, horseshoe tear extending from 12 to I o'clock.

He received a 0.5-cc injection of 100% C3F8 gas through the inferior pars plana. Multiple bubbles rose superiorly and pressed the retinal tear against the adjacent pigment epithelium of the eye. Twenty-four hours later, a persistent retinal detachment was noted secondary to subretinal gas. The patient was taken to surgery and underwent a posterior vitrectomy, scleral buckling procedure, cryotherapy, and air-fluid exchange. The extrusion needle was placed through the retinal break, and the subretinal gas was removed during the exchange.

Postoperatively, the retina has been flat , and two months fol­lowing surgery the patient's vision was 20/60.

Case 5. This 67-year-old female pseudophake presented with a macula-on retinal detachment extending from II to 2 o'clock in the right eye. A V4-clock-hour horseshoe tear was noted in the 12 o'clock meridian, anterior to the equator.

The patient received 0.3 cc of 100% C3F8 gas through the pars plana in the 4 o'clock meridian. Multiple fish-egg bubbles were noted at the end of the injection. Twenty-four hours later the patient was found to have a persistent retinal detachment. Mul­tiple bubbles were still present in the vitreous compartment; no subretinal bubbles were recognized. Seventy-two hours after the injection, the diagnosis of subretinal gas was made.

The patient was admitted for surgery. At the time of the op­eration, no subretinal gas was noted. The surgeon felt that the gas must have passed through the retinal break into the vitreous cavity. The patient underwent a scleral buckling procedure after the intravitreal gas had been removed. This procedure resulted in retinal reattachment. However, the patient developed prolif­erative vitreoretinopathy, and the retina redetached. Subsequent attempts at reattachment failed; the patient's vision has remained at the hand motion level.

Case 6. This 65-year-old-phakic emmetrope presented with a macula-on retinal detachment extending from 9:30 to 12:30 o'clock in the left eye. There was a 3/4-clock-hour horseshoe tear posterior to the equator in the II o'clock meridian, and a smaller flap tear posterior to the equator in the 12 o'clock meridian.

The patient received 0.4 cc of 100% C3F8 gas through the pars plana in the 7:30 o'clock meridian. After the injection there were five small bubbles in the intravitreal space and none under the retina.

Twenty-four hours later the retinal detachment persisted. In the upright position the retina appeared to be dragged superiorly above the ora serrata. A small, glistening, dome-like structure was seen beneath the retina, and the diagnosis of subretinal gas was made. The patient was placed in the supine position with the head slightly elevated. The surgeon then saw the gas bubble

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Table 1. Retinal Detachment Characteristics

Case Age No. (years) Lens

1 37 p p2 33 p3 66 p4 60 pp5 67 p6 65

7 68 A

P = phakic; A = aphakic; PP

Refractile No. Status Breaks

Myope 1 Myope 1 Emmetrope 1 Emmetrope 1

1 Emmetrope 2

= pseudophakic; AEQ =

Location Meridian

PEQ 1:00 PEQ 1:00 AEQ 10:00 PEQ 12:30 AEO 12:00 PEQ 11:00,

12:00 AEQ 1:00

anterior to equator; PEQ =

Retinal Detachment Size

(clock hrs.) Size Macula Visual Acuity

1/2 10:00-5:00 Off 6/200 1 11:00-3:00 Off 20/200

1/2 8:00-12:00 Off 20/200 1 3:00-9:00 Off Hand Motions

1/4 11:00-2:00 On 20/60 3/4 9:30-12:30 On 20/400 1/2 1/2 10:00-2:00 Off Hand motions

posterior to equator.

squeeze itself through the II o'clock retinal break, "like a baby's head during delivery." There was no enlargement of the retinal tear. Later that day, the retina was completely flat.

The retina redetached two weeks later. No new retinal breaks were found, but there was subretinal fluid collecting inferiorly, extending toward the original 11 o'clock tear. A repeat C3F8 gas injection and cryotherapy were performed after the patient de­clined a more definitive surgical procedure. Repetition of pro­cedure failed to reattach the retina, except in the superotemporal area of the originally observed retinal breaks. The patient has refused any further treatment. Vision remains at the hand motion level.

Case 7. This 68-year-old aphake presented with a one-month history of floaters and visual field loss caused by a macula-off retinal detachment extending from 10 to 2 o'clock in the right eye. There was a 1h-clock-hour break in the 1 o'clock meridian.

The patient received a 0.25 cc injection of 100% SF6 gas through the limbus. Twenty-four hours later, a persistent retinal detachment was noted. Two small subretinal gas bubbles were present. The subretinal bubbles were maneuvered towards the retinal break into the vitreous by head positioning. The multiple bubbles were coallesced by snapping a cotton swab on the globe in a spring-like fashion.

The patient was then positioned so that the intravitreal air closed the retinal break. The subretinal fluid disappeared within 24 hours. The retina has remained flat postoperatively, and the vision has improved to 20/20.

DISCUSSION

We report seven cases ofsubretinal gas following pneu­matic retinopexy (Tables 1 and 2). The patients ranged in age from 33 to 68 years. Five eyes were phakic, one was aphakic, and one was pseudophakic. All retinal breaks extended one clock hour or less, and the macula was off in all but two. Only one detachment was associated with more than one retinal break (case 6). Four detachments were created by retinal breaks located posterior to the equator, while three were created by breaks anterior to the equator. Six breaks were at least 1/z clock hour in size; one break was less than 1h clock hour in size.

Injections were given through the temporal pars plana using a 30-gauge needle. At the end of each injection the

eye was examined with indirect ophthalmoscopy. In all cases, multiple bubbles were present in the vitreous cavity. In no patient was subretinal gas noted immediately after injection.

In most cases, the number of subretinal bubbles could only be guessed at, but in at least one eye multiple sub­retinal gas bubbles were confirmed by orbital CT scan (Fig 1 ). The amount of subretinal gas was estimated as small in three eyes, moderate in two eyes, and large in two eyes.

Three surgeons evacuated the subretinal gas by means of head positioning, allowing the subretinal gas to exit through the retinal break and into the vitreous cavity. Of these three, two performed no further surgery other than repositioning the patient to tamponade the retinal break.

One surgeon performed a conventional scleral buckling procedure and succeeded in closing the retinal break de­spite the presence of a small subretinal gas bubble (Case 3, Fig 2). The final three cases were managed with vitrec­tomy, air-fluid exchange, and cryotherapy/endolaser photocoagulation, with or without scleral buckling. All three cases resulted in retinal reattachment. Subretinal gas was extruded mechanically during the air-fluid ex­change.

The diagnosis ofsubretinal gas depends on the amount of gas beneath the retina. If there is a moderate to large amount, the retina will be bullously detached, with the retina dragged toward the position of the gas (Fig 3). The character and location of the retinal detachment will change with changes in the patient's head position. In the supine position, the retina may be pulled upward to the lens. In the upright position, the retina will be draped above the ora serrata in the 12 o'clock meridian. The retina will give off a glistening, refractile, pearly opales­cence, the result of reflecting light off the subretinal gas bubble. 11 The highest point of the detachment may have a smooth, dome-like appearance. However, ifthe amount of subretinal gas is small, the diagnosis may be difficult, especially when viewed through the larger, intravitreal bubble. In one of our cases (case three), subretinal gas was not appreciated as the etiology of the persistent retinal detachment until the larger intravitreal gas was removed and the retinal break mounted on a scleral buckle. Though

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Table 2. Management of Subretinal Gas

Diagnosis of Subretinal Gas

Final Result Case Post No. Injection Amount Removal Retina Visual Acuity Comment

36 Moderate PPV, SB, AFX, L Attached 20/70 Swab used to force residual subretinal gas to break site after AFX, then extruded

2 3 Large PPV,AFX, C Attached 20/20 Residual air nudged to break site with scleral depressor, then extruded

3 120 Small SB, C Attached 20/50 Subretinal gas noted at time of reoperation. Sponge used to close break; small gas bubble left under retina

4 24 Moderate PPV, SB, AFX, C Attached 20/60 All subretinal gas extruded during AFX

5 72 Small Positioning Detached Hand motion Subretinal gas noted post-op, but not present at time of reoperation; presumably delivered into vitreous; developed PVR (redetached)

6 24 Large Positioning Detached Hand motion Subretinal gas seen exiting ,. !(::

through break during head positioning; patient

.~" y:,­ redetached, refused ··i ·<"f

further surgery

7 < 24 Small Positioning Attached 20/20 Positioning resulted in exit of subretinal gas; swab snap

~ ' : formed one bubble in vitreous; patient repositioned; retina flat within 24 hours

PPV = pars plana vitrectomy; SB = scleral buckle; L = endolaser photocoagulation; AFX = air-fluid exchange; C = cryotherapy.

the presence of a persistent retinal detachment following of the subretinal gas was expelled through the drainage pneumatic retinopexy may indicate an unsuspected, in­ site, following an intravitreal injection of gas. adequately treated, or new retinal break, the possibility In our cases, the gas reached the subretinal space of subretinal gas must be considered. through a retinal break. Subretinal gas was not appreciated

Lincoff et al recently presented a case of subretinal air immediately following injection. However, following in­following a scleral buckling procedure. 13 Xenon gas was jection, multiple intravitreal bubbles were present. One injected through the limbus and behind an iris-supported or more of these bubbles passed through the break some­intraocular lens, following buckle placement, cryopexy, time during the early postoperative period. The compli­and subretinal fluid drainage. This procedure was per­ cation of subretinal gas appears to be directly related to formed to restore intraocular pressure and flatten radial the presence of multiple small gas bubbles in the vitreous folds. The air, however, was seen bubbling from the orig­ following injection. inal subretinal fluid drainage site. It was felt that the bubble We do not believe that subretinal gas will complicate had been denied access to the vitreous cavity by a trans­ the pneumatic retinal reattachment procedure ifonly one parent membrane posterior to the iris-supported lens. This large gas bubble is present and the retinal break is one membrane was thought to have diverted the gas behind clock-hour or less in size. As pointed out by Hilton and the iris, to the ciliary body, where it dissected layers of Grizzard, creation of one large bubble may be achieved ciliary epithelium and entered the subretinal space. Most by the following techniques 13

: (1) inject through the pars

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McDONALD et al • SUBRETINAL GAS

Fig 1. Computed tomography scan 48 hours after intraocular gas injec­tion. Note two large intravitreal bubbles (arrow), and three small sub­retinal bubbles (arrow).

Fig 2. Scleral buckling has successfully closed the retinal break despite the presence of a small subretinal gas bubble (arrow).

plana so that the injection site is uppermost in the eye, that is, the needle is 90° to the floor (Fig 4); (2) place the needle tip in the anterior vitreous, just through the pars plana epithelium (Fig 5); and (3) inject in one rapid push.

Nevertheless, these techniques do not insure a single, large bubble. If multiple bubbles are present, a flexible cotton swab can be bent and released against the sclera over the location of the bubbles. This recoil technique sounds a dull thump as the cotton tip snaps against the eye, often resulting in a single, large gas bubble. The pos­sibility of subluxed lenses, dislocated intraocular lenses, or hyphema secondary to displaced intraocular lenses must be considered as potential complications of this technique. We consider the presence ofa single gas bubble

Fig 3. The subretinal gas bubbles give the retina a refractile sheen, and drag (arrow) the retina towards the lens, when the patient is examined in the supine position.

Fig 4. The injection should be given with the patient's head turned to the side, so the needle is perpendicular to the floor. This guarantees that the needle tip enters the uppermost part of the eye.

of paramount importance in avoiding subretinal gas, and we recommend that no patient leave the supine position until a single bubble has been produced.

In cases where positioning allows the subretinal gas bubble(s) to pass back through the retinal break into the vitreous cavity, the hole must presumably be large enough to accommodate the bubble(s). It is not known how much larger than the break the bubble can be and still pass into the vitreous. There would seem to be an advantage in diagnosing subretinal gas early, before the expansile gas has reached its largest volume. Whether one large bubble would pass back through a retinal break earlier than mul­tiple smaller bubbles is unknown; we have seen both types ofbubbles pass back through a retinal break. Even a small

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OPHTHALMOLOGY • APRIL 1987 • VOLUME 94 • NUMBER 4

Fig 5. The needle tip should be located in the anterior vitreous, just through the pars plana epithelium. Note injected gas forming one bubble.

solitary subretinal bubble can result in persistent detach­ment if it prevents closure of the retinal break (case 3).

Three cases were managed with posterior vitrectomy and gas-fluid exchange. In one of these cases, the retina flattened following gas-fluid exchange, when the extrusion needle was passed through the retinal break to extrude the gas. In the other two cases, this technique removed most of the subretinal gas but a small amount remained. This residual subretinal gas was manipulated with an ex­ternal probe and moved to the site of the break, where it was removed with the extrusion needle (Fig 6). In one of these cases, a small amount of residual gas was left beneath the retina and resorbed without complication.

Management of subretinal gas should start with posi­tioning the patient's head in an attempt to allow the sub­retinal gas to pass into the vitreous space. Ifmultiple bub­bles are recognized beneath the retina, and positioning has failed to deliver the bubble, an attempt might be made to form one subretinal bubble using the swab snap tech­nique. It should be noted that this abrupt snap over the area of the bubbles should follow a retrobulbar anesthetic injection, or the patient will be caused significant discom­fort. If the subretinal bubble does exit through the retinal break, another snap would be advisable to join the original intravitreal bubble with the newly added intravitreal bub­ble. Then the surgeon could choose to re-treat the break with cryopexy, to position the patient to flatten the break and later perform laser treatment of the tear, or to proceed with a conventional scleral buckling procedure. We would recommend simply positioning the patient to allow break closure by the large bubble, as performed in case 7.

Fig 6. After a total posterior vitrectomy and complete air fluid exchange, subretinal gas may still be present. The subretinal gas bubble may be manipulated toward the retinal break site and mechanically extruded (arrow).

If the subretinal gas cannot be delivered by head po­sitioning, surgery will be required. If the subretinal bubble is small, or can be positioned away from the break, a scleral buckle may be placed to close the break. If this occurs, either with or without drainage, the small subret­inal gas bubble can be left alone. Early postoperative po­sitioning might be advisable in cases like this, to allow the cryo treatment surrounding the retinal break to take effect.

Vitrectomy for the purpose of subretinal gas removal presents special hazards. The retina is often pulled toward the lens, above the ora serrata (Fig 7 A). Insertion of the vitrectomy instruments can result in large retinal tears and pars plana incarceration. However, the intravitreal and subretinal gas bubbles can be manipulated to avoid these complications. Specifically, the eye can be positioned to allow the intravitreal gas to rise to the area of planned infusion/instrument insertion (Fig 7B, C). Then the in­strument can be inserted through the intravitreal bubble and can easily be visualized to ensure that it is located safely away from the retina (Fig 7D). Once the instruments are in position, the intravitreal gas can be removed, and a posterior vitrectomy can be performed. Care must be taken to insure infusion arrest when the vitrectomy in­struments are removed from the eye, as the retina will still be bullously detached and dragged above the ora ser­rata, and retinal incarceration may result.

Following vitrectomy, a complete air-fluid exchange can be performed using an automated air pump and an extrusion needle. Since most breaks in these cases are near the equator, and large enough to accommodate a tapered

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McDONALD et al • SUBRETINAL GAS

Fig 7. A, at the time of surgery, with the patient in the supine position, the subretinal gas drags the retina anterior to the ora serrata (arrow). B, the

eye is manipulated to position the intravitreal gas bubble in the area of planned infusion port insertion. Note intravitreal and subretinal gas bubbles

(arrow). C, the eye can then be rotated to move the intravitreal gas bubble to the desired site of instrument insertion (arrow). D, surgeon's view: the

lightpipe can be seen within the intravitreal gas bubble (arrow), safely away from the dragged retina (arrow).

24-gauge extrusion needle, an attempt can be made to should be positioned to allow the bubble to escape through the retinal break. If the bubble fails to escape, scleral

internally drain subretinal gas and fluid. The gas is lodged buckling, with or without drainage, can be considered,

anteriorly beneath the retina, and it may be difficult to reach it with the extrusion needle. In our series, this tech­ particularly if the amount of subretinal gas is small. For

nique resulted in a total removal of subretinal gas in one large amounts of subretinal gas, vitrectomy and air-fluid

case and removal of the majority of gas in two others. exchange may be required.

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