26.8.2  Scleral Sutured Posterior Chamber Intraocular Lens Procedure – 4 Point Fixation

Posterior chamber intraocular lenses (PC-IOL) with eyelets may be sutured to the sclera to enable a four-point fixation. Theoretical advantages of four-point fixated IOLs include improved IOL centration and stability, reduced lens tilt, and potentially lower risk of long-term lens dislocation. Disadvantages include need for multiple sclerotomies and associated conjunctival disruption, risk of suture erosion and the potential for IOL opacification with some currently available hydrophilic lenses (e.g. Akreos AO60). In addition, four-point fixation can’t be used to re-use a dislocated three-piece IOL.

Four-point Haptic IOL Choice

Currently available PC-IOLs, which enables four-point fixation, includes the Akreos AO60 (Bausch and Lomb, North Clearwater, FL), PhysIOL MicroPure 1.2.3 and the enVista MX60 (Bausch and Lomb) (Figure 26.8.2.1). The Akreos AO60 and PhysIOL MicroPure 1.2.3 have four separate haptics, each with its own peripheral eyelet, for a true four-point fixation. The Akreos AO60 is composed of hydrophilic acrylic material, which can opacify when exposed to gas or oil, whereas the PhysIOL MicroPure 1.2.3 is hydrophobic. The enVista MX60 lens is made of hydrophobic acrylic material but only has two eyelets, which are located at the optic-haptic junction. Sutures need to be securely looped around the haptic to enable a pseudo-four point fixation. All these lenses are not designed to be sutured (off-label use) and breakage of the eyelets has been reported.

Figure 26.8.2.1 IOL Available for 4-point Fixation 
A) Akreos AO60 B) EnVista MX60 (Images reproduced with permissions from Bausch and Lomb, North Clearwater, FL)

Figure 26.8.2.1 IOL Available for 4-point Fixation
A) Akreos AO60 B) EnVista MX60 (Images reproduced with permissions from Bausch and Lomb, North Clearwater, FL)

Figure 26.8.2.2 Marking the Sclerotomies

1. Opening and Positioning of Sclerotomies

Use a corneal lens marker (e.g. toric marker) to mark the horizontal axis 180º apart. Mark the sclerotomy sites, which are located 3 mm posterior to the limbus and 4-5mm apart (Figure 26.8.2.2 and Figure 26.8.2.3).

Figure 26.8.2.3
Marks are made for four sclerotomies- each 3mm posterior to the limbus with the temporal marks 5mm apart and the nasal marks 5mm apart.

2. Vitrectomy

It is best to use 25 or 27-gauge valved cannulae for this procedure. Place the infusion line inferiorly away from the sclerotomy sites. Insert the two other cannulae at the superotemporal and superonasal marked sites using a perpendicular non-tunneled approach (Figure 26.8.2.4). If there are additional cannulae, these can be placed at the inferotemporal and inferonasal marks, but it is just as easy to introduce the suture through these sclerotomies using a needle (described below). Standard pars plana vitrectomy is then performed ensuring all anterior vitreous is removed especially around the sites of suture insertion. In the event of a large nose, the nasal suture can be moved superiorly and the temporal one moved inferiorly.

Figure 26.8.2.4 27-gauge Vitrectomy is Performed
Cannulae have only been placed through the superior sclerotomies.

3. ± Remove Retained Lens Material/IOL

If there is retained lens material or a dislocated IOL that needs to be removed, this should be done first. See Chapters See Chapter 26.2 Pars Plana Lensectomy and Chapter 26.8.1 Scleral Sutured IOL- Traditional 2 Point Fixation.

4. Prepare the Clear Corneal Incision and Anterior Chamber

Create a paracentesis and inject viscoelastic to protect endothelium. Use a 2.75mm keratome blade to create a clear corneal incision (CCI).

5. Pass the Suture Through the Eyelets of the IOL (Figures 26.8.2.5, 26.8.2.6 and 26.8.2.7)

Cut the 7-0 CV-8 Gore-Tex suture in half and remove the needles

For the Akreos AO60 lens, thread each half of the suture through the two eyelets on each side going from anterior-to-posterior through the first eyelet and posterior-to-anterior through the second eyelet to keep it sitting flat. The eyelet with the kidney bean shape should be oriented in the position closest to the left shoulder.

For the enVista MX60 lens, thread the suture anterior-to-posterior through the eyelet and loop anteriorly in front of haptic.

Figure 26.8.2.5
Pass the end of a CV-8 Gore-Tex suture into the lumen of a 27-gauge needle. The needle can be bent to keep the tip in as an anterior plane as possible. Iris hooks have been placed in this case to dilate the small pupil.

Figure 26.8.2.6
Using intraocular forceps (e.g. Alcon MaxGrip) passed through the clear corneal incision, grasp the free end of the Gore-Tex suture.

Figure 26.8.2.7 The Gore-Tex Suture is Passed Through the Eyelets of the IOL

6. Thread the Sutures into the Inferior Sclerotomies and the Superonasal Sclerotomy and out Through the CCI

Consider marking the inferior sutures with a marking pen to better identify their position. Insert one end of the CV-8 Gore-Tex into the anterior chamber then pass it to forceps inserted through the pars plana to externalize it out of the sclera. Consider starting with the inferior temporal suture, then the superotemporal suture, and finally the inferonasal suture. If there is difficulty threading the nasal sclerotomies because of the nose, consider bending the forceps (Figure 26.8.2.8).

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