2. • Pneumatic retinopexy (PR) is an office-based, sutureless, no-incision
alternative to scleral buckling or vitrectomy for the surgical repair of
selected retinal detachments.
• Cryotherapy is applied around the retinal break(s) to form a
permanent seal. A gas bubble is injected into the vitreous cavity, and
the patient is positioned so that the bubble closes the retinal
break(s), allowing resorption of the subretinal fluid.
• As an alternative to cryotherapy, laser photocoagulation can be
applied after the intraocular gas has caused the retina to reattach.
3. • Pneumatic retinopexy is less expensive than scleral buckling because
there is no need for
• (1) a preoperative history and physical,
• (2) preoperative laboratory work,
• (3) an anesthesiologist,
• (4) operating room expenses, and
• (5) hospitalization costs.
The cost of scleral buckling with its associated expenses may be ten
times that required for pneumatic retinopexy.
4. Choice of gas
• Sulfur hexal uoride (SF6) is the gas most frequently used with
pneumatic retinopexy.
• Perfluorocarbon gases such as perfluoropropane (C3F8) are
sometimes used
• In selecting a gas, it is important to understand the longevity and
expansion characteristics of the gases.
5. • The initial expansion of SF6 and C3F8 is due to the law of partial
pressures and the solubility coefficients of the gases involved. A 100%
SF6 bubble injected into the eye contains no nitrogen or oxygen, but
these gases are dissolved in the fluid around the bubble.
• Due to the law of partial pressures, nitrogen and oxygen will diffuse
into the gas bubble. SF6 also starts to diffuse out of the gas bubble
into the surrounding fluid which contains no SF6. However, nitrogen
and oxygen diffuse across the gas–fluid interface much more quickly
than SF6 because of the relative insolubility of SF6.
• The diameter of the bubble shrinks at an approximately constant rate
until the gas is gone. C3F8 expands more and reabsorbs more slowly
because it is even less soluble than SF6.
6.
7.
8. What size gas bubble is needed?
• Computerized tomography studies on eyes with intravitreal gas
bubbles showed that a 0.3 ml gas bubble covers over 45 degrees of
arc of the retina but it takes approximately a 1.2 ml bubble to cover
80–90 degrees.
• A highly myopic eye will require a larger volume of gas than an
emmetropic eye to cover the same arc of the retina.
• Usually, 0.4 to 0.6 ml of gas is injected into the eye.
9. How long should the bubble remain in the eye?
• It is optimal for the gas bubble to cover the break(s) for five days and
then disappear as soon as possible.
• gas of choice in most cases is SF6.
• The longevity of air is probably sufficient for most cases, but
sometimes the chorioretinal adhesion may not be sufficiently mature
when the air has been reabsorbed. Air also forfeits the advantage of
postinjection expansion within the eye, necessitating an injection of a
large volume.
10. How gas works ?
• Surface tension allows the gas bubble to occlude a retinal break
instead of passing into the sub-retinal space. The surface tension of
any gas is much higher than that of other substances in the eye. Once
the break is occluded, the retinal pigment epithelial pump can
reabsorb the sub-retinal fluid.
• Buoyancy of the gas provides the force which pushes the uppermost
retina back against the wall of the eye. Apposition of the retina
against the retinal pigment epithelium is necessary in order that an
adhesion can occur, just as two surfaces to which glue has been
applied must be clamped together while the glue dries .When the gas
is gone, a permanent seal remains, preventing reopening of the tear.
11. Indications
• Single or multiple tears or dialyses spanning three clock-hour superiorly
• Retinal detachment imminently threatening the fovea
• Macular holes and other posterior retinal breaks
• Redetachment following scleral buckling
• Filtering blebs
• Isolated tears under the superior rectus
• Optic pit with macular detachment
• Extensively scarred conjunctiva
• Very thin sclera
12. Contra indications
• Breaks larger than one clock-hour or multiple breaks extending over more
than one clock-hour of the retina.
• Breaks in the inferior four clock-hours of the retina.
• Presence of proliferative vitreoretinopathy grade C or D.
• Cloudy media precluding full assessment of the retina.
• Physical disability or mental incompetence precluding maintenance of the
required positioning.
• Severe or uncontrolled glaucoma.
• Lattice degeneration
• Aphakia/pseudophakia ( due to PCO)
13. Operative technique – Summary
1. Anesthetic: retrobulbar, sub.conjunctival, 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
14. Retinopexy
• Pneumatic retinopexy is generally performed in one session with
cryopexy applied to the retinal breaks prior to gas injection. An
alternative technique involves a two-part procedure, utilizing laser
instead of cryotherapy. The first part of the procedure consists of
injection of a gas bubble into the vitreous cavity.
• The patient maintains appropriate head positioning at home, with
follow-up in the surgeon’s office. Once the break is reattached,
usually the next day, laser treatment is applied.
• The photocoagulation is greatly facilitated by use of the laser indirect
ophthalmoscope
15. TREATMENT MODALITIES
Cryotherapy v/s Photocoagulation
• 1.Location of lesion
Equatorial lesions-cryo or Photocoagulation
Postequatorial lesions-Photocoagulation
Peripheral lesions- Cryotherapy
• Clarity of media- In hazy media cryotherapy preferred.
• Pupil size- Small pupils easier to treat with cryotherapy.
16. Laser photocoagulation
200 microns spot size,duration of 0.1-0.2 seconds.
Two rows of confluent burns surrounding the lesion.
LASER used- Argon Green, Krypton Red, Diode Laser,
Nd:yag
18. Cryotherapy
PRINCIPLE
• The normal microvillous interdigitations seen between
retina and RPE are missing.
• If both the RPE and overlying retina are frozen, the
adhesion that results after reattachment demonstrates
cellular connections between the NSR and RPE consisting
of desmosome formation between retinal glia and RPE or
direct contact between retinal glia and Bruch’s membrane.
19. • Current cryotherapy instrumentation employs expansion of
high-pressure nitrous oxide at the tip of a probe generating
temperatures as low as −89°C.
• Temperature effect is confined to the tip of the probe by an
insulating sleeve.
• A probe 2.0 to 2.5 mm in diameter usually is used for retinal
work.
• Treatment of retinal breaks & pathologic conditions requires
accurate placement of the cryoprobe tip.
20.
21. • The goal is to surround all retinal breaks with 1 to 2 mm of
contiguous treatment.
• Treatment should include freezing of overlying retina,
because this results in a stronger adhesion than does
treatment of RPE alone.
• To avoid damage of refreezing, treatment should not
significantly overlap.
22. • The treatment end point is retinal whitening without ice crystal
formation.
• Cryoprobe should not be removed until it has defrosted completely
because premature removal may crack the choroid and give rise to
choroidal haemorrhage.
23. COMPLICATIONS of Cryo
• Chemosis
• Diplopia if rectus muscle is frozen.
• Vitritis if treatment is excessively heavy.
• CAUSES OF FAILURE
• Failure to surround the entire lesion
• Failure to release vitreoretinal traction
• New breaks within or adjacent to treated area due
to excessively heavy treatment.
24.
25. Cryotherapy vs LASER Retinopexy
Cryotherapy
• Use of external probe & IDO
• Can be used with moderate
media opacities
• Promotes dispersion of viable
RPE cells
• CME, wrinkling of ILM
• Increased Postoperative flare,
extensive retinal oedema,
necrosis
LASER Retinopexy
• Endolaser/ IDO with laser
• Difficult in moderate media
opacities
• Ideal for posteriorly located
breaks
26. Sterilizing the eye
• A sterile lid speculum is utilized. About six drops of undiluted
povidone-iodine solution are instilled directly onto the cornea and
conjunctiva, and left in contact with the eye for a few minutes.
• During this time the gas can be prepared. The injection site is then
dried with a sterile cotton-tipped applicator, and the eye is ready for
paracentesis and injection of gas.
27. Preparing the gas
• A pressure-reducing system is attached to the gas cylinder to allow
drawing of the gas from a low pressure reservoir.
• the gas may be drawn into a large syringe and then transferred to a
small syringe
• The selected gas is drawn through a millipore filter into a 3 ml syringe
in a sterile fashion. The tube connecting the gas cylinder with the
syringe, including the filter, is flushed through with gas to ensure no
dilution with room air.
28. • A few millilitres of gas are drawn into the syringe, discarded, and the
syringe is filled again
• A disposable 30-gauge, one-half inch (12 mm) needle is then placed
tightly on the syringe, and excess gas is expelled to leave the exact
amount intended for injection.
• The gas should not be stored in the syringe for more than a few
minutes prior to injection because room air will infiltrate the syringe
and dilute the gas sample
29.
30. Making room for the gas
• The intraocular volume must be decreased before and/or after the gas
injection to make room for the gas.
• Paracentesis (0.45ml to be removed) to be performed before the gas
injection, especially if the globe has been weakened by surgery or trauma
within the past six weeks, or if there is significant glaucomatous optic nerve
damage.
• Paracentesis before or after the injection is usually necessary, but
prolonged ocular massage, including compression from cryopexy, may be
sufficient in some cases.
31. Paracentesis
• Upto about 0.45 ml of fluid is removed
• If the posterior lens capsule is absent or open widely, paracentesis
should not be performed through the limbus to avoid incarceration of
vitreous in the limbal needle tract. With plunger in place, pass the
needle through the pars plana, then angle it through the posterior
capsular opening into the anterior chamber.
32. Ocular massage
• A scleral depressor is placed against the temporal equator, and the
eye is pressed firmly against the bony nasal orbital wall. Firm pressure
is applied for45 seconds, then relaxed for 15 seconds to allow
perfusion of the retinal vasculature.
• This cycle is repeated until the intraocular pressure is low enough.
• This maneuver causes egress of fluid from the eye, and also stretches
the scleral fibers, allowing more ample intraocular volume.
Preoperative medications for reducing the intraocular pressure do not
help much.
33. Injecting the gas
• An injection site is selected 3–4 mm posterior to the limbus. This site
should be away from large, open retinal breaks, highly detached
retina, or detached pars plana epithelium.
• The head of the supine patient is turned 45 degrees to one side to
make the injection site uppermost. The needle is then passed into the
eye perpendicular to the sclera . The needle is pushed 6–8 mm into
the eye to ensure that the tip is well into the vitreous, directing the
tip away from areas of highly bullous detachment.
34. • The needle is then withdrawn until 3 mm of it remains in the eye .This
will ensure that the tip remains in the vitreous but is shallow enough
to prevent multiple small bubbles (fish eggs)
• With the needle in the correct position, a moderately brisk injection
of the entire volume of gas is performed. This facilitates formation of
a single bubble at the needle tip
• The injection should not be so brisk as to force bubbles of gas deep
into the vitreous before their buoyancy can make them rise. Inject
smoothly and fairly quickly, but not with excessive force.
• Hold the plunger down until the needle is withdrawn to prevent
escape of gas back into the syringe.
35. • A cotton tipped applicator can be used to occlude the perforation
site. The applicator must be pressed against the shaft of the needle
and rolled immediately over the hole as the needle is withdrawn.
• The head is then rotated 90 degrees to move the gas away from the
injection site, and the applicator is removed.
36.
37. After gas injection
1. Examine the central retinal artery to ensure its patency.
• Occlusion of the central retinal artery can be safely observed for up to ten
minutes. During this time, the intraocular pressure declines and the artery
may reopen; if it does not, paracentesis or massage should be performed
immediately.
2. Is bubble mobile or trapped? –
• If the bubble is beneath the pars plana epithelium, or trapped in the space
bordered by the pars plana, the anterior hyaloid face, and the lens (the
canal of Petit), it will not move when the head is turned and will take on a
semicircular shape.
• This has been termed the “donut sign,” the “sausage sign,” or the “bagel
sign.”
38. • 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 27-
or 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
• At another site, re- inject the gas deeper into the vitreous, with 4–5
mm of the needle in the globe
39. • 3. Fish eggs are undesirable because a small gas bubble can pass
through a retinal break into the subretinal space.
• 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 it must be kept 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.
40.
41. Measures to prevent fish eggs formation
1.Make sure that the needle is shallowly 1. within the vitreous at the
time of injection.
2. Make sure that the injection site is uppermost.
3. Inject with the needle vertical.
4. Inject briskly but not extremely rapidly.
42. Steam roller technique
• 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. 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 . 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
43. • 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.
• Indications –
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.
44.
45. Post operative management
• 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.
46. • 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.
• the patient may be seen on the first postoperative day, then in three
days, one week, two weeks, one month, and so on.
47. • Frequent postoperative exams are indicated, primarily to look for new
retinal breaks or detachments. These breaks do not jeopardize the
outcome if close follow-up results in early detection and treatment.
• At least half of these can be cured with an additional office procedure
without resorting to scleral buckling.
• Inferior subretinal fluid or loculated pockets of subretinal fluid
sometimes persist for weeks or months. As long as the fluid is not
increasing and the macula is attached, reoperation is not necessary.
48. Complications
1. Sub retinal gas
2. Iatrogenic macular detachment-
This preventable complication is avoided by using the steamroller
technique as described above.
3. New retinal breaks
4.PVR
49. Sub retinal gas
• If a gas bubble does get beneath the retina, it gives the detached retina a
pearly, dome-shaped, relfective sheen.
• Attempt first to massage the bubble back toward the retinal break by
scleral depression, assisted by positioning as needed. If this fails and the
amount of subretinal gas is large, prompt surgical removal with vitrectomy
may be required.
• The smaller subretinal bubble will reabsorb before the larger vitreous
bubble and the detachment can be repaired, injecting additional gas if
needed.
50.
51. New retinal breaks
• New or missed retinal breaks following pneumatic retinopexy appear
to occur in approximately 13% of eyes.
• In the multicenter trial of pneumatic retinopexy, 96% of eyes with
new breaks were successfully reattached.
• New breaks and detachments can often be treated easily with laser or
with pneumatic techniques, without automatically resorting to scleral
buckling and/or vitrectomy.
52. PVR
• Pneumatic retinopexy does not appear to increase the incidence of
proliferative vitreoretinopathy (PVR). In the multicenter clinical trial,
PVR occurred in 5% of eyes following scleral buckling, and 3% of eyes
following pneumatic retinopexy.
53. Comparision with scleral buckling
• A multicenter, randomized, controlled clinical trial with 198 patients
compared pneumatic retinopexy with scleral buckling.
1. The main disadvantages of pneumatic retinopexy 1. are the reduced
single operation success rate with more frequent need for
retreatments, and the need for precise postoperative positioning
and close follow-up care.
2. Failure with pneumatic retinopexy does not jeopardize success with
subsequent scleral buckling, and i nal anatomic results were not signii
cantly different
54. 3. Morbidity was less, and cost was much less with pneumatic retinopexy.
4. Postoperative visual acuity appeared to be better with pneumatic
retinopexy than with scleral buckling for eyes in which the macula was
detached for less than 14 days (p = 0.05).
5. Complications were similar, based on a score system which counted the
need for postoperative laser or cryo as a complication.
6. Cataract surgery was required more often with scleral buckling than with
pneumatic retinopexy.
7. Scleral buckling is the more versatile procedure, with many detachments
not amenable to pneumatic retinopexy. For some surgeons, at least 40% of
detachments are good candidates for pneumatic retinopexy.
55.
56. Summary
• Pneumatic retinopexy is an alternative to scleral buckling or
vitrectomy for the surgical repair of selected retinal detachments.
• Pneumatic retinopexy may be appropriate to consider in selected
cases without inferior or extensive retinal breaks and without
significant proliferative vitreoretinopathy.
