TRANSSCLERAL GORE-TEX FIXATION OF AKREOS AO60 IOL
Brandon D. Ayres, MD
Even in the modern age of cataract surgery, being comfortable with suture fixation of an intraocular lens (IOL) is as important as ever. Surgical complications may prevent placement of an IOL in the posterior chamber, and there are times when an anterior chamber IOL is suboptimal. There seems to be an increasing incidence of IOL subluxation due to zonular instability, and with the popularity of endothelial keratoplasty, an anterior chamber IOL may be problematic. Comfort with at least one technique for suture fixation of the posterior chamber lens is helpful for the for the anterior segment surgeon.
Over the past several years, there has been a transition from suture fixation of single-piece polymethylmethacrylate (PMMA) IOLs to foldable acrylic lenses. One of the first to describe this technique was Herman in 2010 with 4-point fixation of a foldable hydrophilic acrylic IOL. It should be noted that suture fixation of any IOL is off-label use of the implant, and use of Gore-Tex (WL Gore & Associates) suture material is also off-label.
Advantages
The main advantage of scleral fixation of foldable IOLs is in the incision size. Depending on the technique used, the Bausch + Lomb AO60 implant can be implanted through a 4-mm or smaller incision. Use of a single-piece PMMA IOL requires an incision size at least as large as the optic size, typically ranging from 6 to 7 mm. The smaller incision size has several advantages. First and foremost, wound construction and closure is simplified. In many cases, the wound is self-sealing or requires only a single suture to close in comparison to multiple sutures with larger incisions. In many cases, an anterior or posterior chamber infusion cannula will be employed to help maintain the intraocular pressure during the surgical procedure. Smaller incision size reduces intraoperative wound leakage, keeping the globe formed during the surgery. Improved control of eye pressure reduces risk of surgical complications such as development of choroidal effusions or hemorrhage. Reducing incision size also helps reduce wound dehiscence postoperatively in the event of globe trauma.
Surgical Technique
NEEDED MATERIALS AND THE BAUSCH + LOMB AO60 (AKREOS AO IOL)
The AO60, or Akreos AO, is a single-piece hydrophilic acrylic IOL that has 4 loop-shaped haptics capable of looping suture through. The IOL is planar in shape with an overall length that ranges from 10.5 to 11.0 mm, depending on the dioptric power of the implant. It is critical to note that the IOL is too short to reach from sulcus to sulcus and will have to be centered by balancing suture tension. Inspection of the implant will show slightly different shapes to the opening of the haptics on each end of the implant. One of the haptics has an oval opening, and the opposing haptic has a kidney bean–shaped opening. When looking at the IOL along its long axis, the oval haptic should be up and on the left side and the kidney bean–shaped opening up and to the right. Suture fixation of the AO60 implant is off-label.
Figure 31-1. (A) The AO60 IOL by Bausch + Lomb. Notice the different shape of the cut-out in the haptics. Correct orientation of the IOL is with the oval cut on the top left and bottom right and the kidney bean–shaped haptic on the top right and bottom left. (B). The CV-8 suture by Gore-Tex.
Two other important materials needed for suture fixation of the AO60 lens are microinstrumentation and the Gore-Tex CV-8 suture (Figure 31-1). The CV-8 suture is composed of polytetrafluoroethylene and is a nonabsorbable monofilament suture approximately 7-0 US Pharmacopeia size. The double-armed suture comes swaged to the TTc-9 vascular needle. In the technique described below, the needles are removed and 2 suture fragments are used to suture the IOL. Some form of microinstrumentation will be necessary for passing suture in the anterior segment and externalizing through the scleral incisions.
SURGICAL PLANNING
The set-up for scleral suture fixation of the AO60 is critical. The surgical approach can be either from the superior or temporal approach. The IOL can be placed in any axis as long as it crosses directly through the visual axis. Marks can be placed at the limbus with a gentian violet marker 180 degrees across from each other to help ensure proper sclerotomy placement. A radial keratotomy or limbal relaxing incision marker can be used to help verify proper placement. A 3- to 4-mm incision will be necessary to facilitate folding or injection of the lens and 2 paracenteses will be needed, one to facilitate release of the IOL and one for placement of an anterior chamber maintainer. It is critical to have a well-thought-out surgical plan in place in order to accommodate prior surgical procedures, such as a filtering bleb, a tube shunt, or conjunctival scars from vitreoretinal surgery.
SCLEROTOMY PLACEMENT
Proper placement of the scleral incisions may be one of the most critical steps in ensuring proper lens position (Figure 31-2). Four scleral incisions (2 sets of paired incisions) will have to be created for placement of the IOL. A conjunctival peritomy must be created in the 2 areas where the scleral incisions will be placed. The sclerotomies should be placed 3 mm posterior to the limbus and 4 to 5 mm apart. Placing the wounds at 3 mm helps prevent hemorrhage from the ciliary body and keeps the IOL posterior to the iris, reducing chances for iris chafe and pigment dispersion. The 4-mm separation replicates the distance between the haptics on the AO60 implant. Some surgeons prefer to increase the distance between the paired scleral incision to 5 mm (Figure 31-3).
No special equipment is needed to make the scleral incisions. A 15- to 30-degree sharp blade or valved 23- or 25-gauge trocars can be used to create the scleral incisions. Use of trocars may be preferred if suture fixation of the IOL is to be combined with other procedures, such as IOL exchange or vitrectomy. It is critical to make the scleral wounds while the globe is well pressurized. The scleral incision should be made before any penetrating wounds are created or after an infusion line is placed. The scleral incisions are directed circumlimbal (parallel to the limbus), making sure that the internal distance between the paired incisions remains 4 mm.
When using a trocar system, it is important to know what instrumentation can be used through the trocar. When using the Gore-Tex suture technique, the suture will be passed through the scleral incision using a handshake technique. Not all microinstrumentation will fit through the trocars. In many cases, micro anterior segment instrumentation is made with a curved shaft to facilitate use in the anterior chamber. The curve of the shaft may prevent placement through a straight 4-mm trocar. For example, the 23-gauge micro holding forceps made by MicroSurgical Technology will not fit through the 23-gauge valved trocar made by Alcon Laboratories, Inc. In place of using 23-gauge anterior segment forceps, curved shaft 25-gauge forceps will be needed, such as the Snyder Graper (MicroSurgical Technology) or 23-gauge forceps used for vitreoretinal surgery. When using 25-gauge trocars, 25-gauge retinal forceps will need to be used to retrieve suture through the sclerotomy. It does not matter which sclerotomy is made with the trocar and which is made with the lancet. The scleral incision with the trocar will be slightly larger than the lancet-created sclerotomy, facilitating burying of the Gore-Tex knot later in the case.
Figure 31-2. (A) The scleral incisions are placed 3 mm posterior to the limbus and at least 4 mm apart. (B) A marking pen is used to help ensure correct placement of the scleral incisions. (C) A 23-gauge valved trocar is placed in the more proximal scleral incision to facilitate instrumentation use in the eye as well as eventual burying of the suture knot at the end of the surgical procedure. (D) The distal scleral incision is made with the lancet alone.
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