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Cataract Surgery | May 2011

Bimanual MICS and MIVS

Real sutureless combined anterior and posterior segment surgery.

Cataract development or progression is the most common complication of vitrectomy procedures, with an incidence of up to 95% within the first 2 years.1 Inadvertent crystalline lens touch or prolonged gas tamponade during vitrectomy can rapidly exacerbate this complication. Therefore, combined cataract and vitrectomy surgery is not only cost effective but can lead to faster visual recovery.2

Preexisting lens opacity disturbs visualization of the vitreous and retina during vitreous surgery. Removal of the cataractous lens prior to vitrectomy enhances visualization and provides more room for instrument manipulation, which is especially beneficial to attain a more complete vitrectomy near the anterior vitreous base. Today, many retinal surgeons prefer combined surgery, particularly in presbyopic eyes.

MICROINCISION SURGERIES BECOMING POPULAR

Minimally invasive surgery has become a mainstream technique in ophthalmology, and small-incision and sutureless techniques are gaining momentum in both cataract and retinal surgeries. We believe that combining microincision cataract surgery (MICS) and microincision vitrectomy surgery (MIVS) is at the forefront of combined ophthalmic procedures and should become more prevalent in the near future.

When it comes to MICS, there are distinct pros and cons depending on the chosen technique (bimanual or coaxial).3 The advantages of coaxial MICS include stable fluidics and a generally shorter learning curve. However, the obvious objective and advantage of MICS is surgery through a smaller incision. Bimanual MICS currently allows the smallest incisions, despite its limitations of decreased chamber stability, the need for the surgeon to adopt different style phaco techniques, and a higher risk of corneal burns.4

Currently, the lack of commercially available IOLs that can be implanted through these small incisions is the greatest obstacle hindering popularization of MICS techniques. But the advantages of these very small incisions can be maximized when MICS is combined with MIVS.5 Below we introduce our sutureless combined surgery technique for bimanual MICS and MIVS. A video of the procedure can be viewed at http://eyetube.net/?v=kenir.

TECHNIQUE

Trocar insertion.We begin by placing three 23-gauge sutureless vitrectomy trocars (Alcon Laboratories, Inc., Fort Worth, Texas; Figure 1). Alternatively, trocars can be placed after cataract surgery, as in some instances insertion can be met with some resistance. There is no regurgitation of the ophthalmic viscosurgical device (OVD) through the corneal incisions when trocars are placed after bimanual MICS.

Corneal incision. We make two clear corneal incisions using a 1.6-mm disposable blade (Figure 2): one trapezoidal sideport incision for the irrigating chopper, and one main incision for the sleeveless phaco tip. The external dimension of the trapezoidal sideport incision is less than 1.5 mm, and the main incision is 1.6 mm. We have seen no excessive leakage during phacoemulsification and no OVD regurgitation through the wound sites during vitrectomy. We do not think that a smaller incision is necessary at this time because the main incision must be extended to 2.0 mm before IOL implantation. We prefer inserting IOLs with sufficient stability during these combined surgeries, especially in cases with gas tamponade where the gas bubble may push a very pliable IOL into the anterior chamber.

Capsulorrhexis. Performing continuous curvilinear capsulorrhexis (CCC) through small incisions may be cumbersome, but it has the advantage of causing little OVD leakage and thus maintaining the shape of the anterior chamber during the procedure. Our standard CCC is approximately 5.5 mm; however, if gas tamponade is anticipated, we prefer a slightly smaller CCC (5.0 mm) to prevent the IOL from extruding into the anterior chamber.

Phacoemulsification. We use an irrigating chopper (Duet BiManual system; MicroSurgical Technologies, Inc., Redmond, Washington) to perform a primary chop technique (Figure 3), dividing the nucleus into four pieces and removing them with phacoemulsification. We use a sleeveless 30º phaco tip with the Sovereign Phacoemulsification System (Abbott Medical Optics Inc., Santa Ana, California). Minimal phacoemulsification is needed because we utilize the mechanical forces of both instruments for chopping.

Corneal burn is the one of most problematic complications during sleeveless phacoemulsification. This can be prevented by avoiding use of excessively tight phaco incisions and reducing total effective phaco time. In most combined surgical cases, low phaco power should suffice as the cataract is usually not as hard as in conventional cataract cases.

Once cataract extraction is complete, cortical remnants are removed, with special attention paid to the subincisional area. The anterior chamber is filled with Healon (Abbott Medical Optics Inc.), just enough to enlarge the pupil but not enough to cause the posterior capsule to bulge. This will prevent accidental capsular rupture during vitrectomy (Figure 4).

Prolapse of OVD through corneal wounds during vitrectomy can lead to iris prolapse, miosis, and even posterior capsular rupture. Temporarily suturing the incisions to prevent the OVD from prolapsing during vitrectomy, especially during scleral indentation near the corneal incision sites, is not necessary in this technique.

Posterior vitrectomy. We use a noncontact wide-angle viewing system (BIOM; Oculus Optikgeräte GmbH, Wetzler, Germany) during vitrectomy. Clear and full visualization of the entire retina is a key element for successful vitrectomy. Prior removal of the crystalline lens allows excellent visualization of the peripheral retina and clearer visualization of the posterior pole (Figure 5). With the wide-angle viewing system, after the lens is removed, visualization up to the ora serrata can be achieved without scleral indentation. However, scleral indentation allows direct visualization of the anterior retina, facilitating detection of very fine retinal defects and allowing meticulous shaving of the vitreous base (Figure 6). Therefore, we recommend postponing IOL implantation until the completion of the posterior work, because glare from the IOL haptics and optic margins and the magnifying effects of the IOL will hinder visualization during vitrectomy.

IOL implantation. Retinal surgeons usually prefer larger IOLs with larger optics because these are more stable than smaller IOLs. Particularly in cases with gas tamponade, IOL choice is important because the gas bubble may push a smaller, more flexible IOL into the anterior chamber. We prefer using a one-piece hydrophobic IOL (AcrySof; Alcon Laboratories, Inc.), which can be injected through a 2.0-mm incision. We do not have much experience in using IOLs specifically made for MICS in combined surgery.

Completion of surgery. After IOL implantation and OVD removal, the anterior chamber is formed and the corneal incisions are sealed through incision-site hydration. The trocars are then removed and the sclerotomies are checked for leakage (Figure 7). Because of reduced support from the vitreous base after vitrectomy, the eye is more prone to astigmatism. Thus, small incisions and sutureless techniques, both in cataract surgery and vitrectomy, have additional astigmatic advantages.

CONCLUSION

The benefit of bimanual MICS lies in the use of smaller incisions, and this benefit can be maximized when MICS is used in combination with sutureless MIVS.4 Implanting the IOL at the end of vitrectomy provides the best visualization, most notably in the peripheral retina. Smaller incision sizes have now enabled surgeons to perform real sutureless surgery. Combining sutureless MICS and MIVS may currently be the least invasive combined ophthalmologic surgery technique.

Suk Ho Byeon, MD, practices at the Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea. Dr. Byeon states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +82 2 2228 3570; fax: +82 2 312 0541; e-mail: shbyeon@yuhs.ac.

Young Kwang Chu, MD, practices at Siloam Eye Hospital, Seoul, Korea. Dr. Chu states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +82 2 2650 0880; fax: +82 2 2650 0895; e-mail: docchu@hotmail.com.

  1. Thompson JT,Glaser BM,Sjaarda RN,Murphy RP.Progression of nuclear sclerosis and long-term visual results of vitrectomy with transforming growth factor beta-2 for macular holes.Am J Ophthalmol.1995;119(1):48-54.
  2. Dugas B,Ouled-Moussa R,Lafontaine PO,et al.Idiopathic epiretinal macular membrane and cataract extraction: combined versus consecutive surgery.Am J Ophthalmol.2010;149(2):302-306.
  3. Can I,Takmaz T,Yildiz Y,et al.Coaxial,microcoaxial,and biaxial microincision cataract surgery:prospective comparative study. J Cataract Refract Surg.2010;36(5):740-746.
  4. Alio J,Rodriguez-Prats JL,Galal A,Ramzy M.Outcomes of microincision cataract surgery versus coaxial phacoemulsification. Ophthalmology.2005;112(11):1997-2003.
  5. Byeon SH,Kwon OW.Lensectomy using a bimanual microincision cataract surgery technique during pars plana vitrectomy. Ophthalmic Surg Lasers Imaging.2009;40(1):80-84.

TAKE-HOME MESSAGE

 

  • Cataract removal prior to vitrectomy enhances visualization and provides more room for instrument manipulation.
  • Consider postponing IOL implantation until after all posterior segment surgery is complete.

 

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