Indications

The indications for the use of a CTR are:

• Diffuse zonular loss or weakness such as that encountered with aging, pseudoexfoliation, and rarer progressive zonulopathies
  
• Regional zonular loss that is typically caused by blunt or penetrating trauma or may be iatrogenically caused by the surgeon

The first category is by far the most common indication for which I routinely implant a CTR. These are typically older patients with advanced cataracts who invariably have diffuse zonular loss or weakness in association with separation of all vitreolenticular attachments (eg, Wieger’s ligament). This combination results in a floppy posterior lens capsule that hazardously billows and prolapses forward during final fragment removal and cortical stripping. The effect of the CTR is to “drum-skin” the capsule, thereby holding it back under tension and minimizing forward prolapse.

Conversely, the 2 absolute contraindications for inserting a CTR are:

1. The presence of an anterior capsule tear
   
2. The presence of a posterior capsule tear

In both situations, the centrifugal forces generated during insertion together with the expansile force of the CTR once in place will reliably extend any preexisting capsular tear. This diminishes capsular support for any intraocular lens (IOL) model and can cause vitreous prolapse or potential dislocation of the CTR into the posterior segment.

Timing

The vexing question of exactly when is the best time to insert a CTR will generate a range of opinions. You can, of course, implant a CTR at any stage following hydrodissection until after the IOL is implanted in the bag. Based on my experience of more than 20 years using these devices, I believe that the answer is simple: you implant a CTR as soon as you are aware that you need one. For example, if there is preexisting diffuse zonulopathy or a sectoral zonular dialysis from previous trauma, you should put the ring in following hydrodissection, which is as early as you can. That way it is in place from the start of surgery to provide support of the missing zonules and to protect the remaining zonules until the procedure is complete. You may need to use triamcinolone acetonide to check for any vitreous prolapse that must first be excised with anterior vitrectomy before proceeding.

Preparation

Several pearls may be helpful at this stage. First, use trypan blue if it is available to optimize visualization of the capsulorrhexis edge. This makes it much easier to direct and confirm insertion of the leading end of the ring underneath the anterior capsular rim.

Second, you must be certain that you have done a really thorough subcapsular cortical cleaving hydrodissection. This will shear off most of the cortex and prevent it from being trapped in the capsular fornix by the CTR. Ideally you want to be able to freely rotate the nucleus within the capsular bag before attempting to implant the ring. Under no circumstances should you attempt to insert the ring without prior hydrodissection.

The third pearl is to inject a bolus of cohesive ophthalmic viscosurgical device (OVD) under the edge of the capsulorrhexis at the approximate location where you intend to insert the leading end of the ring. This pushes any cortex peripherally away from the anterior capsular rim and expands the subcapsular space, which now becomes the path of least resistance for implantation of the ring.

If phaco, irrigation/aspiration, or IOL implantation causes an iatrogenic zonular dialysis, then you should immediately stop to assess the situation. If necessary, first stabilize the lens with capsule anchors or retractors before implanting the CTR. Once a zonular dialysis occurs, always remember to check for any vitreous prolapse using triamcinolone before proceeding.

Implantation Techniques

There are fundamentally 2 different methods for implanting a CTR:

1. Freehand or bimanual techniques, using 2 pairs of plain forceps
   
2. Injector system: Single-use (usually premounted) or reusable (surgeon loaded)

From a practical perspective, using an injector system is undeniably the easier option. It also has the added advantage that there is no contact of the CTR with the external ocular surface prior to implantation. Using a bimanual technique, it is almost impossible to avoid some surface contact and therefore potential microbial contamination of the ring, which is then permanently implanted into the capsular bag.

When employing the bimanual technique, it is safest to grasp the ring with only one pair of forceps at a time when handling it outside the eye and when feeding it into the bag. If the ring is held using both pairs of forceps, it is easy to unintentionally twist the CTR, which can readily break it.

Bimanual Pre-Phaco Capsular Tension Ring Implantation

After completing the preparatory hydrodissection and opening the subcapsular space with cohesive OVD, the ring is lifted from its container using plain forceps. Because a CTR is so light, it is very easy to knock it out of the circular recess of the plastic retainer pins and lose it somewhere on the drape. A useful tip is to put a small blob of OVD onto the ring before attempting to grasp it. This keeps it adherent to the plastic container while it is being grabbed.

Although it is possible to insert the ring via a side-port incision, maneuverability through a paracentesis is more restricted; it is therefore more easily introduced through the main incision.

The ring should be held initially in the horizontal plane in order to readily pass the leading end through the incision. It is next rotated semivertically so that the leading end now projects downward toward the edge of the capsulorrhexis. The ring is then fed into the eye while keeping a careful view of the leading eyelet to ensure that it passes underneath the edge of the capsulorrhexis. Now rotate it back toward the horizontal plane and keep feeding it forward using both pairs of forceps to make short, incremental hand-to-hand movements. Once the leading end is engaged against the capsular fornix, there will be some resistance and the shaft of the ring will start to flex under pressure until the resistance is overcome. At this point the ring will start to slide along the fornix. This usually happens when the shaft of the ring has slid around 90 degrees away from the initial point of entry under the capsulorrhexis. If the CTR continues to flex still further without feeding into the capsular fornix, then this indicates undue resistance and forcing the ring to advance risks further zonular damage. Stop, withdraw the ring from the eye, and repeat the hydrodissection before trying again.

Continue to feed the ring into the bag until the trailing end is up against the external incision. With a pair of fine forceps in your pronated hand, grasp the eyelet and feed it into the anterior chamber and underneath the edge of the capsulorrhexis before releasing it. Sometimes the trailing end gets caught anterior to the capsulorrhexis. In this situation you can flex the trailing eyelet centrally using a Sinskey or similar hook introduced through a side-port incision. The trailing eyelet is then lowered posteriorly behind the capsulorrhexis before it is released into the bag.

During CTR insertion, it is generally advisable to direct the leading end toward the site of the zonular dialysis. In theory this offers positive support for the weakened sector. However, in practice, directional control can be very difficult, especially if the dialysis is subincisional. In my experience, this is not that important because tractional forces on the remaining zonules are very small. If you wish to direct the leading end toward the affected sector of zonules, remember that the CTR can be implanted clockwise or anticlockwise, depending on which direction is easiest.

Fish-Tail Technique for Bimanual Insertion

Most iatrogenic zonular tears occur during irrigation/aspiration when the capsular bag is empty and therefore floppy. Inserting a CTR under these circumstances presents its own unique challenges. The tendency for the leading end of the ring to snag in the periphery of the bag is high because the capsule is slack and has little countertraction to resist being folded and poked by the tip of the ring. To reduce the risk of this happening, the bag should be overinflated with a cohesive OVD, which places the capsule on maximal stretch.