Pneumatic Retinopexy Technique

From EyeWiki
Original article contributed by: Sami Kamjoo, MD
All contributors: Sami Kamjoo, MD and Vinay A. Shah M.D.
Assigned editor: Vinay A. Shah M.D.
Review: Assigned status Up to Date by Vinay A. Shah M.D. on November 11, 2015.


Pneumatic Retinopexy (PR) is an effective in-office procedure that can treat many retinal detachments that meet the criteria.  The most important factor in determining the success is proper patient selection.  The article below focuses mainly on the technical aspects of the procedure.

Indications

  • Repair of RD caused by retinal breaks located in the upper 2/3 of the fundus (from 8 to 4 o'clock)
  • Breaks should be w/i 1 clock hour of eachother
  • No break in the inferior 4 clock hours
  • No PVR (grabe B or less)
  • Patients must be able to position
  • No Glaucoma

Relative Contraindications

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

  • Pseudophakia or aphakia
  • Multiple breaks
  • Detachment of 20 or more retinal quadrants
  • Lattice degeneration

Contraindications

  • Inferior breaks b/w the 4 and 8 o'clock positions
  • 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 are with a rise in altitude above 4000 feet while gas bubble is present

Success rates

Eyes grouped into High, Intermediate, and Low predicted success rates

High predicted success rate

  • normal AXL, small holes or less than 1 clock-hour HST, breaks w/i 1 clock-hour of 1 o'clock or at the horizontal meridian, detachment of only the superior quadrants, a crystalline lens or posterior chamber implant with a clear intact capsule, and clear media.

Intermediate predicated success rate

  • Long AXL, HST of 1-2 clock-hours, tears just below the horizontal meridian, detachment of one inferior quadrant, aphakia, an ACIOL or PCO, and mild-to-moderate vitreous haze

Lowest predicated success rate

  • very long AXL, large HST more than 3 clock hours apart, inferior retinal breaks, detachment of both inferior quadrants, an iris plan lens or open capsule with peripheral haze, and fixed retinal folds

Advantages of PR

  • Better postoperative vision
  • Less perioperative morbidity
  • Less discomfort than SB procedures
  • No diplopia
  • No refractive error changes
  • No SB materal related complications
  • Faster visual recovery
  • Similar overall success rate
  • Less costly (50-75% less expensive than scleral buckling)
  • No ultimate compromise of reattachment or visual return if PR fails

Perioperative evaluation & considerations

  • Pt must be cooperative and physically and mentally capable of positioning
  • Frequent f/u must be possible
  • Pt cannot fly in an airplane or ascend to greater than 4000 feet in elevation
  • Larger eyes require larger bubbles to subtend similar arcs of retinal contact
  • Recent ocular surgery mandates a paracentesis before gas introduction in order to avoid iris incarceration
  • Eyes with advanced glaucomatous optic neuropathy may not tolerate even a brief, modest elevation of IOP
  • In eyes with filtering blebs, cryopexy must be avoided in those areas
  • Media clarity is important because cataract, PCO, pseudophakia or vitreous opacities may prevent an adequate evaluation of the peripheral retina
  • Posterior breaks and those between 4 and 8 o'clock positions are difficult to close by PR.

Instrumentation & medication

  • Gloves, Betadine solution (10%)
  • Xylocaine 1%, Marcaine 0.5%, gentamycin
  • Antibiotic/steroid ointment
  • Lid speculum, conjunctival forceps, cotton-tipped applicators
  • One eye patch (to draw arrow in axis of the retinal break for positioning)
  • Twotuberculin syringes, two 27g half-inch needles
  • Gas: SF6, or C3F8
  • One Millipore filter (or can use 3)
  • Cryopexy instruments
  • Laser indirect ophthalmoscope delivery system

Gas selection

  • Gas having the shortest duration should be selected, also important to inject the smallest bubble possible
  • SF6 lasts 7-10 days and expands 2-fold
  • C3F8 has a duration of 6-8 weeks and expands 4-fold

Operative procedure

  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. Photocoagulation with/without Cryopexy
    • 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. A 10% Betadine solution should be applied full strength to the cornea and left for 3 minutes. After filling the dead space in the tubing and syringe twice, the gas should be drawn into a tuberculin syringe with a Millipore filter, leaving the exact amount to be injected in the syringe and capping it with a 27g needle.
  4. Paracentesis. A 27g needle is attached to another tuberculin syringe and the plunger is removed. Excess Betadine solution should be removed from the conjunctiva with a CTA. A limbal paracentesis is performed, using conj forceps to stabilize the eye. Approx 0.2-0.4 ml of aqueous is removed.
  5. Gas Injection. With the pt supine, the head is turned so that that pars plana injection site is uppermost. The injection should be performed in an area distant from large, elevated breaks in order to avoid subretinal 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 vesels. The needle is inserted perpendicular to the eye wall (3.5-4mm from the limbus, using needle cap to estimate the distance). With the pt supine and ideally positioned, the eye wall also should be perpendicular to the floor. The needle is inserted into the midvitreous cavity and pulled back so that 3-4mm of the needle tip remains in the eye. The indirect ophthalmoscope light may aid in visualizing the needle tip. Care must be used in eyes with bullous detachments in order to avoid the retina.
    • The gas should be injected at a moderate speed; an injection that is too rapid or too deep in the vitreous cavity forces bubbles away from the neele tip and creates fish eggs. Surgeon can "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 lrage retinal breaks until the fish eggs resolve (usually 24 hours). If the needle does not penetrate the anterior hyaloid, loculted gas in the Space of Petit will result (sausage sign).  Note that there is theoretically a risk of dispersing RPE cells by thumping on the eye, and therefore increasing risk of PVR. 
  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 pt's vision must also be checked and if it si not light perception or better, the pressure is too high and must be lowered promptly. No pt allowed to leave the office until the central retinal artery is patent and the VA is at least LP.
  7. The Steamroller Maneuver.
    Indicated if:
    • Detachment is too bullous to see the central retinal artery at the nerve head
    • The attached macula is threated by displacing SRF beneath it
    • Inferior breaks in the attached retina are threatened by displacing SRF beneath them
    • Technique: Place the pt face down and inject the gas. Over 10 min, slowly rotate the head to roll the bubble toward the larges, elevated break. If the breaks are small, the steamroller maneuver may not be effective.
  8. Cryopexy. 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 find. Make sure you have a good drawing.
  9. Inject abx subconjunctivally and a steroid/antibiotic ointment is applied topically. Pts with a h/o of glaucoma are treated with topical drugs to lower the IOP. A patch is placed over the eye after it has been determined that the pt has light perception. An arrow may be drawn on the eye patch that points to the ceiling when the pt is in the correct position.
  10. Final Discussion. The proper positoning and its importance should be discussed with the pt. Also give written instructions. A f/u appt is scheduled for the next day, and the pt is given abx eye drops for 10 days.


Operative complications and how to avoid and manage them

Anterior hyaloidal gas

  • If the needle is not inserted deeply enough or if it sis inserted too anteriorly, therefore does not penetrate the anterior hyaloid face.
  • Managed by placing the pt 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) is reinserted in the previous gas insertion site.
  • Gas bubble are aspirated from teh Space of Petit in a controlled manner. Reinjection of gas with proper needle placment may be necessary to close the break.

Subretinal gas

  • Fish eggs may enter the subretinal space because the injection site was chosen too close to the break or the gas was injected incorrectly under the retina.
  • Subretinal gas is treated by attempting to massage the gas back into the vitreous cavity through he break while the pt lies supine.
  • A small amt of subretinal gas can be resorbed and may not need positioning.

Gas in the A/C

  • Fish eggs may enter the A/C if there is litle or no lens capsule or if zonules have been torn. This usually happens in eyes with an ACIOL.
  • The gas can expand the seclude the pupil
  • This is managed by dilating the pupil to allow the bubbles to return to the vitreous compartment, and be placing the pt face down.

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, pt not positioning, etc.
  • Peripheral inferior SRF may last for weeks to months.
  • Once the macula is completely attached the pt should be seen weekly for 2 weeks, and then monthly for a total follow-up period of 3 months

(therefore: day 1, week 1, week 2, month 1, month 2, month 3 -- assuming macula attached and no complications).

Postop complications

If the retinal tear does not close or the retina does not attach, examine the following:

  • Is positioning correct?
  • Is the bubble size adequate?
  • Is there another break?
  • Is there delayed resorption of the SRF?

New breaks

  • Manage with the gas bubble already in the eye; and laser it
  • If it is located inferiorly, tx with PPV and or SB.

Single-operation success rates

  • A. 97% if phakic eye, one quadrant detached, one break
  • B. 87% if 'A' but also includes pseudophakia.
  • C. 77% if 'B' but also includes 3 or more quadrants detached
  • D. 67% if 'C' but also includes 2 or more breaks
  • E. Subtract 10-20% from the above if only focal retinopexy is used.

Additional Resources

References

  1. Vitreoretinal Surgical Techniques.  Gholam A. Peyman, 2006.