196 II: Practice

The “steamroller” technique is now used if indicated (see “Special Procedures” below). We instill antibiotic ointment and patch the eye. The meridian of the retinal break is marked as an arrow on the patch to indicate to the patient and family the head position which is to be maintained. We have a mirror available to show the patient that the head should be positioned so that the arrow is pointing directly at the ceiling. The patient is discharged to home and seen the next day.

SPECIAL PROCEDURES

STEAMROLLER

If bullous subretinal fluid extends almost to the macula (Figure 8–7A), placement of a bubble against the bullous detachment may cause a macular detachment (Figure 8–7B). This complication can be easily avoided by using the “steamroller” technique.

Following injection of the gas bubble, the patient’s head is turned to a facedown position in such a way as to cause the bubble to traverse the attached retina en route to the macula (Figure 8–7C). Over one to five minutes, the patient’s head position is very gradually changed until the retinal break is uppermost, causing the bubble to roll toward the retinal break, pushing the subretinal fluid back into the vitreous and flattening the retina (Figure 8–7D).

Subretinal fluid will be expressed through the retinal break into the vitreous cavity at a rate depending in part on the size of the break. Since cryopexy causes liberation of pigment epithelial cells, which may cause proliferative vitreoretinopathy if they get in the vitreous cavity, it is recommended that cryopexy not be performed prior to steamrolling.

Whether steamrolling is necessary to prevent macular detachment depends on several factors:

1.How close the detachment is to the macula. Only detachments well within the arcades usually need steamrolling.

2.How bullous the detachment is.

3.How large the gas bubble is.

Possible indications for steamrolling are as follows:

1.Prevention of iatrogenic macular detachment.

2.Prevention of iatrogenic detachment of an attached retinal break.

3.Reduction of subretinal fluid to encourage more rapid resolution of retinal detachment. This might be of use in cases where all retinal breaks cannot be covered at one time by the gas bubble. Also, where large retinal breaks are present, this may minimize the chance of subretinal gas.

4.Reduction of a bullous detachment overhanging the optic nerve, preventing visualization of the central retinal artery during the procedure.

A B

C D

Figure 8–7. Steamroller maneuver for prevention of iatrogenic macular detachment: (A) Bullous retinal detachment threatening to detach a normal macula (M). (B) Gas bubble may force fluid posteriorly, causing detachment of macula. (C) To prevent iatrogenic macular detachment, the gas bubble is brought to the macula through attached retina. This frequently causes subretinal fluid to pass through the break into vitreous (blue arrow). (D) Patient’s head is slowly moved incrementally along the meridian between macula and retinal break (red arrow), ending with retinal break uppermost. Subretinal fluid is usually forced into vitreous by the steamroller effect of the bubble.

FISH EGGS

Multiple small gas bubbles (“fish eggs”—Figure 8–8) are usually due to a faulty injection technique. In probable order of importance, the following steps will usually prevent this occurrence:

1.Make sure that the needle is shallowly within the vitreous at the time of injection.

2.Make sure that the injection site is uppermost.

198 II: Practice

Figure 8–8. Multiple small intraocular gas bubbles (“fish eggs”) with increased risk of subretinal gas. (Published with permission from Hilton GF, Tornambe PE: RD Study Group. Pneumatic retinopexy: An analysis of intraoperative and postoperative complications. Retina 1991;11:285–294.)

3.Inject with the needle vertical.

4.Inject briskly but not extremely rapidly.

If fish eggs do occur, keep the patient strictly positioned to keep the bubbles away from retinal breaks. If all retinal breaks are small, this may not be necessary, but keep in mind that breaks can stretch a little. The bubbles will usually coalesce spontaneously within 24 hours, and then the patient can adopt a position with the retinal break uppermost.

Some authors recommend inducing fish eggs to coalesce by flicking the eye with a cotton-tipped applicator or gloved finger. Turn the eye so that sclera without underlying retinal breaks is uppermost, and flick this site moderately firmly.

If there is one large bubble with just a few smaller bubbles, usually the above measures are not necessary, but caution is called for in the presence of large tears.

GAS ENTRAPMENT AT THE INJECTION SITE

Following gas injection, if the gas bubble remains trapped at the injection site, it is probably trapped in the canal of Petit. If the trapped bubble is small, no treatment is necessary.

Unless there is an immediate threat of the macula detaching, the problem can usually be solved by face-down positioning for 24 hours. This will encourage the trapped anterior gas bubble to break through the anterior hyaloid face by its own buoyancy, aided by its expansion.

If necessary, a large trapped bubble can be removed by passing a 27or 25-gauge needle back through the injection site. This needle is mounted on a syringe with a

small amount of sterile saline, with the plunger removed. The injection site is positioned uppermost and the needle is passed vertically into the bubble. Sometimes it takes a little manipulating to break the surface tension of the bubble and get it to escape. Most of the gas will escape, bubbling up through the fluid in the syringe. At another site, reinject the gas deeper into the vitreous, with 4–5 mm of the needle in the globe.

SUMMARY OF PROCEDURE

The following constitutes a typical order of events:

1.Anesthetic: retrobulbar, subconjunctival, or topical

2.Cryopexy: if one-part procedure, in lieu of laser

3.Sterilization of ocular surface: Betadine solution

4.Paracentesis: limbal, or via pars plana if capsule is open

5.Intravitreal gas injection: 0.4–0.6 ml of SF6

6.Check for patency of central retinal artery, and perform paracentesis and/or massage if needed

7.Special procedures: for example, steamroller if needed

8.Antibiotic and patch: draw arrow

9.Laser: when retina is reattached, in lieu of cryopexy as two-part procedure

POSTOPERATIVE MANAGEMENT

Acetaminophen (Tylenol) may be helpful for postoperative pain control. We recommend a considerable restriction in activity initially, liberalizing day by day as the retina reattaches, the chorioretinal scar matures, and finally the gas bubble reabsorbs. The patient is allowed to return to work two weeks after the procedure, and should be advised not to fly until the bubble is quite small.

If all retinal breaks are closed, the subretinal fluid usually reabsorbs within 24–48 hours. If the fluid is not reabsorbing, a new or missed break exists, the bubble is too small, or the patient has not been positioning properly.

Ensuring proper patient positioning requires considerable effort. It is helpful to explain to the patient why positioning is important, and to demonstrate the position which allows the bubble to close the breaks. The neck strain of an oblique head position can be eased by explaining that sitting with the head tilted 45 degrees to the left is the same as lying on a couch with the head tilted 45 degrees to the right.

Patient positioning is maintained during waking hours for five days; however, three or four days may be adequate. The patient should not sleep face-up, to avoid gas–lens contact in the phakic eye, or ciliary-block glaucoma in the aphakic eye.

Depending on the response to treatment, the patient may be seen on the first postoperative day, then in three days, one week, two weeks, one month, and so