Pneumatic Retinopexy Technique

From EyeWiki


Pneumatic Retinopexy (PR) is an effective in-office procedure that can be used to treat retinal detachments.  While scleral buckling and pars plana vitrectomy are other management options for retinal detachments, PR offers several potential advantages; it is less invasive, can be performed in-office, avoids post-operative refractive shift or strabismus, and is associated with a faster recovery. The most important factor in optimizing a successful outcome is proper patient selection.  The article below focuses mainly on the technical aspects of the procedure. Note that these are general guidelines, but that others have reported success in situations beyond these listed. For example, the randomized study by Hillier, et al. included patients with breaks within attached retina in the inferior quadrant and still had good success rates; the appropriateness of every case should be determined by the individual patient and his/her surgeon.

Indications

  • Retinal breaks located in the superior 2/3 of the fundus (from 8 to 4 o'clock)
  • Breaks within 1 clock hour of each other
  • No break in the inferior 4 clock hours
  • No PVR grade B or worse
  • Patients must be able to position
  • No glaucoma history

Relative Contraindications

(i.e., the following can lower the success rates)

  • Pseudophakia or aphakia
  • Multiple breaks
  • Detachment of 2 or more retinal quadrants
  • Lattice degeneration

Contraindications

  • Inferior breaks b/w the 4 and 8 o'clock positions, especially if associated with detached retina
  • Inability to find the retinal break(s)
  • Cloudy media
  • Poor patient cooperation
  • Limited experience with indirect ophthalmoscopy
  • Excessive vitreoretinal adhesions
  • Inability of the pt to position self postoperatively for 3-5 days
  • Inability to follow the pt closely during the first two postop weeks
  • Inability of the surgeon to manage potential retinal complications
  • Necessity for the pt to fly or visit an area with a rise in altitude above 2,500 feet while gas bubble is present

Instrumentation & medication

  • Gloves
  • Betadine solution (5% and 10%)
  • Xylocaine 1%/Marcaine 0.5%
  • Antibiotic/steroid ointment
  • Lid speculum
  • Conjunctival forceps
  • Cotton-tipped applicators
  • Two tuberculin syringes with two 27g 1/2-inch needles
  • Gas: SF6, or C3F8 typically used
  • Millipore filter
  • Cryopexy/laser machine

Gas selection

  • The shortest-acting gas that is thought to be adequate should be chosen. SF6 or C3F8 are the most common intraocular gases utilized in the United States; remember that these are generally used in their pure (100% concentration) form in PR whereas they are diluted when used in vitrectomy sugery.
  • Pure SF6 lasts approximately 2 weeks and expands 2-fold within two days
  • Pure C3F8 lasts approximately 6-8 weeks and expands 4-fold within four days

Operative procedure

Again, it is important to note many variations in procedural approach, none of which are necessary superior to others. The author's method is shared below.

  1. Set-up. Pt in supine position. Topical anesthesia, followed by subconjunctival anesthesia (lidocaine 2%) is applied over the area of the pars plana at the gas injection and cryopexy site.
  2. Pre-treatment photocoagulation with/without cryopexy (not done by all retina specialists):
    • Photocoagulation. Apply photocoagulation to areas of attached retina with and without pathology (consider 360 laser, especially in pseudophakes and patients with multiple tears, as this indicates abnormal vitreoretinal interface). Low-intensity photocoagulation should be applied b/w the ora serrata and the insertion of the vitreous base (equator) in all quadrants of attached retina. Laser should not be applied to detached retina, no matter how shallow; nor should it be placed w/i 1 clock hour of detached retina
    • Cryopexy. Apply cryopexy to the elevated retinal pathology. However, if the breaks are highly elevated avoid cryopexy initially.
  3. Fill syringe with gas. Gas should be drawn into a tuberculin syringe with a Millipore filter attached, then wasted and repeated once again. Gas should be expressed until the exact amount to be injected remains (typically 0.3-0.6 cc); attach the 27g needle.
  4. Paracentesis. A 27g needle is attached to another tuberculin syringe and the plunger is removed. Clean the external periocular surface and eyelashes with 10% Betadine solution and then place the speculum in the eye. 5% Betadine should be applied to the ocular surface. A limbal paracentesis is performed, using conjunctival forceps to stabilize the eye if necessary; approximately 0.2-0.4 ml of aqueous is removed.
  5. Gas injection. With the patient supine, the head is turned so that that pars plana injection site is at the highest point. The injection should be performed in an area distant from large, elevated breaks in order to avoid subretinal entry of gas. The safest injection site is just above or below the 3 or 9 o'clock position, to avoid the long posterior ciliary nerves or vessels. The needle is inserted perpendicular to the eye wall (3.5-4mm from the limbus depending on lens status). The needle is inserted into the midvitreous cavity, and the gas should be injected at a moderate speed while slowly withdrawing the needle; an injection that is too rapid or too deep in the vitreous cavity forces bubbles away from the needle tip and creates "fish eggs". Surgeon can gently "thump" the eye with a CTA to cause coalescence of the gas. Should fish eggs persist, it is prudent to position the pt with the gas away from the large retinal breaks until the fish eggs resolve (usually 24 hours). If the needle does not penetrate the anterior hyaloid, loculated gas in the Space of Petit may result (sausage sign). 
  6. Check location of the bubble. If the bubble moves, it is in the vitreous cavity, if not, it is in the Space of Petit.
    • The patency of the central retinal artery must be evaluated. If the artery is not pulsatile after 10 min, perform another paracentesis or remove some gas. The patient's vision must also be confirmed to be light perception or better; if it is not, the intraocular pressure must be lowered promptly.
  7. The steamroller maneuver. Some perform for all patients such that the patient is positioned face-down immediately following the injection of gas. However, others only will utilize in certain circumstances. The technique is to position the patient so that his or her face is parallel with the floor. The head is then slowly rotated upwards in a direction such that the bubble is steadily "rolled" towards the break. This maneuver is thought to propel the subretinal fluid out of the subretinal space.
  8. Consider antibiotic/steroid prophylaxis. Some surgeons inject an antiobiotic/steroid combination; others may apply this topically as per routine retina surgery.
  9. Post-treatment laser retinopexy or cryotherapy. If the breaks are not highly elevated, cryopexy may be applied or may be deferred for 1-2 days until the breaks flatten. Alternatively, laser retinopexy may be applied in 1 or 2 days when the retina is flat. Once the breaks flatten, they may be difficult to locate, so make sure you have noted them in detail prior to PR.
  10. Post-treatment follow-up. Patient counseling regarding proper positioning is critical, and should be reviewed in verbal and written instructions. The first follow-up visit should occur on the first day following PR; this will allow cryotherapy or laser photocoagulation to possibly be applied, and for the correct placement of gas and normal intraocular pressure to be confirmed.

Procedure-related complications and how to avoid and manage them

Complications related to elevated intraocular pressure (IOP) can be managed with additional anterior chamber paracentesis or topical/systemic IOP-lowering drops. If the retina fails to re-attach, this can be managed by repeating the PR procedure or be proceeding to retinal surgery (e.g., scleral buckle or pars plana vitrectomy). Endophthalmitis is always a risk , albeit low in this type of procedure, and standard of care should be followed if this were to occur. PR-specific complications will be discussed below.

Anterior hyaloidal gas

  • Can occur if the needle is not inserted deeply enough or if it is inserted too anteriorly.
  • Manage by placing the patient face down for 24-48 hours. As the gas expands, it usually will break through the anterior hyaloid.
  • If above fails in 24-48 hours, a 27g needle on a plungerless 3-cc syringe (with 1cc of sterile water so that the gas externalization process can be better-visualized) is reinserted in the previous gas insertion site. Gas bubbles are aspirated from the Space of Petit in a controlled manner. Reinjection of gas with proper needle placement may be necessary to close the break.

Subretinal gas

  • Can occur because the injection site chosen was too close to the break, the gas was injected incorrectly under the retina, or the gas was injected in "fish egg" form (smaller bubbles are more easily mobilized into the subretinal space).
  • Manage by attempting to position the patient so that the gas is able to work its way back into the vitreous cavity.
    • A small amount of subretinal gas can be resorbed and may not need positioning.

Gas in the anterior chamber

  • Fish eggs may enter the A/C if there is missing lens capsule or zonular compromise. This often happens in eyes with an anterior chamber intraocular lens.
  • As the gas can expand the seclude the pupil, this observation must be managed by dilating the pupil and positioning the patient face-down to allow the gas to return to the vitreous cavity.

Follow-up examinations

  • Pt is examined daily until the macula is attached; if the retina is not attached on POD#1 or 2, suspect that something is wrong - e.g., new break, missed break, small gas size, patient not positioning, etc. The exception to this rule is with peripheral inferior subretinal fluid which may persist for weeks to months (but should still trend in a decreasing amount)
  • Once the macula is completely attached, the patient can be seen weekly for 2 weeks, and then monthly for a total follow-up period of 3 months.

References

  1. Vitreoretinal Surgical Techniques.  Gholam A. Peyman, 2006.
  2. Hillier RJ, Felfeli T, Berger AR, et al. The Pneumatic Retinopexy versus Vitrectomy for the Management of Primary Rhegmatogenous Retinal Detachment Outcomes Randomized Trial (PIVOT). Ophthalmology. 2019 Apr;126(4):531-9.