CORNEAL CONSIDERATIONS FOR NONCAPSULAR IOL FIXATION

Sadeer B. Hannush, MD

The 3 most common scenarios for considering noncapsular (or extracapsular) posterior chamber intraocular lens (PCIOL) fixation are:

1. The presence of an anterior chamber IOL (ACIOL) implant with recalcitrant cystoid macular edema that is not responsive to topical, peribulbar, or intravitreal anti-inflammatory agents
   
2. The presence of a suboptimally positioned PCIOL with iris chafing, chronic inflammation, elevated intraocular pressure (IOP), or recurrent uveitis-glaucoma-hyphema syndrome
   
3. The increasingly common late subluxation of a capsular bag-PCIOL complex, usually in the setting of pseudoexfoliation syndrome

Management of these 3 scenarios usually requires surgical intervention to exchange, reposition, or refixate the IOL. It is incumbent on the surgeon to be aware of the following corneal considerations in these situations:

• Is the cornea contributing to the patient’s visual compromise through one of multiple possible mechanisms including, but not limited to, high astigmatism, surface irregularity, stromal opacification and/or edema, and endothelial dystrophy or decompensation?
  
• Will the cornea, even if clear at the time of presentation, likely tolerate anterior segment intervention or repair without proceeding on to endothelial failure and decompensation?

Helpful preoperative evaluation may include:

• Placido-based corneal topography
  
• Elevation-based corneal tomography
  
• Anterior segment optical coherence tomography
  
• Specular or confocal microscopy

In most instances the corneal surface is smooth and the stroma is clear or with mild edema only. If slit-lamp biomicroscopy reveals significant guttate endotheliopathy, or specular/confocal microscopy demonstrates a low endothelial cell count, the surgeon is faced with the decision of whether to offer the patient endothelial replacement at the same time as IOL surgery or separately in a staged sequential manner. Descemet’s stripping automated endothelial keratoplasty (DSAEK) or Descemet’s membrane endothelial keratoplasty (DMEK) are the usual corneal procedures of choice, with consideration rarely given to penetrating keratoplasty. In most instances, DSAEK is chosen for complex anterior segment reconstructive cases.

Options for PCIOL implantation in the absence of capsular support include:

• Iris fixation (suture or claw haptic)
  
• Scleral fixation of rigid polymethylmethacrylate (PMMA) IOL with Prolene (Ethicon) or Gore-Tex (WL Gore & Associates) suture¹
  
• Scleral fixation of foldable IOL with Gore-Tex suture
  
• Intrascleral haptic fixation of a 3-piece foldable PCIOL with fibrin sealant (glued IOL), introduced by Dr. Agarwal²
  
• Intrascleral haptic fixation of a 3-piece foldable PCIOL using the double-needle flanged haptic technique, introduced by Dr. Yamane^3–5

I.    The glued IOL technique2

A. Advantages

1. Small self-sealing incision using a foldable IOL
   

   a. Well-formed globe throughout the surgery

   
   

   b. Less risk of iris prolapse

   
   

   c. Less chance of suprachoroidal hemorrhage

   
   

   d. Avoids complications of large surgical wounds such as leakage, shallow anterior chamber, and astigmatism

   
   
2. All maneuvers are performed under direct visualization.
   
3. No need for scleral sutures. Avoids suture-related complications (knot extrusion, cheese-wiring through tissues, suture breakage).
   
4. The ability to vary the length of haptic embedded into the scleral tunnel. This may be adjusted to optimize IOL centration and minimize rotation.
   
5. Stable IOL fixation
   

   a. Effectively compartmentalizes the eye into 2 chambers

   
   

   b. No pseudophacodonesis

   
   
6. Decade-long postoperative track record

B. Limitations

1. Requires familiarity with the technique of injecting the lens through the surgical incision and avoiding dropping the IOL into the vitreous cavity. The surgeon should be familiar with the handshake technique, which includes first injecting the lens with one hand and using the other hand to grab and to exteriorize the leading haptic through a sclerotomy. The trailing haptic is then delivered into the eye with one hand, exteriorizing out through the other sclerotomy with microforceps using the second hand.
   
2. Requires conjunctival peritomy and creation of scleral flaps
   
3. Requires familiarity with anterior vitrectomy techniques, ideally through a pars plana incision
   
4. Uses fibrin sealant underneath the scleral flaps and conjunctiva

C. Procedure

1. Two peritomies are made 180 degrees apart, usually in the vertical hemimeridians
   
2. Pars plana or anterior chamber infusion cannula is inserted
   
3. Two partial-thickness limbal-based scleral flaps (3 x 3 mm) are fashioned 180 degrees apart
   
4. Anterior vitrectomy, possibly via a pars plana sclerotomy, is performed, if indicated
   
5. Two oppositely located sclerotomies are created with a 23-gauge microvitreoretinal blade beneath the scleral flaps, 1.5 to 2.0 mm posterior to the limbus, again 180 degrees apart from each other
   
6. Corneal incision is made that permits implantation of a 3-piece foldable IOL
   
7. Unless aphakic, explantation of the subluxated IOL is performed
   
8. While the foldable IOL is introduced into the anterior chamber with one hand, the other hand introduces 23- or 25-gauge forceps through one sclerotomy site to grasp the leading haptic and externalize it. Through the other sclerotomy site, grasp and externalize the trailing haptic using the handshake technique.
   
9. Centration is important, especially if using a multifocal lens
   
10. Deliver IOL haptics into scleral tunnels created with 26-gauge needles, adjusting the length of the haptic that is inserted into the tunnel in order to center the lens
    
11. After placing air in the anterior chamber, inject reconstituted fibrin sealant under the scleral flaps and to close the conjunctival peritomies
    
12. Close the corneal incisions with 10-0 nylon suture, if necessary
    
13. Remove the pars plana or anterior chamber infusion cannula

D. Note: The procedure may be combined with endothelial keratoplasty if indicated.

II.   The transconjunctival, double-needle flanged haptic technique^3–5

A. Advantages

1. The technique is conceptually simple
   
2. Obviates the need for conjunctival peritomy and creation of scleral flaps
   
3. It allows implantation of a foldable IOL through a small incision
   
4. It is currently the fastest method of sutureless intrascleral haptic fixation of a PCIOL
   
5. Eyes tend to be very quiet postoperatively with rapid visual rehabilitation

B. Limitations

1. Despite its conceptual simplicity, it is surgically challenging, even for a surgeon who is experienced in methods of scleral haptic fixation
   
2. It requires familiarity with anterior vitrectomy techniques, ideally performed through a pars plana sclerotomy
   
3. As with the glued technique, and possibly more importantly, haptic placement is critical (entering 180 degrees apart and 2 mm posterior to the limbus)
   
4. The surgeon’s view is obstructed during the intrascleral needle passes (with or without a guide)
   
5. To decrease the chance of optic rotation, it is important to achieve a 1.5- to 2-mm-long tunnel during the intrascleral needle pass that is circumlinear with the limbus
   
6. Limited international experience and long-term follow-up

C. Procedure (Figures 61-1 through 61-14)

1. Pars plana infusion cannula or anterior chamber maintainer is inserted (see Figure 61-3)
   
2. Anterior vitrectomy, possibly via a pars plana sclerotomy, is performed, if indicated (see Figure 61-4)
   
3. Make a clear corneal incision for injectable 3-piece foldable IOL
   
   
   

   

   
   

   Figure 61-1. Subluxated in-the-bag PCIOL with Soemmering ring and corneal edema.

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