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Cataract Surgery | Jun 2011

Combined Fluid-Gas Exchange and Cataract Extraction

Rapid visual rehabilitation can be achieved after macular hole surgery.

There is currently much debate about whether to position patients face-down after vitrectomy and gas for the treatment of macular holes.1 However, macular holes close within a few days of surgery,2 and it is increasingly recognized that hole closure can be achieved by ensuring that the macula is kept dry for a relatively short time after surgery. Two techniques are commonly employed to achieve this. In the first, a shortacting gas such as air or sulphur hexafluoride (SF6) is used with a brief period of face-down posturing; in the second, a longer-acting gas such as perfluoropropane (C3F8) is used to keep the macula dry without posturing. Longer-acting gases can be used with varying orientations of the eye because they produce a larger, more sustained bubble in the immediate postoperative period compared with short-acting gases.

The use of long-acting gas bubbles is, therefore, particularly helpful for patients who have difficulty positioning, such as the elderly or those with musculoskeletal problems. The gas bubble remains in the eye for many weeks after surgery, yet it has no useful function beyond the first few days. It does, however, limit air travel and work and may cause significant visual morbidity in patients with poor vision in the fellow eye. In response to this problem, we adopted a new technique of combined phacoemulsification and fluid-gas exchange to achieve rapid visual rehabilitation in this select group of patients.

We have audited the hole closure rates, the complications, and the visual outcomes of the first eight patients to undergo combined phacoemulsification and fluid-gas exchange. In these patients, we encountered no significant complications and obtained long-term outcomes that compare favorably to conventional management.3 The technique is designed to use minimal equipment other than what is required for standard phacoemulsification and to require little or no specialist vitreoretinal expertise. For a video depiction of the technique, visit http://eyetube.net/?v=gepor.

SURGICAL PROTOCOL

Patients suitable for early gas removal after macular hole surgery should be identified in advance, and informed consent should be obtained for both procedures. Biometry should be done prior to the initial surgery. In our unit, macular hole surgery is performed using standard 20-gauge instrumentation and includes peeling the internal limiting membrane (ILM) with Membrane Blue (DORC Surgical Instruments, Zuidland, Netherlands) and 14% C3F8 gas. The patient is asked to lie face-down overnight to prevent pupil block during the period of maximal gas expansion and is otherwise advised to avoid looking up. The patient is also advised to minimize physical activity on the basis that excess head movement might cause fluid in the posterior segment to wash over the hole and break the surface tension.

Two weeks after the initial surgery, the patient is readmitted for the second procedure, during which the gas is removed and cataract extraction with lens implantation is performed. With the patient in the supine position, indirect ophthalmoscopy is used to confirm hole closure. At this stage, the gas fill is typically 50%, and clear visualization of the macula is usually achievable. If the hole remained open at this point, we might advocate a further period of posturing or the use of silicone oil tamponade, but to date this has not been necessary.

TECHNIQUE

The process of gas removal and phacoemulsification is achieved using equipment readily available during conventional cataract surgery. Following is a description of each step.

Establishing infusion. To maintain positive pressure within the posterior segment and to displace the gas within it, infusion is established by inserting a needle through the pars plana. We temporarily disconnect the irrigation line from the phaco handpiece—in our center we use the Millennium phacoemulsification system (Bausch + Lomb, Rochester, New York)—and attach it to a 27-gauge, 0.5-in needle (AW-NS1109296; Telluride Systems, Sterling, Virginia). The needle is passed obliquely through the conjunctiva and sclera, 4 mm posterior to the limbus in the inferotemporal quadrant of the eye, avoiding the site of the original vitrectomy infusion port (Figure 1A). The needle can be held in place by hand.

Achieving flow. Once the needle tip is visible through the pupil, the bottle of balanced saline solution is raised to 2 m and infusion commences. Free flow can be confirmed by observing the Purkinje image of the fluid level, appearing as regular wave-like golden splashes through the lens. Irrigation flow slows and eventually ceases within 15 to 20 seconds, coinciding with the equilibrium of intraocular pressure (IOP) and infusion pressure.

Controlling escape of gas. With the infusion pressure stabilized, the next stage is to allow controlled escape of gas by inserting a 29-gauge, 0.5-in needle (NN-2713R; Terumo Medical Products, Leuven, Belgium) obliquely through the conjunctiva and sclera, 4 mm posterior to the limbus in the superonasal quadrant (Figure 1A). To obtain optimal internal depth within the eye, the needle is clamped 2.5 mm from its tip with a pair of 95-mm Wells curved artery forceps (0101475; John Weiss International, Milton Keynes, United Kingdom). This also provides a secure grip for the needle in one hand while the other hand holds the infusion line. At 2.5 mm depth from the conjunctival surface, the needle tip sits within the vitreous cavity, just beyond the vitreous base (Figure 1B).

With both needles in position and the infusion running (Figure 1C), the maximum amount of gas can be displaced by appropriately tilting the eye while guarding against lens touch. Sustained release of gas can be confirmed indirectly by observing a trickling of the infusion fluid, causing a rippling of the golden fluid level reflex seen through the pupil. Toward the end of gas removal, the fluid level rises to meet the posterior surface of the lens, and the red reflex is restored. At this point, the eye is rotated inferotemporally with the 29-gauge needle uppermost, allowing removal of the residual pocket of gas (Figure 1D).

Withdrawing the needles from the eye. When the fluid-gas exchange appears to be complete, the 29-gauge needle can be withdrawn from the eye. This often triggers the release of a few more gas bubbles. The eye is rotated back into the neutral position, and the IOP is checked manually before stopping the infusion and withdrawing the 27-gauge needle connected to it. A small cotton tip or swab massaged against the conjunctiva after needle removal helps to improve wound integrity. In one case in our series, it was necessary to inject extra fluid through the pars plana to correct a mild hypotony that otherwise might have compromised the wound architecture of the subsequent cataract incision.

Performing phacoemulsification. With the red reflex and a firm eye restored, conventional phacoemulsification through a clear corneal incision can be performed. During the I/A phase, a small residual gas bubble occasionally rolls under the posterior capsule if the anterior chamber is allowed to shallow. This causes anterior bulging of the posterior capsule and loss of the red reflex, but by maintaining the infusion pressure and tilting the eye inferiorly the bubble can easily be displaced behind the zonules.

CONCLUSION

We have developed a technique for fluid-gas exchange and phacoemulsification following macular hole surgery. This method is best used in patients who have difficulty maintaining face-down positioning or who require early visual rehabilitation. Our outcomes in eight patients have shown that the success of hole closure is comparable with that of standard surgery in which the gas is left to reabsorb spontaneously over several months.

Combined early gas removal and cataract surgery can be performed safely and without an additional procedure. This may be a particularly useful technique for patients who have poor vision in the fellow eye or who need to travel by air in the immediate postoperative period.

perform the fluid-gas exchange and minimizing the costs of the additional procedure. The increasingly widespread use of posterior segment anti-vascular endothelial growth factor (VEGF) agents has made injections through the pars plana a commonplace procedure, and we believe that this technique is suitable for the general ophthalmologist without specialist vitreoretinal expertise.

Robert E. MacLaren, DPhil, FRCOphth, is a Professor of Ophthalmology at the Nuffield Laboratory of Ophthalmology, University of Oxford, United Kingdom, and at the University College London Moorfields NIHR Ophthalmology Biomedical Research Centre, United Kingdom. Professor MacLaren states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: robert.maclaren@eye.ox.ac.uk.

Niall Patton, MD, FRCOphth, is a Specialist Registrar at Moorfields Eye Hospital, London. Dr. Patton states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: niallpatton@hotmail. com.

Nelson A. Sabrosa, MD, PhD, is a Clinical Research Fellow at Moorfields Eye Hospital, London. Dr. Sabrosa states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: nsabrosa@terra.com.br.

Henry B. Smith, MRCOphth, is a Specialist Registrar in the Vitreoretinal Research Department, Moorfields Eye Hospital, London. Dr. Smith states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: hbs@doctors.net.uk.

  1. Dhawahir-Scala FE,Maino A,Saha K,Mokashi A,McLauchlan R,Charles S.To posture or not to posture after macular hole surgery.Retina.2008;28:60-65.
  2. Sato H,Kawasaki R,Yamashita H.Observations of idiopathic full-thickness macular hole closure in early postoperative period as evaluated by optical coherence tomography.Am J Ophthalmol.2003;136:185-187.
  3. Smith HB,Sabrosa NA,Patton N,MacLaren R.Combined phacoemulsification and removal of gas following macular hole surgery.J Cataract Refract Surg.2011;37:229-234.

TAKE-HOME MESSAGE

 

  • Combined fluid-gas exchange and cataract extraction is designed to use minimal equipment other than what is needed for standard phacoemulsification and require little or no specialist vitreoretinal expertise.
  • The gas-removal technique includes establishing infusion, achieving flow, controlling a sustained release of gas, and withdrawing the needle from the eye once fluid-gas exchange is complete.
  • After fluid-gas exchange and once red reflex and a firm eye are restored, conventional phacoemulsification is performed.

 

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