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Surgical Techniques to Remove Subretinal Perfluoro-n-Octane

An examination of benefits and risks

By: RAZIYEH MAHMOUDZADEH, MD, SAMIR N. PATEL, MD, Carl D. Regillo, MD, FACS, DONALD J. D'AMICO, AJAY E. KURIYAN, MD, MS
New Retinal Physician November 1, 2021 Vol Retinal Physician 18, Issue November/December 2021 Page(s): 16, 17

Perfluorocarbon liquids (PFCL) have high specific gravity and optical clarity, which permit intraoperative retinal tissue manipulation. Perfluoro-n-octane (PFO; C8F18; Perfluoron, Alcon) has the most visible interface among other types of PFCL, which helps to have the best intraoperative removal rate.1 Generally, PFCLs have a postoperative subretinal retention rate of 0.9% to 11.1%, with a lower rate for PFO being in the 1% to 3.5% range.2,3 Risk factors for subretinal retention are large retinotomy of 120 degrees or more and failure to perform a saline rinse after fluid-air exchange.2

WHY REMOVAL IS VITAL

Pastor et al. showed that PFO has a toxic effect on the human retinal pigment epithelial (RPE) cells (ARPE-19).4 Elsing et al. also showed that histopathologic analysis of five eyes with retained PFO after vitreoretinal surgery for retinal detachment revealed an inflammatory response.5 This inflammatory response consisted mainly of macrophages with intracellular vacuoles containing PFO. However, removal of the PFO in all five eyes resulted in the resolution of the inflammatory response.5 Given the toxic effect of PFO on RPE and loss of retinal functions, subfoveal or sub-juxtafoveal PFO is often removed.6 However, sub-extramacular or subperipheral retina PFO does not result in a negative functional or anatomical outcome, and may be safely left alone2 (Figure 1).


FIGURE 1: Subperipheral macula PFO which was managed by observation only.IMAGE COURTESY OF CARL REGILLO, MD.
FIGURE 1: Subperipheral macula PFO which was managed by observation only. IMAGE COURTESY OF CARL REGILLO, MD.

REMOVAL TECHNIQUES 

Direct aspiration. Several techniques have been described to remove the submacular PFO. One common approach is direct aspiration using a small gauge (36-gauge or smaller ) that is passed through the retina into the subfoveal space. The aspiration can be performed manually or via the extrusion line to enable foot pedal control.7-10 However, this method can damage the RPE and photoreceptors, and cause vision-threatening complications, such as choroidal neovascular membrane, macular hole, or submacular hemorrhage.11

Removal through slit. To minimize these risks, another method utilizes a 25-gauge microvitreoretinal (MVR) blade to create a small full-thickness slit above the PFO bubble, followed by the use of a soft-tip cannula to massage the subretinal PFO through the slit and displace it from the subretinal space.12

Transretinal aspiration. Another technique eliminates the need for any entry through the retina, but instead utilizes a 23- or 25-gauge silicone-tip cannula placed right above the retina overlying the subretinal PFO to aspirate the PFO transretinally with passive or active aspiration13 (Figure 2).

FIGURE 2: The submacular PFO was aspirated transretinally using a softtip cannula. Before surgery (A) vs. postsurgery (B). IMAGE COURTESY OF CARL REGILLO, MD.
FIGURE 2: The submacular PFO was aspirated transretinally using a softtip cannula. Before surgery (A) vs. postsurgery (B). IMAGE COURTESY OF CARL REGILLO, MD.

Displacement. Another technique that attempts to minimize the potential risks of direct aspiration of the PFO involves displacing the subfoveal PFO to a more peripheral location prior to removal. In this approach, a temporary therapeutic retinal detachment is created by injecting balanced saline solution into the subretinal space using a small-gauge cannula (36-gauge or smaller) in the peripheral macula.14 This detachment should involve the entire macula (or beyond) to allow the sub-foveal PFO droplet to move peripherally.

A few different methods can be utilized to manage the PFO droplet once it has moved away from the subfoveal location. One technique is to remove the displaced subretinal PFO using direct aspiration through the retina using a small-gauge cannula (36-gauge or smaller). Another technique is to make a small retinotomy just outside the macula through which to aspirate the subretinal PFO and balanced salt solution (BSS). Displacement of the PFO toward an inferior retinotomy may be aided by intraoperative patient head elevation and vibration.15

If the PFO has been displaced sufficiently peripherally, a technique of not removing the subretinal BSS and allowing the RPE to reabsorb the BSS has also been described in a patient—the subretinal PFO remained in a more peripheral location. One potential complication of this method is injecting the BSS at high pressure, which may rupture the thinned foveal neuroepithelium and create a full-thickness macular hole or cause RPE atrophy.14

Kim et al. described two cases of surgical removal of subfoveal PFCL through a subretinal BSS injection-induced macular hole, which subsequently closed with gas tamponade.16

CONCLUSION

Although surgical removal of retained submacular PFCL can improve vision and improve the secondary central scotoma, decreased vision or loss of retinal sensitivity does not necessarily indicate the need for surgery.17 Many patients with submacular PFCL have limited visual potential secondary to their retinal detachments, and the potential benefits and risks must be discussed with the patient.11,18 If the decision is made to remove centrally located submacular PFCL, the surgery is best performed within several weeks of detection to get the best potential visual outcome. NRP

FIGURE 3: The submacular PFO was removed with subretinal BSS injection and PFO removal through induced macular hole. Before surgery (A) vs. postsurgery (B). IMAGE COURTESY OF CARL REGILLO, MD.
FIGURE 3: The submacular PFO was removed with subretinal BSS injection and PFO removal through induced macular hole. Before surgery (A) vs. postsurgery (B). IMAGE COURTESY OF CARL REGILLO, MD.

RAZIYEH MAHMOUDZADEH, MD, is a postdoctoral research fellow at Willls Eye Hospital in Philadelphia.

SAMIR N. PATEL, MD, is affiliated with Wills Eye Hospital, Mid Atlantic Retina, and Thomas Jefferson University in Philadelphia.

CARL D. REGILLO, MD, FACS, is chief of the Retina Service at Wills Eye Hospital.

DONALD J. D’AMICO, MD, is a professor and chairman of Ophthalmology at Weill Cornell Medical College and ophthalmologist-in-chief at the New York Presbyterian Hospital, both in New York City.

AJAY E. KURIYAN, MD, MS, is an active member of the Retina Service at Wills Eye Hospital, and is an associate professor of ophthalmology at Sidney Kimmel Medical College of Thomas Jefferson University.

REFERENCES

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