Since it was first reported in 2005 by Eckardt,1 the utilization of 23-gauge pars plana vitrectomy (PPV) has rapidly increased. Intermediate in size, 23-gauge PPV has several reported advantages over both larger (20-gauge) and smaller (25-gauge) vitrectomy techniques. Compared with 20-gauge PPV, there is less need to close the sclerotomies with sutures, approaching sutureless retinal surgery.2 Compared with 25-gauge instruments, 23-gauge instruments are less flexible, allowing the surgeon to more closely replicate experience with large gauge vitrectomy.
Pars plana lensectomy of the crystalline lens in situ and management of the subluxated or posteriorly dislocated (ie, luxated) crystalline lens are examples of an expanding list of indications for exploiting these advantages. Regardless of the etiology for lens subluxation or dislocation, whether it is pseudoexfoliation syndrome, trauma, hyperhomocystinuria, ectopia lentis, or Marfan syndrome, the surgical approach with the 23-gauge PPV system will be the same. Long-term outcomes of dislocated lens fragments managed with 23-gauge PPV have not been reported. However, outcomes with 25-gauge surgery have shown promising results.3,4 This article focuses on the technique employed to manage the crystalline lens with 23-gauge vitrectomy technology.
REMOVAL OF THE
CRYSTALLINE LENS IN SITU
When phacoemulsification of the crystalline lens with an
anterior or limbal approach is undesirable, such as with lens
instability secondary to zonular dehiscence, violation of the
lens capsule following penetrating ocular trauma, or mature
nuclear sclerosis, a pars plana approach is preferable.
Whereas 20-gauge technology would be adequate for lens
extraction, a 23-gauge system may be beneficial. Similar to
other indications for 23-gauge PPV, the three standard ports
are created through the pars plana with angled incisions.
Because the goal is removal of the lens, the trocars can be
placed 3.0 mm posterior to the limbus. If the infusion cannula
cannot be visualized because of dense cataract, an
anterior chamber maintainer can be placed until removal of
the lens is sufficient to allow verification of the cannula's
position in the vitreous cavity.
Incision of the lens capsule and cleavage of the lens nucleus is achieved in one of two ways: either a 23-gauge microvitreoretinal (MVR) blade can be passed through the cannula and into the lens equator, or the 23-gauge trocar can be used in a similar fashion after the cannula is placed in the appropriate location. Once this is performed from both the nasal and temporal directions, the surgeon can use the vitrector to engage the lens through these incisions and begin removing the nuclear material, taking care to avoid the anterior and posterior capsule.s The endoilluminator can act as a second instrument from the opposite port, stabilizing the lens during removal.
If the lens material is too hard from cataractous changes, the phacofragmatome can be used. This requires removing of the 23-gauge sclerotomy, creating a local conjunctival peritomy, and enlarging the scleral wound with a 20-gauge MVR blade. Marking the 23-gauge trocar blade with a pen prior to transconjunctival sclerotomy formation often facilitates finding the conjunctival incision and sclerotomy for future enlargement, if necessary. Phacofragmentation of the lens can then take place in a fashion similar to a 20-gauge approach. Care must be taken not to engage vitreous with the phacofragmatome because cutting of the vitreous collagen does not occur; only suction and subsequent vitreoretinal traction occurs. To avoid this, once a red reflex is present, vitrectomy just posterior to the posterior lens capsule should be performed prior to reintroduction of the phacofragmatome. Once all lens material has been removed, we suggest removal of the remaining capsular bag. In our experience, the lens capsule can be engaged and removed efficiently with disposable 23-gauge serrated forceps (Alcon Laboratories, Fort Worth, TX).
POSTERIORLY DISLOCATED LENS MATERIAL
The vitreoretinal surgeon encounters retained lens fragments
following phacoemulsification cataract extraction with
posterior capsule compromise (either same day or several
days following) or in relation to pars plana lensectomy (same
day). Timing of PPV for retained lens fragment following phacoemulsification
does not appear to affect visual outcomes
with 20-gauge instrumentation,5-9 and the same can probably
be assumed for a 23-gauge approach.The strategy for lens removal is to avoid vitreoretinal traction, and all vitreous
associated with the lens or lens fragments should be removed
prior to removing the lens material. Vitreous staining with triamcinolone
acetonide is an excellent way to ensure that all
traction is removed.10
Whether the vitrector or the phacofragmatome is used, the lens fragments should be gently aspirated into the mid-vitreous cavity and then be cut or fragmented and suctioned out (Figure 1). To protect the macula during removal, injection of perfluorocarbon liquid (PFCL) or viscoelastic to elevate large, dense lens fragments has been suggested (Figures 2 and 3).11-14 However, limited data with larger gauge vitrectomy does not suggest any improvement in outcomes such as retinal breaks, retinal detachments, or cystoid macular edema (CME). Also, great care must be taken to remove all PFCL to avoid further complications. Following removal of all the apparent lens material, a thorough search for both residual lens fragments and retinal breaks should be performed. Lens fragments and retinal breaks are often located in association with the vitreous base, and, therefore, scleral depression should be performed.
The high flow rate as well as the large size and distal location of the 23-gauge vitrector port facilitate gentle dissection of vitreous associated with anterior lens fragments. Also, the relative stiffness of the 23-gauge instrumentation facilitates this search greatly compared with smaller gauge vitrectomy. For similar reasons, any repair of retinal detachment may be easier with 23-gauge instrumentation compared with a 25- gauge approach. However, one study comparing 25- and 20- gauge vitrectomy for retinal detachment repair found similar outcomes with the two techniques.15 Thus, experience with the smaller gauge system may be more important than instrument flexibility in this regard. Additionally, with the advent of improved 25-gauge instrumentation (eg, 25+; Alcon Laboratories), the 25-gauge approach may be significantly improved.
CURRENT CHALLENGES
AND FUTURE DIRECTIONS
All cases of retained lens fragments may be complicated
by glaucoma, CME, and retinal break or detachment.
A challenge specific to 23-gauge vitrectomy surgery system
is ocular hypotony because at least two of the three
sclerotomies are ideally sutureless. The need to suture the
enlarged sclerotomy used for the phacofragmatome (if
needed) is another potential limitation, but this limitation
is present in all vitrectomy systems. The development
of a smaller gauge phacofragmatome would eliminate
this limitation and make a 23-gauge approach even
more appealing. Ho and colleagues4 reported 17 cases of
retained lens fragment removal with a 25-gauge vitrectomy
system that employed a high flow rate, long duty
cycle, and large port size on the vitreous cutter. In addition,
they utilized a bimanual technique with the endoilluminator,
guiding and forcing lens pieces into the cutter's
port. Newer surgical systems may also facilitate lens
removal with the vitreous cutter by improvements in
flow, cut rate, and duty cycle parameters, and possibly
obviate the need for a phacofragmatome in 23-gauge vitreoretinal
surgery.
Aziz A. Khanifar, MD, is an Instructor in the Department of Ophthalmology at Weill Cornell Medical College. He can be reached via e-mail at azizkhanifar@gmail.com.
Harry K. Roux, MD, is a Research Fellow in the Department of Ophthalmology at Weill Cornell Medical College. He can be reached via e-mail at harry.roux@gmail.com.
R.V. Paul Chan, MD, is an Assistant Professor of Ophthalmology at Weill Cornell Medical College in New York City. He can be reached at +1 646 962 2540; fax: +1 474 962 0600; or via email at rvpchan@aol.com.
The authors report that they have no financial interests to disclose.
Rohit Ross Lakhanpal, MD, is a Partner at Eye Consultants of Maryland, PA, and Principal of Timonium Surgery Center LLC. He is also a Clinical Assistant Professor of Ophthalmology at The University of Maryland School of Medicine. He reports no financial or proprietary interest in any of the products or techniques mentioned in this article. He has been a consultant in the past for Bausch + Lomb and Alcon Surgical. He is currently the Vice President of the Vit-Buckle Society (VBS). Dr. Lakhanpal is Section Co-Editor of the VBS page in Retina Today and on EYETUBE.NET. He can be reached at +1 410 581 2020 or via e-mail at retinaross@yahoo.com.
Thomas Albini, MD, is an Assistant Professor of Clinical Ophthalmology at the Bascom Palmer Eye Institute in Miami, FL. He specializes in vitreoretinal diseases and surgery and uveitis. He has served as a speaker for Bausch + Lomb and Alcon Surgical and as a consultant for Alcon Surgical. He is currently the Membership Chair of the Vit- Buckle Society (VBS). Dr. Albini is Section Co-Editor of the VBS page in Retina Today and on EYETUBE.NET. He can be reached at +1 305 482 5006 or via e-mail at talbini@med.miami.edu.
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